DNA Replication

Question 1

What is the base pairing mechanism?

Answer 1

new A,T,G,Cs can bond with old A,T,G,Cs with very low likelihood for error

Question 2

What is replication?

Answer 2

making copies of DNA

Question 3

What is an enzyme?

Answer 3

the enzymes used for DNA replication are Helicase, polymerase, and ligase

Question 4

what does helicase do?

Answer 4

unzips the double helix by breaking the hydrogen bonds

Question 5

what does polymerase do?

Answer 5

links nucleotides during DNA replication

Question 6

What does Ligase do?

Answer 6

It seals the nucleotides and forms the sugar-phosphate backbone

Question 7

what are weak hydrogen bonds and why are they weak?

Answer 7

Weak hydrogen bonds hold the two strands of DNA together between complementary bases; and are weak so they can easily be broken apart for transcription and replication.

Question 8

What is Chromatin?

Answer 8

A long and thin, tangled strand of DNA (when the cell is not dividing)

Question 9

What are chromosomes made out of?

Answer 9

A very long strand of helical DNA

Question 10

What is a Chromatid?

Answer 10

Condensed, strong, thicker strands of DNA (in cell division)

Question 11

Compare chromosomes in prokaryotes and eukaryotes.

Answer 11

Prokaryote DNA (including mitochondria and chloroplasts) is circular, unbound, found in the cytosol and has no introns. Eukaryotic DNA is linear, bound to histones (proteins), found in the nucleus, and has introns and exons.

Question 12

What are weak hydrogen bonds and why are they weak?

Answer 12

Weak hydrogen bonds hold the two strands of DNA together between complementary bases; and are weak so they can easily be broken apart for transcription and replication.

Question 13

Describe and represent the process of semi-conservative replication of DNA.

Answer 13

1. DNA unwinds and DNA helicase breaks weak hydrogen bonds, splitting the DNA strands.2. Free DNA nucleotides link into position and complementary base pair. 3. DNA polymerase links the nucleotides to form new strands and Ligase seals the sugar-phosphate backbone.4. Two new DNA molecules are created which are replicas of the original. This is “semi-conservative” because each strand contains 1 old and 1 new strand.

Question 14

Describe the process of semi-conservative replication of DNA

Answer 14

Initiation: The DNA double helix unwinds and separates into two strands with the help of enzymes like helicase. This forms a replication fork.

Primer Binding: Primase enzyme synthesizes a short RNA primer on each DNA strand to provide a starting point for DNA polymerase.

Elongation: DNA polymerase adds complementary nucleotides to the growing DNA strands. On the leading strand, DNA polymerase synthesizes the new strand continuously in the 5’ to 3’ direction. On the lagging strand, DNA polymerase synthesizes the new strand in short segments called Okazaki fragments, also in the 5’ to 3’ direction.

Proofreading and Correction: DNA polymerase checks for errors in the newly synthesized strands and corrects them by replacing incorrect nucleotides.

Termination: DNA replication is completed when DNA polymerase reaches the end of the DNA strands or encounters an existing RNA primer. The RNA primers are removed, and the gaps are filled with DNA nucleotides by DNA polymerase and sealed by DNA ligase.

Question 15

distinguish between coding (gene) and template strand of DNA

Answer 15

template strand is what is coded and the coding strand stays behind

Question 16

what is the importance of complementary base pairing ( A-T, C-G)

Answer 16

Complementary base pairing (A-T, C-G) is crucial for maintaining the structure and integrity of DNA and ensuring accurate replication and transmission of genetic information during cell division and protein synthesis.