Ch. 5-8 Practice Questions

Source:  Ch. 5-8 Practice Questions    Tag:  nondisjunction mutation

1. Which regulatory mechanisms occur at the DNA-level, which occur at the protein-level? Gene level= DNA to condense for enzymes to get close to bases shielded by chemical groups

Protein prevents enzymes from doing job factors disable and degrade enzymes

2. How do acetylation, methylation, repressors, activators, and siRNA control gene expression? What role do inducers play? Acetylation-DNA causes it to relax and spread out; methylation- alters the gene expression pattern in cells repressors-genes are blocked when repressors bind to a regulatory site

3. What is an enhancer and how does it help control how much of a particular protein is made?

4. How do allosteric inhibition and competitive inhibition differ in the ways they accomplish feedback inhibition? decrease the protein's activity

5. What are the three phases of the cell cycle? What occurs at each phase?

G1 phase: primary growth phase. Cell does its housekeeping activities

M phase-Mitosis- (nuclear division) (prophase, metaphase, anaphase, and Telophase).

C phase-Cytokinesis- (cytoplasmic division), daughter cells form

6. What are the four phases of mitosis? What occurs at each phase? Prophase- During prophase, the first phase of mitosis, the chromosomes condense and become visible when stained and viewed under a microscope. During the latter part of prophase, the nuclear membrane disappears and the newly formed spindle fibers attach to a region of the centromere called the kinetochore.

Metaphase- During metaphase, the spindle fibers move the replicated chromosomes to the middle of the cell where they line up in single file along the equatorial plane

Anaphase- During anaphase, the sister chromatids are "pulled" apart (separated) and move toward opposite poles of the cell. The separated chromatids are now called daughter chromosomes.

Telophase- During Telophase, the last phase of mitosis, the spindle apparatus disappears and nuclei reform around each set of daughter chromosomes. Cytokinesis also occurs during Telophase. In animal cells, a cleavage furrow forms and eventually divides the cytoplasm in half among the two daughter cells. In plant cells, cytokinesis is accomplished with the formation of the cell plate.

7. What are cell cycle checkpoints? Why are they important? Occur in which enzymes block cell cycle from progression until certain conditions are met.

8. What is apoptosis? What role does it play in the cell cycle?

9. What is the difference between chromatin and chromosomes? Relaxed, condensed

10. What is the role of the centromere? (What would happen without it?) keeps them together/ separate mixed up or lost

11. What is the difference between a chromatid and a chromosome? Centromere, kinetochore

12. What events must happen in order for two sister chromatids to separate from one another and move to opposite sides of the cell? (What happens at the centromere? What happens to the centromere? What is the role of the mitotic spindle?) completed; go away; pull in opposite directions

13. What would happen if two sister chromatids moved to the same side of the cell? Nondisjunction lead to cancer

14. What happens to the mitotic spindle after mitosis? Microfiber broken, copies itself back to sytoskelton

15. What are gametes? Where are they made in the body? How are they made? Sex cells; females- ovaries eggs; males testes sperm

16. What are the eight phases of meiosis? What occurs during each phase? How does meiosis differ from mitosis? Interphase- During this phase there is a duplication genetic material, DNA replication

Prophase I- the chromatin condenses into chromosomes the nuclear envelope disappears, and a spindle apparatus begins to form

Metaphase I- the tetrads line up on the center of the cell.

Anaphase I- the microtubules pull the pairs of homologous chromatids toward each pole

Telophase I- the nuclear envelope begins to reform and nucleoli reappear. The cell begins to split, forming a cleavage furrow in the middle.

Prophase II- During this phase there is a duplication genetic material, DNA replication

Metaphase II- the chromatin condenses into chromosomes the nuclear envelope disappears, and a spindle apparatus begins to form

Anaphase II- the microtubules pull the pairs of homologous chromatids toward each pole

Telophase II- the nuclear envelope begins to reform and nucleoli reappear. The cell begins to split, forming a cleavage furrow in the middle

17. How do crossing over and random assortment “mix up” genes so that children are genetically different from their parents? Increase number of different kinds of gametes an individual can produce, and increase variation

18. Why are insertion and deletion mutations usually more harmful than substitution mutations? Substitution single nucleotide change from normal DNA causing the entire frame to shift to the right by one base changing all subsequent codons

19. How does nondisjunction affect the genes present in an organism? Specifically, why does it cause deformities? Failure of members of homologous pair of chromosomes to separate from each other during meiosis, x & y are not the same genes

20. What “super powers” must a cell acquire to become cancerous? How does it acquire these powers? Activated oncogenes + inactivated tumor suppressor genes

21. Compare and contrast oncogenes and tumor suppressor genes. What are they? How are they similar? How are they different? Oncogenes- normal pront-oncegenes undergo mutations and become oncegenes that become capable causing cancer. Tumor suppressor- carry instructions for producing proteins that suppress similar cancer developing; stop cell division not favorable

22. Why is cancer primarily a disease of old age? It develops over time

23. How do mutations cause genetic variation? Is this good or bad for the organism? It can cause a typographical error don’t occur often in same genes, not expected to occur in same various individuals; mostly bad but sometimes good

24. How do genetic diseases caused by point mutations differ from those caused by chromosomal mutations like nondisjunction? X & Y chromosomes don’t carry same genes, to many chromosomes can result in failure of homologous to separate meiosis

25. What causes spontaneous mutations? What causes induced mutations? Spontaneous- point mutations or disjunction incurred during mitosis

Induced- caused by mutagens(chemical, radiation)

26. How accurate is DNA replication? (That is, how often do point mutations occur?) not very accurate can cause many errors

27. What type of mutation is shown here? AGTGCCGTCAC
TCACGGCCAGTG

Frame shift