DNA Replication D1.1

Question 1

What is DNA replication?

Answer 1

the production of EXACT copies of DNA with identical base sequences

Question 2

What is the result of DNA replication and what does the molecule formed by DNA replication consist of?

Answer 2

the result of DNA replication is TWO DNA molecules:
one new strand and one old strand (conserved from the parent DNA molecule).

Question 3

Why is DNA replication necessary?

Answer 3

it is required for organisms to GROW, REPRODUCE, and REPAIR

Question 4

How does DNA replication assist with growth?

Answer 4

it increases the size of organisms by increasing the number of cells in the organism. it does not increase individual cell size.

Question 5

How does DNA replication assist with reproduction?

Answer 5

offspring need copies of the base sequences of the parents and therefore they must replicate their DNA when reproducing sexually/asexually.

Question 6

How does DNA replication assist with repair?

Answer 6

DNA replication does tissue replacement and repair which require cell division in tissues where they have been lost or damaged.
new cells with full set of organism’s base sequence are needed and therefore need DNA replication

Question 7

What does semi-conservative mean in DNA replication?

Answer 7

DNA replication is semi-conservative. it is the idea that one parent strand is conserved in the replication product.
it means TWO strands of DNA come apart and each strand acts as a template for DNA replication. the new strands formed by adding nucleotides and linking them together. when replication is complete there are two DNA molecules, both composed of one new and one old.

Question 8

What is complementary base pairing in DNA replication?

Answer 8

the idea that one nitrogenous base only pairs with one other nitrogenous base. A to T/U, G to C.

Question 9

What does complementary base pairing help with?

Answer 9

maintain and conserve the correct sequence of bases in the molecules and to create an identical copy in DNA replication. it is ALSO essential for protein synthesis.

Question 10

What does Helicase do?

Answer 10

it is an enzyme that unwinds DNA double helix and separates the two strands by BREAKING HYDROGEN BOND.
- ATP required to do this.

Question 11

What does DNA polymerase do?

Answer 11

it is an enzyme that adds nucleotides one by one in positions on the template where hydrogen bonds between complementary bases can form.
- a covalent bond is formed between the pentose and the previous phosphate group of the new.

Question 12

What are Helicase and DNA polymerase parts of?

Answer 12

essential parts of replisomes.

Question 13

What is polymerase chain reaction (PCR)?

Answer 13

it is an automated procedure used to copy SPECIFIC sections of DNA molecules in a cell sample.

Question 14

How does PCR work?

Answer 14

it follows a repeated cycle of heating and cooling to replicate small quantity of DNA using a polymerase: Taq.
- each cycle doubles the amount of DNA.

Question 15

What is the polymerase Taq?

Answer 15

thermus aquaticus, an extremophile bacteria that lives in harsh conditions. needed to replicate DNA in PCR.

Question 16

Why is Taq used in PCR?

Answer 16

it is heat resistant because it lives in harsh conditions. it can withstand high temperatures required in PCR without denaturing.

Question 17

What are the three stages of PCR?

Answer 17

denaturation, annealing, elongation.

Question 18

What happens in denaturation of PCR?

Answer 18

DNA sample heated to separate into two strands. 95C for 1min.

Question 19

What happens in annealing of PCR?

Answer 19

DNA primers attach to the 3’ ends of target sequence. 55C for 1min.

Question 20

What happens in elongation of PCR?

Answer 20

Taq binds to the primer and copies stand by adding nucleotides. 72C for 2mins.

Question 21

What are DNA primers?

Answer 21

short RNA sequences that serve as starting point for polymerase replication.

Question 22

What is gel electrophoresis and what does it do?

Answer 22

it separates DNA molecules by length. it allows for smaller molecules to pass further than long ones therefore the DNA at the bottom are the smallest and top the biggest.

Question 23

What is the gel used in gel electrophoresis and what does it do?

Answer 23

agarose gel. it serves as a molecular sieve.

Question 24

What section of DNA does DNA profiling use?

Answer 24

STRs, the non-coding sequences

Question 25

What are Short Tandem Repeats and Variable Number Tandem Repeats both?

Answer 25

short repetitive sequences on the DNA that differ slightly between individuals. it allows for a specific DNA fingerprint per person

Question 26

What are STRs?

Answer 26

micro-satellites that have shorter base sequences repeated many times. number of times the sequence is repeated is compared to find differences.

Question 27

What are VNTRs?

Answer 27

mini-satellites that have longer base sequences repeated a few times. also inherited from both parents therefore no one will have the same VNTRs as either two parents. the number of times the sequence is repeated is compared.

Question 28

Where is PCR/gel electrophoresis used?

Answer 28

• identification
• DNA profiling
• crime scenes
• paternity

Question 29

How is PRC/gel electrophoresis used in identification?

Answer 29

FBI uses STRs in identification of perpetrators of violent crime.

Question 30

How is PRC/gel electrophoresis used in crime scenes?

Answer 30

DNA material from the crime scene compared with DNA profile of a sample of DNA taken from a suspect or victim.

Question 31

How is PRC/gel electrophoresis used in paternity?

Answer 31

DNA from suspected father is compared to the DNA profile of the mother and the child. child has half of mother’s and father’s DNA.