Test 3 - Cellular And Molecular Genetics

Question 1

What is a gene?

Answer 1

Region of DNA that controls a hereditary characteristic, usually corresponding to a single protein or RNA.

Question 2

What is the most common form of DNA?

Answer 2

Nucleosomes
-DNA wrapped around histones
—DNA in nucleosome form is called chromatin

*In general, DNA is organized into chromosomes

Question 3

How many chromosomes do humans have?

Answer 3

46

44 autosomes

2 sex chromosomes

Question 4

What is a LINE?

What is a SINE?

Answer 4

LINE - Long interspersed nuclear elements

SINE - Short interspersed nuclear elements

Question 5

What are the different stages of the cell cycle?

Answer 5

3 main:

Interphase

• G0 - Majority of cell life and function
• G1 - Cell organelles duplicated
• S - Chromosomes duplicated
• G2 - Cell double checks chromosomes

Mitosis

• Prophase - Chromosomes condense
• Prometaphase - Kinetochore microtubules formed and breakdown of nuclear envelope
• Metaphase - Line up in middle
• Anaphase - Pull apart
• Telophase - Start separation process, chromosomes decondense

Cytokinesis - Cell splits via a contractile ring of actin and myosin filaments that pinches the cell

Question 6

DNA replication is __________.

What part of the cell cycle does that occur in?

Answer 6

Semiconservative

S phase

Question 7

DNA must be synthesized in what direction?

And at what?

Answer 7

5’ to 3’

Replication forks

Question 8

What does DNA polymerase do?

Answer 8

Polymerizes new DNA strands

Question 9

What does topoisomerase do?

Answer 9

Places nicks in the DNA to relax coils

Question 10

What does DNA primase do?

Answer 10

Creates RNA primers on the lagging strand

Question 11

What does DNA helicase do?

Answer 11

Unwinds the DNA

-Into a leading strand and lagging strand

Question 12

What primary DNA polymerase creates strands?

Answer 12

Epsilon

Question 13

4 most common types of DNA damage?

Answer 13

Mismatch

Deamination
-Amine removed

Depurination
-Purine removed

Double strand break

Question 14

What increases genetic diversity and by what processes?

Answer 14

Chromosome assortment

Independent assortment

Recombination
-Bivalent chromosomes
—Crossing over

Question 15

Recombination is directed by what?

Answer 15

Recombinases

• DS - Recombinase DNA Merging
• SS - Hollday Junctions

Question 16

What are the 3 classes of transposable elements?

How are transposons inserted? (3 ways)

Answer 16

DNA-only transposons

• Short inverted repeats at ends
• encodes transposase
• NO RNA INTERMEDIATES

Retroviral-like retrotransposons

• Directly repeated long terminal repeats at ends
• encodes reverse transcriptase and resembles retro virus
• RNA INTERMEDIATE REQ’D BY PROMOTER IN LTR (long terminal repeats)

Nonretroviral retrotransposons

• Poly A at 3’ end of RNA transcript, 5’ is often truncated
• RNA INTERMEDIATE REQ’D BY NEIGHBORING PROMOTER

Cut and paste
Viral insertion
Replication