Biology Semester Final Review

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1 Name BUNDLE 2 - Viruses vs. Cells Biology Semester Final Review Period 1. How are plant cells different from animal cells? Plant cells have a cell wall, chloroplasts, and a large central vacuole that animal cells do not have. Animal cells have lysosomes and centrioles that plant cells do not have. 2. What is homeostasis? constant internal state or balance 3. How do cells maintain homeostasis? Which cell part(s) is responsible for this? Cells maintain homeostasis primarily by osmosis 4. Where are carbohydrates (sugar, starch, glucose) made in the cell? chloroplasts 5. What is the function of: cell membrane, cell wall, nucleus, mitochondria, chloroplast, vacuole, ribosomes, smooth ER, chromosomes, cilia/ and flagella? - you ll find all functions on this link (you will have to create a login) Virus Viruses are infections particles made only of a strand of DNA or RNA surrounded by a protein coat. They are very small ( nm) and cannot be seen with a light microscope. Viruses are also called phages. 6. What are the characteristics of living things? Made of cells complex organization Obtain and use energy - metabolism Grow and develop Reproduce Respond to stimuli - responsiveness Adapt (populations) 7. How are viruses different from cells? They do not do all of these things; they only multiply and they can only do that with the help of a host cell. Viruses do not metabolize nutrients, they do not respond to stimuli, they do multiply (always inside of a host (living) cell, and they do evolve. 8. What structures do viruses have in common with cells? Which are different? Viruses have a genetic core either out of DNA or RNA (not both as in organisms). 9. How do viruses reproduce? In a host cell (know what the pictures look like and put them in order) Viruses multiply by either the lytic or lysogenic (dormant period) cycle Lytic Attachment Entry (penetration) Synthesis (biosynthesis) Assembly Lysis (release) Lysogenic Once the phage has entered the host cell, the viral DNA gets incorporated into the cell s chromosome (it s now call a prophage). Whenever the cell divides or replicates, so does the prophage because it is in the cell. We refer to this time as dormancy. A later event will trigger to go into the lytic cycle and eventually all of the host cells will lyse. 10. How do viruses cause disease such as HIV? HIV is a retrovirus and causes disease by reverse transcription. 11. What are some diseases caused by viruses? A disease causing agent is often described as a pathogen. Common cold, HIV, flu, rabies, mumps, rubella, chicken pox, hepatitis, polio, West Nile, Ebola, Herpes, 1

2 12. Draw a bateriophage, what does it infect? Bacteriophages are viruses that attack and invade bacteria 13. Draw a HIV virus. 14. What s the difference between the lytic cycle and the lysogenic? see #9 above 15. What s an antigen? beginning of the against reaction An antigen is a protein. Your immune system will produce antibodies against antigens. Antigens may be foreign substances from the environment, such as cheicals, bacteria, viruses, or pollen. Antigens may also originate within the body. If your cells don t recognize the antigens on invading pathogens, your cells will mount an immune response. 16. Why don t antibiotics work on viruses? Antibiotics kill bacteria by working on or destroying the bacteria s cell wall. Other antibiotics prevent bacteria from dividing. (Vaccines work to prevent viruses) 17. What s a vaccine? A vaccine is small dose of a live or attenuated virus given to stimulate the immune response, so that on subsequent exposures you have antibodies, in large enough numbers, ready to combat the invading virus. 18. What nucleic acids could a virus have? DNA or RNA not both; retroviruses, like HIV have RNA BUNDLE 3 Biochemistry & Enzymes 1. Identify and draw examples of the 4 types of biomolecules. Carbohydrates (H:O ratio = 2:1) Monosaccharides Disaccharides Polysaccharides (If sugars, such as glucose are not dissolved in water, their structure is linear) Lipids Triglyceride Fatty Acids saturated Fattty Acids unsaturated Phospholipid Steroid Proteins Amino Acids 2

3 Nucleic Acids Nucleotide DNA RNA 2. Identify what the monomers (building blocks) are for the following biomolecules a. Carbohydrates? monosaccharides b. Lipids? 3 fatty acids + glycerol c. Proteins? Amino acids d. Nucleic acids? Nucleotides 3. Describe the functions of the following biomolecules: a. Carbohydrates? Primary energy source for cells. Some of the larger ones (cellulose) are for structure; i.e. plant cell walls. Other large one (amylose or starch) are for short term storage in a plant b. Lipids? Insulation, long-term, back-up energy reserve, some hormones (steroid), fat-soluble vitamins, cell membrane (phospholipid) everything in this category is nonpolar, which means they won t dissolve in water c. Proteins? Building blocks for all tissues/organs; growth, maintenance, and repair, organic catalysts (enzyme) which are necessary for any chemical reaction that occurs in the body, muscle tissue and the contractile elements (actin and myosin) in muscle fibers, transport molecules such as hemoglobin and myoglobin, antibodies defense, some hormones. d. Nucleic acids? DNA genetic code, instructions that new cells need in order to divide and that are passed on to offspring of future generations. DNA is also the code or recipe by which proteins are made RNA copies the code or recipe and puts it into amino acid language (mrna) and then assembles the amino acids according to these directions (trna) to assemble a protein ATP while ATP is a nucleotide and not technically a nucleic acid, if it were to be classified into 1 of these 4 groups, it would be classified with this group. It is the cellular energy molecule of the cell and is produced by cellular respiration. The majority of ATP is synthesized by mitochondria of eukaryotic cells. 4. Identify where are each of the 4 biomolecules are made in the cell? Carbohydrates synthesized by chloroplasts in autotrophic eukaryotic cells (plants and algaes) (the process is called photosynthesis) Lipids synthesized by smooth ER Proteins synthesized by ribosomes (the process is called translation) Nucleic Acids DNA synthesized in the nucleus (the process is called replication and occurs during the S-phase of the cell cycle) RNA synthesized in the nucleolus ATP the majority is synthesize in the mitochondria of all eukaryotic cells 5. What are examples of: (include examples found inside the cell where applicable) a. Carbohydrates? Generally referred to as sugars and starches, examples include the monosaccharides: glucose, galactose, fructose (fruit), the disaccharides: sucrose (table sugar), 3

4 lactose (milk sugar), maltose, and the polysaccharides: amylose or starch (plant short-term storage), glycogen (animal short-term storage), and cellulose (plant structural material used to build plant cell walls) b. Lipids? Fats, oils, and waxes (triglycerides), cell membrane (phospholipid), steroid hormones such as estrogen and testosterone, Vitamins A, D, E and K. c. Proteins? Muscle fibers actin and myosin, insulin, glucagon and other peptide hormones, antibodies, enzymes, hemoglobin, myoglobin d. Nucleic acids DNA, RNA, ATP 6. Describe hydrolysis and dehydration synthesis. What is lost or gained? What is the end result, a monomer or polymer? Dehydration Synthesis literally means making by removing water Small subunits or monomers (building blocks) are chemically combined by removing H, H, and O (water) to make larger molecules (polymers) Hydrolysis literally means lysis (breaking) by adding water Large molecules or polymers are broken apart by adding H, H, and O (water) to make smaller molecules 7. Which biomolecule determines the sequence of amino acids in a protein? DNA BUNDLE 4 Cellular Energy 1. What is the purpose of photosynthesis? Convert light energy into chemical energy stored in the chemical bonds of glucose. 2. Where does photosynthesis occur in the cell? Chloroplast 3. What is the purpose of cellular respiration? To make cellular energy (ATP) from the energy stored in glucose. 4. Where does cellular respiration occur in the cell? Mitochondria 5. Why are photosynthetic organisms called autotrophs? Make their own food using light energy 6. Give an example of an autotroph. Plants 7. What is the chemical reaction for photosynthesis? 8. What is the chemical reaction for cellular respiration? 9. What are the products of photosynthesis? Glucose and oxygen gas 10. What are the reactants of cellular respiration? Glucose and oxygen 11. How do the products of photosynthesis and reactants of cellular respiration compare? Same 12. How do the reactants of photosynthesis and products of cellular respiration compare? Same 13. How are photosynthesis and cellular respiration similar? They are opposite processes. The products of photosynthesis are reactants for cellular respiration. The Products of cellular respiration are the reactants for photosynthesis. 14. What is the main product of photosynthesis? Glucose Where is this product made in the cell? Chloroplast 4

5 15. Draw and label the parts of ATP molecule. Where is ATP made in the cell? Mitochondria 16. What is the purpose of the green pigment chlorophyll? Absorb sunlight energy. 17. Why do most leaves appear green? Reflect green spectrum of visible light. 18. What type of energy does the plant use to convert CO 2 and H 2O into sugar? Light (sun) 19. Which type of fermentation requires the presence of oxygen gas? Aerobic 20. During a strenuous workout, Jill noticed her muscles began to feel tired and weak. This is most likely due to (lactic acid fermentation, alcoholic fermentation). BUDNLE 5 Cellular Transport 1. Define solute and solvent. Solute the part of the solution in the lesser amount sometimes described as the solid part of the solution (though this is only partially correct); i.e. Kool-Aid powder in a glass of Kool-Aid, tea leaves in ice tea. In cells, cytoplasm is a solution and the proteins, sugars, ions, electrolytes are the solutes in this solution. When solutions are classified: hypertonic, hypotonic, isotonic the tonic refers to the amount of solute in a solution. Solvent part of the solution in the greater amount sometimes this is described as the liquid part of the solution (though this is only partially correct); i.e. In Kool-Aid and ice tea, water is the solvent; in chocolate milk, milk is the solvent. In cells, water is the solvent in the cytoplasm and extracellular fluid (fluid that bathes the cells, abbreviated ECF). NOTE Even though water is what moves freely across the cell membrane, the solutions are classified by the amount of solute the solution contains. 2. What is cytoplasm? Describe how cytoplasm is a solution, what is the solvent and what are the solutes? Cytoplasm is the gel part of the cell. It is like the jello in a jello sald. It supports the organelles. It is a solution water is its solvent and proteins, sugars, and ions are the solutes dissolved in it. 3. What portion of the cell helps maintain homeostasis? Cell membrane aka (also known as) plasma membrane 4. Draw a section of the cell membrane. 5. Describe semi-permeable: Semipermeable literally means half permeable ; permeable means able to pass through. A cell membrane is described as semipermeable b/c (because) some things can pass through it and some things cannot. This characteristic of the cell membrane allows the cell to maintain homeostasis. If you are given a choice between describing the cell membrane as semipermeable or selectively permeable, the better choice is selectively permeable. 6. How are passive and active transport different from each other? 5

6 Passive Transport molecules pass through the cell membrane from greater to lesser concentrations, which requires no energy from the cell. This would be like float downstream on a river. Active Transport molecules pass through the cell membrane from lesser to greater concentrations which does require energy (ATP) from the cell. This would be like rowing upstream on a river. 7. During passive transport, how do molecules move relative to the concentration gradient? Down or with the concentration gradient 8. What are examples of passive transport? 1)Simple diffusion 2)osmosis (diffusion of water) 3)facilitative diffusion (diffusion with a helper molecule which is a carrier protein; even though this requires a carrier protein, it still doesn t require energy (ATP), so is still passive) 9. How is osmosis different from diffusion? Osmosis is the diffusion of water; since water diffuses through all cell membranes, it is given a special name 10. How is diffusion different from facilitated diffusion? Facilitative diffusion requires the help of a carrier protein for medium-sized molecules (such as glucose) to pass through; in diffusion, molecules pass through the pores in the phospholipid layers of the cell membrane 11. What are examples of active transport? Na-K Pump, proton pumps, minerals deposited in the roots of plants, iodine being stored in the thyroid gland, endoand exocytosis. 12. During active transport, how do molecules move relative to the concentration gradient? Up or against the concentration gradient 13. If a cell is placed in a hypertonic solution, how does it react? Hypotonic solution? Isotonic solution? Solution = hypertonic Cell = hypotonic Water always moves from hypotonic to hypertonic. (High water low water) The water in the cell will move out of the cell, leaving an animal cell crenated (shrunk, raspberry-like in appearance) or a plant cell flaccid or plasmolyzed. Solution = hypotonic Cell = hypertonic Water always moves from hypotonic to hypertonic. (High water low water) The water in the solution will move into the cell, increasing its size. In animal cells, since there is no cell wall, the cell could cytolyze (burst). In plant cells, the cell will become turgid (stiff). Solution = isotonic Cell = isotonic Since the cell is isotonic to the solution, water amounts are equal. Water will move from the cell to the environment and from the environment into the cell, but the water movement will be balanced. There will be no net change in the size of the cell. 14. In a U tube with sides separated by a semi-permeable membrane, the concentration of the solute is much higher on the left side than the right side. Sketch a diagram. What term describes the solution on the left when compared to the right? What term describes the solution on the right when compared to the left? What side will have an increase in the water level AFTER a period of time? What side will have a decrease in the water level? Left concentration of solute is much higher = hypertonic Right = hypotonic Water always moves from hypotonic to hypertonic. (High water low water) Water will move from the right (hypotonic) to the left; therefore, the water on the right side will decrease and the amount of water on the left side will increase. 15. Osmosis will occur until what state is reached in a cell when compared to the surrounding environment? Dynamic equilibrium (equilibrium) 6

7 BUNDLE 6 - DNA vs. RNA, DAN Replication, Protein Synthesis - Gene expression, & POINT Mutations 1. What are the components of DNA? Draw and label a nucleotide. DNA nucleotides that are composed of these three parts: Pentose sugar deoxyribose Phosphate group 1 of 4 nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C) The nucleotides are bonded by phosphodiester linkages and the 2 strands are antiparallel in orientation and are held together at their nitrogenous bases by hydrogen bonds; therefore, the shape looks somewhat like a ladder (double helix) 2. What are the differences between mrna and trna? mrna goes back and forth between nucleus and ribosome in the cytoplasm triplets are called codons codons are complementary to DNA triplets and trna anticodon simple strand broken down after translation trna only in the cytoplasm triplets are called anticodons (b/c they fit against the codon) anticodon is complementary to mrna s codon and specific amino acids coils into a clover-shaped loop (tertiary) reactivated with a new amino acid after translation 3. Give an example of a Point/ Substitution Mutation. A point mutation is a mistake in one nucleotide of a nucleic acid. A substitution is when one nucleotide (that doesn t match the complementary strand) is substituted for the one that should. Most of the time, mistakes are caught and corrected by proofreading enzymes, but when they aren t a mutation in the polypeptide, thus trait, results. An example is sickle cell anemia. 4. Give an example of a Frameshift Mutation- Insertion vs Deletion. 5. How is a frameshift mutation different from a point substitution? Nucleotides are read in sets of 3, known as a codon; this is also called a reading frame. For example UUU codes for the amino acid, phenylalanine. In this transcript: AUA CCC AUG there are 3 codons. Substitutions occur when a nucleotide is substituted for another; there is no change in the reading frame. Often times if the substitution occurs in the 3 position of a reading frame, the mutation has no consequence (wobble) and sometimes they cause serious problems as in sickle cell anemia. 7

8 Frame shift mutations are caused by insertions or deletions that cause a change in the reading frame. When this happens every amino acid after to the frameshift mutation is affected; if this happens near the beginning of a transcript, this would have a most serious effect on the polypeptide produced and therefore, the trait. 6. Why is a frameshift mutation at the beginning of a transcript more serious than one further down the genome? All amino acids after the frameshift mutation would be changed; therefore, not the same protein or nonsense. A frameshift mutation at the beginning changes everything. 7. Compare DNA vs RNA DNA Double stranded, forming a double helix Sugar = deoxyribose ATGC thymine present In eukaryotes, is composed of introns and exons RNA Single stranded Sugar ribose AUGC uracil present instead of thymine BOTH - What they have in common Sugar phosphate backbone, though the sugars are different AGC are common to both Both can be in the nucleus, but only RNA can leave to go to the cytoplasm 8. Who discovered the structure of DNA? Watson and Crick Describe transcription (What is the product? Where does it take place) RNA copies a gene from DNA in the nucleus (where it takes place) RNA transcript is processed: introns cut out, and ends capped with GTP and PolyA RNA transcript or mrna (product) moves out of the nucleus to the ribosomes 10. Describe translation (What is the product? Where does it take place?) trna goes and picks up an amino acid (complementary pairing of bases). It brings the amino acid to the ribosome (where it takes place) and using its anticodon, matches it up with the mrna transcript of DNA s gene. Once peptide bonds are formed between adjacent amino acids, the ribosome moves down releasing trna and leaving space for the next incoming amino acid. In this way the polypeptide chain elongates until a termination (STOP) codon is read. At the termination codon the process stops and the mechanism breaks apart releasing the polypeptide (product) for cell use. 11. Look at the following molecule. Be able to make a complementary DNA strand, a mrna strand and be able to translate it into a protein. Also include the processes that are taking place at each of these steps. DNA strand: 5 TAC GCG AAA TGG CCA 3 DNA: Complementary strand = 3 ATG CGC TTT ACC GGT 5 mrna from the given template: = 3 AUG CGC UUU ACC GGU 5 Amino Acids from the given template: Met Arg Phe Thr - Gly 12. What information does DNA contain? Genetic Code 13. Which part of DNA carries information? Sequence nitrogenous bases 14. How does DNA relate to proteins and proteins to traits? DNA is the code (recipe) for making proteins and is used to pass traits on to offspring 8

9 15. Which molecule determines sequence of amino acids in a protein? DNA 16. Why are proteins important? What are the functions of proteins? Function in growth, maintenance, and repair of body tissues; also function as transport molecules as in hemoglobin and myoglobin, help in the immune response as in antibodies, and function as contractile units for muscle fibers as in actin and myosin. Some proteins are used as structural units and some function as messengers (neurotransmitters and some hormones. All enzymes, or organic catalysts, are proteins and lower the activation energy for chemical reactions to be able to occur in living things. These are SOME of the functions. 17. How do components of the genetic code compare in living organisms? The genetic code is universal each codon codes for the same amino acid. It is redundant, but not ambiguous. 18. What is purpose of transcription? Where does it occur? The purpose of transcription is to copy a desired gene of DNA into RNA language so that it can be exported out of the nucleus. Transcription occurs in the nucleus. It is the synthesis of RNA from the use of a DNA template. 19. What is the purpose of translation? Where does it occur? The purpose of translation is to convert DNA language (nucleotides) into amino acid language (amino acids) with the end product being a polypeptide chain (protein). This process occurs in the ribosomes. 20. Know the purpose of translation and what it looks like. mrna attaches to the rrna (ribosome) which is the site of protein synthesis. trnas bring amino acids to the mrna on the ribosomes. trna anticodons are complimentary to mrna codons. Amino acids link together to form peptide bonds. The product of translation is a polypeptide chain (amino acid) chain called a protein. 21. What is a mutation? Any change in DNA 22. What effect do mutations have? Are they helpful, harmful, or of no effect? Explain why. (frameshift or substitution i.e. sickle cell anemia) Mutations can have a harmful effect, beneficial effect, or no effect at all in the polypeptide produced. IF a nucleotide is in the 3 rd position of a reading frame or codon, wobble accounts for less specificity in the code. Therefore, if a substitution mutation occurs there, it is less likely to have a harmful effect versus if the point mutation affects the first or second nucleotide in the codon. 23. What is the role of mrna? What is the role of trna? mrna transcribes DNA s code and takes it out of the nucleus and brings it to the ribosomes = transcription trna picks up amino acids that are free floating in the cytoplasm and takes them to the mrna where it lines them up according to the transcript s sequence = translation The end product of these 2 processes is a polypeptide chain or protein 24. What is a codon? 3 sequential nucleotides of mrna (the reading frame) 25. How is the genetic code read? The genetic code is read three letters at a time (codon). The intersection of the nucleotide on the left side, top side, and right side 26. How is gene expression regulated? Is it different in prokaryotes and eukaryotes? 9

10 All cells in all organisms have the same follow the same genetic code. It is universal. So how do we get different proteins? traits? Genes that are normally off can be turned on and a polypeptide product will be produced. Genes that are normally on can be turned off (gene silencing) and a polypeptide product which is normally made will no longer be produced. This is basically for supply and demand efficiency This is basic premise of regulating gene expression and it can be carried out different ways and happen at different levels of the process see diagram Repressor proteins bind to the operator closing the promoter region; therefore transcription cannot occur Activators enhance transcription 27. Describe the role of RNA in differentiation. After the first few cell divisions following fertilization the new daughter cells are identical to the zygote. All the cells in this morula have the potential to become any cell in the body or placenta (totipotent). A few days later, the cells become pluripotent which means they can become any cell in the body (lasts 3-5 days). A few days later there is a fate decision and the cells are then referred to as multipotent and can become any cell within a specific germ layer or cell lineage. BUNDLE 7 - Cell Cycle Mitosis Meiosis Chromosome Mutations Karyotype 1. Describe and draw a picture of what happens in each stage of the cell cycle Interphase (G1, S, G2), Mitosis (all phases), and Cytokinesis. - animation Interphase the period between cell divisions (mitosis); it appears as a resting or quiescent stage (under the microscope) because chromosomes are not visible; however, this is a misnomer because this is when the cell is doing the rest of its activities G 1 Gap 1 cells grow and increase in size until their surface area to volume ratio stimulate cell division R Restriction point go or no go (if go, the cell will proceed to the S-phase where DNA will be replicated and proceed to the finish of the cycle) G 0 if the signal is no go, the cell can leave the cell cycle and enters a resting phase where the cell no longer divides; some cells stay here and some cells have the ability to return to G1 and complete the cell cycle depending on stimuli from their environment S-Phase Replication of DNA occurs (replication always proceeds in the 5 to 3 direction) G2 Gap 2 cell growth continues; Mitosis (sometimes called the M-phase) - Cell division (2n 2n; diploid to diploid) produces daughter cells identical to the parent cell; sometimes called cloning Prophase Cell is getting ready for cell division Metaphase chromosomes line up along the equatorial plane Anaphase sister chromatids split into separate chromosomes and migrate to opposite poles of the cell Telophase cell returns to its normal state Cytokinesis division of the cytoplasm 10

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12 2. Why is the cell cycle important to the growth of organisms? So more cells can be produced (identical to the parent cell) 3. What is the importance of the checkpoints in the cell cycle? At checkpoints, the cell checks for damage and makes sure everything is progressing as should be. When damage is found, repairs are made or the cell destructs (apoptosis) see red arrows on diagram above 4. What happens if the checkpoints fail to do their job in the cell cycle? Mutation or uncontrolled cell division (cancer) 5. How does the chromosome number compare from parent to offspring? Mitosis = 2n 2n or diploid to diploid 6. Which cycle increases genetic variation, mitosis or meiosis? Meiosis (prophase I crossing over and metaphase I & II independent assortment) 7. Describe haploid vs. diploid using mitosis and meiosis, and chromosome number. 2n 2n or diploid to diploid = mitosis 2n n or diploid to haploid = meiosis 8. How do you determine the number of kilobases at each stage of the cell cycle if you are only given the starting number at the G1 stage?it should double in the S-phase and then ½ in cytokinesis 9. What does a karyotype show? If a karyotype showed trisomy 21, what would that mean? A karyotype is a picture of a person s chromosomes arranged in homologous pairs from largest to smallest. In each somatic cell of a person s body, he should have 22 pairs of homologous chromosomes + a pair of sex chromosomes (if the sex chromosomes are homologous = XX = female; if heterozygous = XY = male). A trisomy means have 3 homologous chromosomes instead of a pair. In the case of Trisomy 21, the person would have three of the 21 st chromosomes which would result in Downs Syndrome. 10. How is meiosis different from mitosis? In meiosis the chromosome number is reduced by ½ and the gametes (sperm and egg) and different from each other (not clones) from the crossing over that occurs in Prophase I and independent assortment that occurs in Metaphase I & II. 11. What are sources of variation in the genome? Mutation Recombination Crossing over Prophase I of meiosis Independent assortment of chromosomes Metaphase I & II of meiosis Random fertilization of gametes Mutation is the only spontaneous source; all other sources of variation are like shuffling and reshuffling a deck of cards. 12. What is the difference between a zygote and a gamete? A gamete is a germ or sex cell; the male gamete is a sperm cell (spermatozoa) and the female gamete is the egg (ova). Gametes are n in chromosomes number. The zygote is a fertilized egg and is 2n 13. XX = female; XY = male; who determines the sex of a child? father 14. A complete set of chromosomes is known as diploid; and half set is known as haploid. 15. If the diploid number of chromosomes in humans is 46, what is the haploid number? 23 Number in gametes? 23 Number in sperm? 23 Number in eggs? 23 (all asking the same thing but different ways) 16. If this is an example chromosome, draw an example of: a. Deletion b. Duplication c. Inversion d. Translocation 17. If there are 1,000kb of DNA in G1 of mitosis, how many will there be in S? 2,000kb In the daughter cells after cytokinesis? 1,000kb 18. If there are 1,000kb of DNA in G1 of meiosis, how many will there be in S? 2,000kb In the daughter cells after cytokinesis? 500kb after telophase II 19. If there are 400kb of DNA in S of mitosis, how many were there in the parent cell? 200kb 20. If there are 400kb of DNA in S of meiosis, how many were there in the parent cell? 200kb 12

13 21. Draw a picture of crossing over? When, during the cell cycle does it occur? Prophase I What is its significance? Adds genetic variation to the genome; most variation comes from crossing over. Bundle 8 - Genetics (1 point) For additional Genetics help (step by step walk through procedure on how to work various types of Genetics problems, I d recommend the Biology Project - and click on Mendelian Genetics. 1. If fur color is determined by a single gene, what is the expected outcome of crossing two rabbits that are heterozygous for black fur? (B-black, b-brown) Bb x Bb Genotypic ratio: 1 BB : 2 Bb : 1bb Phenotypic ratio: 3 Black fur : 1 Brown fur 2. What percentage of the offspring from a WwRr x wwrr cross would be expected to be heterozygous for both traits? (W- widow s peak, R- tongue roller) Answer: you are looking for WwRr Gametes: female WR, Wr, wr, wr Male all wr Genotypic ratio: 1 WwRr : 1 Wwrr : 1 wwrr : 1 wwrr 25% 25% 25% 25% 3. If 76 out of 100 seeds were yellow in color and the rest are green. What were the parents genotypes? 76 : 24 is about 3:1 ratio. Both parents are heterozygous. 4. A mom is a carrier for colorblindness (a sex linked trait) and the father is not colorblind. What are the predicted phenotypes of their kids? Carrier Mom s genotype: X C X c Dad s genotype: X C Y Genotypic ratio: 1 X C X c : 1 X c X c : 1 X C Y : 1 X c Y Phenotypic ratio: 25% females carriers; 25% females colorblind; 25% males normal vision; 25% males - colorblind 5. Define heterozygous, homozygous, dominant, and recessive. Heterozygous 2 different alleles (Ex. Aa) Homozygous same alleles (Ex. AA, or aa) Dominant vs. recessive: When a dominant allele is present is shows up in the phenotype of the organism; it masks the recessive allele. Having a widow s peak is dominant to a straight hairline. Conventionally, dominant traits are indicated by a capital letter, so in this case W = widow s peak and w = straight hairline (this is true, unless the condition is a disease and if it is a disease, the first letter of the disease is used). 6. How does your DNA determine your traits? DNA has instructions (code) how to make a specific protein, which in turn determines a trait. 13

14 Semester Final Essays Of the following 3 POSSIBLE essays, you will have 1 of these essays on the final to write about. Practice writing all 3 of these essays thoroughly, as you do not know which one will show up! 1. Explain how the cell membrane helps maintain homeostasis. 2. Explain the following diagram by labeling each part and explaining where it occurs and what happens during the process. DNA RNA Protein 3. Explain what the 4 biomolecules are, where they are made, their monomers and how they are used in a cell or your body 14