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Genetics > module 7 lec 3 > Flashcards

module 7 lec 3 Flashcards

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Biology 101 flashcards
1
Q

What are the two strands of DNA in information flow.

A

The two strands of DNA are the RNA-like strand and the template strand.

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2
Q

What are the two components of the RNA polymerase in prokaryotes?

A

The core enzyme and the sigma factor.

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3
Q

What is the role of the sigma factor in prokaryotic transcription?

A

The sigma factor helps RNA polymerase recognize and bind to the promoter sequence, determining the important sequences for initiatio

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4
Q

What is the equivalent of RNA polymerase in eukaryotes?

A

Eukaryotes have RNA polymerase (several types depending on the class of genes being transcribed).

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5
Q

How does DNA separate during transcription initiation?

A

The DNA strand separates temporarily into a RNA-like strand and a template strand.

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6
Q

Which DNA strand is used to synthesize mRNA?

A

The template strand is used to synthesize messenger RNA, which is complementary to it

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7
Q

In which direction is mRNA synthesized?

A

mRNA is synthesized in the 5’ to 3’ direction.

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8
Q

Where is the termination region found?

A

The termination region is encoded in the DNA

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9
Q

What happens during transcription elongation?

A

During transcription elongation, the transcription bubble moves down the DNA, continuing the process of RNA synthesis.

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10
Q

What is the transcription bubble?

A

The transcription bubble is a region where the DNA is locally unwound so that RNA polymerase can access the template strand.

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11
Q

How does the transcription bubble move?

A

The transcription bubble moves along the DNA, as RNA polymerase adds complementary nucleotides to the growing mRNA strand.

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12
Q

What direction is RNA synthesized during elongation?

A

RNA is synthesized in the 5’ to 3’ direction during transcription elongation.

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13
Q

How is the mRNA strand formed during elongation?

A

The mRNA strand is formed by RNA polymerase adding complementary RNA nucleotides to the template strand of DNA.

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14
Q

What happens to the DNA ahead of the transcription bubble?

A

Ahead of the transcription bubble, the DNA re-winds back into its double-stranded form.

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15
Q

How does RNA polymerase advance along the DNA during elongation?

A

RNA polymerase advances by unwinding the DNA in front of it, adding nucleotides to the mRNA, and rewinding the DNA behind it.

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16
Q

What is the role of the template strand in transcription elongation?

A

The template strand of DNA provides the sequence for RNA polymerase to synthesize the complementary mRNA strand.

17
Q

What signals RNA polymerase to release during transcription termination?

A

A hairpin loop formed in the mRNA signals RNA polymerase to release and stop transcription

18
Q

What is a hairpin loop in the context of transcription termination?

A

A hairpin loop is a secondary structure in the mRNA formed by complementary base pairing that causes RNA polymerase to dissociate from the DNA.

19
Q

How does the hairpin loop affect RNA polymerase?

A

causes RNA polymerase to release the mRNA and stop transcription.

20
Q

Where is the hairpin loop formed during transcription termination?

A

The hairpin loop is formed in the mRNA sequence as it is being transcribed, typically at the terminator sequence.

21
Q

What happens to the mRNA after RNA polymerase is released during termination?

A

The mRNA is released from the DNA, completing transcription.

22
Q

What marks the end of the transcription process in prokaryotes?

A

In prokaryotes, transcription termination is often marked by the formation of a hairpin loop in the mRNA, followed by the dissociation of RNA polymerase.

23
Q

Is transcription termination the same in all organisms?

A

No, transcription termination mechanisms vary between prokaryotes (e.g., hairpin loop) and eukaryotes, where additional factors are involved.

24
Q

What is the role of the template strand in transcription?

A

The template strand serves as the pattern for synthesizing mRNA during transcription.

25
Q

What is the role of the RNA-like strand?

A

The RNA-like strand is complementary to the template strand and has the same sequence as the mRNA (except for thymine being replaced by uracil).

26
Q

How does mRNA relate to the information flow in the central dogma?

A

mRNA serves as the messenger carrying genetic information from DNA to the ribosome for translation into a polypeptide.

27
Q

What is the final outcome of information flow from DNA to protein?

A

The information in DNA is transcribed into mRNA, which is then translated into a polypeptide (protein).

28
Q

How is mRNA related to the polypeptide?

A

mRNA provides the sequence of codons that directs the synthesis of a polypeptide during translation.

29
Q

What happens during translation?

A

During translation, the mRNA sequence is used to assemble amino acids into a polypeptide chain.

30
Q

What is a promoter in transcription?

A

A promoter is a DNA sequence that signals where transcription should begin.

31
Q

What key sequences are found in bacterial promoters?

A

Bacterial promoters typically have -10 (Pribnow box) and -35 sequences that help RNA polymerase bind and initiate transcription.

32
Q

What is the TATA box in eukaryotic promoters?

A

The TATA box is a conserved DNA sequence (~TATAAA) found in eukaryotic promoters, typically around 25-30 bases upstream of the transcription start site.

33
Q

How do bacterial promoters guide transcription initiation?

A

In bacteria, the sigma factor binds to the -10 and -35 regions of the promoter, allowing RNA polymerase to initiate transcription.

34
Q

What role does the TATA box play in eukaryotic transcription initiation?

A

The TATA box helps recruit transcription factors and RNA polymerase II to the promoter, initiating transcription in eukaryotes.

35
Q

How do promoters determine where transcription starts in both prokaryotes and eukaryotes?

A

Promoters contain specific sequences (-10 and -35 in bacteria, TATA box in eukaryotes) that direct RNA polymerase and associated factors to the transcription start site

36
Q

what does sigma factor do

A

responsible for determining what are important sequences in promoter.

37
Q

sigma factor is

A

prokaryotic

Genetics (29 decks)

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