Lecture 10: Replication and Transcription

Question 1

What is the central dogma of information flow?

Answer 1

DNA contains the instructions for how a cell will function. Proteins carry out these functions. (Recall the diagram)

Question 2

What is the process of DNA Replication?

Key Words: Separation and Template

Answer 2

1. Start with a double stranded parental DNA molecule
2. SEPERATION of the two DNA strands
3. Each parental strand serves as the template for the order of complimentary nucleotides in the new daughter strand
4. The nucleotides are connected to form the sugar phosphate backbone

Question 3

What nucleotides bases are origins of replication most likely to be?

Answer 3

A/T nucleotides as they are easier to split apart due to their 2 hydrogen bonds

Question 4

What catalyses the formation of the new daughter strand in DNA replication?

Answer 4

DNA polymerase

Question 5

Out of DNA and RNA which is more chemically stable?

Answer 5

DNA

Question 6

Are start and stop codons used for DNA transcription?

Answer 6

No.

Question 7

What are the three steps of DNA transcription?

Answer 7

1. Initiation
2. Elongation
3. Termination

Question 8

What is the promoter and the terminator?

Answer 8

Promoter: an A/T rich region of the DNA that lies just upstream of a gene that the RNA polymerase attaches to
Terminator: A sequence past the gene that causes the association of the RNA polymerase to be relaxed

Question 9

A sequence of 3 mRNA nucleotides is called a ___?

Answer 9

Codon

Question 10

How does protein synthesis defer in prokaryotic and eukaryotic cells?

Answer 10

Prokaryotic cells: Do not have a nucleus. Hence, as soon as the mRNA is made, the ribosome binds to it and protein synthesis begins. To control the amount of polypeptide made, you must control when the gene is turned on or off.

Eukaryotic cells: Do have a nucleus. mRNA is formed as pre-mRNA in the nucleus. It is then extensively modified before it is exported to the cytoplasm, where the ribosomes are. This is called processing.

Question 11

What are the protective mechanisms of mRNA again intracellular nucleases?

Answer 11

there is a 5’ cap (a modified guanine) and a poly (A) Tail usually around 100A’s

Question 12

Introns vs Exons?

Answer 12

Introns=cut here

Exons= expressed sequences

Question 13

Where does proteins synthesis occur?

Answer 13

In ribosomes