Week 7 - Biochemistry DNA

Question 1

What is the central dogma of biology

Answer 1

The central dogma of biology is a fundamental principle that describes the flow of genetic information within a biological system, typically from DNA to RNA to protein.

Question 2

what process turns DNA into 2 helixes of DNA

Answer 2

replication

Question 3

What process transforms DNA into RNA

Answer 3

transcription

Question 4

What process turns RNA into Protein

Answer 4

translation

Question 5

What are properties of DNA(5)

Answer 5

• Macromolecule
• polymer
• 2 supercoiled polymers
• self replicating
• carries genetic information

Question 6

What is DNA comprised of

Answer 6

Nucleotides which consists of 3 parts:
- phosphate group
- deoxyribose sugar molecule
- Nitrogen base (Adenine or thymine or cytosine or guanine)

Question 7

What are the binding pairs of the nitrogen groups

Answer 7

A and T
G and C

*remember Apple in the Tree
*remember Car in the Garage

Question 8

What is the structure of DNA

Answer 8

the 2 nucleotide strands are complementary and perfectly matched to each other, which is also thermodynamically favorable. They then form into a helical structure, which compresses the strands into as tight as a space as possible. These strands are also antiparallel of each other traveling from either 3 prime to 5 prime, or 5 prime to 3 prime.

Question 9

What type of replication model is DNA replication

Answer 9

semi-conservative model

Question 10

What does the semi conservative DNA model mean

Answer 10

during DNA replication, the parental DNA molecule serves as a template for the synthesis of a complementary strand, resulting in two daughter DNA molecules, each containing one parental strand and one newly synthesized strand.

Question 11

What’s the difference between prokaryotic DNA replication and eukaryotic DNA replication

Answer 11

there’s only 1 origin of replication forms in prokaryotic replication while multiple origins of replication forms in eukaryotic replication

Question 12

What is the replication bubble

Answer 12

the region of DNA where the double helix is being unwound and replicated. The replication bubble forms at the origin of replication, which is a specific sequence of DNA where the replication process begins

Question 13

What is the leading strand in DNA replication

Answer 13

In DNA replication, the leading strand is one of the two newly synthesized DNA strands that is synthesized continuously in the 5’ to 3’ direction. It is called the leading strand because it is synthesized in the same direction as the movement of the replication fork

Question 14

What is the lagging strand in DNA replication

Answer 14

the lagging strand is one of the two newly synthesized DNA strands that is synthesized discontinuously in the 5’ to 3’ direction. It is called the lagging strand because it is synthesized in the opposite direction of the movement of the replication fork

Question 15

What is the direction which DNA polymerase function

Answer 15

5’ to 3’
5 prime to 3 prime

Question 16

What are the step in DNA replication

Answer 16

1. Initiation
   - DNA replication begins at specific sites on the DNA molecule called origins of replication.
   - Helicase enzymes then unwind the DNA double helix, breaking the hydrogen bonds between the complementary base pairs and creating a replication bubble
2. Unwinding and formation of replication forks
   - As helicase unwinds the DNA, it forms 2 single stranded DNA templates, each exposed within the replication bubble
3. Primer synthesis
   Before DNA polymerases can begin synthesizing new DNA strands, they require a short RNA primer to start the process
4. DNA synthesis
   - DNA polymerases catalyzes the addition of deoxyribonucleotides to the growing DNA strand
   - DNA polymerase can only add nucleotides to the 5’ to 3’ direction , so DNA synthesis occurs in different ways on the leading and lagging strands
   - On the lagging strand, DNA synthesis occurs discontinuously in short fragments called Okazaki fragments
   - As the replication fork progresses, primase repeatedly synthesizes RNA primers, and DNA polymerase synthesizes DNA fragments between the primers (in the lagging strand)
5. Termination
   - DNA replication continues bidirectionally until the entire DNA molecule is replicated

Question 17

What is the function of helicase

Answer 17

Responsible for unwinding the DNA double helix ahead of the replication fork. It breaks the hydrogen bonds between complementary base pairs, separating the 2 DNA strands and creating the replication bubble where replication occurs

Question 18

What is the function of Primase

Answer 18

Primase synthesizes short RNA primers complementary to the DNA template at the replication fork. These RNA primers provide a starting point for DNA polymerase to begin synthesizing new DNA strands

Question 19

What is the function of DNA polymerase 3

Answer 19

Responsible for synthesizing new DNA strands during replication. It adds deoxyribonucleotides to the growing DNA strand, sing the parental DNA strand as a template. It moves in a 5’ to 3’ direction.

Question 20

What is the function of DNA Ligase

Answer 20

Seals the the gaps between the Okazaki fragments in the lagging strand. It catalyzes the formation of phosphodiester bonds between the 3’ hydroxyl group of one DNA fragment and the 5’ phosphate group of another

Question 21

What is the function of single strand DNA binding proteins (SSDs)

Answer 21

SSBs bind to single stranded DNA regions exposed during replication. They stabilize the ingle stranded DNA templates, preventing them from re-forming double helices and protecting them from degradation by nucleases.

Question 22

What is the function of topoisomerase

Answer 22

Helps relieve the tension and supercoiling that occurs ahead of the replication fork. It does this by creating temporary breaks in the DNA strands, allowing them to rotate and unwind, and then resealing the breaks to prevent permanent damage

Question 23

What is the function of DNA polymerase 1

Answer 23

in the lagging strand before the DNA ligase joins the broken segments DNA poly 1 removes the primer and adds nucleotides

Question 24

What is broken when unwinding DNA

Answer 24

H-bonds

Question 25

What are the fragments between DNA strands on the lagging strand

Answer 25

Okazaki fragments