Answer Key Biology Microgenetics

Biology Microgenetics Chromosomes and Meiosis Objectives: • Describe how the process of meiosis results in the formation of haploid gametes and analyze the importance of meiosis in sexual reproduction. • Illustrate that the sorting and recombining of genes in sexual reproduction results in a great variety of possible gene combinations in offspring. Practice Questions Multiple Choice 1. The products of meiosis are: a. two genetically identical cells b. two genetically different cells c. four genetically identical cells d. four genetically different cells 2. a. b. c. d. A human gamete that has 24 chromosomes, instead of the normal 23, is a product of: translocation insertion nondisjunction deletion 3. a. b. c. d. In meiosis, the phase during which sister chromatids separate from each other is: prophase II metaphase II anaphase II telophase II 4. cell is: a. b. c. d. In meiosis, the phase during which homologous chromosomes line up along the middle of the 5. a. b. c. d. The sex of a child is determined by: the sex chromosome from their father the sex chromosome from their mother autosomes from their mother autosomes from their father prophase I metaphase I anaphase I telophase I Constructed Response 1. Identify two ways in which meiosis can lead to genetic variation within a family. Crossing over during prophase I causes increased genetic variation because genetic material from homologous pairs are exchanged. During metaphase, homologous pairs and sister chromatids will randomly assort which causes different chromosomes to end up in different gametes. The gametes end up with half the normal number of chromosomes so that fertilization will combine those chromosomes with the chromosomes of another parent. 2. Explain the difference between a deletion and insertion mutation. A deletion mutation occurs when a portion of a chromosome is permanently removed. An insertion mutation occurs when a piece of a different chromosome is inserted into a non-homologous pair. Each mutation can affect how the affected genes are transcribed and translated. DNA Structure and Replication Objectives: • Describe the basic structure of DNA, including the role of hydrogen bonding. • Explain the basic process of DNA replication. • Explain how the process of DNA replication results in the transmission and conservation of the genetic code. Practice Questions Multiple Choice 1. The monomers of DNA are: a. amino acids b. fatty acids c. nucleotides d. monosaccharides 2. What holds the nitrogenous bases together in the middle of the DNA double helix? a. covalent bonds b. hydrogen bonds c. ionic bonds d. nitrogen bonds 3. What are the base pairing rules for DNA are: a. thymine pairs with adenine and cytosine pairs with guanine. b. adenine pairs with cytosine and guanine pairs with thymine. c. adenine pairs with guanine and thymine pairs with cytosine. d. cytosine pairs with thymine and guanine pairs with thymine. 4. a. b. c. d. The enzyme responsible for unzipping the helix, so that new nucleotides can be placed, is: DNA polymerase ligase helicase primase Constructed Response 1. Identify the parts of DNA that are the exact same from person to person. Everyone has the same basic parts: a deoxyribose sugar, a phosphate group, and the four nitrogenous bases (adenine, thymine, cytosine, and guanine) 2. Identify the parts of DNA that vary from person to person. The order of the nitrogenous bases are different from person to person. This accounts for the slightly different traits humans have. 3. Explain how the enzymes helicase and DNA polymerase allow DNA to replicate. Helicase will break the hydrogen bonds to “unzip” the DNA molecule. DNA polymerase builds a new strand of DNA using one of the original strands as a template. Cell Cycle Objectives: • Describe the events that occur during interphase. • Explain the role of mitosis in the formation of new cells. • Describe the importance in maintaining chromosome number during asexual reproduction. • Compare and contrast the function of mitosis and meiosis. Practice Questions Multiple Choice a. b. c. d. 2. a. b. c. d. 1. Cells spend the most time in: interphase metaphase anaphase telophase The phase of mitosis during which DNA condenses and the nuclear membrane dissolves is: prophase metaphase anaphase telophase 3. a. b. c. d. When cells reproduce without stopping, which disease is occurring? diabetes cancer nondisjunction heart disease 4. a. b. c. d. Mitosis forms: two genetically identical cells two genetically different cells four genetically identical cells four genetically different cells 5. a. b. c. d. Normal somatic cells are ____ and mitosis produces ______ cells. haploid; diploid diploid; diploid haploid; haploid diploid; haploid Constructed Response 1. Explain how mitosis ensures that the new cells produced are exact clones. During mitosis, the sister chromatids all line up in the middle of the cell and are pulled to opposite ends to ensure that each new cell gets one of every chromosome. No crossing over occurs during mitosis and both daughter cells are also diploid. 2. Identify two situations in which your body would signal cells to start going through mitosis. Mitosis occurs once the cells are large enough to split. If the cell continued to grow, it would become inefficient at getting nutrients and getting rid of waste. Mitosis needs to occur in order for us to grow and develop into multicellular organisms. Mitosis will also occur after injury so the body can make more cells to heal. Protein Synthesis and Gene Expression Objectives: • Explain the functional relationships between DNA, genes, alleles, and chromosomes and their roles in inheritance. • Explain the process of protein synthesis. • Describe the role of ribosomes, endoplasmic reticulum, Golgi apparatus, and the nucleus in the production of specific types of proteins. • Describe how genetic mutations alter the DNA sequence and may or may not affect phenotype (e.g., silent, nonsense, frameshift). Big Ideas: Big Idea 2 page 205. Practice Questions Multiple Choice a. b. c. d. 1. A three base sequence on mRNA is known as a/an: anti-codon gene allele codon 2. a. b. c. d. A three base sequence on tRNA is known as a/an: anti-codon gene allele codon 3. a. b. c. d. Which molecule should never leave the nucleus DNA mRNA tRNA ribosome 4. a. b. c. d. Which organelle packages proteins to be sent out of the cell? ribosome golgi apparatus lysosome mitochondria 5. a. b. c. d. Which type of mutation does not have an effect on the protein produced? nonsense missense silent frameshift Constructed Response 1. Using epigenetics, explain why identical twins look less similar as they get older. Epigenetics affects the phenotype of an organism without changing their original DNA. Environmental factors and the different choices a person might make throughout their lives (diet, fitness level, smoking, etc) may turn genes on or off, which can cause differences in the phenotype of a person. 2. Explain why a frameshift mutation can have such a large impact on a protein. A frameshift mutation occurs when a nucleotide is inserted or deleted from a DNA sequence. This causes a shift in the mRNA codons and will potentially change every single codon after the place where the mutation occurred. This will have severe effects on the resulting protein. 3. Explain how, even though DNA does not leave the nucleus, it is able to determine the proteins produced by the cell. DNA contains the instructions to make proteins, but in order to get the message to the ribosomes, it must first copy that information onto mRNA during transcription. The mRNA can leave the nucleus and find a ribsome in the cytoplasm. Then the information can be translated into a protein. Reproduction and Development Objectives: • Explain the differences between asexual and sexual reproduction. • Describe the advantages and disadvantages of asexual and sexual reproduction. • Describe the development of offspring. Practice Questions Multiple Choice a. b. c. d. 1. Which of the following is a disadvantage of asexual reproduction, compared to sexual reproduction? allows organisms to reproduce faster allows organisms to reproduce without a mate allows populations to have less genetic diversity allows organisms to reproduce without producing gametes 2. a. b. c. d. Which of the following organisms are prokaryotes? plants bacteria animals fungi 3. a. b. c. d. Internal fertilization is necessary for: trout frogs dogs sea urchins 4. a. b. c. d. The fertilized egg, an animal’s first cell is referred to as a: gamete neurula zygote gastrula Constructed Response 1. Identify two advantages of asexual reproduction over sexual reproduction. Asexual reproduction can happen quickly because the organism does not have to wait to find a mate. It is more energetically efficient than sexual reproduction because the organism does not have to produce gametes. Aexual reproduction also allows for all of the parents traits to be passed on to the offspring. 2. Identify two advantages of sexual reproduction over asexual reproduction. The offspring produced from sexual reproduction are genetically different from both parents, so if there was an unfavorable trait, it may not be passed on. Sexual reproduction leads to increased genetic diversity which can be beneficial in changing environments. 3. Identify the differences between identical and fraternal twins. Identical twins are produced from one sperm and one egg cell. During the early stages of cell division, the embryo divides into two separate embryos that have the same DNA. The embryos develop inside of the same placenta, but two different amniotic sacs. Fraternal twins are produced from two separate sperm and two separate eggs. They have different DNA. The embryos develop in different placentas and different amniotic sacs. Biotechnology and Genetic Engineering Objectives: • • Identify costs and benefits of technologies such as gene therapy, cloning, and tissue engineering. Explain how different biotechnologies work. Practice Questions Multiple Choice a. b. c. d. 1. What technique is used to insert a beneficial gene into a person’s genome? gene splicing gene therapy cloning forensics 2. a. b. c. d. What technique is used to investigate for criminal and civil cases? gene splicing gene therapy cloning forensics 3. a. b. c. d. What technique is used to produce a genetically identical cell or organism? gene splicing gene therapy cloning forensics 4. a. b. An organism that has genes from another organism is a: clone transgenic organism c. d. stem cell Gamete 5. a. b. c. d. A cell that can become any type of cell is referred to as a: gamete stem cell transgenic clone Constructed Response 1. Explain how DNA fingerprints are used by forensic scientists. DNA fingerprints use restriction enzymes to cut DNA into strips. These strips are different lengths and travel at different speeds through a gel. When they settle, a DNA fingerprint is made. This can be compared to previous DNA samples to try to narrow down a suspect, prove someone innocent, or check for relation. 2. Identify two examples of GMO’s (genetically modified organisms). Corn, cotton, soybeans, golden rice, etc. Essential Vocabulary Terms Meiosis and Chromosomes 1. Chromosome - a single piece of coiled DNA and proteins found in the nucleus of eukaryotic cells. 2. Chromosomal Mutation - a change in the structure of a chromosome. 3. Crossing over - an exchange of genetic material between homologous chromosomes during prophase I of meiosis. 4. Diploid - a cell containing two homologous chromosomes (2n). 5. Duplication - when a segment of a chromosome is duplicated and is displayed more than once on the chromosome. 6. Gametes - a specialized cell (egg or sperm) used in sexual reproduction containing half the normal number of chromosomes of a somatic cell. 7. Gene recombination - a result of crossing over in which DNA is broken and then joined to a different molecule. 8. Haploid - a cell containing one chromosome (n) from each homologous pair. 9. Homologous Pair - maternal and paternal copies of a chromosome. 10. Insertion - when a portion of one chromosome has been deleted from its normal place and inserted into another chromosome. 11. Inversion - when a segment of a chromosome breaks off and reattaches in reverse order. 12. Karyotype - a visual display of a complete set of chromosomes. 13. Meiosis - a two-phase division of the nucleus that results in the production of gametes with half the normal number of chromosomes. 14. Monosomy - having only one copy of a chromosome. 15. Mutation - a permanent change of genetic material that can be passed on to offspring. 16. Nondisjunction - the process in which homologous chromosomes or sister chromatids fail to separate during meiosis. 17. Sister chromatids - two identical strands of a replicated chromosome. 18. Somatic Cells - cells that form the body of the organism (non-reproductive cells). 19. Translocation - when a segment of one chromosome breaks off and attaches to a nonhomologous chromosome. 20. Trisomy - having three copies of a chromosome. DNA Structure and Replication 1. Deletion Mutation - A genetic mutation in which one or more nucleotides are removed from a section of DNA. 2. Deoxyribonucleic Acid (DNA) - a biological macromolecule that encodes the genetic information for living organisms and is capable of self-replication and the synthesis of ribonucleic acid (RNA). 3. DNA Replication - the process in which DNA makes a duplicate copy of itself. 4. Enzyme - A protein that increases the rate of a chemical reaction without being changed by the reaction. 5. Gene Mutation - A permanent alteration that changes a segment of DNA within a gene. 6. Hydrogen Bonds - a weak chemical bond formed between the slightly positive hydrogen atoms of one molecule and the slightly negative charged atoms of a different molecule. 7. Insertion Mutation - A genetic mutation in which one or more nucleotides are inserted into a genetic sequence. 8. Nucleic Acid - A biological macromolecule composed of the elements C, H, N, O, and P that carries genetic information. 9. Nucleotide - the monomers of nucleic acids that when combined make up the polymers DNA and RNA. 10. Nucleus - A membrane-bound organelle in eukaryotic cells functioning to maintain the integrity of the genetic material and, through the expression of that material, controlling and regulating cellular activities. 11. Point Mutation - A single-base substitution causing the replacement of a single-base nucleotide with another nucleotide. 12. Semiconservative Replication - The process in which the DNA molecule uncoils and separates into two strands. Each original strand becomes a template on which a new strand is constructed, resulting in two DNA molecules identical to the original DNA molecule. Cell Cycle 1. Anaphase - the third phase of mitosis, in which sister chromatids are pulled apart by spindle fibers. 2. Cancer - a disease in which abnormal cells divide uncontrollably and destroy body tissue. 3. Cell Cycle - The series of events that take place in a cell leading to its division and duplication. 4. Cytokinesis - the final phase of a cell cycle resulting in the division of the cytoplasm. 5. Interphase - the longest-lasting phase of the cell cycle in which a cell performs the majority of its functions, such as preparing for nuclear division and cytokinesis. 6. Metaphase - the second phase of mitosis, in which the sister chromatids line up at the center of the cell. 7. Mitosis - a nuclear division resulting in the production of two somatic cells having the same genetic makeup as the original cell. 8. Prophase - the first phase of mitosis, in which the nuclear membrane breaks down and chromosomes condense. 9. Telomeres - the caps at the end of each strands of DNA that protect our chromosomes. 10. Telophase - the fourth phase of mitosis, in which the the chromosomes uncoil and the nuclear membrane reforms around them. Protein Synthesis and Gene Expression 1. Amino Acid - the monomers of protein that include C, H, O and N. 2. Anti-codon - a sequence of three nucleotides on a tRNA molecule that is complementary to the mRNA’s codon. 3. Codon - a series of three nucleotides that codes for a particular amino acid. 4. Endoplasmic reticulum - an organelle, containing folded membranes and sacs, responsible for the production, processing and transportation of materials for use inside and outside a eukaryotic cell. 5. Gene Expression - the process in which a nucleotide sequence of a gene is used to make a functional product, such as a protein. 6. Golgi apparatus - an organelle found in eukaryotic cells responsible for the final stages of processing proteins for release by the cell. 7. Messenger RNA (mRNA) - a type of ribonucleic acid (RNA) that copies the information found in the DNA and transports that message to the ribosomes in the cytoplasm. 8. Protein - a macromolecule that performs a variety of structural and regulatory functions for cells. 9. Protein synthesis - the process in which amino acids are arranged in a linear sequence through the process of transcription of DNA to RNA and the translation of RNA to a polypeptide chain. 10. Ribosome - a cellular structure found in all living cells that is the site for protein synthesis. 11. Transcription - the process in which a strand of messenger RNA (mRNA) is synthesized by using the genetic information on a strand of DNA as a template. 12. Transfer RNA (tRNA) - RNA that transfers specific amino acids to ribosomes for protein synthesis. 13. Translation - the process in which the messenger RNA (mRNA) molecule on a ribosome is decoded to produce a sequence of amino acids for protein synthesis. Reproduction and Development 1. Asexual Reproduction - involves the production of offspring by a single individual without contribution of genetic material from another individual. 2. Binary Fission - a type of sexual reproduction in which the parent cell divides into two genetically identical daughter cells. 3. Eukaryote - A type of organism composed of one or more cells containing a membrane-bound nucleus, specialized organelles in the cytoplasm, and a mitotic nuclear division cycle. 4. Prokaryote - A single-celled organism that lacks a membrane-bound nucleus and specialized organelles. 5. Sexual Reproduction - involves two individuals contributing genetic material to produce offspring. Biotechnology and Genetic Engineering 1. Biotechnology - the modification of organisms, cells, and their molecules for practical benefits. 2. Cloning - the production of genetically identical cells, organisms, or DNA molecules. 3. DNA fingerprinting - a test to identify and evaluate the genetic information in a person’s cell. 4. Forensics - the application of science to criminal and civil laws. 5. Gene splicing - the post-transcription modification in which a single gene can code for multiple proteins. 6. Gene therapy - a therapy designed to treat or cure a disease by insertion of a functional gene to replace a defective version of that gene. 7. Genetic Engineering - the manipulation of an organism’s genetic material by adding, deleting, or transplanting genes from one organism to another. 8. Genetically modified organisms (GMO’s) - plants, animals or microorganisms in which the genetic material has been altered in a way that does not occur naturally. 9. Plasmids - a circular DNA molecule found outside the main chromosome in bacteria. 10. Stem Cells - undifferentiated cells that have the ability to develop into any type of cell in the body. Transgenic organisms - an organism that contains DNA from another organism.