Chapter 6 -> DNA Replication, Repair, and Recombination

Question 1

What type of cells divide via Mitosis and what is the literal meaning of the word?

Answer 1

Somatic Cells AKA Body Cells

Question 2

What type of cells divide via Meiosis

Answer 2

Gametes

Question 3

Before the division of a cell by either mitosis or meiosis, what must occur within the DNA?

Answer 3

It must replicate itself

Question 4

In the beginning of DNA replication, the two complementary strands of the DNA double helix are pulled apart into _ single strands, which serve as ________ for copying two new strands

What is the resulting DNA’s name since it is half old strand and half new strand?

Answer 4

2, templates

SEMI-CONSERVATIVE

Question 5

Replication is initiated by DNA _____ enzyme that separates the two strands of nucleotides like “unzipping” them, breaking down the hydrogen bonds between the complementary bases, creating what is known as a _______

Answer 5

Helicase

Replication Fork

Question 6

As the Helicase enzyme unzips the DNA double helix, _______ _______ binding proteins attach to each strand and prevent the double helix from reforming

Answer 6

Single Strand

Question 7

The separation of the DNA double helix occurs in areas known as the __________

Answer 7

Origin of Replication

Question 8

Why is the Origin of Replication typically AT rich instead of GC?

Answer 8

AT bases only have 2 hydrogen bonds holding them together, making it easier to unzip rather than 3

Question 9

Bacterial Chromosomes have ____ origin of replication while eukaryotic chromosomes have ______ origins of replication

Answer 9

1, Multiple

Question 10

DNA is ______ because there are two ___________ forks that begin to move in opposite directions

Answer 10

Bidirectional, replication

Question 11

After a replication fork has formed in DNA, short sequences of RNA, called ___________, are synthesized by the enzyme ________
This short RNA primer allows DNA polymerase 3 to function

Answer 11

RNA Primers, Primase

Question 12

DNA polymerase 3 binds to each nucleotide of DNA moving along the strand using it as a template to copy a new strand of DNA
What direction does DNA polymerase 3 work and what is this strand called?
What happens to the strand that is not 5’ to 3’ since DNA polymerase only works in that direction?

Answer 12

5 Prime to 3 Prime direction, Leading Strand
The other strand is known as the lagging strand because replication is not continuous and results in the formation of Okazaki Fragments

Question 13

What are the fragments of DNA that DNA polymerase creates when working on the lagging strand?

Answer 13

Okazaki Fragments

Question 14

What enzyme removes the RNA primers when they are done being used?

Answer 14

DNA polymerase 1

Question 15

What fills in the gaps left by RNA Primer removal?

Answer 15

DNA polymerase 1

Question 16

What enzyme forms the covalent bonds between DNA fragments to ensure that there are no gaps?

Answer 16

DNA LIgase

Question 17

While DNA replication is occurring, torsional forces build up. What two things provide relief?

Answer 17

Topoisomerase & Supercoiling

Question 18

What strand loses a little bit of DNA due to the telomere caps?

Answer 18

The lagging strand

Question 19

DNA Replication Summary:

1) DNA Helicase ______ the double strand starting at an AT rich origin of replication
2) Both ________ and ________ relieve torsional stresses
3) Single strand binding proteins stabilize the unzipped DNA
4) ________ ________ builds a short RNA primer to allow DNA polymerase 3 to function
5) DNA polymerase 3 enters and begins adding complementary ________ to the 3’ end
6) DNA polymerase can only function in the __ to _____ direction- the leading strand involves continuous synthesis
7) * The antiparallel lagging strand must be synthesized in the direction leading ______ from the replication fork
8) The lagging strand also requires short (____ nucleotide) primers for DNA polymerase to function in this direction
9) In this manner, Okazaki fragments are formed- lagging strand discontinues synthesis
10) When DNA polymerase 3 reaches the previously added RNA primer, it is replaced by __________
11) DNA polymerase 1 then removes the RNA primer nucleotides and replaces them with _____ nucleotides
12) DNA ligase then enters and connect the backbones via ________ bonds
13) DNA polymerase 3 then jumps ahead to the newly added RNA primer and begins to synthesize the next ______ fragments
14) In realtime, both strands are synthesized by a dimer of ____ _______ _ made possible by a loop in the lagging strand

Answer 19

1) Unzips

2) Supercoiling and Topoisomerase

4) RNA Primase

5) Nucleotides

6) 5’ to 3’

7) Away

8) 10

10) DNA polymerase 1

11) DNA

12) Covalent (Phosphodiester)
13) Okazaki

14) DNA polymerase 3

Question 20

What 3 things can cause Mutations?

Answer 20

1- Error in DNA replication
2- Change in the DNA
3- X-rays, UV light, mutagens

Question 21

Most common mutations are _________

Answer 21

Single nucleotide polymorphisms
DNA is read in codons (group of 3 Nucleotides) so one changed nucleotide fucks it up

Question 22

What is a silent mutation?

Answer 22

The codon that was changed still codes for the same amino acid so there is “no” difference

Question 23

What is a missense mutation?

Answer 23

Mutates to form a different amino acid that changes the protein’s structure and function

Question 24

What is a nonsense mutation?

Answer 24

The mutation changes an amino acid into a stop codon which ultimately forms a short proteins

Question 25

What is a frameshift?

Answer 25

The frame AKA the 3 nucleotides that make up the codon will be off every frame after say an insertion or deletion takes place

Question 26

How are mutations inherited?
How are mutations acquired?

Answer 26

They can be passed on through gametes BUT ONLY GAMETES NOT SOMATIC
They can be acquired by occurring in the genome of somatic cells BUT WILL NOT BE PASSED TO OFFSPRING

Question 27

What is Sickle Cell Anemia-> Inherited or Acquired

Answer 27

Inherited-> Change from an A to a T in the B chain causes a change in amino acid- glutamic acid to a valine
Individuals must inherit 2 copies of mutant gene

Question 28

What is Sickle Cell Anemia-> Inherited or Acquired

Answer 28

Inherited-> Change from an A to a T in the B chain causes a change in amino acid- glutamic acid to a valine
Individuals must inherit 2 copies of mutant generate

Question 29

What is so special about DNA polymerase?

Answer 29

It has a proof reading ability so that before it adds a new nucleotide onto a growing chain it checks to see if the previous nucleotide was correct

Question 30

If the is a mismatch in DNA, what happens?

Answer 30

DNA mismatch repair system removes replication errors and re-synthesizes it

Question 31

What is Depurination?

Answer 31

Loss of A and G basses

Question 32

What is Deamination?

Answer 32

Loss of amino groups from C to form a U

Question 32

What occurs when an individual has thymine dimers and what is the disease called?

Answer 32

Occurs when two thymine bases form a covalent bond because of the UV light that was present. It is called Xeroderma Pigmentosum, causing severe skin lesions to skin

Question 33

One Cell produces two daughter cells that each contain an ______ copy of DNA from the parent cell

Answer 33

Identical