Biology Final Exam
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1. What are the stages of the cell cycle?
- Interphase: the cell is not dividing; it is growing and replicating its organelles and its DNA
- Mitotic Stage: division of the nucleus (mitosis) and division of the cytoplasm (cytokinesis)
2. List AND describe the stages of interphase
- G1: Growing; cell is metabolically active, duplicates organelles and cytosolic components; centrosome replication begins (8-10 hours)
- S: DNA relicated (8 hours)
- G2: Prepare for division; cell growth continues, enzymes and other proteins are synthesized; centrisome replication completed (4-6 hours)
3. What is cytokinesis? mitosis?
- Cytokinesis : division of the cytoplasm
- Mitosis: division of the nucleus
4. Name the stages of mitosis and the events that occur during each stage.
- Prophase: chromatin fiber condense and become visible
- Metaphase: microtubules align the centromeres of the chromatid pairs at the metaphase plate
- Anaphase: the chromatid pairs split at the centromere and move to opposite poles of the cell; the chromatids are now called chromosomes
- Telophase: two identical nuclei are formed around the identical sets of chromosomes now in their chromatin form
5. Explain the process of meiosis.
- 2 divisions produce 4 daughter cells that are genetically different from the parent cell (have ½ the number of chromosomes as the parent)
- reproductive cell division that occurs in the gonads (ovaries and testes) that produce gametes (egg, sperm) with half the number of chromosomes
6. How does meiosis differ from mitosis?
- mitosis: 1 cell> 2 genetically identical daughter cells; used by single celled organisms to reproduce;
- meiosis 1 cell> 4 genetically different daughter cells ;sexual reproduction of organisms
7. What happens to the chromosome number of a cell that underges mitosis? meiosis?
- mitosis: same number (46) of chromosomes
- meiosis: ½ the number of chromosomes (23)
8. How does meiosis increase genetic diversity?
the chromosomes of the daughter cells are different from the chromosomes of the parent cell
9. What is chromatin? chromosomes? What does it do and where is it located in the cell?
- chromatin: the material of which chromosomes of organisms are composed consisting of protein, RNA, and DNA
- job: compose chromosomes
- location: chromosomes in nucleus
- chromosomes: long molecules of DNA combined with protien molecules sectioned off into genes/ thread-like structures of nucleic acids and proteins found in the nucleus of most living cells, carrying genetic information in the form of genes
- job: carry genetic information in the form of genes
- location: nucleus
10. Explain independent assortment.
Mendel’s law that allele pairs separate independently during the formation of gametes
11. What happens during a crossing-over event and when does it occur?
- Occurs during meiosis I between the nonsister chromatids or a tetrad (set of 4 chromosomes). Two of the resulting chromosomes have a different combination of chromosomes.
- homologues sometimes exchange genetic material between nonsister chromatids
12.Compare anaphase I of meiosis and anaphase of mitosis.
- Anaphase I of meiosis: entire chromosome of each pair will separate and move toward opposite poles of the cell
- Anaphase of mitosis: spindle fibers attached to the centromeres of every chromosome causing two chromatids to separate and move apart
13. What are the sex chromosomes and how is gender determined?
- x and y
- females: xx
- males: xy
14. Who is Gregor Mendel, and why is he called the father of genetics?
- a monk who studied the pattern of inheritance via pea plants
- he was the first to theorize and experiment with the idea of dominant and recessive genes being the cause for various traits within organisms.
15. State and explain Mendel’s laws.
- Law of Dominance: some alleles interact with each other in a dominant and recessive manner whereby the dominant allele masks the recessive allele
- Law of Segregation: when a diploid organism forms gametes, the two alleles for a characteristic separate from one another; in doing this, they move to different gametes and retain their individuality
16. Define non-disjunction, monosomy, and trisomy.
- non-disjunction: “not coming apart”; when chromosome pairs do not separate properly during anaphase of meiosis I or sister chromatids do not separate properly during anaphase of meiosis
- monosomy: daughter cell is missing one chromosome
- trisomy: daughter cell gains an extra chromosome
17. Describe the genotype and phenotype of a person with Turner’s Syndrome, Downs Syndrome, and Jacob’s Syndrome.
- genotype: monosomic for the X chromosome
- phenotype: women are shorter than average, usually infertile, webbed neck, swelling of hands/feet, skeletal abnormalities, heart defect, kidney problems
- genotype: trisomy 21
- phenotype: growth delays, special facial characteristics, severly mentally handicapped
- genotype: trisomy y
- phenotype: men are tall and of low intelligence
18. Describe the composition and function of DNA and RNA
- DNA - deoxyribonucleic acid - long-term storage of information; double helix;
- RNA - ribonucleic acid - a carrier of DNA; single-stranded
19. Describe how the information in DNA is transferred to the cytoplasm for the building of proteins
“During the process of transcription, the information stored in a gene’s DNA is transferred to a similar molecule called RNA ( in the cell nucleus. Both RNA and DNA are made up of a chain of nucleotide bases, but they have slightly different chemical properties. The type of RNA that contains the information for making a protein is called messenger RNA) because it carries the information, or message, from the DNA out of the nucleus into the cytoplasm.”
20. What is the role of mRNA? tRNA? Ribosomes?
- mRNA - it is produced in the nucleus where DNA serves as a template for its formation (has codons - sequence of 3 RNA bases complementary to DNA) role is to carry information for making a protein from the DNA out of nucleus and into cytoplasm
- tRNA - (has an anticodon - sequence of 3 RNA bases complementary to codon) role isto transfer amino acids to the ribosomes where the amino acids are joined, forming a protein
- Ribosomes - the sites in a cell in which protein synthesis occurs
21. What is a point mutation? a frameshift mutation?
- point mutation - change in a single DNA nucleotide
- frameshift mutation - insertion or deletion of one or more nucleotides
22. How do point mutations and frameshift mutations impact protein structure and function?
- single nonfunctioning protein can have a dramatic effect on the phenotype
- example: point mutations cause a block to the flow of blood that circulates through the tissues of the body causing damage based on the lack of oxygen to the tissues leading to severe disabilities (sickled red blood cell)
23. Define wobble base and explain its significance.
- base pairing between 2 nucleotides in RNA molecules.
- often several codons will code for the same amino acid, allowing room for error
24. Describe the general structure of an amino acid. How many amino acids are there and how do they differ?
- hydrogen, amino group, carboxyl group, varying R group
- 22 different acids
- the R group is different
25. Describe the primary, secondary, tertiary, and quaternary structure of a protein.
- primary - single strand
- secondary - single strand pleated sheet
- tertiary - pleated sheet and alpha helix
- quaternary - 3D pleated sheet and alpha helix
26. Who were Darwin and Lamarck and what theories did they propose?
- Darwin - natural selection - traveler who studied flora and fauna of the world - the slow gradual change in a population of organisms over time
- Lamarck - acquired traits - Use and disuse - organisms could change the size or shape of organs by using them or not using them
27. Contrast the theories of natural selection and acquired characteristics.
- natural selection - the unequal ability of individuals to survive and reproduce leads to a gradual change in population, with favorable characteristics accumulating over generations
- acquired - they are hereditary
28. Explain the assumptions of the theory of natural selection.
individuals who inherit characteristics more fit for their environment are likely to leave more offspring than less fit individuals.
29. Explain the process of natural selection and how it leads to changes in gene frequencies within a population.
- ex: green beetles
- individuals who inherit characteristics most fit to their environment are likely to leave more offspring than less fit individuals
- change occurs because the less fit will die out
30. Explain the role of artificial selection in producing cauliflower, broccoli and brussel sprouts.
- selective breeding to enhance desired traits among stock or crops
- nature provided the variation among different organisms and humans selected the ones they want
31. Explain the speciation process.
- A gene flow is interrupted between 2 populations causing them to become genetically differentiated (adapt to environment)
- The evolutionary formation of new biological species, usually by the division of a single species into two or more genetically distinct ones.
32. What is macroevolution? Microevolution?
- macroevolution -Long time sale and events that create and destroy species
- microevolution - changes in the genotypes or phenotypes of populations that take place over a short period of time
33. List the evidence that led to the theory of macroevolution.
34. Give an example of how microevolution might occur.
- life span of gnats
- moth population from light-winged to dark-winged
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