Ch3: Molecular Genetics Flashcards
(15 cards)
Which of the following is the primary purpose of DNA replication?
a) To synthesize proteins based on genetic information.
b) To ensure each new cell after division has an exact copy of DNA.
c) To transcribe DNA into mRNA molecules.
d) To modify primary transcripts before they leave the nucleus.
B
During DNA replication, which enzyme is responsible for relieving tension from the unwinding double helix by smoothing out supercoiling?
Topoisomerase
The lagging strand is synthesized discontinuously due to the fact that:
a) It runs 5’ to 3’ towards the replication fork.
b) DNA polymerase can only add nucleotides away from the replication fork on this strand.
c) It requires more ATP for synthesis.
d) DNA ligase cannot join the fragments continuously.
B
he semi-conservative nature of DNA replication refers to?
Each replicated DNA molecule having one original strand and one new complementary strand.
What is the primary advantage of having multiple replication bubbles in the human genome?
To allow replication to happen at multiple sites, saving time.
Which of the following is NOT a characteristic of RNA polymerase compared to DNA polymerase?
a) RNA polymerase generally performs more steps without relying on as many other enzymes.
b) RNA polymerase does not require primers.
c) RNA polymerase does not require helicase.
d) RNA polymerase can add new nucleotides in both 5’ to 3’ and 3’ to 5’ directions.
d
What would be the most likely consequence if introns were not removed from the primary transcript?
The reading frame would be thrown off, and the protein would not fold properly.
A nonsense mutation is characterized by?
he introduction of a stop codon instead of an amino acid codon.
An operon is defined as?
A cluster of genes under the control of a single promoter.
In the Lac operon, when lactose is present:
a) The repressor binds to the operator, blocking transcription.
b) RNA polymerase cannot transcribe the operon.
c) Lactose binds to the repressor, changing its shape so it cannot bind to the operator, allowing transcription.
d) Glucose levels are high, keeping the operon mostly off.
C
The trp operon differs from the Lac operon in that it is typically:
a) Turned on when tryptophan is present.
b) Turned off when tryptophan is absent.
c) Turned off when tryptophan is present, as tryptophan acts as a corepressor.
d) Regulated independently of tryptophan levels.
C
Restriction enzymes do what?
Cut DNA at specific nucleotide sequences, often diagonally.
Which molecular tool is used as a vehicle to transfer foreign genetic material into another cell, often being bacterial plasmids or viruses?
Vectors
Compare and contrast the leading strand and the lagging strand during DNA replication.
Similarities: Both strands are synthesized in the 5’ to 3’ direction. Both use a DNA template and require DNA polymerase.
Differences:
Direction relative to fork: The leading strand runs 5’ to 3’ towards the replication fork. The lagging strand runs 5’ to 3’ away from the replication fork.
Continuity: The leading strand is made continuously. The lagging strand is made discontinuously through Okazaki fragments.
Primers: The leading strand requires only one primer. The lagging strand requires multiple RNA primers (one for each Okazaki fragment).
Ligase activity: The leading strand requires minimal or no DNA ligase activity. The lagging strand requires significant DNA ligase activity to join the Okazaki fragments.
