Bio 190 Study guide
Bio 190 Study guide Bio 190
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This 15 page Study Guide was uploaded by Danielle Francy on Sunday May 15, 2016. The Study Guide belongs to Bio 190 at Towson University taught by Joseph Velenovsky in Fall 2015. Since its upload, it has received 17 views. For similar materials see Intro Biology for Health Professions in Biology at Towson University.
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Date Created: 05/15/16
Biology 190 Study Guide Cells Prokaryotic Cells: ● Bacteria and archaea ● No membrane enclosed nucleus ● Nucleoid ● Cell walls ● Membrane enclosing the cytoplasm=plasma membrane ● Protects and maintains shape=cell wall ● No lysosomes Eukaryotic Cells: ● Organelles ● Membrane bound ● Not in animal cells: ○ Central vacuole ○ Chloroplast ○ Cell wall ○ Plasmodesmata ● Cytoskeleton: ○ Microfilament ○ Intermediate filament ○ Microtubule DNA: DNA contains: ● two strands ● each made up of repeating nucleotide subunits ● phosphate, sugar, and base ● strands are oriented in opposite directions (antiparallel) ● Adenine and Thymine have 2 hydrogen bonds ● Guanine and Cytosine have 3 hydrogen bonds Bases: ● There are 4 bases in DNA: 1. Thymine 2. Cytosine 3. Adenine 4. Guanine ● T and C are Pyrimidines (small) ● A and G are Purines (big) Hershey and Chase experiment: Background of the experiment: 1. Bacterial viruses (phage) were used to demonstrate that DNA is the genetic material. 2. The phage had a DNA molecule surrounded by a protein coat. 3. When phage infect bacteria, they attach to the surface of the cell and inject their DNA into the cell (protein coat remains on the outside of the cell). Conclusion: The DNA, not the protein, carries the genetic information for a new generation of phage. Replication, Transcription, and Translation DNA has two funtions 1. Control: Transcription and Translation 2. Heredity: Replication Replication: ● Complementary nitrogenous base pairing ● Two nucleotide strands separate ● Parental DNA ● Complementary (daughter) strands ● Free floating nucleotides ● Nucleotides are added using enzymes ● 1 parental DNA molecule yields 2 identical daughter DNA molecules ● Semiconservative model How replication works 1. There is one parent DNA strand. 2. DNA helicase separates the two parent strands (untwists them). 3. There are now 2 DNA templates. 4. Free nucleotides come to complementary base pair to each parent strand with the help of DNA polymerase. 5. Two new daughter cells are formed (semiconservative because half of the parent cell is conserved). Three Important Enzymes in DNA Replication and their function 1. DNA Helicase: Untwists parent strands (separates them) 2. DNA Polymerase: Adds nucleotides to growing strands and also repairs (mismatches) 3. DNA Ligase: Connects lagging fragments together and also repairs (single strand breaks)(proofreads) *Usually anything with “ase” is an enzyme. How transcription works 1. Occurs in the nucleus 2. Transcribing DNA to RNA 3. There is DNA and a promoter site which starts theinitiatioprocess by RNA polymerase linking onto the promoter site. 4. RNA polymerase creates RNA by traveling down the DNA which is known as the elongation process. 5. Once RNA polymerase hits the terminator site on the DNA, RNA is finished being made (termination process). Translation: ● Codons ● PolyU, UUU, Ribosomes, other factors required for translation ● Interpreter is tRNAs with the help of other factors ● The site of interpretation is the ribosome Description of translation s: e 1. Occurs in the cytoplasm because RNA made in transcription comes out of the nucleus. 2. There is a larger subunit and smaller subunit. 3. Inside the larger subunit are the P and A sites. 4. The mRNA messenger is inbetween the two subunits. How translation works: 1. tRNA comes into the A site and complementary base pairs anticodons of tRNA with codons of mRNA. 2. After the anticodons and codons complementary base pair, the amino acid is made in the A site where the polypeptide chain is going to be made. 3. Polypeptide chain forms a structure which gives the protein its function. Electrons and Molecules: ● Electrons account for the chemical activity of atoms ● The further an electron is from the nucleus, the greater the energy ● In electron shells, the quantity is based on the atomic number ● The number of electrons in the outer shell determines chemical properties ● Unpaired electrons in the valence shell tend to be reactive ● Complete valence shell elements are chemically inert ● Two atoms with incomplete valence shells will either share, donate, or receive electrons completing valence shells. Covalent bonds: ● Strongest chemical bond, two atoms share one or more pairs of valence shell electrons ● Two or more atoms held together by covalent bonds form a molecule ● Atoms within a molecule are constantly trying to take the electrons they share ● ***An atom’s attraction for shared electrons is calectronegativity ● The more electronegativity, the more strongly electrons are pulled Hydrogen Bonds: ● Weak, but just as important as covalent bonds ● Most large molecules are held together by weak bonds. These bonds are generally eaily breakable and able to be formed ● Partial charges and water ● Hydrogen bonding in water ● Hydrogen bonds in protein shape and function Macromolecules: 1. Carbohydrates 2. Proteins 3. Nucleic Acids ***Lipids arNOT macromolecules ● Monomers and polymers ● Dehydration reaction lose a water molecule ● Hydrolysis add water Structures of Proteins: Primary Order of amino acids formed by dehydration synthesis which forms covalent bonds Secondary Alpha helix and Beta pleated sheet along a protein chain. Form is twisted. Hydrogen bonding. TertiaryFolding due to hydrophobic/hydrophilic chains. Hydrophobic side chains are on the inside. Polar, charged chains are on the surface. Quaternary Finally considered proteins. Two or more polypeptides interacting. Protein Denaturation: ● No enzyme required ● loss of quaternary, tertiary, and secondary structures ● Polar amino acids dissolve very well in water; aqueous ● Nonpolar amino acids dissolve very well in membranes ● in response to change from heat, pH, or salt Heat: ● Heat breaks hydrogen bonds Salt: ● Na+ ● Cl pH: ● H+ add acid ● OH ***Cell Theory: ● All things are composed of cells ● All cells come from other cells Cells: ● Need surface area large enough to service the volume of a cell ● Active cells have a huge amount of traffic across their outer surface (oxygen, nutrients, waste, etc) ● Need surface area/volume ratio that is favorable to functions ● Cell site governed by the ability to perform cellular functions Functions of Plasma Membrane: 1. Limiting boundary ● Separate and protect cell from its environment 2. Transport (in and out) 3. Identification and recognition 4. Communication ● Receptor protein empty ○ ex. insulin Extracellular Matrix(ECM) ● Tissues and protection ● Main component= glycoproteins long polysaccharide and complex ● Strong and abundant=collagen fibers ● ECM attaches to cell ● Influence each other ● Integrin directly affects/influences cellular behavior Tight Junctions: ● Neighboring cells and digestive tract. ● Water tight seal ● Looks like the adjacent membranes are sewn together ● Forms a watertight seal between two membranes ● Prevent passage of material between the cells ● Seen in intestinal epithelium where they prevent the passage of gut contents between gut lining cells Anchoring Junctions(aka desmosomes): ● Plasma membrane pressed and knit ● Screws fasten cells together into sheets ● Composed of Intermediate filaments ● Common in skin and heart muscle ● Stretching or mechanical stress ● Connect the intermediate filaments of the cytoskeletons of adjacent cells(desmosomes) ● May also anchor a cell’s intermediate filaments to the ECM ● Provide mechanical strength to the tissue by connecting many cells firmly together ● Seen between keratinocytes in the skin epidermis, where the multiple layers of dead, but firmly connected keratinocytes form the barrier that separates you from the environment Gap Junctions: ● Communicating junctions ● Allow small molecule ions in the cell ● Form pores that provide direct connection between the cytoplasm of adjacent cells ● Allow flow of molecules and ions from one cell to the next ● Permit communication between adjacent cells that coordinate the tissue’s reaction to stimuli Plasmodesmata: ● Keeps plants upright ● Cellulose and other polysaccharides and proteins ● Primary cell wall is thin and flexible ● Some cells add secondary cell wall ● Lignin ● Pectin glues cells together(polysaccharide) ● Plasmodesmata prevents isolation ● Water, nutrients, and chemicals Tonicity: ● Isotonic ○ Same=normal ● Hypertonic ○ More=shriveled ● Hypotonic ○ Less=burst Cell Organelles: Exocytosis: ● Export bulky materials(proteins and polysaccharides) ● Pancreas and insulin Endocytosis: ● Import of large molecules ● Cellular eating ● ***Wraps extensions calledseudopodia and “eats it” ● Lysosome breaks things down ● ex: amoeba Pinocytosis: ● Cellular drinking ● Gulps droplets of fluid ● Nonspecific all solutes taken in that are present within a gulp ● Cell that lines small blood vessels **ReceptorMediated Endocytosis: ● Highly selective ● Gets what it wants through receptor proteins ● Binds only to specific proteins ● Coat proteins How it works: ● Coat proteins (aka clathrin) form a coated vesicle ● Coated pit has coated proteins on the outside of it ● Will eventually form a coated vesicle LDL receptor Low density lipoproteins (cholesterol) First Law of Thermodynamics: ● “Law of energy conservation”: energy in the universe is constant and therefore can be transferred and transformed but not created or destroyed. Why can organisms not recycle their energy? ● Every transfer or transformation some energy becomes unusable ● In most energy transformations, some energy is converted to heat ● Heat is a very disordered as measured by entropy. ● Measure of disorder ● Random arrangements of matter have greater entropy Exergonic Reaction: ● More energy in reactants than products ● Covalent bonds more energy ● Energy is equal to the difference ***Cellular respiration is exergonic Endergonic Reaction: ● More energy in products than reactants ● Energy is equal to difference between products and reactants ● ***Photosynthesis is endergonic ● Makes glucose using carbon dioxide, water, and sun Metabolic Pathways: ● Series of chemical reactions that either build a complex molecule or break down complex molecules into simpler compounds. Energy Coupling: ● Use energy released from exergonic reactions to drive essential endergonic reactions Catalytic Cycle: 1. Enzyme available with empty active site 2. Sucrose enters active site attaching through weak bonds ○ Active site changes shape “hugging” the substrate ○ Induced fit model ○ Contort substrate bonds or place R groups in the active site in position to catalyze ○ In reactions with two or more reactants, active site holds the substrates close enough and in the proper placement for the reaction 3. Contorted weakened bond between monosaccharides react with water; products are fructose and glucose ● Reaction is called hydrolysis 4. Product is unchanged. ***Two key characteristics of enzymes: 1. Biological catalyst 2. Not consumed in the reactions they catalyze. ***Enzymes are proteins, but some RNA can act as enzymes(splicing). Krebs Cycle: ● Hans Krebs ● Each turn of the cycle 1 ATP through substratelevel phosphorylation ● 3 NADH ● 1 FADH2 ● 2 molecules of acetyl Coenzyme A for each glucose ● Overall yield= enzymes located in mitochondrial matrix or embedded in the inner membrane Right side of the Cycle: ● Redox reactions ● Strip hydrogen atoms off of intermediates ● Intermediates lose carbon dioxide ● Iodized citric acid Left side of the Cycle: ● Enzymes rearrange chemical bonds ● One turn is considered complete whexaloacetateas been regenerated Cells must divide because: ● Growth ● Replacement of damaged cells ● Development embryo into an adult organism Diploid vs Haploid: Diploid: ● Number of chromosomes in a body cell ● Characteristics of a species ● Always even number because chromosomes occur in pairs ● Both homologous chromosome members of each pair present in the cell Haploid: ● Number of chromosomes in a gamete ● One half the diploid number, but not just any half ● Only one member of each type/pair present ● When two haploid cells fuse, the diploid state is restored Homologous Chromosome Pairs: ● Each body/somatic cell contains two copies of each human chromosome/DNA molecule ● Are present in all stages of cell cycle ○ G1, G0, S, G2, MP, M,A,T,C ● Can be in chromatin (fully extended) or chromosomes (fully compacted) form depending on stage of cell cycle ● Can be replicated or unreplicated ● These two copies are: ○ A pair ○ “Homologous” because they have: ■ Same length ■ Same centromere position ■ Same sequence of genes, but… ■ Not necessarily same “variants” (alleles) for each gene because each member of the pair is from a different parent ● Same length, same centromere position, and same sequence of genes because they are the same chromosome ● Not same sequence of alleles because ○ One= maternal (a, b, c, d, e, F) ○ One= paternal (a, B, C, D, e, f) ● Never attached at centromere Sister Chromatids: ● Each= one side (one half) of a replicated chromosome ● Each contains one of the 2 daughter DNA molecules made during the S phase ● Are identical in both gene and allele sequence ● Always held together by the centromere ● When separated at anaphase, they become independent chromosomes Three Subphases: 1. G1 phase 2. S phase 3. G2 phase Checkpoints: ● G1, G2, M ● Progress cell cycle ● Stop progression Chromosomes: ● Tightly packaged DNA ● Found only during cell division ● DNA is not being used for macromolecule synthesis Chromatin: ● Unwound DNA ● Found throughout interphase ● DNA is being used for macromolecule synthesis Synapsis: ● Chromatids of homologous chromosomes exchange segments ● Crossing over Meiosis Metaphase I: ● Chromosomal tetrads align on metaphase plate ● Midway between the two poles of spindle ● ***Sister chromatids still attached to each other at centromere ● Spindle microtubules attached to kinetochores ● Homologous chromosomes are held together at the sites of crossing over ● Microtubules from one pole vs. other pole ● Opposite movement Anaphase I: ● Chromosomes move toward opposite poles of the cell ● Sister chromatids composing each doubled chromosome remain attached at the centromere ● Only the tetrads split up ● Haploid number of chromosomes move towards each spindle pole ● If this was mitosis, six daughter chromosomes would be moving toward each pole Telophase I: ● Chromosomes arrive at opposite poles ● Each pole has a haploid chromosome set ● Each chromosome is still duplicated ● Each chromosome consists of two sister chromatids ● Cytokinesis usually occurs concurrently with telophase I ● Two haploid daughter cells are formed ● In some species, chromosomes uncoil and the nuclear envelope reforms ● Interphase between meiosis I and meiosis II ● In other species, daughter cells of first meiotic division proceed directly into meiosis II ● Either way, no chromosome duplication occurs between cytokinesis and meiosis II Meiosis II: ● Same as mitosis ● Starts with a haploid cell ● Prophase II ○ Spindle forms ○ Chromosomes are moved towards the middle of the cell ● Metaphase II ○ Aligned on metaphase plate ○ Kinetochores face opposite poles ● Anaphase II ○ Sister chromatids finally separate ○ Individual daughter chromosomes move towards opposite poles ● Telophase II ○ Nuclei envelope reformation ○ Cytokinesis occurs concurrently ○ Four daughter haploid cells Crossing Over: ● Exchange of corresponding segments between nonsister chromatids of homologous chromosomes ● Crossing over occurs during prophase I of meiosis ● Tetrads, four chromatids ● Chiasma; sites of crossing over Chiasma: ● Two homologous (nonsister) chromatids are attached to each other ● Crossing over occurs early in prophase I ● Loci are aligned precisely ● Sister chromatids don’t break because they are genetically identical Mitosis M Phase ● 10% of time during cell cycle ● Mitosis and cytokinesis ● Nucleus and its contents (duplicated chromosomes) divide ● Two daughter nuclei ● Cytokinesis is divided in two ● Two genetically identical daughter cells ● Single nucleus ● Cytoplasm; organelles ● Plasma membrane ● Each daughter cell begins the cell cycle in the first gap ● Mitosis unique to eukaryotes ● Development of human body ● Single cell ● Fusion of mother’s egg and father’s sperm ● Mitotic division results in embryonic growth Interphase: ● Animal cell ● Cell growth ● Synthesize new molecules and organelles ● Late interphase (G2) doubled much of its contents ● Two centrosomes (microtubuleorganizing centers) found in cytoplasm ● Each centrosome one pair of centrioles (microtubules) ● Chromosomes are duplicated but are still in chromatin form (cannot tell individual chromosomes apart) Prophase: ● Changes in the nucleus and cytoplasm ● Formation of discrete chromosomes (folding and coiling) ● Two identical sister chromatids joined together at centromere ● Different from centrosome and centrioles ● Mitotic spindle begins to form (early mitotic spindle) ● Microtubules grow out of the centrosomes ● Centrosomes (2) move away from each other Prometaphase: ● Nuclear envelope breaks down ● Microtubules from centrosomes are present at the poles (ends) of the mitotic spindle ● Microtubules reach the chromosomes which at this point are higher condensed ● Within the centromere region, each sister chromatid has a kinetochore ● This protein structure attaches to a portion of the microtubules from the mitotic spindle(both poles) ● This attachment causes the chromosomes to begin an agitated motion ● Other microtubules (not attached to kinetochores) contact microtubules that have extended from the opposite pole ● ***Protein motors (enzymes called kinesins use ATP) associated with spindle microtubules move the chromosomes toward the center of the dividing cell ● Kinesins similar to myosin ● ***Dynein also involved; a separate motor protein complex ● Kinesins and Dynein work together Metaphase: ● Mitotic spindle fully formed and functional ● Poles are completely at opposite ends of the cell ● Chromosomes converge on the metaphase plate ● Metaphase plate is an imaginary area equidistant between the two ends of the spindle ● Centromeres are lined up on the metaphase plate ● Within each chromosome, the kinetochores face opposite poles ● Microtubules attached to a particular chromatid are from one pole; its sister Anaphase: ● Sister chromatids are separated as the two centromeres of each chromosome come apart ● Upon this separation, each sister chromatid is labeled a daughter chromosome ● Kinesins and Dynein walk daughter chromosomes centromere first along microtubule towards opposite poles of the dividing cell ● At the same time, spindle microtubules attached to kinetochores shorten ● Spindle microtubules not attached to kinetochores lengthen ● Poles are moved farther apart Telophase: ● Cellular expansion or elongation that started in anaphase continues ● Daughter nuclei appear at opposite ends of the cell ● Nuclear envelopes form around the chromosomes at each pole ● Telophase is reverse of prophase ● Chromatin structure starting ● Presence of a nuclear envelope ● Shrinking of the mitotic spindle ● By the end of telophase, chromosomes are nearly coiled as chromatin ● Mitotic spindle has disappeared ● Mitosis is complete after telophase ● Defined as the equal division of one nucleus into two genetically identical daughter nuclei ● Still undergo cytokinesis ● Cytokinesis occurs often concurrently with telophase Shortterm explanation of Mitosis(easily able to be drawn): Interphase: Centrosomes and DNA replicate themselves and get ready to split Prophase: Chromosomes form and centrosomes start to spread apart to either side of the cell Metaphase: C hromosomes align in the middle of the cell Anaphase: Separate chromosomes from their copies Telophase: Each of the new cell structures are reconstructed Cytokinesis: Cell movement Mitosis is responsible for: 1. Cell replacement 2. Growth 3. Asexual reproduction Ecology: ● The study that determines how organisms interact with their environment. Biotic factors: ● Living parts of the environment Abiotic factors: ● Nonliving parts of the environment ○ Temp, energy, water, available nutrients Ecological Levels of Organization: 1. Individual 2. Population 3. Community 4. Ecosystem 5. Biome 6. Biosphere Natural Selection: ● Preexisting genetic variation in all populations ● Overproduction of offspring ● Competition for limited resources and escape from predation, disease ● Unequal reproductive success Evolution: ● The gradual development of something, usually from simple to complex. Ecological Footprint: ● Area of land needed by individual/nation/globally to : ○ Produce all needed resources ○ Absorb all waste ● Differs by individual and by nation J and S curves J curve: Stays continuous, keeps getting larger S curve: Tapers off after a certain point. Reaches maximum capacity. Human population: S curve Chemiosmosis: ● The movement of ions across a selectively permeable membrane, down their concentration gradient.
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