Chapter 10

Question 1

Differentiate between “point mutations” and “chromosomal mutations”

Answer 1

Point: the change only involves a small portion of DNA Chromosomal: changes involve large segments of DNA

Question 2

How can the consequences of mutations vary depending on the timing of the mutation? (Germline mutations vs. Somatic mutations)

Answer 2

Mutations in gamete before fertilization: all cells will have the mutation and the mutation is passes to the next generation (blue eyes) NO mutation in gamete before fertilization: arise in one cell and its daughter cells, not passed to the next generation (cancer)

Question 3

What type of mutation results in sickle cell anemia, and why?

Answer 3

Germline mutation, because all of the cells have the mutation

Question 4

Explain how mutations in the following genes can cause a cell to become cancerous: Ras

Answer 4

Ras – GTP-binding protein that regulates the sell cycle, GTP hydrolysis INACTUVATED GTP-binding proteins, Mutant Ras that cannot hydrolyze the GTP: ‘Stuck in the ACTIVE form, cell division is out of control. ‘gain of function’ mutation

Question 5

Explain how mutations in the following genes can cause a cell to become cancerous: p53

Answer 5

p53 – Tumor-suppressor, loss of function, cell division is out of control (no ‘breaks’)

Question 6

What is the difference between a “spontaneous mutation” and an “induced mutation?”

Answer 6

Spontaneous mutations are NOT caused by outside influence while induced mutations ARE caused by outside influence.

Question 7

Chemical & physical mutagens, what are their effects on DNA?

Answer 7

Physical mutagens cause the DNA double-strand to break while chemical mutagens (probably:) alters the DNA causing mutations and alterations in the DNA

Question 8

Number of mutations that occur in one cell on a typical day?

Answer 8

About 16000

Question 9

What are 3 of the main types of RNA made by transcription?

Answer 9

mRNA (messenger RNA) RNA that codes for protein, tRNA (treanser RNA) RNA that decodes mRNA at the ribosome, rRNA (ribosomal RNA) protein synthesis factory, each ribosome is made of protein and ribosomal RNA

Question 10

Necessary components to initiate transcription?

Answer 10

DNA template, four RNA bases (CTP + GTP + ATP + TTP = NTP)

Question 11

Define “promoter.” Where is it?

Answer 11

Special DNA sequence, this is where RNAP starts to transcribe; how RNAP ‘knows’ what a gene is and what is not a gene

Question 12

Describe the mechanism of RNA polymerase (what does it do, specifically?)

Answer 12

Writes 5’ > 3’, reads template DNA 3’ > 5’, (just like DNA polymerase

Question 13

What is a “terminator”?

Answer 13

Specific DNA sequence that signifies the ‘end’ of a gene, new DNA is released

Question 14

Define Intron

Answer 14

Intron: INTERVENING region- REMOVED from the RNA during splicing

Question 15

Define Exon

Answer 15

Exon: EXPRESSED region- codes for amino acids, STAYS IN THE RNA after splicing

Question 16

What do “snRNPs” do & how do they do it? (Fig. 10.6 & 10.9)

Answer 16

One binds to each end of the intron – Both come together, intact complex: the SPLICOSOME – Splicosome cuts out the intron by forming an intron loop – Exon are ligated together – Spliced intron is degraded

Question 17

Explain the purposes of a 5’ end cap and a poly A tail

Answer 17

Protects RNA from nucleases; ensures that only full-length RNAs are translated