Brainscape's Knowledge GenomeTM

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


See full index

Biology (Grade 12) > Transcription, Translation, Mutations, Gene Expression, etc. > Flashcards

Transcription, Translation, Mutations, Gene Expression, etc. Flashcards

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

What are chemical mutagens? Give an example.

A

molecules that can enter the nucleus of a cell and induce mutations by reacting chemically with the DNA
~ ex. nitrites, gasoline fumes

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

What’s RNA polymerase

A

enzyme that unwinds DNA strands
~ opens the DNA molecule at the promoter

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

Where does transcription occur?

A

in the nucleus

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

What is each amino acid attached to a tRNA molecule by?

A

aminoacyl-tRNA synthetase

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

What are physical mutagens? Give an example.

A

mutagens that tear through DNA molecules, causing random changes that range from point mutations to the loss of large portions of chromosomes
~ ex. x-rays, UV radiation

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

What is epigenetics

A

the study of these chemical reactions and the factors that influence them.

  • How behaviours and environment can cause changes that affect the way your genes work (DOES NOT CHANGE DNA SEQUENCES)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What’s the template strand/antisense strand?

A

contains complementary bases that need to be read to generate mRNA

(transcribed strand)

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

What’s a point mutation?

A

a single change in the DNA nucleotide sequence (occurs when 1 base is substituted for a different base)
~ also known as single-base substitution

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

Where does translation occur?

A

outside the nucleus, in the cytoplasm at a ribosome

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

What is the POST-TRANSCRIPTIONAL level of eukaryotic regulation?

A
  • alternative splicing of an mRNA produces different mRNA molecules
  • modifications of the mRNA can be altered so that the 5’ cap and/or 3’ poly-A-tail are not added
  • mRNAs lacking in the modification will either not be transported from the nucleus or undergo rapid degradation in the cell (for either, mRNA is no longer available for protein synthesis in the cytoplasm)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What’s the coding strand/sense strand

A

the non-transcribed strand (not copied)

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

What happens when lactose is present and glucose isn’t (- GLUCOSE, + LACTOSE)

A
  • activator protein is bound to DNA
  • repressor protein is lifted off operator site
  • RNA polymerase is bound to promoter site (is stabilized)
  • TRANSCRIPTION OCCURS IN LAC OPERON
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Compare the lac operon and the trp operon.

A
  • lac operon has enzymes that synthesize lactose into glucose and galactose (β-galactosidase); trp operon has enzymes which are required for the biosynthesis of tryptophan (allows the cell to produce tryptophan when it is not available from the environment)
  • lac operon is an INDUCIBLE operon (normally off; genes are not expressed, and activated in the presence of lactose and absence of glucose); trp operon is a REPRESSIBLE operon (normally on; genes are expressed, repressed when tryptophan levels are high)
  • lac operon has a repressor that binds to the operator to block transcription in the absence of lactose; trp operon has a repressor that binds to the operator when tryptophan is abundant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the POST-TRANSLATIONAL CONTROL of eukaryotic regulation?

A
  • many polypeptides that are synthesized are not active immediately after synthesis
    ~ this activation involves different modifications like removing amino acids or the covalent linkage of a phosphate to one or more amino acids in the polypeptide to make the protein functional
  • regulating how long a protein is available in the cell can also be a form of gene regulation
    ~ an important pathway that eukaryotic cells have involves the attachment of a chain of ubiquitin molecules to a protein; this acts as a signal for the protein to be degraded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What’s a transcription factor?

A

one of a set of proteins required for the initiation of transcription; it is required for the RNA complex to bind to the promoter

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

What are some environmental factors that can impact the epigenome?

A
  • diet & nutrition
  • exposure to pollutants & toxins
  • stress & psychological factors
  • drugs & alcohol consumption
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the 5 levels of eukaryotic regulation?

A
  1. pre-transcriptional
  2. transcriptional control
  3. post-transcriptional
  4. translational control
  5. post-translational control
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the initiation step of TRANSLATION?

A
  • small ribosomal subunit binds to mRNA and finds the start codon, AUG
  • the initiator tRNA with its UAC anticodon binds to the mRNA
  • large ribosomal subunit joins to form the active ribosome
  • Methionine is the first amino acid for every protein and sets the reading frame for all the subsequent mRNA codons (protein recipe)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What’s the promoter? What’s the other name for it?

A

a series of nucleotides, high in adenine and thymine bases adjacent to the start of gene

“TATA box”

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

What’s the terminator

A

a sequence of nucleotides marking the END of the gene

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

What are operons?

A

(in bacteria) a single promoter region where many genes are clustered together and are under control; this is where RNA polymerase binds to begin transcription

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

What happens when glucose and lactose is present (+ GLUCOSE, + LACTOSE)

A
  • activator protein is not bound to DNA
  • repressor protein is lifted off the operator site
  • RNA polymerase keeps falling off promoter site
  • NO TRANSCRIPTION IN LAC OPERON
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What’s a mutation?

A

any change to the nucleotide sequence of a cell’s DNA

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

What’s the structure of tRNA? (specifically the ends)

A
  • one end contains the anticodon loop (a sequence of 3 nucleotides 3’ to 5’ complementary to a specific mRNA codon 5’ to 3’)
  • the opposite end has an acceptor stem with an attached amino acid, specified by the anticodon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is tRNA? What does it do?

A

transfer RNA; brings amino acids to ribosome

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

What is transcription

A

stage 1 of the protein synthesis; process of copying genetic “code” into mRNA

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

What type of operon is the lac operon

A

inducible

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

What are the roles of histones and methylation in regulating gene expression?

A

HISTONES

  • proteins on which DNA is rolled up and wounded around
  • when histone acetylation happens (an acetyl group is added to the histone), this changes how tightly that histone grips the DNA; the packing of DNA becomes looser and transcription factors can access the DNA

METHYLATION

  • the addition of methyl groups to DNA bases in certain locations which prevents transcription from occurring
29
Q

What are advantages to traits passed through the epigenetic genome? Disadvantages?

A

ADVANTAGES

  • allow an organism to continually adjust its gene expression to fit its environment - without changing its DNA code
  • as epigenetic changes are reversible, this allows for flexibility in gene expression as conditions can be changed without any alteration to DNA
  • better survivability in traumatic situations

DISADVANTAGES

  • traits linked to cancer and other diseases could be passed through the epigenome
  • could lead to epigenetic instability (disruption by environmental factors, toxins, etc.)
30
Q

What is a silent mutation?

A

a mutation that does not change the amino acid sequence of a protein (has NO effect)

31
Q

What are 3 important things about the genetic code?

A
  1. It is REDUNDANT (more than one codon codes for the same amino acid)
  2. It is CONTINOUS (reads as a series of 3-letter codes without spaces)
  3. It is NEARLY UNIVERSAL (almost all organisms build proteins with the code)
32
Q

EPIGENETICS: what is meant by ‘reprogramming’ (and why is this process important?)

A
  • Reprogramming means erasing the epigenome so that eggs and sperm can have stable gene expression profiles.
  • As they have epigenetic tags from before, the epigenetic tags must be erased to grow into a healthy embryo.
  • This process is important as it allows the cells to develop into any type of cell without a certain restriction.
33
Q

What is the elongation step of TRANSLATION

A
  • a tRNA occupies the P site with attached amino acid
  • a second tRNA molecule enters the A site with attached amino acid, complementary to mRNA codon
  • a peptide fond forms between the amino acids and growing polypeptide chain is transferred to A site
  • the mRNA moves forward by one mRNA codon and the chain moves to the P site
  • the empty tRNA molecule exits the ribosome from the E site
34
Q

What is the expression of a gene?

A

the synthesis of a protein that is encoded by that gene

35
Q

What is a gene

A

a segment of DNA containing code for a protein

36
Q

What is a chromosomal mutation? What are the 4 types; describe each.

A

a mutation that involves changes in chromosomes & may involves many genes

4 types:
Deletion - loss of part of chromosome
Duplication - extra copy made of chromosome part
Inversion - reverses direction of part of chromosome
Translocation - part of one attaches to another chromosome

37
Q

What’s a codon

A

part of a gene, containing the code for each specific amino acid in a protein

38
Q

What is the TRANSCRIPTIONAL CONTROL level of eukaryotic regulation?

A
  • eukaryotic genes are not organized into operons; instead, each gene has its own promoter and control of transcription is distinct
  • transcription factors must interact with the promoter for RNA polymerase to start transcription
  • certain types of activator proteins also enhance transcription initiation by binding to transcription factors, RNA polymerase, and specific DNA sequences (enhancers)
39
Q

What is gene regulation?

A

refers to the control of the level of gene expression in response to different conditions in the cell

40
Q

What type of operon is the trp operon

A

repressible

41
Q

What happens when glucose and lactose are not present (- GLUCOSE, - LACTOSE)

A
  • activator protein bound to DNA
  • repressor protein bound to operator site
  • RNA polymerase is blocked by the repressor
  • NO TRANSCRIPTION IN LAC OPERON
42
Q

What are introns

A

sections of nucleotides/mRNA that DON’T contain information needed to build the protein

43
Q

What are constitutive genes?

A

genes that are needed to be expressed all the time and are involved in vital biochemical processes such as respiration

eg. glycotic enzymes

44
Q

What is the epigenome?

A

consists of chemical compound that modify, or mark the genome in a way that tells it what to do, where to do it, and when to do it

45
Q

What is the PRE-TRANSCRIPTIONAL level of eukaryotic regulation

A
  • DNA is associated with histones to form nucleosomes (these assemble into more condensed structures to form chromatin)
  • DNA in highly condensed areas of chromatin is not transcribed as chromatin acts as a physical barrier to the proteins needed to synthesize pre-mRNA
  • for regions of the genome that need to be expressed, different processes are used to alter chromatin structure and loosen the nucleosomes; once this is done, proteins for initiation of transcription can gain access to the DNA
46
Q

What is the TRANSLATIONAL CONTROL level of eukaryotic regulation

A
  • small RNA molecules can control gene expression by a mechanism called RNA interference (inhibits gene expression by degrading mRNA or inhibiting translation)
  • two of these small RNAs are micro RNA and small interfering RNA
    ~ these small RNAs associate with protein complexes and turn off gene expression by either promoting mRNA cleavage or inhibiting translation
    ~ the small RNAs can target and interact with specific mRNAs by forming complementary base pairs
47
Q

What are the 3 types of point mutations?

A

silent, missense, nonsense

48
Q

is there any mRNA modification in prokaryotes?

A

no; a mRNA molecule can be used in protein synthesis as soon as it is made

49
Q

What is the initiation step in TRANSCRIPTION

A
  • RNA polymerase finds the beginning of a promotor with the help of transcription factors and opens the DNA molecule at the promoter (TATA box)
  • the RNA polymerase uses only 1 DNA strand as a template to build the mRNA
50
Q

What is mRNA

A

messenger RNA; a copy of the coding strand, except with URACIL instead of THYMINE

51
Q

What is mRNA modification in eukaryotes (transcription)

A
  • converts pre-mRNA into mature mRNA
  • a 5’ cap is added; this involves the linkage of a modified G nucleotide to the 5’ end of the mRNA (recognized by protein synthesis machinery)
  • a 3’ poly-A-tail is added; involves the linkage of a series of A nucleotides to the 3’ end of mRNA (this makes it stable so it can exist longer in cytoplasm)
52
Q

What is the elongation step in TRANSCRIPTION

A
  • RNA polymerase brings RNA nucleotides to the template strand (it pairs them with there complements on the original DNA molecule)
    ~ follows base pair rules except uracil binds with adenine instead of thymine
  • RNA polymerase reads the DNA template strand in 3’ to 5’ and builds the mRNA is 5’ to 3’
    ~ no primer is needed and the promoter region itself is not transcribed
53
Q

what is the termination step in TRANSCRIPTION

A
  • the RNA polymerase continues to add new nucleotides to the 3’ end until it reaches the terminator
  • the mRNA drops off the DNA and the transcription ceases; this mRNA molecule is called the precursor mRNA
  • pre mRNA is processed by cutting out introns and joining exons to form the mature mRNA (this process is called splicing)
54
Q

What happens when glucose is present and lactose isn’t? (+ GLUCOSE, - LACTOSE)

A
  • activator protein is not bound to DNA
  • repressor protein is bound to operator site
  • RNA polymerase is blocked by the repressor
  • NO TRANSCRIPTION IN LAC OPERON
55
Q

What are two different ways that changes in the epigenome can lead to cancer?

A

Cancer cells have a lower level of methylation (more active DNA) than healthy cells. Too little methylation causes:

  • Activation of genes that promote cell growth.
  • Chromosome instability: highly active DNA is more likely to be duplicated, deleted, and moved to other locations.
  • Loss of imprinting

Cancer cells can also have genes that have more methyl (are less active) than normal. The types of genes that are turned down in cancer cells:

  • Keep cell growth in check
  • Repair damaged DNA
  • Initiate programmed cell death
56
Q

What is an epigenetic tag? What do they regulate?

A

heritable alterations that are not due to changes in DNA sequence

these modifications regulate gene expression and control the turning “on” and “off” of genes (active or inactive)

ex. DNA methylation, histone modification

57
Q

What is the Trp operon?

A
  • has a coding region with 5 genes for enzymes that synthesize the amino acid tryptophan
  • regulatory region contains a promoter and an operator region
  • the trp operon is turned on when tryptophan levels are LOW and turned off when they are HIGH
  • when tryptophan is present in the cell, 2 tryptophan molecules bind to the trp repressor which changes shape to bind to the operator
    ~ binding of the tryptophan-repressor complex at the operator physically prevents the RNA polymerase from binding and transcribing the downstream genes
  • under normal conditions, tryptophan must be synthesized, so the repressor DOES NOT BIND to the operator & transcription takes place
58
Q

When does gene regulation occur in prokaryotes?

A

during transcription, during translation, after protein synthesis

59
Q

What is the termination step of TRANSLATION?

A
  • the process continues until a stop codon is reached (UAA, UAG, and/or UGA)
  • translation machinery is disassembled and new protein is released
60
Q

What is a missense mutation?

A

a mutation that changes the amino acid sequence of a protein (usually 1st or 2nd base is exchanged)

61
Q

What is a frameshift mutation?

A

a mutation caused by the addition or deletion of one or more nucleotides which results in a shift/change in the reading frame of the codons

62
Q

What do the three genes in the lac operon process?

A

the sugar lactose

63
Q

What is splicing? What enzyme is it carried out by?

A

splicing is taking out the introns and putting together exons (removing introns before the protein can be built and joining exons to form finished mRNA)
~ carried out by spliceosome complex

64
Q

What is a nonsense mutation?

A

a mutation that shortens a protein by introducing a stop codon

65
Q

Which enzyme hydrolyzes lactose into glucose and galactose in the lac operon?

A

Beta - galactosidase

66
Q

What are imprinted genes?

A

when one copy of a gene in an individual (either from their mother or father) is expressed while the other copy is suppressed

67
Q

What are exons

A

sections that contain protein recipe and are joined together to form the finished or mature mRNA

68
Q

What are the binding sites in ribosomes?

A

P site (peptide)

A site (amino acid)

E site (Exit)

Biology (Grade 12) (11 decks)

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