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Essay Prompt #1

Essay Prompt #1. AP BIO QUESTION 1996 The unique properties (characteristics) of water make life possible on Earth. Select three properties of water and for each property, identify and define the property and explain it in terms of the physical/chemical nature of water.

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Essay Prompt #1

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  1. Essay Prompt #1 AP BIO QUESTION 1996 The unique properties (characteristics) of water make life possible on Earth. Select three properties of water and • for each property, identify and define the property and explain it in terms of the physical/chemical nature of water. • for each property, describe one example of how the property affects the functioning of living organisms.

  2. Note: you will need to print this slide out to see the words better. Key for Essay #1 -Prop. of water

  3. Essay Prompt #2 AP BIO QUESTION 1991: Carbon is a very important element in living systems.a. Describe the various characteristics of the carbon atom that makes possible the building of a variety of biological molecules. b. Explain how reactions involving carbon-containing compounds can contribute to the greenhouse effect. c. The following structures are examples of two different categories of biological compounds. Describe how each category of compounds is important to the structure and function of living systems.

  4. KEY TO ESSAY #2 STANDARDS: A. CHARACTERISTICS OF CARBON ATOMS: (Max of 4 points) __Ready availability, abundance __Atom small in size, outer (valence) electrons close to nucleus, so forms stable (strong) bonds __4 electrons in a valence-capacity of 8, forms 4 bonds to 4 other atoms __Forms covalent bonds __Can bond to other carbon atoms, no upper limit to size of carbon compounds __Bond angles form tetrahedron, resulting in 3-D structures, chains, rings, not just planar __Can form multiple C-C, C=C, C=C bonds __Can form isomers, different structures - same number and kind of atoms __Functional groups/combine with a variety of other elements __BONUS POINT: if get 3 above - Uniqueness, only Carbon has all of these characteristics

  5. B. REACTIONS CONTRIBUTING TO GREENHOUSE EFFEC (Max of 4 points) __Overview: Increase in gas concentration (CO2, CO, CFC) causes greenhouse effect __CO & CO2 from respiration and combustion, or volatilization of limestone __CH4 from correct source - livestock, microbes, landfills, swamps, oil wells, etc. __CFCs from industrial activities, refrigerants, plastic foam, etc. PHYSICAL MECHANISMS OF HEATING: __Ozone destruction / more energy (UV) gets in __Trapping of Energy - "Blanket" traps heat or Reflection of Sun's Energy (technically incorrectbut common use in texts) __Good technical description of absorption, reradiation and wavelength shift leading to production or long wave infrared absorbed by greenhouse gases __Concept of sinks: CO2 removal by photosynthesis, CaCO3 formation, soluble in oceans, etc. CO2 addition by forest destruction, industry, etc.

  6. C. BIOLOGICAL MOLECULES:(Max of 5 points) (Cannot get 10 points for this question without mentioning both category I and II) CATEGORY I: __Identification of molecule / category: Phospholipid, phosphoglyceride, fat, lipid, phosphatidylethanolamine / polypeptide. __Characteristics of molecule: Hydrophobic/hydrophilic, polar/nonpolar, amphipathic, or non-water soluble, high E bonds, sat/unsat C-C bonds. __Structural uses of molecule: membrane, lipid bilayer, fluid mosaic. __Functions of molecule (for example): (2 Max) Phospholipids: Regulation of membrane permeability, fluidity Fats: Structural, insulation, energy storage, water-proofing Steroids/Sterols: Hormonal, membrane fluidity Cholesterol: Animal membranes Fat soluble Vitamins: Coenzymes Prostaglandins: Neural modulators Waxes: Water-proofing

  7. CATEGORY II: __Identification of molecule / category: Amino acid / protein / cysteine __Recognizing cysteine's role in disulfide bond formation __Characteristics of molecule: Side chains variable Peptide bonds may be formed Subunit (monomer, building block) of protein Levels of protein structure / zwitterion / as buffers __Structural roles: Keratin, collagen, cytoskeletal (tubulin, actin), etc. __Functional roles: Enzymatic - speed reactions (2 Max) (pepsin, glucose oxidase, etc.) Transport (Hb, Myb, permeases, HDL/LDL) Regulatory (oligopeptides, ex. hypothalamic releasing factors, insulin, glucagon, etc.) Contractile - actin, myosin Protection - antibodies

  8. ESSAY Prompt #3 • CELL QUESTION 1992: • A laboratory assistant prepared solutions of 0.8 M, 0.6 M, 0.4 M, and 0.2 M sucrose, but forgot to label them. After realizing the error, the assistant randomly labeled the flasks containing these four unknown solutions as flask A, flask B, flask C, and flask D. • Design an experiment, based on the principles of diffusion and osmosis, that the assistant could use to determine which of the flasks contains each of the four unknown solutions. Include in your answer • a description of how you would set up and perform the experiment; • the results you would expect from your experiment; and • an explanation of those results based on the principles involved. • (Be sure to clearly state the principles addressed in your discussion.)

  9. Key to Essay #3 • EXPERIMENTAL SET-UP (1 point each) • ___ 1. Experiment based on concentration gradient • ___ 2. Experiment based on semipermeable membrane (dialysis tubing, thistle • tubes, plant or animal cells) • ___ *3. Experimental set-up (design) adequate to produce measurable results • ___ *4. (2 max) Experimental variables are eliminated (mass, volume, time, • temperature, tissue type, etc.) • ___ *5. Experimental set-up is exemplary (must include semipermeable • membrane) • B. RESULTS ( 1 point each) • ___ *1. Describes a measurable change • ___ *2. Correctly correlates the observed changes with molarities of unknowns • C. APPLICATION OF PRINCIPLES TO RESULTS (1 point each) • ___ *1. Correctly applies principles of diffusion and osmosis in the interpretation • of results (a correct analysis) • ___ 2. Demonstrates an understanding of the concept of water potential • (hydrostatic/turgor pressure) in analysis of results

  10. Key to Essay #3 continued D. PRINCIPLES (1 point each) ___ 1. Demonstrates an understanding, or gives a correct definition of diffusion ___ 2. Demonstrates an understanding, or gives a correct definition of osmosis ** (must include both water and semipermeable membrane) ___ 3. Demonstrates an understanding, or gives a correct definition of selective permeability ___ 4. Describes how solute size and/or molar concentration (hypertonic/hypotonic) affects the process of diffusion through a membrane _______________________ Max possible = 14 * No points if the lab will not work. **Osmosis: the diffusion of water through a selectively (semi)permeable membrane in the following directions: -from higher water potential toward lower water potential -from hypotonic (hypoosmotic) solution toward hypertonic (hyperosmotic) solution -from higher water concentration toward lower water concentration -from lower solute concentration toward higher solute concentration -from region of lower osmotic pressure toward regions of higher osmotic pressure -from region of higher osmotic potential toward region of lower osmotic potential

  11. ESSAY Prompt #4 Enzymes are important biological molecules. They are one of the primary means of regulating chemical processes within cells. Describe how enzymes affect chemical reactions. Describe environmental factors that affect enzyme action. Describe how enzymes are important for the process of DNA replication. (see chapter 16) **NOTE: Be sure to include the structure and what enzymes are composed in your answer.

  12. Grading Rubric for Essay #4 Part a: (1 point for each of the following) Enzymes increase the rate of chemical reactions Enzymes bind to the substrate at the active site The enzymes and substrate bind through hydrogen bonding The substrate that binds to the enzyme is one of the reactants in the reaction The substrate is changed to products and consumed by the reaction The enzyme is not consumed by the reaction and can be used again The enzyme reduces the activation energy of the reaction causing the increase in reaction rate The enzyme is a protein with a complicated three dimensional shape The shape of the enzyme’s active site had to be complementary to the substrate molecule

  13. Part b (4 pt max-1 pt for each of the following An increase in temp. causes substrate and enzyme molecules to move more rapidly The increased movement causes more collisions that increase the reaction rate Extreme temp. denature enzymes and slow reaction Competitive inhibitors are shaped similarly to the substrate Competitive inhibitors compete for the active site with the substrate, slowing the reaction rate Noncompetitive inhibitors bind to the site outside of the active site The non competitive inhibitors change the shape of the enzyme and its active site and slow the reaction Each enzyme operates most efficiently at an optimum pH pHs outside of that optimum can disrupt or denature the enzyme

  14. Part C (3pt max; 1 pt for each of the following) Helicase causes the DNA double helix to unwind DNA polymerase copies the exposed single strands of DNA DNA polymerase can only add nucleotides to a free three prime side DNA ligase seals Okazaki fragments together DNA polymerase proof-reads the new strands

  15. Other Information about Enzymes Enzyme question • QUESTION I-2000 • 1. The effects of pH and temperature were studied for an enzyme-catalyzed reaction. The following results were obtained. • a) How do (1) temperature and (2) pH affect the activity of this enzyme? In your answer, include a discussion of the relationship between the structure and the function of this enzyme, as well as a discussion of how structure and function of enzymes are affected by temperature and pH.b) Describe a controlled experiment that could have produced the data shown for either temperature or pH. Be sure to state the hypothesis that was tested here.

  16. Question I • Part a. (maximum 6 points)• Optimum temperature and pH concept [must include both temp and pH]• Enzyme/Substrate Fit concept (function dependent on conformation complernentarity between enzyme and substrate)• Tertiary (and sometimes quarternary) structure determines function• Description of enzyme structure or function, e.g.Structure • Elegant description of primary to tertiary or primary to quarternary levels of structure • Protein folding/coiIing • Co-enzymes/co-factors • Zymogens • Allosteric effectors • Function • Increases rate of reaction • Increases proximity of reactants • Decreases activation energy of the catalyzed reaction • Decreases time to reach equilibrium • Induced fit and/or orbital steering ("bond stress") • Denaturation concept [temp and/or pH] linked to decreased enzyme activity (e.g. "denaturation" in context or unfolding or change in 3D shape. not "enzyme breaks down")• How temperature affects conformation (increased temperature breaks specific bonds e.g. hydrogen, Van dcr Wuals, eljsrtllide bridges)• How pH affects conformation (change in H concentration causes a change in specific bond interactions, e.g. hydrogen: ionic, R-group interactions)• Kinetics (increased or decreased molecular movement ) linked to effect on enzyme activity due to increase or decrease in temperature up to the optimum.

  17. Part b. (maximum 6 points)Experimental design must be relevant to the data shown• What is measured (e.g. product formed or substrate used)• How is it measured (titration or spectrophotometry or color change or bubbles counted. etc.)• The independent variable (temperature/pH) is manipulated to produce the results at least 3 data points are identified]• The described experiment could produce these dataExperimental design included sufficient range, varied the temp/pH of the reaction mix not the enzyme, what was measured, and how it was measured)• Held experimental factors constant (specified at least one)• Specified a control group for comparison (no enzyme or boiled enzyme or no Substrate)• Verified results (e.g. repeated trials: results represent an average)• Hypothesis clearly related to experiment of choice, and clearly identified as a hypothesis can use the if/then... form.

  18. Essay Prompt #5 • AP BIO CELL RESPIRATION 1977 • Explain how the molecular reactions of cellular respiration transform the chemical bond energy of Krebs Cycle substrates into the more readily available bond energy of ATP. Include in your discussion the structure of the mitochondrion and show how it is important to the reactions of the Krebs Cycle and the Electron Transport Chain.

  19. Answer Key to Essay #5: STANDARDS: 1/2 point for each of the following • ___Krebs and ETS occur within mitochondria • ___Krebs - enzymes freely present in matrix fluid • ___ETS - respiratory chain (respiratory assembly) arranged in order inner membrane of mitochondria (Diagram OK) • ___more active cells - more respiratory assemblies & more cristae • ___Aerobic - O2 necessary as final H acceptor (-> H2O) (most eukaryotic cells all of the time) • ___Glycolysis is 1st required (outside mitochondria) • ___Glucose (6C) is broken down into 2 Pyruvic Acid (3C) molecules • ___Phosphorylation must 1st occur • ___Net production: 2 ATP & 2 NADH MITOCHONDRIA • ___Pyruvic Acid & 2NADH enter mitochondria • ___2 NADH will transfer H (electrons) into ETS • ___yields 2 x 2 ATP = 4 ATP (some loss due to point of entry into ETS)

  20. KREBS CYCLE SUBSTRATES • ___2 Pyruvic Acid loses CO2 & H -> 2 NADH & combines w/CoA -> Acetyl CoA • ___(2C) Acetyl CoA + (4C) Oxaloacetic Acid -> (6C) Citric Acid • ___Citric Acid -> Isocitric Acid • ___(6C) Isocitric Acid - DEHYDROGENATION & loss of CO2 -> (5C) Ketogluatric Acid NAD -> NADH • ___(5 C) Ketoglutaric Acid - DEHYDROGENATION & loss of CO2 -> (4C) Succinic Acid NAD -> NADH • ___(4C) Succinic Acid - DEHYDROGENATION -> (4C) Malic Acid FAD -> FADH2 • ___(4C) Malic Acid - DEHYDROGENATION -> Oxaloacetic Acid NAD -> NADH • ___specific mention of 2 x 3 NADH & 2 x 1 FADH2 produced during Krebs • ___ATP (1) produced in Krebs

  21. ETS RECEIVES THE FOLLOWING: NADH or FADH2 WHICH RESULTS IN ATP PRODUCTION • ___Glycolysis -> 2 NADH x 2 ATP = 4 • ___Pyruvic Acid -> Acetyl CoA + 2 NADH x 3 ATP = 6 • ___Krebs -> 8 NADH (FADH2) x 3 ATP = 24 Total = 34 • ___34 ATP gained through ETS • ___Respiratory Assembly: CoQ, cytochromes b, c, a, a3 • ___Ring Compounds w/Fe (porphyrin ring) • ___Changing Oxidation states as "go down" assembly • ___Fe III -> Fe II change ionic state as accept electrons • ___Release energy in "packets" - small amounts sufficient to produce ATP (about 7 kcal/mole) • ___Occurs at 3 places in the chain for each NADH, FADH2 • ___mention of various hypotheses: Chemiosmotic, Conformational, Chemical Coupling • ___O2 final acceptor ( -> H2O)

  22. Essay Prompt #6 • Ap Bio question 1995: Energy transfer occurs in all cellular activities. For 3 of the following 5 processes involving energy transfer, explain how each functions in the cell and give an example. Explain how ATP is involved in each example you choose. • Cellular movement • Active transport • Synthesis of molecules • Chemiosmosis • Fermentation

  23. KEY TO ESSAY #6 • 1 pt function of process • 1 pt example • 1 pt additional for detail • 1 pt ATP involvement 4 pts = MAX/process • ATP <====> ADP + Pi + Energy 1 pt

  24. Cellular Movement • Function: Locomotion, Mitosis, Cytoplasmic Streaming, Muscle Contraction (sliding filaments) • Examples: Cilia, Flagella, Pseudopodia, Exocytosis, Endocytosis, Microfilaments, Spindle Fibers • Details: 9 + 2 Microtubules, Dynein, Actin-Myosin (Myosin heads), Kinesins • ATP Involvement: ATP used Motor molecules powered by ATP hydrolysis (Conformational change with ATP use)

  25. Active Transport • Function: Concentration gradient low to high / Protein carrier w/use of ATP • Examples: Sodium/Potassium Pump, Other Transports Specified • Details: Protein carrier related to example • ATP Involvement: ATP used Conformational change with ATP use

  26. Synthesis of Molecules • Function: Small to Large / Monomer to Polymer • Examples: Intermediates to Monosaccharides to Polysaccharides Intermediates to Fatty Acids (Glycerol) to Lipids Intermediates to Amino Acids to Proteins Intermediates to Nucleotides to Nucleic Acids Intermediates to Vitamins • Details: Charging tRNA Reactions catalyzed by enzymes • ATP Involvment: ATP used ATP's energy stored in chemical bonds

  27. Chemiosmosis • Function: Form electrochemical proton (H+) gradient • Examples: Mitochondria, Chloroplasts, Bacterial Cell Membrane • Details: Cristae, Thylakoids, Direction/ H+ vs e- • ATP Involvement: ATP formed Proton pump/gradient with ATP synthase yields ATP

  28. Fermentation Start with glucose • Function: breakdown of organic compounds • Examples: Ethanol / Lactic Acid • Details Anaerobic, Less energy produced Cytosolic process, Yeast, Muscle • ATP Involvement: ATP used and formed Substrate-level Start with pyruvate • Function: recycling NADH • Examples: Ethanol / Lactic Acid • Details: Anaerobic, Regenerate oxidized NAD, Cytosolic process Yeast, Muscle • ATP Involvement: (No direct involvement) Makes ATP production Phosphorylation possible in glycolysis

  29. Overall Commentary on Question: • This question was a cell biology energetics question that required both breadth and depth of knowledge to answer the question successfully. Full credit could only be obtained by responding to three of the process examples listed in the question. Also, if more than three processes were discussed, readers were directed to grade the first three unless specifi indications directed one to be omitted. Each process had a four point maximum score. One point was available for description of the function of the process, which might also be a definition or description of a mechanism. One point came from an example in context with the process. One point was available for showing how ATP was involved in the process. For each of these points, it was possible to get an additional point for detail (elaboration). In addition, it was possible to obtain a point frordescription of the ATP <==> ADP cycle.

  30. EssayPrompt #7 Discuss the process of cell division in animals. Include a description of mitosis and cytokinesis, and of the other phases of the cell cycle. Do not include meiosis. Be sure to be detailed in your response

  31. Answer Key/Grading Rubric for Essay #7 PART I. DESCRIPTION OF MITOSIS IN ANIMAL CELLS: Max. = 7 points General • __ division of nucleus • __ daughter cells acquire the same number and kinds of chromosomes as in the mother cell • __ process for growth or repair or asexual reproduction • __ list phases in correct order (P,M,A.T) Prophase (one point each / max. 2) __ • centrioles move apart • __ chromosomes condense • __ nucleolus is no longer visible • __ nuclear envelope disappears • __ asters and spindle form Metaphase • __ sister chromatids (chromosomes) are in a line at the midpoint of the spindle Anaphase (one point each / max. 2) • __ centromeres uncouple (split) • __ chromosomes move to opposite poles • __ microtubules involved in the push/pull movement Telophase (one point each / max. 2) • __ reverse of prophase • __ nuclear envelope reforms • __ nucleolus reappears • __ chromosomes become diffuse • __ spindle and aster disappear • __ centrioles are replicated Points less frequently mentioned: • __ function of centrioles • __ definition of kinetochores • __ description of polar microtubules and kinetochore microtubules • __ definition of chromatids *In order to obtain a score of 10, there must be points in all three sections. If only two sections are written the maximum is 9.

  32. PART II. CYTOKINESIS: • __ division of cytoplasm • __ formation of a cleavage furrow • __ occurrence of cytokinesis in the cell cycle Points less frequently mentioned: __ function of cytokinesis __ dense belt of actin and myosin microfilaments __ purse-string mechanism __ furrow occurs at location of equatorial plane __ cytochalasin blocks activity of microfilaments (stops cytokinesis)

  33. PART III. OTHER PHASES OF THE CELL CYCLE (INTERPHASE): General • __ list G1, S, and G2 in correct order • __ G1, S, and G2 are part of interphase • __ chromosomes appear as a mass of chromatin material G1 • __ synthesis of cell organelles or cell doubles in size • __ restriction (decision) point or point of no return S • __ synthesis or replication of DNA or DNA replication occurs during interphase G2 • __ synthesis of microtubular assembly, or prepare for mitosis Points less frequently mentioned: • __ description of nucleosomes • __ times in each phase • __ growth factors • __ some cells do not go beyond G1 • __ after cell passes "S", mitosis will usually continue • __ colchicine prevents the formation of microtubules

  34. Essay Prompt #8 The Cell Cycle functions in regulating information flow through organisms. Discuss how alleles are distributed by the process of meiosis to the gametes. Explain how the cell cycle is controlled. Explain how these controls prevent errors in inheritance. Note: It is important t answer all three parts (a-c) and to include all of the key proteins and concepts discussed in class. ie. Cyclin, MPF, three checkpoints, p53 genes, tumor suprerssor genes, etc.

  35. Essay Prompt #8 Grading Rubric

  36. Activity (#9): Solve the Following Genetic Problems End of Chapter 14 On Pgs 272-273 Do # 2,3,7,9,14, and 15 Be sure to SHOW ALL WORK An answer only will not be given full credit.

  37. Activity (#9): Answer See Appendix A in the back of your Textbook. Note: (Page # is not shown but it would be on 1236 after the final chapter.

  38. Essay Prompt #10 Read the following question and on a separate sheet op paper give your answer in an ESSAY FORM. Outline alone is not acceptable. Labeled diagrams may be used to supplement discussion, but in no case will a diagram alone suffice. It is important that your read each question completely before you begin to write. In Fruit flies, the phenotype for eye color is determined by a certain locus. E indicates the dominant allele and e indicates the recessive allele. The cross between a male wild-type fruit fly and female white-eyed fly produced the following offspring: Wild-type Wild-type White-eyed White eyed Brown eyed Male Female Male Female Female F1 0 45 55 0 1 The wild-type and white-eyed individuals from F1 generation were then crossed to produce the following offspring: Wild-type Wild-type White-eyed White eyed Brown eyed Male Female Male Female Female F2 23 31 22 24 1 1.Determine the genotype of the original parents (P generation) and explain your reasoning. You may use Punnett squares to enhance your description, but the results from the Punnett squares must be discussed in your answer. 2. Use a Chi-squared test on the F2 generation data to analyze your prediction of the parental genotypes. Show all your work and explain the importance of your final answer. BE sure to write the Chi-Square formula next to your work. The brown-eyed female in the F1 generation resulted from a mutational change. Explain what a mutation is, and discuss two types of mutations that might have produced the brown-eyed female in the F1 generation. **Note: Your response to these three questions will be a major part ofyour grade for this lab. Therefore, be thorough and complete in your response

  39. ESSAY Prompt #10: Rubric (Key) A) maximum 4 pts 1 pt Genotypes of the parents (words or symbols) XEY (or X+Y) and XeXe 1 pt Discuss/show how these resulted in this F1 (may be annotated Punnett) 1 pt Explain that it is a sex-linked (X-linked) gene (not just the word) 1 pt How you know which type is dominant 1 pt F2 results (may be annotated Punnett square) B) Maximum 4 pts 1 pt Correct F2 hypothesis (1:1:1:1 or 25/genotype) 1 pt Show work (components): o e o-e (o-e)2 (o-e)2/e (or correct numbers (4/25 of 36/25 + 1/25 + 9/25 = 50/25 = 2; or at least the last term) 1 pt Sum; correct chi-square result ~ 2.0 or 1.85 1 pt degrees of freedom = 3 (critical value is 7.82) 1 pt correct interpretation of chi-square in terms of p p = probability that the difference between the observed and the expected value is due to chance alone. This p value shows we accept our hypothesis. The null hypothesis is supported in this case. (alternative: 2 X2 tests of white vs. red males and white vs. red females. C) Maximum 4 pts 1 pt Explain what a mutation is: (heritable) change in the DNA (code) 1-2 pts Discuss 2 types of mutations May be: point mutation, frameshift (deletion/duplication), insertion, transposition, break, inversion within gene, base substitution, nonsense/stop, missense) May NOT be: chromosomal aberration, nondisjunction, silent/neutral, transcription or translation or processing error 1 pt Molecular or biochemical elaboration beyond the explanation required

  40. Essay Prompt #11 Describe the chemical nature of genes. (a) Discuss the replication process of DNA naming all of the steps and key enzymes involved. (b) Name TWO types of gene mutations that occur during replication.

  41. Essay Prompt #11-Rubric (Key) A gene is a hereditary unit located at a specific locus along a chromosome. Genes are made up of DNA, and DNA is made up of repeating subunits of nucleotides. A nucleotide consists of three parts: a 5-carbon sugar (ribose), a phosphate group, and a nitrogenous base. When a chromosome replicates, the two DNA strands unwind and the hydrogen bonds between them are broken (Helicase). Single stranded binding protein will stabilize and hold open the strands. Topoisomerase will then cut each side of the replication fork alleviating strain that reults from excessive coiling. Each strand serves as a template for the synthesis of a complementary strand. Once the process initiated (by RNA primase), DNA polymerase III adds the nucleotides to each growing strand. One strand serves as the leading strand (made continuously) and the other strand serves as the lagging strand (made discontinuously). Each base matches the appropriate bases in the template strand: they are complementary. DNA Polymerase I then will replace the RNA nucleotides (Uracil-to-Thymine) that were laid down with DNA nucleotides.

  42. Essay Prompt #11-Rubric (Key) Cont’d Once the complementary strands are formed, hydrogen bonds form between the new base pairs, leaving two identical copies of the original DNA molecules. The process was determined by Meselson & Stahl to be semiconservative. A gene mutation is a change in the sequence of base pairs in a DNA. It results from defects in the sequence of bases. Mutations that involve a single base change in the DNA sequence are called point mutations. Point mutations fall into two general categories: base substitutions and insertions/ deletions. A base substitution involves a single DNA nucleotide replaced by another nucleotide. An insertion or deletion occurs when a base pair is added or removed from the DNA sequence. Any insertion or deletion results in a frameshift when the mRNA is translating resulting in a completely new unique protein formed. The beginnings of possible adaptations and maybe an advantage evolutionarily.

  43. Essay Prompt #12 Describe the different types of mutations and the process of how genes are expressed (transcription & translation) in a eukaryotic cell. Be sure to include a discussion of how point mutations affect proper protein synthesis at the level of translation. You must mention all the key structures, molecules, and enzymes involved (ex. mRNA, tRNA, snRNA, RNA polymerase, aminoacyl-tRNA synthestase, ribosome & sites, TATA box, etc) NOTE: Labeled drawings & diagrams may be useful in your response but you must draw them don’t cut & paste images in.

  44. No Rubric Available Yet. We might grade this one specifically in class!!! So make sure that you’ve included as much detail as possible to receive full credit. Essay Prompt #12

  45. Essay Prompt #13 How does Darwin’s Explanation of Natural Selection complement modern genetic knowledge to produce the current model of evolution? Offer an example of how this model could explain the change of a population characteristic through time? e.g. eye color, limb length, etc.)

  46. Essay Prompt #13 Grading Rubric 1. Populations have a tremendous biotic potential to increase their numbers. As an example of the possibility of growth rate, consider a female sunfish in a pond. It can lay 200,000 eggs per reproductive cycle. About one-half of these eggs could develop into female sunfish. Each of these 100,000 females could lay 200,000 eggs as this trend multiplies to astronomical figures after very few generations of sunfish. However, only two or three of the hatched sunfish may survive. Among wild populations, high death rates among the young is the rule. This leads to the next point.

  47. Essay Prompt #13 Grading Rubric cont’d 2. Darwin was influenced in his thinking by an economist named Malthus Taking a page from supply-side economics. Darwin concluded that the amount of resources to support a population is limited. There is just so much oxygen, food, space, etc. in the pond to support a maximum number of fish. With the tremendous biotic potential of a species, competition for resources is inevitable 3. By studying populations of reptiles and birds of the Galapagos Islands off the coast of South American. Darwin concluded that variation, genetic difference, is a characteristic of any population. During his study in the mid-nineteenth century, however, he did not know the basis for the variation, the actions of genes, yet undiscovered.

  48. Essay Prompt #13 Grading Rubric cont’d 4. Those with adaptive variations favorable in the given environment have better probabilities of surviving and leaving offspring. Thus, broader leaves, taller giraffes, faster predators, or better-camouflaged prey all have adaptions to promote survival. This survival power for increased life span yields increased reproductive fitness, the individual’s ability to pass its genes onto future generations 5. This higher probability of survival and reproductive fitness allows affected members to have more of an effect on the gene pool of the next generation Thus, a superior gene for tallness, among more surviving members processing it. Leads to higher odds that it will be genetically passed on and lead to a higher percentage of taller members in the next generation.

  49. Essay Prompt #13 Grading Rubric cont’d The merger of these principles with genetics came with the understanding of mutations. Mutations are changes in a gene and the raw material for evolution. Without a source of change a population cannot change or evolve. For example, if the only form of an eye color gene were dark, “B”, all members of the population would be homozygous for “B,” BB. All mating would be BBxBB and produce homozygous organisms with dark eye color. If the “B” dominant gene mutates to a recessive “b,” then there is n eye color alternative. A mating of two heterozygous organisms, BbxBb, can produce blue-eyed offspring, bb, with a 25%chance. If blue eyes is adaptive against the environment, more blue-eyed individual with survive longer. Over time they will leave their blue eye genes hereditarily and gradually in crease the frequency of blue-eyed individuals in the future gene pool

  50. Essay Prompt #14 (Last one yeah!!!) Discuss the web of life in a biological community. Your essay should focus on energy flow, conversion, and loss in food chains, including the concepts of trophic levels and pyramids.

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