Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

IB Biology > 7.2 Transcription and gene expression > Flashcards

7.2 Transcription and gene expression Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is a gene?

A

A sequence of DNA which is transcribed into RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the three parts of a gene?

A

Promoter
Coding sequence
Terminator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the promoter?

A

The non coding sequence responsible for the initiation of transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is the promoter typically located?

A

Immediately upstream of the genes coding sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does the promoter function as?

A

A binding site for RNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What controls and mediates the binding of RNA polymerase to the promoter?

A

An array of transcription factors in eukaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do the transcription factors bind to?

A

Proximal or distal control elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the coding sequence?

A

The region of DNA that is transcribed by RNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens after RNA polymerase has bound to the promoter?

A

It causes the DNA strands to unwind and separate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does the mechanism for transcriptional termination differ between?

A

Prokaryotes and eukaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What stops RNA polymerase transcribing the DNA?

A

The terminator (sequence)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How many strands does a gene have?

A

Two

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How many strands are transcribed into RNA?

A

One

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the antisense strand?

A

The strand that is transcribed into RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the sense strand?

A

The strand that is not transcribed into RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the sequence of the antisense strand complimentary to?

A

The RNA sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

When will the antisense strand be the DNA version?

A

During the tRNA anticodon sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the antisense strand referred to as?

A

The template strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

When will the sense strand be the DNA verion?

A

In the RNA sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What else is sense strand referred to as?

A

The coding strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why is the determination of sense and antisense gene specific?

A

Either of the 2 polynucleotide strands may contain a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is transcription?

A

The process where a DNA sequence is copied into a complementary RNA sequence by RNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How do free nucleotides exist in cells as?

A

Nucleoside triphosphates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do nucleoside triphosphates line up?

A

Opposite their complementary base partner

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What type of bond does RNA polymerase use to bing NTPs together?

A

Covalent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is released when RNA polymerase binds NTPs together?

A

Two additional phosphates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What direction does transcription occur in?

A

5’ - 3’ direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Why does transcription occur in a 5’ - 3’ direction?

A

The 5’ phosphate is linked to the 3’ end of the growing mRNA strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are the three stages of transcription?

A

Inititation
Elongation
Termination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What happens in initiation?

A

RNA polymerase binds to the promoter and causes the unwinding and separating of the DNA strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What happens in elongation?

A

The RNA polymerase moves along the coding sequence in a 5’ - 3’ direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What happens in ternination?

A

The RNA polymerase reaches the terminator and both the enzyme and nascent RNA strand detach and the DNA rewinds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Why can a large number of transcripts be produced?

A

Many RNA polymerase enzymes can transcribe a DNA sequence sequentially

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

In eukaryotes what is necessary to form mature mRNA?

A

Post transcriptional modification of the RNA sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

In eukaryotes what are the three post transcriptional events that must happen for mature mRNA?

A

Capping
Polyadenylation
Splicing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is capping?

A

The addition of a methyl group to the 5’ end of the transcribed RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What does the methylated cap provide in capping?

A

Protection against degradation by exonucleases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What does capping allow the transcript to do?

A

Be recognised by the cells translational machinery

39
Q

What is polydenylation?

A

The addition of a long chain of adenine nucleotides to the 3’ end of the transcript

40
Q

What is the long chain of adenine nucleotides also known as?

A

poly-A-tail

41
Q

What does the poly-A-tail improve?

A

The stability of the RNA transcript and facilitates its export form the nucleus

42
Q

What is splicing?

A

The process by which introns are removed

43
Q

In eukaryotic genes what must be removed prior to forming mature mRNA?

A

Introns

44
Q

What are introns?

A

Intruding Non-coding sequences

45
Q

What are the coding regions called?

A

Exons

46
Q

What happens to exons when introns are removed?

A

They are fused together to form a continuous sequence

47
Q

In splicing are introns or exons being kept?

A

Exons are being kept

48
Q

What is alternative splicing?

A

When splicing can also result in the removal of exons

49
Q

What does the selective removal of specific exons result in?

A

The formation of different polypeptides from a single gene sequence

50
Q

What is transcriptional activity regulated by?

A

Two groups of proteins

51
Q

What do transcription factors form?

A

A complex with RNA polymerase at the promoter

52
Q

What do levels of transcriptional factors regulate?

A

Gene expression

53
Q

Why do transcriptional factor levels regulate gene expression?

A

As RNA polymerase cannot initiate transcription without them

54
Q

What do regulatory proteins bind to?

A

DNA sequences

55
Q

Where do regulatory proteins bind to DNA sequences?

A

Outside the promoter

56
Q

What do regulatory proteins interact with?

A

The transcription factors

57
Q

What do activator proteins bind to?

A

Enhancer sites

58
Q

How do activator proteins affect the rate of transcription?

A

Increase it by mediating complex formation

59
Q

What do repressor proteins bind to?

A

Silencer sequences

60
Q

How do repressor proteins affect the rate of transcription?

A

Decrease it by preventing complex formation

61
Q

In gene expression what may be tissue specific?

A

The presence of certain transcription factors or regulatory proteins

62
Q

How can chemical signals mediate a change in gene expression?

A

By moderating protein levels

63
Q

What are control elements?

A

The DNA sequences that regulatory proteins bind to

64
Q

Where are control elements located?

A

proximal or distal to the promoter

65
Q

What are the two types of control elements?

A

Distal control elements
Proximal control elements

66
Q

What typically binds to distal control elements?

A

Regulatory proteins

67
Q

What typically binds to proximal control elements?

A

Transcription factors

68
Q

Why is gene expression a tightly controlled and coordinated process?

A

As most genes have multiple control elements

69
Q

What can cause changes to gene expression patterns?

A

Changes in the external or internal environment

70
Q

What can chemical signals within the cell trigger?

A

Changes in levels of regulatory proteins or transcription factors in response to stimuli

71
Q

What does chemical signals allow in gene expression?

A

To change in response to change to intracellular and extracellular conditions

72
Q

How can humans change their gene expression patterns in response to environmental changes?

A

Producing different amounts of melanin depending on light exposure

73
Q

How can hydrangeas change their gene expression patterns in response to environmental changes?

A

Can change colour depending on the pH of the soil

74
Q

How can himalayan rabbits change their gene expression patterns in response to environmental changes?

A

By producing a different fur pigment depending on the temperature

75
Q

What is eukaryotic DNA wrapped around?

A

Histone proteins

76
Q

Why is eukaryotic DNA wrapped around histone proteins?

A

To form compact nucleosomes

77
Q

What determines how tightly packaged DNA is?

A

The histone proteins have protruding tails

78
Q

Why do histone tails associate tightly with DNA?

A

As histones have a positive charge and DNA has a negative charge

79
Q

How does adding an acetyl group to the tail affect the charge?

A

It neutralises it

80
Q

How does adding an acetyl group to the tail affect transcription?

A

It increases transcription as it makes DNA less tightly coiled

81
Q

How does adding a methyl group to the tail affect the charge?

A

It maintains the positive charge

82
Q

How does adding a methyl group to the tail affect transcription?

A

Reduces it as it makes DNA more coiled

83
Q

What is acetylation?

A

Adding an acetyl group to the tail

84
Q

What is methylation?

A

Adding a methyl group to the tail

85
Q

What is condensed heterochromatin?

A

When DNA is supercoiled and not accessible for transcription

86
Q

What is euchromatin?

A

When DNA is loosely packed and accessible for transcription

87
Q

Are segments of DNA always supercoiled?

A

Sometimes but it can change over the life cycle of the cell

88
Q

What can direct methylation of DNA also affect?

A

Gene expression patterns

89
Q

How does increased methylation of DNA affect gene expression?

A

Decreases it by preventing the binding of transcription factors

90
Q

What types of genes exhibit more DNA methylation?

A

Genes that are not transcribed

91
Q

What is epigenetics?

A

The study of changes in phenotype as a result of variations in gene expression

92
Q

What does epigenetic analysis show about DNA methylation?

A

The patterns may change over the course of a lifetime

93
Q

What influences DNA methylation patterns?

A

Heritability but it is not genetically pre-determined
and environmental factors

94
Q

Can different cell types in the same organism have different DNA methylation patterns?

A

Yes

IB Biology (57 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions