Chapter 12

Question 1

Why were proteins a choice to be the heritable gene?

Answer 1

It could carry information, be transmissible, could replicate in the cell, and there was variation.

Question 2

What are bacteriophages?

Answer 2

Viruses which attack bacteria, made up of DNA and protein; Hershey and Chase used them to determine if the hereditary material was DNA or proteins.

Question 3

What is the Lytic Cycle?

Answer 3

Phages are bacterial viruses, phage attaches to bacterial cell, phage injects DNA, phage DNA directs host cell to make more phage DNA and protein parts, new phages assemble. Cell lyses and releases new phage.

Question 4

What is Chargaff’s Rule?

Answer 4

The amount of purines (double ringed Adenine and Guanine) were equal to the amount of pyrimidines (one ring Thymine and Cytosine).
A + G = C + T
A = T
G = C

Question 5

Describe the Double Helical Structure of DNA

Answer 5

Anti-parallel DNA strands wind around each other, with the purine and pyrimidine bases facing each other; held together by hydrogen bonds. 3’ -> 5’ bonds.

Question 6

What is Semiconservative Replication?

Answer 6

Saves half the parent.

Question 7

What is Conservative Replication?

Answer 7

Conserves original parent.

Question 8

What is Dispersive Replication?

Answer 8

Little bits get copied at different times.

Question 9

What is the difference between bacterial chromosome replication and eukaryotic replication?

Answer 9

Bacterial has one origin of replication, meaning one replication complex per chromosome.
Eukaryotes have multiple points of origin, meaning DNA is replicated from multiple points at once.

Question 10

What is Polymerase Chain Reaction?

Answer 10

Copying DNA in vitro to make billions of copies of DNA in a few hours.

Question 11

What are the three main steps of PCR?

Answer 11

Heating (to 95 degrees) to separate the DNA molecule strands, cooling (to 55 degrees) so that DNA primers can base pair with the DNA template, heating (to 72 degrees) for the Taq polymerase.

Question 12

What is Transformation?

Answer 12

The conversion of a cell’s hereditary type by the uptake of DNA released by the breakdown of another cell.

Question 13

What is the Polynucleotide Chain?

Answer 13

A sugar-phosphate-sugar-phosphate backbone with a phosphate group bridged between the 3’ carbon of one sugar and the 5’ carbon of another.

Question 14

What is a phosphodiester bond?

Answer 14

The phosphate group bound to the 5’ carbon end and the hydroxyl group bonded to the 3’ carbon end.

Question 15

What are DNA Polymerases?

Answer 15

The primary enzymes of DNA replication; dATP, dGTP, dCTP, dTTP. DNA polymerase can only add a nucleotide to the 3’ end - it writes the copy in the 5’ -> 3’ direction.

Question 16

What is the Sliding DNA Clamp?

Answer 16

A protein that encircles the DNA and binds to the rear of the DNA polymerase in terms of the enzyme’s forward movement during replication. Tethers the DNA polymerase to the template strand.

Question 17

What is the Origin of Replication?

Answer 17

The small, specific, sequence in the chromosome where the unwinding of the DNA for replication begins.

Question 18

What is DNA Helicase?

Answer 18

The enzyme that catalyzes the unwinding of DNA template strands.

Question 19

What is the Replication Fork?

Answer 19

The region of DNA synthesis where the parental strands separate and two new daughter stands elongate.

Question 20

What are Single-Stranded Binding Proteins? (SSBs)

Answer 20

Proteins that coat single-stranded segments of DNA, stabilizing it for the replication process and keeping the two strands from pairing back together.

Question 21

What is Topoisomerase?

Answer 21

An enzyme that relieves the over-twisting and strain of the DNA molecule ahead of the Replication Fork by cutting DNA and twisting it and rejoining it.

Question 22

What are RNA Primers?

Answer 22

A short nucleotide chain made up of RNA that is laid down as the first series of nucleotides in a new DNA strand or made of DNA for use in the polymerase chain reaction; synthesized by primase.

Question 23

What is Discontinuous Replication?

Answer 23

Replication in which a DNA strand is formed in short lengths that are synthesized in the opposite direction of DNA unwinding - the lagging strand.

Question 24

What are Okazaki Fragments?

Answer 24

Relatively short segments of DNA synthesized on the “lagging” stand.

Question 25

What is the leading strand?

Answer 25

The DNA strand assembled in the direction of DNA unwinding.

Question 26

What is DNA Polymerase 3?

Answer 26

The main “general purpose” polymerase for replicating DNA, extends the primer by adding DNA nucleotides.

Question 27

What is DNA Polymerase 1?

Answer 27

A specialized polymerase responsible for removing RNA primers and replacing them with DNA.

Question 28

What is DNA Ligase?

Answer 28

Seals nicks left between adjacent bases after RNA primers have been replaced with DNA.

Question 29

Define Replication Bubble

Answer 29

A structure resulting from bi-directional DNA replication from a given origin; two forks traveling in opposite directions

Question 30

What is Telomere?

Answer 30

The repeating of simple-sequence DNA to maintain the end of linear chromosomes. The telomere repeat is the buffering zone.

Question 31

What is Telomerase?

Answer 31

An enzyme that adds telomere repeats to chromosome ends, it carries its own template in the form of a single-stranded RNA molecule and adds telomere repeat to the 3’ end of DNA.