Biology I Fall Semester Exam Review

Name ______Date ______Biology I Fall Semester Exam Review Directions: Answer the following on your own paper for extra credit on your exam. VIII. The Cell Cycle 1. Draw and label a chromosome. Be sure to include labels for the centromere and sister chromatids.

2. Describe the contents of the chromosome drawn. Chromosome are made of DNA and proteins.

3. D iagram the cell cycle. Place the following labels on your diagram in the appropriate places: a. Interphase h. Cytokinesis b. G1 phase i. Prophase c. S phase j. Telophase d. G2 phase k. Anaphase e. M phase l. Metaphase f. Cell division m. Cell growth G1 g. Mitosis n. Preparation for mitosis/organelles q. DNA is in the form of chromatin are copied G2 Interphase o. DNA replication S r. Longest phase of mitosis p. Chromosomes are visible Prophase Prophase s. Longest phase of the cell cycle Interphase

4. What is the difference between mitosis and cytokinesis? Mitosis – separation of nucleus. Cytokinesis – separation of cytoplasm a. Is cytokinesis a part of mitosis? No b. Is cytokinesis a part of cell division? Yes c. Is cytokinesis a part of the M phase? Yes d. What is the result of cytokinesis? 2 identical daughter cells e. Describe the daughter cells – compare them to each other and the parent. Identical. Both are diploid. 5. Draw, label, and briefly summarize the events occurring during each phase of mitosis in an animal cell. Label each phase. You must include the following labels in EACH phase: a. Centrioles b. Nuclear envelope (if applicable) c. Nucleolus (if applicable) d. Cell membrane h. Spindle fibers e. Chromosomes f. Sister chromatids g. Centromere

Prophase – chromatids condense and become visible, the nuclear envelope and nucleolus disappear. Centrioles move towards the poles. Metaphase – chromatids line up in the center of the cell. Spindle fibers attach to the centromere. Anaphase – Chromosomes are pulled to opposite poles by the spindle fibers. Telophase – Cleavage furrow is present, the nuclear envelope begins to reform, chromosomes uncondense into chromatin.

6. How would the diagrams from #5 differ in a plant cell? Plants cells have a cell wall so there would not be a cleavage furrow, rather a cell wall would begin to form (called a cell plate) between the two new nuclei. 7. Name and describe the process of cell division in prokaryotic cells. Binary fission – cell grows replicates DNA and then splits in two. 8. Describe 3 reasons why cells divide that were discussed in class. Surface area vs volume ratio (volume grows too fast the organelles can not get nutrients), DNA overload (not enough DNA to make enough proteins), Diffusion (organelles do not get nutrients fast enough and die). 9. Is it more efficient for a cell to have a large surface area to volume ratio or a small one? Large. Waste can leave the cell and nutrients can enter the cell more efficiently. 10. Explain what happens to the functionality of DNA in a cell that gets too large. DNA gets overloaded with demands of a large cell and can not make enough RNA or proteins to keep up. 11. What proteins regulate the cell cycle? Cyclins 12. What happens when cells do not properly respond to their regulators? Cells may grow out of control. Can lead to tumors/cancer.

IX. Meiosis 1. Define the following terms: a. Meiosis – Cell division to form gametes. b. Gamete – Cells used for reproduction. Ex: sperm and eggs c. Zygote – A diploid cell created when a sperm and egg fuse together. d. Haploid – A cell that contains only one copy of a homologous chromosomes (1/2 the number of chromosomes (N)). e. Diploid – A cell that contains both copies of homologous chromosomes (2N). f. homologous chromosomes – similar chromosomes. g. crossing-over – An exchange of genetic information between homologous chromosomes. Occurs during prophase 1. h. Tetrad – Formed during crossing over. Consists of 4 chromatids. 2. Describe the major differences between meiosis I and meiosis II. Meiosis I separates homologous chromosomes and Meiosis II separated identical (sister) chromatids. 3. Describe the main results of meiosis. 4 haploid cells (4 gametes) 4. What are the principal differences between mitosis and meiosis? Mitosis produces two identical daughter cells and meiosis produces four gametes. Mitosis takes place in your somatic cells to grow, develop, and repair. Meiosis takes place to produce gametes for reproduction. 5. In human cells, 2N = 46. How many chromosomes would you expect to find in a sperm cell? In an egg cell? In a skin cell? Explain. Sperm- haploid 23 Egg- haploid 23 Skin – diploid 46 6. If we begin with a diploid cell with 8 chromosomes, describe the products of each of the following (tell whether it is diploid or haploid and how many): a. mitosis: 2 b. meiosis I: 2 c. meiosis II: diploid haploid 4 haploid 7. In asexual reproduction, mitosis occurs, but not meiosis. Which type of reproduction- sexual or asexual- results in offspring with greater genetic variation? Explain. Sexual. You have chromosomes from two organisms rather than just one. 8. What is non-disjunction? In which phase(s) does it occur? Unequal separation of chromosomes. Occurs during anaphase 1 9. Define the following terms: a. karyotype – display (picture) of all of an organisms chromosomes b. sex chromosome – The last pair on a karyotype. (pair 23 for humans) c. autosome – All of the chromosomes except the sex chromosomes (pairs 1-22 for humans) 10. Sketch an original chromosome and sketch chromosomes with the following chromosomal mutations: a. Deletion b. Duplication c. Inversion d. translocation

11. Know how to read a karyotype! (p. 341) 12. Describe the characteristics of a karyotype for the following individuals: a. normal female XX d. male with Down Syndrome b. normal male XY trisomy 21 c. female with Down Syndrome e. female with Turner’s Syndrome trisomy 21 Monosomy 23… only one X! 13. What is polyploidy? Extra set of chromosomes.

X. Biotechnology

Selective Breeding 1. What is the purpose of selective breeding? To choose desired traits to be inherited and passed on to the next generation by choosing the parents with those desired characteristics. 2. What are 2 types of selective breeding? Give an example for each. Hybridization – a disease resistant plant crossed with a high food producing plant. Inbreeding – crossing a brother and sister pure-bred dog to keep the offspring pure. (little genetic variation) 3. Which type of selective breeding increases the risk for a genetic defect due to two recessive alleles? inbreeding 4. Why might breeders try to induce mutations? Add genetic variation. 5. Compare selective breeding to genetic engineering. Selective breeding – restricted to the genes that are currently found in the population. Genetic engineering – altering the DNA.

Genetic Engineering techniques 6. DNA extraction. 1)Explain how scientists extract DNA out of a cell. Remove cell parts and isolate the DNA 7. Cutting DNA. 1) Explain why DNA is cut. Easier to work with. Easier to study. 2) What enzymes are used to cut DNA? Restriction enzymes 3) The cut ends of DNA are called “sticky ends.” Explain why they are called this way. What do they “stick” to? They stick out, pair with complimentary side. 4) What is the advantage of sticky ended DNA over blunt ended DNA? Can be added into a vector for cell transformation. 5) Draw a diagram showing how restriction enzymes cut DNA into fragments.

Label all the parts.

8. Separating DNA. 1) Explain why DNA is separated. Isolate genes, compare DNA samples 2) What procedure is used to separate the DNA? Gel electrophoresis

9. Reading the DNA sequence. 1) Explain why scientists want to know the sequence of the organism’s DNA? Study specific genes 2) What are the steps involved in this process? 1. DNA is placed in a test tube. 2. DNA polymerase, and 4 nucleotide bases are also added. 3. Enzyme makes new DNA strands using DNA that’s in the test tube as a template. 4. Some bases have chemical dye attached. They stop the synthesis. 5. Result- a series of dye tagged DNA fragments of different lengths. f.

10. Cutting and Pasting DNA. 1) Explain how DNA can be combined from different sources. Cut both samples with the same restriction enzyme. Pair up the complimentary sticky ends and “glue” the desired gene into the new DNA sample using ligase. 2) Define the term “recombinant DNA”. DNA from different organisms.

11. Making Copies. 1) Explain why scientists might want to make copies of DNA. So that you perform more tests because you have more copies of DNA. 2) What technique is used to copy the DNA? PCR – Polymerase chain reaction 3) Explain how PCR works. Heat – Breaks H bonds/separates strands, cool to add primers, DNA polymerase copies the template strands. 4) Draw a diagram showing 3 cycles of PCR. (Use one DNA fragment) Cell Transformation

13. What is cell transformation? The process of a cell taking in DNA from another source

13. When cell transformation is considered successful? When the cell expresses the gene that was inserted. 14. What is a plasmid? Most common vector found in bacteria 15. How is a plasmid used to transform bacteria? Acts as a vector – carries the gene of interest into the bacteria. 17. Explain the purpose of a vector used in genetic engineering? Carries DNA from one place to another. 18. Provide examples of vectors. Viruses, plasmids, mosquitos

Applications of Genetic Engineering 19. What is a clone? Genetically identical organism that came from a single body cell. 20. Name the first multicellular organism ever cloned. Dolly - sheep 21. List the main events taking place in the process of cloning. See the diagram

22. Define transgenic organism. An organism that contains recombinant DNA – contains DNA from a different organism – ex: tobacco plant that contains DNA from a fire fly 23. Name some of the research areas that Genetic Engineering is applied. Agriculture, food, livestock, medicine, dog/cat breeding, etc