Genetics 101A

Question 1

Transposons

Answer 1

Movable elements that hop or transpose into DNA at specific sequences.

• Smallest bacterial sequences are called insertion sequences (IS-elements)
• Encodes the transposase enzyme that allows them to “jump”
• Almost all bacteria contain IS-elements

Question 2

Composite Transposons

Answer 2

When any two IS-elemtents of the same type form a larger transposon by bracketing other genes.

Question 3

What are the possible outcomes of transposition at the inside ends of a chromosome?

Answer 3

1. Insertion
2. Deletion

Question 4

_____ provide bacteria with multi-resistance to antibiotics.

Answer 4

Transposons

Question 5

What are the main forms of transposition?

Answer 5

1. Conservative (cut and paste)
2. Replicative (copy and paste)
3. Rolling circle duplication

Question 6

What are the five requirements of Polymerase Chain Reaction?

Answer 6

1. Template DNA
2. Forward and Reverse Primer
3. Taq polymerase
4. Buffer → pH 7, Mg²⁺
5. Deoxyribonucleotide triphosphates (dNTPs: A T C G)

Question 7

What does a “round” of PCR entail?

Answer 7

1. Denature dsRNA for 1 min. at 94 ºC
2. Primers anneal for 1 min at 45-65 ºC
3. Elongation for 1-10 min. at 72 ºC

Question 8

PCR generally requires _____ rounds until completion.

Answer 8

30-33

Question 9

Round ___ is the first round of replicating solely the region of interest.

Answer 9

3

Question 10

What is the function of the protein that repA codes for, and what does it substitute for?

Answer 10

Function: DNA helicase

Substitutues for: DnaB DnaC

Question 11

What is the function of the protein that repB codes for and what does it substitute for?

Answer 11

Function: Primase

Substitutes for: DnaG

Question 12

What is the function of the protein that repC codes for and what does it subsitute for?

Answer 12

Function: Initiator protein

Substitutes for: DnaA

Question 13

Topoisomerase I

Answer 13

Cuts one strand of DNA and passes another segment of the dsDNA molecule through the break, altering the linking number by ~1.

Question 14

Topoisomerase II

Answer 14

Cuts both strands of a dsDNA molecule and passes another segment through the break, altering the linking number by ~2.

Question 15

DNA Initiator Complex

Answer 15

Denatures strands and opens replication bubble.

Question 16

DNA Helicase

Answer 16

Extends replication forks.

Question 17

DNA Gyrase

Answer 17

Relieves supercoiling ahead of replication fork. Gyrase is a type II topoisomerase.

Question 18

Single-Stranded Binding Protein

Answer 18

Stabilizes and prevents instrastrand pairing of ssDNA.

Question 19

DNA Pol III

Answer 19

Synthesizes leading strand and elongates lagging strand.

Question 20

Primase

Answer 20

Synthesizes RNA primers.

Question 21

DNA Pol I

Answer 21

Replaces RNA primer with DNA.

Question 22

DNA Ligase

Answer 22

Joins Okazaki fragments and the ends of the leading strand fragment.