Lecture 4

Question 1

What are the components of DNA (deoxyribonucleic acid)?

Answer 1

DNA is composed of NUCLEOTIDES

• deoxyribose (ribose sugar with ONE hydroxyl group)
• a phosphate group (PO43-)
• nitrogenous base (A, G, C, T)

Question 2

How many carbons is in deoxyribose (sugar)?

Answer 2

5

Question 3

Where is DNA found in a cell?

Answer 3

nucleus

Question 4

Is DNA basic or acidic?

Answer 4

acidic

Question 5

Nitrogenous bases fit into two groups based on their structure. What are they?

Answer 5

Purines: double ring structure. A, G

Pyrimidines: single ring structure, C, T

Question 6

In dAMP (deoxyadenosine 5’-monophosphate) where is the 1’ position? 2’? 5’?

Answer 6

1’: where the base is attached
2’: position of ribose is missing a hydroxyl group
5’: attached to the phosphate group (linked to 3’ oxygen of next nucleotide via phosphodiester bond when linked in a chain)

Question 7

Eukaryotic replication has 2 main problems. What are they?

Answer 7

The speed/size problem: occurs because eukaryotic chromosomes are huge and one ori would be too slow. Solution: thousands of oris per chromosome, so replication forks spread out from each ori and meet in the middle

The end replication problem: occurs because eukaryotic chromosomes are linear, and DNA polymerase can’t replace the final RNA primer on the lagging strand or else the 5’ ends would get shorter each cell cycle. Solution: telomerase extends 3’ overhang with repetitive sequences to ensure no loss of coding DNA and prevents progressive shortening

Question 8

Telomeres are made with a telomerase. What is telomerase made of?

Answer 8

RNA and protein

Question 9

What is the difference in the function of normal DNA polymerases and telomerases?

Answer 9

Normal DNA polymerases extend DNA 5’ to 3’ using a ssDNA template (the parental strand)

Telomerase: extends the 3’ ends of linear chromosomes by adding telomeric repeats (instead of using a DNA template, it uses its own internal RNA molecule (TERC) as the template

Question 10

Telomerases are (DNA/RNA) dependent (DNA/RNA) polymerases:

Answer 10

RNA dependent DNA polymerases

template: RNA
product: DNA (adds repeats to chromosome ends)

reverse transcriptase

Question 11

Metaphase chromosomes are made of what?

Answer 11

DNA
histone proteins
cohesin proteins
condensin proteins

Question 12

Regular RNA polymerase (transcription) are (DNA/RNA) dependent (DNA/RNA) polymerases:

Answer 12

DNA-dependent RNA polymerase

template: DNA
product: RNA

Question 13

Primase is a (DNA/RNA) dependent (DNA/RNA) polymerases:

Answer 13

DNA-dependent RNA polymerase

template: DNA
product: RNA

Question 14

Regular DNA polymerase (replication, repair) are (DNA/RNA) dependent (DNA/RNA) polymerases:

Answer 14

DNA-dependent DNA polymerase

template: DNA
product: DNA