semester 2 unit 2

Question 1

Helicase

Answer 1

Unzips DOUBLE HELIX by breaking HYDROGEN BONDS at ORIGIN OF REPLICATION forming REPLICATION BUBBLES. Within replication bubbles are replication forks that elongate DNA.

Question 2

Gyrase

Answer 2

Unwinds the supercoil of DNA in a way that keeps DNA from breaking, relieving strain.

Question 3

Single Stranded Binding Proteins

Answer 3

Keeps the DNA strands separated and stabilized.

Question 4

Primase

Answer 4

Adds RNA nucleotides (primer) to complementary base pairs.

Question 5

DNA Polymerase III

Answer 5

Adds DNA nucleoside triphosphate to RNA primer sequence in 5’ to 3’ direction.

Question 6

DNA polymerase I

Answer 6

RNA primers are digested and replaced with DNA nucleotides.

Question 7

DNA ligase

Answer 7

Joins okazaki fragments on lagging strand to form a single DNA strand.

Question 8

Complementary Base Pairs

Answer 8

Complementary Base Pairs ensure genetic message will be conserved.

Question 9

Backbone

Answer 9

Made by covalent bonding. Keeps the double helix together by maintaining the order of the bases.

Question 10

How many origins do prokaryotes and eukaryotes have?

Answer 10

Prokaryotic: one origin, eukaryotic: many origins.

Question 11

Leading Strand

Answer 11

DNA polymerase III synthesizes complementary strand on one side of strand with no problem.

Question 12

Lagging Strand

Answer 12

DNA polymerase III makes short strand of DNA, okazaki fragment, one at a time.

Question 13

Primers

Answer 13

Short segments of RNA. Must have primer because polymerase can only add a nucleotide to an existing nucleotide.

Question 14

P-P-P

Answer 14

Energy for bonding.

Question 15

DNA Replication Order:

Answer 15

Gyrase, Helicase, Single Stranded Binding Proteins, Primase, DNA Polymerase III, DNA Polymerase I, Ligase

Question 16

DNA is a _ strand, RNA is a _ strand

Answer 16

Double, single.

Question 17

What are DNA’s nitrogenous bases?

Answer 17

Adenine, thymine, guanine, cytosine.

Question 18

What are RNA’s nitrogenous bases?

Answer 18

Adenine, uracil, cytosine, guanine.

Question 19

What nitrogenous bases do PURINES have and how many rings do they have?

Answer 19

A & G, 2 rings

Question 20

What nitrogenous bases do PYRIMIDINES have and how many rings do they have?

Answer 20

T U & C, 1 ring

Question 21

How many bonds does Guanine and Cytosine have?

Answer 21

3 hydrogen bonds

Question 22

How many bonds does Adenine and Thymine have?

Answer 22

2 hydrogen bonds

Question 23

Meselson and Stahl experiments

Answer 23

They designed experiments showing how DNA replication progresses in a semi-conservative way (1 strand original, 1 strand newly synthesized). They did do by culturing E. coli in a heavy vs lighter nitrogen isotope, and after putting the samples together, the DNA moved positions based on its density.