BSCI105 Exam 1 Study Guide
BSCI105 Exam 1 Study Guide Bsci105
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This 13 page Study Guide was uploaded by clcindy.lin on Monday February 15, 2016. The Study Guide belongs to Bsci105 at University of Maryland taught by Dr. Alewall in Summer 2015. Since its upload, it has received 133 views. For similar materials see Intro to biological sciences in Biological Sciences at University of Maryland.
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Date Created: 02/15/16
Bio study guide exam 1 1. Properties of Life: order, evolutionary, adaptation, regulation, reproduction, response to the environment, energy processing 2. Levels of Biological Organization: a. Biosphere: consist all life on Earth b. Ecosystems: living things in a particular area with nonliving things c. Communities: array of organisms inhabiting a part of an ecosystem d. Population: all individuals of a species in an area e. Organisms: individual living things f. Organs and Organ Systems: multiple tissues g. Tissues: group of cells that work together h. Cells: fundamental unit of structure & function i. Organelles: functional components present in cells j. Molecules: chemistry structure consisting of 2 or more units called atoms 3. Emergent Properties: a. Are due to the arrangement and interactions of parts as complexity increases (In other words, in order for something to happen, there must be organization and a specific arrangement.) b. Emergence: the whole is greater than the sum of the parts. c. Systems biology: explore emergent properties- the exploration of a biological system by analyzing the interaction among its parts. Attempt to understand the behavior of entire biological system. 4. Cells: An Organism’s Basic Unit of Structure & Function a. A membrane that regulates the passage of materials between the cells & its surroundings encloses every Cell. b. Prokaryotic cells: cells of 2 groups of single-celled organisms: Bacteria and Archaena c. Eukaryotic cells: other forms of life, such as plants and animals 5. Genetics: a. Chromosomes: contain genetic material in form of DNA b. Cell division: DNA is replicated and each cellular offspring inherits a complete set of chromosomes identical to the parent. c. DNA: i. Made up of 2 long chains (strands) ii. Arranged in a double helix iii. Each chain is made up of 4 chemical building blocks called nucleotides (A, T, G, C) d. Many genes provide the blueprints for making proteins, which are a major player in building and maintaining cell and activities. e. Genes control protein production indirectly using RNA i. The sequence of nucleotides along a gene is transcribed into RNA, which is then translated into linked series of protein building blocks called amino acids f. Gene expression: entire process by which the info. in a gene directs the manufacture of a cell product. g. Genetic code: particular sequence of nucleotides says the same thing in 1 organism as it does in another h. RNA: manufactures proteins & regulate the function of protein-coding genes. 6. Analysis of DNA Sequence a. Genome: entire library of genetic instructions that an organism inherits b. Genomics: researchers study whole sets of genes in 1 or more species. c. Proteomics: study of sets of proteins & their properties d. Proteome: entire set of proteins expressed by a given cell/group of cells 7. Life Requires the transfer & transformation of Energy & Matter a. Energy: primarily from the sun and then transferred from one form to another. (from plant to consumers) b. Energy is lost to the surroundings in a form of heat c. Energy is a one-way flow. Enter from light and exit as heat d. Chemicals are recycled within an ecosystem. i. Plants absorb chemicals from air, sun, and soil -> consumers receive chemicals from eating plants -> chemicals are returned to the environment by decomposers e. In an ecosystem, nutrients are recycled and energy flow through. 8. From Ecosystems to Molecules. Interactions are important in biological systems a. Ecosystems: an organism’s interactions with other organisms and the physical environment. b. Molecules: interactions within organisms i. The molecules inside the organism interact with one another to maintain the body’s balance, such as glucose level c. Feedback regulation: the output or product of a process regulates that very process i. Negative feedback – response reduces the initial stimulus ii. Positive feedback – end product speeds up its own process d. Evolution – adaptation of organisms to their environments; the concept that the organisms living on Earth today are modified descendants of common ancestors. 9. Evolution Accounts for the Unity and Diversity of Life • 1.8 millions species named by scientists. o 100,000 fungi; 290,000 plants; 57,000 vertebrate; 1 million insects; other single cell organisms. i. 10-100 million species (estimated) exist on Earth. b. Evolution causes in the population level not species. c. Grouping species: i. Taxonomy: branch of biology that names & classifies species into groups based on similar characterizes. ii. Kingdom & Domains: broadest units or classification ▯ 3 domains: ▯ Bacteria: most diverse and widespread a. Archaea: live in extreme environments b. Eukarya: 3 kingdoms (based on their modes of nutrition)- Plantae (photosynthesis); Animalia (eating and digesting); Fungi (absord dissolved nutrients from surrounding) and Protists: unicellular eukaryotes, which are more similar to plants, animals, and fungi than other protists, so they are split into several other kingdoms. 10. Charles Darwin & the theory of Natural Selection: a. “On the Origin of Species by Means of Natural Selection” i. Contemporary species arose from a succession of ancestors that differed from them – “descent with modification”. Unity in the kinship among species that descended from common ancestors & diversity in the modifications that evolved as species branch from common ancestors. ii. Natural selection; evolutionary mechanism for descent with modification - evolutionary adaptation. The natural environment “selects” for the propagation of certain traits among naturally occurring variant traits in the population. In other words, individuals with inherited traits that are better suited to the local environment are more likely to survive & reproduce than less-suited individuals. iii. Darwin synthesized his theory of natural selection from all of the listed observations and inferences. b. Unity among organisms is determined by the structure and function of DNA 11. The Tree of Life: a. One population fragments into several subpopulations isolated in different environment. In separate areas of natural selection, one species could gradually radiate into multiple species as the geographically isolated populations adapted over many generations. 12. In studying Nature, Scientists make Observations, and Form and Test Hypothesis: a. Hypothesis: testable explanations b. Inquiry: search for information and explanations of natural phenomena c. Making observations: i. Gather data (recorded observation); can be qualitative (description) or quantitative (numerical). ii. Collecting and analyzing observations can lead to important conclusions based on inductive reasoning. d. Forming and testing hypothesis: i. Experiment: test – under controlled environment - involves manipulation of one factor in a system in order to see the effects of changing it. ii. Deductive reasoning: logic that flows in the opposite direction (general to specific) – used to see if the hypothesis is correct (test if the conclusion/thought made is correct). Used when establishing a test of a hypothesis. e. The flexibility of scientific process: i. The scientific process is not linear, but circular – involving backtracking, repetitions, and interactions of different parts of the process. ii. Choice of ideas to test, the interpretation and evaluation of results and the decisions about which ideas to pursue for further study are influences by: 1. Exploration and discovery 2. Community analysis & feedback 3. Societal benefits & outcomes f. Experimental Variables and Controls: i. Variables: factors that vary in an experiment. 1. Independent variable: factor manipulated by the researchers 2. Dependent variable: factor that is measured in the experiment ii. Controlled experiment: one that is designed to compare an experimental group with a control group and tests experimental and control groups in parallel. g. Theory: i. More broader than a hypothesis ii. General enough to spin off many new, specific hypotheses that can be tested. iii. Generally supported by a much greater body of evidence 1. Matter Consist of Chemical Elements on Pure Form & in Combinations called Compounds a. Organisms are composed of matter – anything that takes up space & has mass b. Elements & Compound: i. Elements: a substance that can't be broken down to other substances by chemical reactions (92 elements) ii. Compound: substance consisting of 2 or more different elements combined in a fixed ratio. c. Elements of Life: i. Essential elements: 20-25% of the 92 elements are needed for organism to live a healthy life and reproduce, but there are some variations; humans need 25 elements and plants 17. ii. 4 elements (oxygen, Carbon, Hydrogen, and Nitrogen) make up 96% of living matters and calcium, phosphorus, potassium, sulfur and a few other account for the rest of the 4% . iii. Trace elements: are required by an organism in only minute quantities and are all needed by all forms of life. (Fe (Iron) and iodine (I) are the most important.) 2. An element’s properties depend on the structure of its atoms a. Atom: is the smallest unit of matter that still retains the properties of an element. b. Subatomic particles: i. Neutrons: electrically neutral (mass around 1.7 x 10^-24 g) ii. Protons: 1 unit of positive charge (mass around 1.7 x 10^-24 g) iii. Electrons: 1 unit of negative charge (1/2000 of the mas above) iv. Atomic nucleus: where protons and neutrons are packed together (why the nucleus has a positive charged) v. Orbital: where rapidly moving electrons are located around the nucleus 90% of the time. It is the attraction between opposite charges that keeps the electrons in the vicinity of the nucleus. vi. Dalton: unit of measurement used for atoms and subatomic particles. (same as the atomic number or amu) vii. Because the mass of an electron is 1/2000 of a neutron or proton we can ignore the electrons when computing mass. c. Atomic number and atomic mass: i. All atoms of a particular element have the same # of protons ii. Atomic number: number of protons (unique to that element) is written as a subscript to the left of the symbol for the element (ex: He 2hows that there are 2 protons in helium) 1. An atom is neutral in electrical charge, which means that its protons must be balanced by electrons. And at this state the numbers of protons and electrons are the same, therefore the atomic number will also tell us how many electrons there are. iii. Mass number: the sum of protons and neutrons (the number above the atomic number) iv. Atomic mass: the mass # is an approximation of the total mass of an atom. d. Isotopes: different atomic forms of the same element i. Most common one is carbon-12, which has 6 neutrons; carbon-13, which has 7 neurons. ii. Radioactive isotopes: “unstable” – the nucleus decays spontaneously, giving off particles and energy. 1. When radioactive isotope decay it leads to a change in the number of protons, therefore it transform the atom to an atom if a different element. (ex: carbon-14 decays to Nitrogen-14) iii. Radioactive Tracers: 1. The radioactive isotopes are incorporated into biologically active molecules, which are then used as tracers to track atoms during metabolism, the chemical process of organisms. 2. Radioactive tracers are also used in combination with sophisticated imaging instruments, such as PET scanners that can monitor growth & metabolism of cancer in the body. 3. Although radioactive isotopes are very useful in bio. Research & medicine, it can be hazardous to life by damaging cellular molecules. iv. Radioactive dating 1. Half-life: the time it takes for 50% of the parent isotope to decay. 2. Radioactive dating: scientists measure the ratio of different isotopes & calculate how many half-lives (in years) have passed since an organism was fossilized or a rock has formed. e. Energy Levels of Electrons: i. Only electrons are directly involved in chemical reactions ii. An atom’s electron varies in the amount of energy possessed. iii. Energy: capacity to cause change by doing work iv. Potential energy: energy that matter possesses because of its location or structure. v. The electrons have potential energy due to their distance from the nucleus. It takes work to move an electron that is far away from the nucleus, so the more distant an electron is from the nucleus, the greater its potential energy. vi. Electron shells: where the electrons are found in, each with a characteristic average distance and energy level. vii. An electron can exist only at certain energy levels, not between them viii. When the electron gains energy, it moves to a shell further away from the nucleus and vice versa. ix. Electrons in the outermost energy level (valence electrons) are the chemically important electrons. If the outer electron shell is full, then the atom is non- reactive. If the outer shell is not full, then the atom reacts with other atoms to share their electrons, lose the electrons or steal them away from another atom to fill the shell. 1. First energy level (electron shell) can hold two electrons. 2. The second and third electron shells hold 8 electrons each. f. Electron Distribution & Chemical Properties: i. Rows (periods): correspond to the number of electron shells. The left-to-right sequence of elements in each row corresponds to the sequential addition of electrons & protons. ii. Valence electrons: the outer electrons. iii. Valence shells: outmost electron shell. 1. Atoms with the same number of electrons in their valence shells exhibit similar chemical behavior. 2. Atoms with complete valance shell is unreactive or inert (it will not interact readily with other atoms.) g. Electron Orbitals: i. Orbital: the 3-D space where an electron is found 90% of the time. Each electron shell obtains electrons at a particular energy level, distributed among a specific number of orbitals of distinctive shapes and orientations. No more than 2 electrons can occupy a single orbital. 1. The 1 electron shell has only one spherical (s) orbital (called 1s). The 2 shell has 4 orbitals: 1 large spherical s orbital (called 2s) and 3 dumbbell-shaped p orbitals (called 2p). The 3 2p lie at right angles to one another along imaginary x-, y-, z-axes of the atom. 1. Organic chemistry: the study of carbon compounds a. Organic Molecules & the origin of life on Earth i. Stanley Miller: concluded, in his experiment, that complex organic molecules could arise spontaneously under conditions thought at that time to have existed on early Earth. 1. The experiment also supported that idea that abiotic synthesis of organic compounds could have been an early stage in the origin of life. 2. 4.2: Carbon atoms can form diverse molecules by bonding to 4 other atoms. a. Electrons configuration: determines the kinds and number of bonds an atom will form w/other atoms b. Formations of bonds with carbon: i. Carbon has 6 electrons: 2 in the 1 electron shell & 4 in the 2 shell. nd However, the 2 shell can hold up to 8 electrons and wants it complete. ii. To complete the 8 electrons: carbon will share its 4 electrons with other atoms. Each pair of shared electrons constitutes a covalent bond (usually single or double bonds). iii. When a carbon atom forms 4 single covalent bonds the arrangement of its 4 hybrid orbitals causes the bond to angle toward the corners of an imaginary tetrahedron. iv. Carbon’s most frequent bonding partners: hydrogen, oxygen, and nitrogen. 1. They are the 4 major atomic components of organic molecules. c. Molecular diversity arising from variation in carbon skeletons: i. carbon chains form the skeletons of most organic molecules. The skeletons vary in length and may be straight, branched or arranged in closed rings. ii. Hydrocarbons: organic molecules consisting only carbon and hydrogen atoms. (undergo reactions that release a relatively large number of energy.) iii. Isomers: compounds that have the same number of atoms of the same elements but different structures and properties. 1. 3 types: a. Structural isomers: differ in the covalent arrangement of their atoms i. Ex: C H5–12 forms; C H – 88 18rms; C H – 366320 42 forms b. Cis-trans isomers: (aka: geometric isomers) carbons share covalent bonds to the same atoms, but these differ in their spatial arrangement due to the inflexibility of double bonds. c. Enantiomers: are isomers that are mirror images of each other and that differ in shape due to the presence of an asymmetric carbon, one that is attached to 4 different atoms or group atoms. 3. 4.3: A few chemical groups are key to molecular function a. The chemical groups are the most important in the processes of life. i. Chemical groups attached to the carbon skeletons of organic molecules participate in chemical reactions (Functional groups) or contribute to function by affecting molecular shape. ii. 7 chemical groups 1. Ionic and Covalent Bonds a. Ionic i. Between two ions of opposite charges - When one atom strips an electron away in an interaction ii. Don’t involve shared electrons only electrostatic interactions iii. Much weaker than covalent bonds iv. Characteristic of inorganic compounds b. Covalent i. When atoms share equally one or more valence electrons ii. Not necessarily shared equally – if shared unequally than bond is polar iii. Electronegativity describes the pull of an atom in an bond iv. Nonpolar binds are when the electron[s] are equally shared v. Polar covalent bond: the electrons of the bond are not shared equally. c. Structures: 1. Molecular formula: indicates how many atoms are consisted in the molecule. (ex: H2) 2. Lewis dot structure: element symbols are surrounded by dots that represents the valence electrons 3. Structural formula: where the line represents a single bond (a pair of shared electrons). 4. Double bond: sharing 2 pairs of valence electrons. (2 lines in structural formula) 5. Valence: the number of unpaired electrons required to complete the atom’s outmost (valence) shell. (hydrogen is 1, oxygen is 2) 2. Molecules are held together by a. Hydrogen bonds i. The small bind between hydrogen’s and oxygen’s in a water solution ii. Are really weak iii. Electrostatic interactions between atoms with partial charges b. Hydrophobic interactions i. Nonpolar molecules cluster together and try and have the least amount of the least of them touching water as possible so form clumps c. Van der Waals bonds i. Weak interactions between non-polar molecules in the clump ii. Temporary + and – charges caused by movement of electrons causes this weak attraction 3. Properties of Carbohydrates a. How do they get across membranes? i. It depends on whether they are polar or non polar, polar molecules go across the membrane through facilitated diffusion whereas non polar can simply diffuse across the nonpolar area in the inter-membranous space b. How to recognize an asymmetrical carbon i. Carbon atoms with 4 different atoms or groups attached. 4. Properties of Lipids 1. Lipids are not soluble in H 2 because they mainly consist of carbons and hydrogen, which means that most of their bonds are non-polar. a. Why do phospholipids form bilayers? i. Phospholipids form bilayers because they have hydrophilic heads and hydrophobic tails so arrange in a formation so that the tails are protected from the water and the heads get to bathe in the water b. What are the properties of biological membranes? i. Biological membranes have a polar outer skin and a nonpolar area within the membrane c. How do ions, water, sugars, O2 get across i. Ions, water, sugars, and o2 get across through the use of gap junctions which are the communication lines between most cells d. What determines the stability of a fatty acid? i. The stability of the fatty acid is determined by whether or not it is a saturated or unsaturated fatty acid ii. Unsaturated fat has a bend in the hydrocarbon chain due to the presence of a double bond whereas saturated fatty acids have straight tails iii. This bend allows more space between the molecules which lessens the stability of the fatty acid which is why margarine is a paste and butter is a solid – margarine has more unsaturated fat than butter 5. What are proteins? a. What gives each protein a unique tertiary structure? i. The tertiary structure is determined solely by the primary structure and the identity of the R groups 1. polar r groups and charged r groups are hydrophilic and want to be in contact with water b. What are primary, secondary, tertiary, quaternary structures of proteins? i. Primary structure: Every protein has a different primary structure (although a particular protein may be found in thousands of copies in a cell) -The primary structure of a protein is its amino acid sequence (the order of its amino acids). Recall that there are 20 different amino acids -The theoretical number of proteins that could be synthesized (made) with 100 amino acids is 20 100(a number millions of times larger than the number of grains of sand. -Even a change of a single amino acid in a protein can dramatically affect its shape and ability to function ii. Secondary Structure -Secondary structures results from hydrogen bonds along the polypeptide backbone (NOT the R groups) -Some combinations of amino acids form a helix called an a helix, which is stabilized by hydrogen bonds between amino acids iii. Tertiary structure is the whole mass of 3 dimensional shape of a polypeptide iv. Quaternary – the whole interactions between different polypeptides and all of their various structures c. Process of protein folding 1. Protein folding proceeds by way of several distinct intermediates before finally achieving their final finished form. 2. Unfolded proteins and finished (native) proteins are not “sticky” (unless they are meant to form a quaternary structure) 3. Protein intermediates ARE sticky. They stick to each other and form masses of sticky, gunky protein messes. These insoluble protein messes are what cause disease 4. “Stickiness” is caused by intermediates having hydrophobic regions on their surface (in b pleated sheets) that are buried in the mature finished protein. These hydrophobic regions on two intermediates of the protein cause them to stick to each other. The B pleated sheet actually forms two-polypeptide chains hydrogen bonding with each other. This hides the hydrophobic regions from the surrounding water. Any event (or mutation) that stabilizes this intermediate will promote disease
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