DNA REPLICATION

Question 1

When do we need to make new body/somatic cells?

Answer 1

During mitosis

Mitosis is the process of cell division that results in two identical daughter cells.

Question 2

When do we need to make new sex cells/gametes?

Answer 2

During meiosis

Meiosis is the process that produces sperm and egg cells.

Question 3

How are the carbons in the sugar labeled?

Answer 3

From 1’ to 5’

This labeling helps identify the structure of nucleotides in DNA.

Question 4

What type of bonds join the 3’ carbon of one nucleotide to the 5’ carbon of another?

Answer 4

Phosphodiester bonds

These bonds form the backbone of the DNA strand.

Question 5

DNA has a 5’ end and a _______.

Answer 5

3’ end

This orientation is crucial for DNA replication and function.

Question 6

DNA strands run from the 5’ to 3’ direction. True or False?

Answer 6

TRUE

This directional property is essential for the synthesis of new DNA strands.

Question 7

What does antiparallel mean in the context of DNA strands?

Answer 7

Two complementary strands run in opposite directions

One strand runs 5’ to 3’ and the other runs 3’ to 5’.

Question 8

What is the term for the original strand of DNA?

Answer 8

Parent strand

This strand serves as a template for the new strands during replication.

Question 9

What are the new strands of DNA called?

Answer 9

Daughter strands

These strands are synthesized based on the parent strand.

Question 10

What enzyme unwinds the DNA helix?

Answer 10

DNA helicase

This enzyme is crucial for initiating DNA replication.

Question 11

What enzyme adds new complementary nucleotides in the 5’ to 3’ direction?

Answer 11

DNA polymerase

This enzyme is responsible for synthesizing new DNA strands.

Question 12

Replication does not start at a single end of the DNA strand. True or False?

Answer 12

TRUE

Replication occurs at multiple sites, forming replication bubbles.

Question 13

What is the replication fork?

Answer 13

Where DNA is being unwound to create a replication bubble

This structure is critical for the replication process.

Question 14

What do single-strand binding proteins (SSBPs) do?

Answer 14

Keep the DNA strands separated & stable

They prevent the strands from re-annealing during replication.

Question 15

What is the role of topoisomerase?

Answer 15

Prevents DNA strands from over-winding

This enzyme helps relieve tension ahead of the replication fork.

Question 16

What does primase do in DNA replication?

Answer 16

Lays down RNA primers for DNA polymerase III

RNA primers provide a starting point for DNA synthesis.

Question 17

What is the difference between the leading strand and the lagging strand?

Answer 17

• Leading strand: synthesized continuously from 3’ end
• Lagging strand: made in Okazaki fragments from 5’ end

This difference is due to the antiparallel nature of DNA.

Question 18

What enzyme joins Okazaki fragments?

Answer 18

Ligase

This enzyme seals the gaps between newly synthesized DNA segments.

Question 19

What is the function of DNA Polymerase I?

Answer 19

• Edits and proofreads DNA
• Corrects typos
• Removes abnormal bases
• Replaces RNA primers with DNA

This enzyme significantly reduces the error rate during DNA replication.

Question 20

How fast does DNA Polymerase III add nucleotides?

Answer 20

1000 bases/sec

This high speed is crucial for efficient DNA replication.

Question 21

What is the error rate of DNA replication in human cells?

Answer 21

Approximately 1 in 100 million bases

This indicates the high fidelity of DNA replication.

Question 22

what is 1

Answer 22

DNA Polymerase
(pol a)

builds new DNA strands by adding complementary nucleotides (A, T, C, G) to a template strand

Question 23

what is 2

Answer 23

DNA ligase

acts as “molecular glue,” joining DNA fragments by forming phosphodiester bonds between the 3’-hydroxyl and 5’-phosphate ends

Question 24

what is 3

Answer 24

RNA Primer

provides a starting point for DNA synthesis by creating a short RNA sequence that a DNA polymerase can extend

Question 25

what is 4

Answer 25

DNA primase ## Footnote synthesizes short RNA segments, called primers, which act as a starting block for DNA polymerase to begin building a new DNA strand

Question 26

what is 5

Answer 26

SIngel strand bindong proteins ## Footnote proteins that coat exposed single DNA strands during replication, repair, and recombination

Question 27

what is 6

Answer 27

Topoispmerase ## Footnote manages DNA structure by controlling its supercoiling

Question 28

what is 7

Answer 28

replication fork ## Footnote a double-stranded DNA helix unwinds to be copied

Question 29

what is 8

Answer 29

helicase ## Footnote unwinding the double-stranded DNA helix by breaking the hydrogen bonds between base pairs

Question 30

what is 9

Answer 30

DNA Polymerase ## Footnote synthesizes new DNA strands by adding complementary nucleotides to the separated parental strands

Question 31

what is 10

Answer 31

leading strand ## Footnote serve as the template for continuous, uninterrupted DNA synthesis during replication

Question 32

what is 11

Answer 32

Okazaki fragment ## Footnote enable the discontinuous synthesis of the lagging DNA strand during replication

Question 33

what is 12

Answer 33

lagging strand ## Footnote synthesizes DNA discontinuously in short pieces (Okazaki fragments) away from the replication fork