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NS 201 Midterm Notes, Team U

by: Vaishnavi Kothapalli

NS 201 Midterm Notes, Team U NS 201

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Vaishnavi Kothapalli

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- all notes on the covered material for exam - things either highlighted or in red are MUST KNOWS - make sure to read and be knowledgeable on the Learning Objectives for each topic - 2nd...
Biology I
Study Guide
Biology, Biodiversity, population, community, Science, Theory, cellular biology, DNA, Chromosomes
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This 27 page Study Guide was uploaded by Vaishnavi Kothapalli on Thursday October 13, 2016. The Study Guide belongs to NS 201 at Boston University taught by Weikel in Fall 2016. Since its upload, it has received 12 views. For similar materials see Biology I in Natural Sciences at Boston University.


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Date Created: 10/13/16
Lecture #1 - 9/7 I. Often, scientists have to rely on indirect evidence to form conclusions II. Why mass extinction? a. The bacteria from below the surface will slowly rise up to the top and kill things in the way b. Ex. Bryozoans – who died first? i. Hypothesis: oxygen disappeared at bottom first, causing carbon dioxide and sulfur to form, killing species ii. Results: species deep in ocean dies off first, then up at top; hypothesis is correct III. Ideas and theories are constantly changing and evolving a. Ex. Einstein combined ideas from Newton and Huygens regarding light particles b. Ex. Before, we though Earth was center of universe  Now, Sun is center of universe IV. Theory a. Much more than a guess; supported by scientists worldwide b. Over-arching set of mechanisms that explains some aspect of the natural world i. Abundance of evidence ii. Independently produced by many scientists iii. Can be used to generate more hypotheses c. Ex. Theory that DNA holds genetic material for organisms; been tested, but still open to the fact there is an organism who doesn’t transport genes that way ---------------------------------------------------------------------------------------------------------------------------- --- Lecture – Understanding Biodiversity Though Populations - 9/14 I. Types of Biodiversity a. Genetic – diversity within one organism i. Ex. Different breeds of dogs b. Species – how many different species in a selected area c. Ecological – different types of environments i. Ecology encompasses both the biotic (living) components and the abiotic (non-living) components of an environment II. What is Species? a. Carl Linnaeus - came up with organism classification system; same species since God created world b. Charles Darwin – new species evolve over time as others die; these species are shaped by environment c. Ernst Mayr – species are reproducing organisms III. Importance of Biodiversity a. Food supply b. Medical research c. Adaptation to environmental stress (genetic diversity) i. If there is some genetic diversity in a group of species, then all members of that species won’t die d. Maintenance of resources (cleaning water, providing oxygen) e. Helps ecosystem adjust to disturbances (fires, floods, etc.) IV. Threats to Biodiversity a. Extinction b. Why is it threatened? i. Habitat Loss ii. Over-exploitation iii. Climate Change V. Population a. a group of individual organisms of a species that live together in space and time b. Characterized by… i. Size (average vs. variation) ii. Density iii. Patterns of dispersion iv. Demographics v. Rates of growth vi. Limits on Population Growth VI. Population Dispersion Patterns a. Clumped (aggregated) i. Ex. Wolves, sheep, swans ii. Tells us about… location/availability of resources and the social behavior of species b. Regular/Uniform i. Ex. Penguins ii. Tells us about… competition, territorial behavior, aggressive social interactions c. Random i. No strong attractions or repulsion among individuals VII. Types of Dispersion a. Natural Dispersion b. Human-driven dispersion VIII. What Determines Population Size? a. Study of vital statistics of population i. Birth/Death rate ii. Immigration/emigration rate b. Sex Ratio – M/F i. Differentially affects growth rate, depending on species mating pattern ii. Males compete for females 1. Ex. Mice iii. More monogamous species 1. Ex. Some elephants, wolves, birds, humans c. Generation time i. When you compare species with long generations, those with short generations can alter population size quickly ii. As size of organism increases, generation time of organism increases iii. Ex. Mouse has life span of 2 years and begin to reproduce at 5 weeks; Humans have a longer life span and reproduce around age 15; mice will quickly repopulate compared to humans iv. Are short generations advantageous? Yes ---------------------------------------------------------------------------------------------------------------------------- --- Lecture (continued from last week) – 9/19 I. Age Structure a. The relative # of individuals of each age in a population b. Age structure influence population growth II. Cost of Reproduction a. Why don’t individuals just reproduce as soon as they are born, so that they have more lifespan to care for their offspring? i. To find food, shelter, avoid predators b. The cost of reproduction rises to the reduction in future reproductive potential (energy) due to the current reproductive efforts i. Low Cost of Reproduction 1. Abundant resources; no predators 2. Protection among peers – it takes a community to raise a baby 3. High mortality – if you’re offspring are dying early, you don’t have to put the energy to care for them  you can put more energy into making more offspring ii. High Cost of Reproduction 1. Deferred/decreased reproduction 2. Less offspring has increased survival rates; get more care/nurture from parents c. Investment in offspring – need to be nurtured so that they themselves can reproduce d. Future Reproductive Events i. Semelparity 1. One big reproductive event in their life 2. Most likely because of high cost of reproduction 3. Ex. The Pacific salmon and most aquatic species ii. Iteroparity 1. Tend to reproduce yearly 2. Low cost of reproduction 3. Most of the offspring don’t survive that long 4. Ex. Pig, most large mammals and humans III. Survivorship Curve a. A plot of the proportion out of a cohort alive at each age i. Late Loss – Type I 1. High  Low survivorship 2. Ex. Mountain goats and humans ii. Constant Loss – Type II 1. Steady survivorship 2. Ex. birds iii. Early Loss – Type III 1. Those who are young die quickly 2. Low survivorship 3. Ex. Plants IV. Variation in Vitals a. Ex. Coconut trees i. Few offspring ii. Large in size iii. High survivorship b. Ex. Dandelion flowers i. Many offspring ii. Small in size iii. Low survivorship c. # of offspring is inversely proportional to vital rates V. Changes in Population Size a. These can change the size of a population… i. Birth/Death ii. Immigration/Emigration VI. Population Density a. # of individuals per unit area or volume b. we measure by sampling… i. full census (count everyone) ii. representative counts & extrapolations iii. mark and recapture method VII. What Factors Limit Population Densities? a. A smaller body size, shorter duration of residence and less competition foster a higher population density (more organisms in a given area at a given time) b. Generation time affects population growth, NOT how crowded a certain area is with a population at a given time VIII. How to Sample Populations a. Indirect sampling i. Ex. Bee nests, fecal pellets, beaver dams b. Direct Sampling i. Mark and Recapture 1. The proportion of recaptured animals gives estimate of population size c. Counting Methods: stake out quadrants i. Must take into account patterns of spacing (dispersion) IX. Example Problems a. What would contribute to an increase in the growth of a population when there are abundant resources? i. Decrease in generation time b. When reproductive costs are high, reproduction decreases and individual lifespans increases c. Type III Survivorship i. Many offspring will be produced and most will die young X. ***SEE BIODIVERSITY AND POPULATION PDF FOR REST OF LECTURE NOTES*** ---------------------------------------------------------------------------------------------------------------------------- --- LEARNING OBJECTIVES ­ Explain what a population is and how it can be characterized.  o Population = a group of individual organisms of a species that live together in space and time o Characterized by: Size, Density, Dispersion Patterns, Demographics, Rates of Growth/Decline,  Limits on population growth ­ Describe three population dispersion patterns and the environmental factors that may contribute  to each.  o Clumped o Random o Uniform/Regular ­ Explain what demography is and how changes in birth, death and immigration/emigration rates  influence population size. Explain how sex ratio, generation time and age structure influence birth rate.  o Demography = study of vital statistics of populations  o Increase in birth and immigration rates = increase in population o Decrease in death and emigration rates = decrease in population  ­ Describe how reproductive costs shape population growth.  o High reproductive cost = takes more time to reproduce = increased survival o Low reproductive cost = high mortality = decrease in population ­ Describe the three types of survivorship curves.  o Type I – Late Loss = dies near end of life span; ex. humans o Type II – Constant Loss = constantly dies off as years pass; ex. birds o Type III – Early Loss = those who are young die quickly ­ Describe how population density is measured in the field. What factors influence it? o Full census (count everyone) ~ Representative counts & extrapolations ~ Mark and Recapture  method o Influential factors:  Species that use abundant resources generally reach higher population densities than  species that use scarce resources  Species w/ small body size usually reach high densities  Complex social organization can facilitate high densities (e.g. ants, termites)  Some newly introduced species reach high population densities  ­ Calculate growth rate from population vitals. Describe exponential and logistic growth.  o Exponential = grows more and more rapidly as the population increases o Logistic = grows exponentially at first, then levels off to carrying capacity ­ Explain the difference between density dependent and density independent factors on population  size.  o Density dependent = Limitations to population growth that are influenced by the size of a  population in a given area (e.g. resource supply, predation, disease, habitat supply) o Density independent = factors that limit a population size that are not related to the density of the population (e.g. floods, fires, earthquakes) ---------------------------------------------------------------------------------------------------------------------------- --- Lecture: Origin of Variation – 9/26 I. Cell Theory a. All life is composed of at least one cell i. All genetic material stored in nucleus, etc. b. Cells are the fundamental unit of organization i. Structure, physiology ii. Cells  Tissues  Organ  Organ System  Organism c. Cells can only come from pre-existing cells by cell division II. How does a cell “do” anything? a. PROTEINS!! i. Composed of amino acids (20) ii. Amino acids are arranged in different combinations and structures  proteins with different sizes, functions, locations III. Four levels of protein organization a. Primary i. Amino acids joined together by a peptide bond ii. What order are they in? b. Secondary i. Form in either a coil or helix structure ii. How are they folded? c. Tertiary i. Once they become three-dimensional d. Quaternary i. Multiple 3-D peptides join ii. Interaction of these peptide chains IV. Why do we care about this? a. Ex. Myosin i. Helps things move around in cells and muscle structure b. Tells you how it affects the structure of an organism c. What determines the amino acid sequence? V. Deoxyribonucleic Acid (DNA) a. Two chains of repeating phosphate molecules… i. Chain of sugar and phosphate b. … Connected by a pair of nucleic acids (bases)… i. Thymine (T) ii. Guanine (G) iii. Cytosine (C) iv. Adenine (A) c. … Arranged in a double helix VI. Walther Fleming (1882) a. Studied mitosis (cell division) in somatic cells (any cell in your body that is not involved in making offspring) b. Discovered chromatin i. Chromatin is split when a cell divides VII. Eduard van Beneden (1883) a. Cell division in somatic cells b. Gametes – cells responsible for making offspring i. Haploid  diploid VIII. August Weismann (1887) a. Studied meiosis (formation of germ cells) b. Germ Plasm Theory i. When germ cells duplicate, they either produce somatic cells or more germ cells ii. Germ cells not affected by anything somatic cells acquire during lifetime (“Weismann barrier”) IX. Theodor Boveri (1888-1890) a. We find DNA in chromosomes X. Eukaryotic DNA is organized into chromosomes a. Found in the nucleus of a cell XI. Chromosomes come in homologous pairs a. Humans have a total of 23 pairs i. 22 identical, 23 determines sex 1. XX = female 2. XY = male XII. Ploidy = # of copies of unique chromosomes in a cell a. Diploid = having two sets of unique chromosomes b. Haploid = only having one set of unique chromosomes ---------------------------------------------------------------------------------------------------------------------------- --- Lecture (continued) – 9/28 I. Gene Expression a. Process by which information from a gene is transformed into product II. DNA vs. RNA a. SIMILARITIES i. Sugar-phosphate backbone ii. Nucleotide Unit iii. Deoxyribose (sugar) b. DNA = Deoxyribonucleic acid i. Double strand ii. Bases 1. Adenine 2. Guanine 3. Cytosine 4. Thymine c. RNA = ribonucleic acid i. Single strand 1. Adenine 2. Guanine 3. Cytosine 4. Uracil III. Transcription and Translation a. Transcription = DNA  RNA b. Ribosomes translate mRNA into protein c. mRNA molecules bond to tRNA molecules with complementary bases (C <--> G; A <--> U) d. if you know of the mRNA’s, you know what amino acids you have and what proteins you are making e. RNA splicing can create multiple proteins from a single gene i. Introns – unused parts f. Most of our DNA is not destined to become protein – non-coding regions i. Non-coding regions include: 1. miRNA 2. Pseudo genes 3. Regulatory regions (enhancers) a. Regulation of gene expression is flexible (see Table 5.1 in Lecture 6 PowerPoint) fd IV. Variations in DNA: Mutations a. Where do mutations come from? i. Random ii. Age iii. UV iv. Radioactivity b. Types of Mutations (see Lecture 6 PowerPoint) c. Effects i. Can range from no effect to fatality ii. Can increase/decrease protein activity iii. Alter regulation of other genes iv. Somatic Mutations 1. Affect cells in an organism’s body 2. Not heritable v. Germ-line mutations 1. Affect gametes 2. Are heritable 3. Regulate evolution V. Variations in DNA: Sexual Reproduction a. Meiosis i. Split into 2 daughter cells  cell division  each daughter cell splits into two daughter cells = 4 non-identical haploid cells ii. Maternal and paternal chromosomes pair up to form bivalents 1. Formation of a bivalent allows recombination to occur 2. Homologous recombination is the exchange of DNA b/w homologous chromosomes b. Mitosis i. One cell division 2 Daughter cells are genetically identical to parent cells c. Crossing Over: why gene location matters? i. Genes that are closer together on the chromosome tend to be inherited together VI. Sources of Genetic Variation a. Random 23sortment of6homologous chromosome i. 2 = 8.4 x 10 b. Recombination i. 2-3 crossovers/chromosome pair = infinite possibilities VII. Meiosis is not flawless a. Non-disjunction: when homologs fail to separate; cause of Down syndrome and some miscarriages VIII. Alleles = different forms of a single gene a. Occurs at the same location on a chromosome b. Same version of gene on chromosome = homozygous c. Different forms of gene on chromosome = heterozygous ---------------------------------------------------------------------------------------------------------------------------- --- Lecture – 10/5 – Community Ecology (Lecture #9) I. Community vs. Population a. Population – a group of individuals of the same species living in the same area, potentially interacting b. Community – an assemblage of plant and animal populations that live in a particular area or habitat i. Populations of the various species in a community interact and form a system with its own emergent properties II. Emergent Properties of a Community a. Scale i. Size of a community b. Spatial and Temporal Structure i. Spatial = how species are distributed ii. Temporal = timing of a species’ arrival or activity 1. Ex. When a species dies, the timing of how long it takes to decompose and stuff c. Species Richness i. # of species in a community ii. sensitive to sampling procedure 1. area 2. researcher d. Species Diversity i. # of different species, relative abundances ii. not usually equal iii. use the Simpson Index e. Trophic Structure i. How does a community feed itself? ii. Food Chains V. Food Webs (see PowerPoint for Venn diagram) iii. Trophic Cascades f. Disturbance and Succession III. Food Web vs. Food Chain a. See Lecture 9 PowerPoint for Venn Diagram IV. Trophic Cascades a. How environmental changes affect trophic level species i. See Lecture 9 PowerPoint for more info b. Disturbance  Invasion i. Disturbance creates opportunities for new species to invade an area and establish themselves 1. Species modify the environment and create opportunities for other species to invade 2. The new species eventually displace the original ones and modify the environment enough to allow a new series of invaders, which ultimately replace them, etc. ii. Agents of Disturbance – tornados, volcanoes, wildfires, floods, global warming c. Invasion  Succession i. Succession: recovery from ecological disturbance ii. Types 1. Primary succession 2. Secondary succession iii. The sequence of succession is driven by… 1. Tolerance 2. Facilitation 3. Inhibition V. Boston 2014: Applying the Concept of Disturbance-Succession a. 1 stage - disturbances – infrastructure; greenery nd b. 2 stage – tourism increase; no more construction; massive shift in economics VI. ***SEE LECTURE 9 POWERPOINT FOR MORE INFORMATION!!*** ---------------------------------------------------------------------------------------------------------------------------- --- Lecture (continued) – 10/11 – Community, Part 2, Lecture 10 I. ***SEE LECTURE 9 POWERPOINT FOR MORE INFORMATION!!*** II. Are Biological Communities Real Functional Units? a. We will never know the answer b. Clements: every area should have the same species at a given time c. Gleason: unstable and variable species composition III. Competitive-Exclusion Principle a. Two species cannot compete for the same competing resource b. Ex. Two species flourish when in separate environments; but when put together, one dies off first IV. Resource Partitioning a. Use resources in different ways to avoid competition and from species dying off b. Ex. Birds i. Different species occupy different parts of trees ii. Allows all Warblers to survive V. Results of Competition a. Drives lifestyle changes – character displacement b. Shape and size of species differs based on what they eat and amount of competition – over time, adjusted habits to keep up with competition VI. The Niche a. The way an organism utilizes its environment – its lifestyle i. Habitat, food consumption, mating, etc. b. Competition can lead to Niche Differentiation i. This change in resource use is called niche differentiation or resource partitioning ii. The change in species traits is called character displacement c. Keystone species i. Maintain species diversity ii. Modifies the environment in a way so other organisms can live VII. Types of Symbiosis a. Mutualism i. Both partners benefit ii. Endosymbiosis: one mutualist lives inside another 1. Smaller genomes 2. Ex. Mitochondria iii. Two Ways 1. Facultative a. Don’t exactly need each other for survival 2. Obligate a. Both species NEED each other to survive iv. Examples 1. Bees and flowers (facultative and obligate) 2. Parasitoids wasps and polydna viruses (obligate) b. Commensalism i. Benefit to one, other not affected c. Amensalism i. One is harmed, other not affected d. Parasitism ---------------------------------------------------------------------------------------------------------------------------- --- Lecture (continued) – 11/12 – Community, Part 3, Lecture 11 I. Parasitism a. One benefits, one is harmed b. Parasite Host Coevolution i. Ex. Milkweed and butterflies – milkweed has poisonous toxin that the plant itself is immune to but dangerous to other plants; monarchs have developed immunity to toxin as well; when butterfly gets eaten, the predator gets subject to toxin c. Levels of pathogenicity: parasites and hosts i. Ebola virus  horrific death; cold virus  under the weather for a few days ii. Single host usually infected with two or more strains at the same time 1. More virulent strains reproduce in host quicker – competition results in more virulent strains becoming dominant a. Don’t want to be too virulent b/c then host will die b. If you want virus to be transmitted to a new host, you need to reduce virulence of virus II. Predation a. One species feeds on another i. Enhances fitness of predator but reduces fitness of prey b. Predators, parasites, parasitoids, and herbivores obtain food at the expense of their hosts or prey i. Herbivory is a form of predation III. Predator-Prey Population Dynamics a. Predation = density-dependent mortality factor to the host population b. Density of prey population affects the birth and death rates of predator population IV. Anti-predator strategies a. Chemical defense b. Cryptic coloration (camouflage) c. Mimicry i. Mullerian 1. Two or more species develop the same characteristic to ward off predator 2. Ex. Paper wasp, bumblebee, honeybee ii. Batesian 1. A harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both 2. Ex. Hornet moth, wasp beetle, hoverfly d. Try to intimidate their predator e. Fight back f. Run away g. Armor h. Masting i. Species time their release of offspring because they know some will die from predation and some will survive V. Defense Tactics a. Constitutive defenses i. Ex. Camouflage, Schooling (safety in numbers), Weaponry (fighting back) ii. Always active opposed to a inducible defense b. Inducible defenses i. Defensive traits that are produced only in response to the presence of a predator ii. Fight or flight reaction VI. Coevolution a. Reciprocal evolutionary change = adaptations one species does to improve its fitness b. All species are interconnected – subject to the forces of natural selection c. Prey adapt much quicker than predators i. Prey need to survive ii. Predator just need food d. Coevolution increases biodiversity as species learn to adapt to one another i. Escape and radiate model 1. Milkweed developed toxins to stop caterpillars from eating them  caterpillars cut holes in fluid vessel of milkweed to disarm toxin  milkweed learns a new defense ii. Diffuse coevolution VII. Geographic mosaic theory of coevolution a. Coevolution depends on where organisms are at a certain point b. Hotspots: constantly changing c. Cold spots: little change in coevolution ---------------------------------------------------------------------------------------------------------------------------- --- LEARNING OBJECTIVES  Define a community and its emergent properties  Define ecological succession and describe its two forms. What is the Intermediate Disturbance hypothesis?  Describe a niche. What type of regulation affects the trophic structure of a community?  Describe each type of interspecies interaction.  Define competition and its forms. How does it affect fitness? What is the competitive exclusion principle?  Define predation. How do populations of predators and preys influence one another?  Describe coevolution and how it affects diversity  Describe the geographic mosaic theory of evolution. What is meant by the “co-evolutionary arms race”? LEARNING OBJECTIVES – Populations ­ Explain what a population is and how it can be characterized. Population = a group of individual organisms of a species that live  together in space and time Characterized by: Size, Density, Dispersion Patterns, Demographics,  Rates of Growth/Decline, Limits on population growth ­  Describe three population dispersion patterns and the  environmental factors that may contribute to each.  Clumped, Random, Uniform/Regular ­  Explain what demography is and how changes in birth, death and  immigration/emigration rates influence population size. Explain how  sex ratio, generation time and age structure influence birth rate.  o  Demography = study of vital statistics of populations o  Increase in birth and immigration rates = increase in population o  Decrease in death and emigration rates = decrease in population ­  Describe how reproductive costs shape population growth. o  High reproductive cost = takes more time to reproduce = increased  survival o  Low reproductive cost = high mortality = decrease in population ­  Describe the three types of survivorship curves.  o  Type I – Late Loss = dies near end of life span; ex. humans o  Type II – Constant Loss = constantly dies off as years pass; ex. birds o  Type III – Early Loss = those who are young die quickly ­  Describe how population density is measured in the field. What  factors influence it? o  Full census (count everyone) ~ Representative counts & extrapolations ~ Mark and Recapture method o  Influential factors: § Species that use abundant resources generally reach higher population  densities than species that use scarce resources § Species w/ small body size usually reach high densities § Complex social organization can facilitate high densities (e.g. ants,  termites) § Some newly introduced species reach high population densities ­  Calculate growth rate from population vitals. Describe exponential  and logistic growth. o  Exponential = grows more and more rapidly as the population increases o  Logistic = grows exponentially at first, then levels off to carrying capacity ­  Explain the difference between density dependent and density  independent factors on population size.  Density dependent = Limitations to population growth that are  influenced by the size of a population in a given area (e.g. resource supply, predation, disease, habitat supply) o  Density independent = factors that limit a population size that are not  related to the density of the population (e.g. floods, fires, earthquakes) LEARNING OBJECTIVES ­ Back to Basics: Where does variation come from? 1) Describe the three main tenets of cell theory.  a.  All life is composed of at least one cell b.  Cells are the fundamental unit of organization c.  Cells can only come from pre­existing cells by cell division 2) Describe the role and organization of proteins and DNA.  1.  Proteins are composed of amino acids (20 in humans) – based on a carbon chain a.  Four levels of protein organization                              i  Primary – what order they are in single chain                             ii  Secondary – how are they folded                            iii. Tertiary – three dimensional orientation of the folds                            iv.  Quaternary – multiple 3­D peptides join (interaction of two chains of these  peptides) b.  All levels of protein organization matter the most!! 2.  DNA stands for Deoxyribonucleic Acid a.  Arranged in a double helix b.  Two strands: chain of sugar and phosphate c.  Four possible nucleic acids bases: adenine, thymine, guanine, cytosine 3) Explain the Germ Plasm theory.  a)   First used by German biologist August Weismann (1834­1914) i)   While observing germ cells (meiosis) he suggested that maternal & paternal chromosomes join at  fertilization to restore chromosome number in offspring (1)  Germ plasma Theory: (a)  Germ cells produce somatic cells and more germ cells (b)  Germs cells not affected by anything somatic cells acquire during lifetime (“Weismann barrier”) 4) Describe how DNA is stored in the cell.  a)   Eukaryotic DNA is organized into chromosomes b)   Chromosomes come in homologous pairs (humans have 23) 5) Describe what occurs during transcription and translation and how they regulate gene  expression.  a)   Gene expression: process by which information from a gene is transformed into product b)   Transcription: DNA à RNA; DNA unwinds à bases lose their binding partner à end product is a strand of RNA i)   DNA – RNA (1)  Adenine – Uracil (2)  Thymine – Adenine (3)  Guanine – Cytosine (4)  Cytosine – Guanine c)   Differences between RNA & DNA: i)   RNA has Uracil while DNA has Thymine ii) RNA is a single strand while DNA is double strand iii DNA always found in nucleus of cell while RNA is more versatile 6) Explain the difference between coding and noncoding segments of DNA.  a)   Most of our DNA is not destined to become protein à non­coding regions b)   Non­coding region include: i)   miRNA ii) Pseudogenes iii Regulatory regions (enhancers) c)   Regulation of gene expression is flexible 7) Describe the causes and effects of genetic mutations. How do somatic mutations differ fromgerm­line mutations?  a)   Variations in DNAà Mutations i)   Mutations come from: (1)  Random (2)  Age (3)  UV (4)  Radioactivity ii) Somatic Mutations: (1)  Affect cells in the body of an organism (2)  Are not heritable iii Germ­line mutations (1)  Affect gametes (2)  Are heritable (3)  Regulate evolution   8) Explain how sexual reproduction increases genetic variability in a population. What are the effects of chromosome rearrangement, homologous recombination and sex­linked  genes?  a)   Variation in DNA à sexual reproduction i)   Process of cell division and how we make our egg and sperm cell (random assortment of homologous chromosomes 2 = 8.4 x 10 ) 23  6 (1)  Meiosis (a)  Consists of a single round of DNA replication followed by two cell divisions à generates four  (daughter cells), non­identical haploid cells (2)  Mitosis (a)  Involves one round of DNA replication and division to produce two identical diploid cells à  daughter cells are identical to the parental ii) Recombination à 2­3 chromosomes crossing over (1)  Formation of a bivalent allows recombination to occur (a)  Maternal and paternal chromosomes pair up to form bivalents (b) Homologous recombination is the exchange of DNA between homologous chromosomes (2) Genes that are closer together on the chromosome tend to be inherited together 9) Explain why most phenotypes cannot be directly linked to genotypes.  a)  Genotype à observable, measurable trait i   Human height has a genetic component b)  Phenotype à sequence of nucleic acids c)  1 genotype à many phenotypes § you don’t need phenotypes to directly affect genotypes à the environment can be a factor as  well   LECTURE – O3/10/16   IN­CLASS (LECTURE) QUIZ 1.  TRANSCRIPTION (DNA TURNS INTO MRNA) à TRANSLATION (THE CONVERSION OF  THE MRNA INTO PROTEINS) 2.  DNA TO RNA: ADENINE à URACIL 3.  PRIMARY à TRNA TURNS IMRNA INTO A PROTEIN;  PRIMARY MOST REICTLY  AFFECTS THE RECUIRTMENT OF TRNA MOLECULES 4.  THE DIPLOID CHROMOSOME NUMBER FOR THE HOUSE FLY IS 12. GAMETES IN THE HOUSEFLY ARE PRODUCED THROUGH THE PROCESS OF MEIOSIS AND CONTIANT 6  CHROMOSOMES EACH. 5.  EXPOSURE TO HIGH LEVELS OF RADIATION CHANGED THE DNA SEQUENCE OF A  SOMATIC CELL OF AN OTTER FROM GGTTACCT TO GGATACCT. POINT MUTATIONS; NO  EFFECT. 6.  ALL OF THE MOUSE PUPS IN A LITTER HAVE EXTREMELY LONGTIALS. A THIRD OF  THE PUPS HAVE BROWN FUR WHILE THE REMAINDER OF THE PUPS HAVE BLACK FUR.  THIS TELLS US THAT THEY ARE LOCATED FAR PARAT FROM ONE ANOTHER ON THE  SAME CHROMOSOME. COMMUNITY ECOLOGY: OCT. 3, 2016 1. Define a community and its emergent properties.  § Population: a group of individuals of the same species living in the same area, potentially interacting § Community: an assemblage of plant and animal populations that live in a particular area or habitat § Emergent properties o  Scale: the size of community o  Spatial structure: how species are distributed o  Temporal Structure: timing of a species’ arrival or activity o  Species richness: # of species in a community § Sensitive to a sampling procedure § Area, researcher o  Species diversity: # of different species, relative abundances § Not usually equal o  Tropic structure: hierarchy of feeding o  Trophic interaction: transfer of energy § Eating, decomposing, photosynthesis § Illustrated in a food web or a food chain o  Trophic cascades: species at one trophic level influence species at other levels; the addition or  subtraction of species affects the entire food web. § This causes positive effects for some species and negative effects for others § EX: removing a secondary consumer might positively affect the primary consumers they feed upon,  and negatively affect the producers that are food for primary consumers. 2.  Define ecological succession and describe its two forms. What is the Intermediate Disturbance  hypothesis?  o  Disturbance creates opportunities for new species to invade an area and establish themselves o  Succession; recovery from ecological disturbance o  Tolerance o  Facilitation o  Inhibition o  Primary succession: the sequence of species on newly exposed landforms that have not  previously been influence by a community, e.g. areas exposed by glacial retreat (starting from ground 0,  building from scratch) o   Seconda succession: occurs in cases which vegetation of an area has been partially or completely removed, but where soil, seeds, and spores remain o  Intermediate disturbance hypothesis: o  Communities are usually in a state of recovery from disturbance 3. Describe a niche. What type of regulation affects the trophic structure of a community? The way an organism utilizes its environment – its lifestyle o   What does eat, where it lives ∙   “Fundamental” niche: the entire niche an organism can possibly use ∙   “Realized” niche: the actual niche used – usually restricted by competition ∙   If natural selection favors individuals that do not compete à leads to niche differentiation or  resource partitioning ∙   Keystone species are disproportionately important in communities because they act to  maintain species diversity à a keystone species modifies the environment in such a way that other  organisms are able to live 4. Describe each type of interspecies interaction.  ∙   Predations o  Predator­prey; good for predator and bad for prey §  EX: Oxpecker birds eat the ticks §  EX: Carnivores such as timberwolves hunt and kill herbivorous mammals ∙   Herbivory o  Plant­herbivore; good for herbivore but bad for plant §  EX: The African buffalo feeds on the grasses of the savanna ∙   Parasitism o  Parasite/pathogen­host; one partner benefits from the relationship; the other partner is  harmed (+,­) §  EX: The buffalo’s hide is infested with parasitic ticks o  Parasites consume their host either from inside (endoparasites) or from the outside  (ectoparasites). o  Parasite­host coevolution § EX: the common milkweed is poisonous to most herbivores however the  monarch butterfly larvae have evolved the ability to tolerate these toxins o  In Australia (1859) à rabbit myxoma virus introduced to kill rabbits 1950’s § Virulence of rabbit myxoma à Rabbit myxoma virus became less virulent over  time because natural selection favored strains that did not immediately kill the rabbit  hosts, enhancing the likelihood of spreading and infecting other rabbits § If it had occurred, the myxoma virus in Australia would have remained more  virulent then it ultimately became The rabbit population remained dense even after  introduction of the virus ∙  Mutualism o  Both partners benefit from the relations (+,+) o  Facultative Mutualisms à when individuals of each species engage in mutualism when  the other species if present o  Obligate mutualism are essential for the survival of one or both species o  EX: since the Oxpecker birds eat the ticks that are live on the buffalo – mutual benefits of the birds and buffalo ∙  Competition o  Two organisms fighting for resources o  EX: the grizzly bear attempting to take over the wolves’ kill ∙  Commensalism o  One partner benefits from the relationship; the other partner is not affect (+,0) o  Commensal­host §  E: the large mammal unwittingly destroys insects and their nests §  E: Anemone fish live within the tentacles of anemones ∙  Amensalism o   One partner is harmed from the relationship; the other partner is not affected (+, ­) o   EX: the white cattle egrets feed on insects disturbed by the buffalo’s passage 5. Define competition and its forms. How does it affect fitness? What is the competitive exclusion  principle?  o  Competition occurs when organisms in the same community seek the same limiting resources o  EX: prey, water, light, nutrients, nest sites o  Competition reduces the fitness of one or both species o  Exploitation competition: occurs when individuals use the same limiting resource or resources, thus depleting the amount available to others o  EX: both species have same access to resource, but one is more efficient in  getting to it à runs faster, eats faster o  Interference competition: occurs when individuals interfere with the foraging, survival, or  reproduction of others, or directly prevent their physical establishment in a portion of a habitat o  EX: one species limits access of another species à fight, chemical defense, sting o  Chemical Competition: one species produces toxins that negatively affect another o  Consumptive Competition: the resource is what one is eating o  The Competitive Exclusion Principle o  Two species cannot compete for the same limiting resource for long à a minute  reproductive advantage leads to the replacement of one species by the other 1.   EX. Birds living in a tree a.  Species occupied different heights and portions in the tree and thus  each probably fed on a different range of insects 6. Define predation. How do populations of predators and preys influence one another?  o  Predation: one species feeds on another à enhances fitness of predator but reduces fitness of  prey o  EX: predators, parasites, parasitoids, and herbivores obtain food at the expense  of their hosts or prey o  Predator­Prey Population Dynamics o  Density­dependent mortality factor o  The degree of prey mortality o  The density of the prey population à affects the birth and death rates of the  predator population o  Antipredator Strategies o  Chemical defense o  Cryptic coloration 1.  Camouflage: blending into the background 2.  Mimicry: a.  Mullerian mimicry – species that does not taste good à will  adapt a similar color pattern b.  Batesian mimicry – prey that taste really good resemble an  unpalatable color pattern o  Display of intimidation o  Fighting o  Escape o  Armor o  Masting: time their release of seed so they release a huge amount of offspring in  one season à this allows some young to survive for the next season) o  Inducible defenses: defensive traits that are produced only in response to the presence of a  predator o  EX: mussels increasing investment in defense (thickness of shell) in the presence of crabs 7. Describe coevolution and how it affects diversity.  o  Coevolution: reciprocal evolutionary change between ecologically intimate species o  All species are interconnected – subject to the forces of natural selection o  As one species adapts to another, its partner may also evolve o  Prey adapt quicker than predators o  Genetic variation can fuel rapid evolution o  EX: balloon vine and fruit introduced in Australia à beak length evolved 8. Describe the geographic mosaic theory of evolution. What is meant by the “coevolutionary arms  race”?  o  Geograp mosaic theory of coevolution: co­evolutionary hotspots where partner species are  coevolving rapidly and cold spots where little coevolution is occurring o  EX: antagonism – arms race between snakes and newts § Garter snakes eat newts à newts make tetrodoxin (TTX) à snakes build resistance to  TTX (a single DNA mutation alters the toxin receptor) ∙ Howeve, resistance snakes are poorer hunters §  New make more potent TTX (through a series of DNA mutations) §  Snak and newts in the Geographic mosaic theory of coevolution ∙ Snake only need a single DNA mutation while Newts ended a series of DNA  mutations) à easier for the snakes to adapt (costlier for newt to make toxin than for snake  to build resistance) o   Coevolution increases biodiversity as species learn to adapt to one another o   When species depend on each other, loss of one can trigger loss of other if not replaced  (especially if mutualistic)  


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