Brainscape's Knowledge GenomeTM

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


See full index

BI157 > Chapter 17 > Flashcards

Chapter 17 Flashcards

1
Q

What is gene expression?

A

a process in which DNA directs the synthesis of proteins

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

What is the one gene-one enzyme hypothesis?

A

a gene dictates the production of a specific enzyme

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

What is the one gene-one polypeptide hypothesis? (2)

A

Some proteins are not enzymes

Some proteins are made up of multiple polypeptides with different genes

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

What is transcription? (3)

A

Synthesis of RNA using the information in the DNA

Two nucleic acids are written in different forms of the same language

Information is transcribed from DNA to RNA

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

Messenger RNA

A

Carries a genetic message from the DNA to the protein-syntehsizing machinery of the cell

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

What is translation? (2)

A

Synthesis of polypeptides using the information in the mRNA

Cell must translate the nucleotide sequence of an mRNA into the amino acid sequence of a polypeptide

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

What are ribosomes? (2)

A

sites of translation

facilitates the orderly linking of amino acids into polypeptide chains

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

Bacteria vs Eukaryote gene expression (3)

A

Bacterial DNA is not separated by nuclear membranes from ribosomes

allows translation and transcription to occur at the same time

eukaryotic cells transcript first in the nucleus, transport into the cytoplasm where it translates

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

What is pre-mRNA?

A

RNA transcripts that are modified into mRNA

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

What is primary transcript?

A

Initial transcript from any gene that is not translated into a protein

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

What is the triplet flow? (4)

A

genetic instructions for a polypeptide chain are written in the DNA as a series of three-nucleotide words

series of nucleotides is transcribed into three specific orders, which is then translated

gene determines the sequence of nucleotide bases along the length of the RNA being synthesizes

for each gene, only one strand of DNA is transcribed

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

What is the template strand? (3)

A

DNA strand being transcribed

the same strand is used as the template every time for a given gene

synthesized in an antiparallel direction to the template strand

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

What are codons?

A

mRNA nucleotide triplet written in teh 5’ > 3’ direction

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

Coding strand (2)

A

non-template strand is identical to codons but with T instead of YOU

during translation, it is read in the 5’ > 3’ direction

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

What are codons for? (5)

A

64 exists

61 of them are designated for amino acids

3 are termination codons

AUG acts as a start signal and codes for methionine

enzymes can remove methionine

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

What is the reading frame?

A

Correct groupings of symbols for an intended language

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

What are the stages of transcription?

A

Initiation, elongation, and termination

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

What is RNA polymerase? (4)

A

An enzyme that pries two strands of DNA apart and joins together RNA nucleotides complementary to the DNA template strand

Bacteria have one type

Eukayrotes have at least three

do not need primers

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

What is a promoter?

A

DNA sequence where RNA polymerase attaches and initiates transcription

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

What is a terminator?

A

A squence that signals the end of transcription

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

What is a transcription unit?

A

A stretch fo DNA downstream from the promoter that is transcribed into an RNA molecule

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

What is the start point?

A

The nucleotide where RNA synthesis begins

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

What is the transcription factor? (3)

A

Mediates the binding of RNA polymerase and the initiation of transcription

after transcription factors attach to the promoter, the RNA polymerase 2 binds to it

forms the transcription initiaition complex

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

TATA box (2)

A

nucleotide sequence containing TATA upstream around 25 nucleotides from the start point

once the transcription factors bind to the TATA box, polymerase can bind to it

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

Elongation process

A

When the RNA polymerase moves along the DNA, and the new RNA molecule peels away

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

Termination in Bacteria (2)

A

Transcription proceeds through a terminator sequence in the DNA

terminator functions as the termination signal, requiring no further modification before translation

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

Termination in eukaryotes (4)

A

Transcribes a polyadenylation signal (AAUAA) in the pre-mRNA

once it appears, it is immediately bound by certain proteins in the nucleus

proteins cut it free from the polymerase, releasing the pre-mRNA

RNA polymerase continues to transcribe until enzymes catch up and dissociates it

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

What is RNA processing? (2)

A

Enzymes in the eukaryotic nucleus modify pre-mRNA in specific ways before genetic message I dispatched to the cytoplasm

both ends are altered and some inner sections are cut out

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

How is mRNA altered? (2)

A

5’ end receives a 5’ cap, a modified form of guanine added to the first 20-40 nucleotide

3’ end adds adenine to form a poly-A tail

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

What is the mRNA ends for? (30

A

Facilitate export of the mature mRNA from the nucleus

helps protect the mRNA from degradation by hydrolytic enzymes

helps ribosomes attach to the 5’ end of mRNA

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

What is RNA splicing?

A

Removal of large portions of the RNA moleculues

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

What are introns?

A

Noncoding segments of nucleic acid that lie between coding regions

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

What are exons?

A

epxressed regions of the nucleic acids

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

What is UTR

A

Part of the mRNA that will not be translated but help ribosome binding

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

How does RNA get spliced?

A

Introns get cut out and exons get joined together

36
Q

What are spliceosomes?

A

A complex of proteins and small RNA that removes introns

37
Q

What are ribozymes?

A

RNA molecules that function as enzymes

introns can function as ribozymes, catalyzing its own excision

38
Q

How can RNA enable some RNA molecules to function as enzymes? (3)

A

Because it is single-stranded, a region of an RNA molecule may base-pair in an antiparallel arrangement with a complementary region elsewhere, forming a 3d structure like an enzyme

Some of the bases in RNA contain functional groups that can participate in catalysis

ability of RNA to hydrogen bond with other nucleic acid molecules add specificity to its catalytic activity

39
Q

Why are introns important? (3)

A

A single gene can encode more than one kind of polypeptide

depends on which segments are treated as exons (alternative RNA splicing)

allows humans to work with small numbers of genes

40
Q

What are domains? (3)

A

Discrete structural and functional regions of proteins

one domain can act as an active site, while another binds to a cellular membrane

different exons code for different domains

41
Q

What is exon shuffling?

A

Introns can facilitate the evolution of new and potentially beneficial proteins

42
Q

What is transfer RNA (tRNA)?

A

Translator that reads a series of codons along an mRNA molecule and transfers amino acids from the cytoplasmic pool of amino acids to a growing polypeptide in a ribosome

43
Q

What are ribosomes? (2)

A

Structures made of proteins and RNA

Adds each amino acid brought to it by tRNA to the growing end of a polypeptide chain

44
Q

How is tRNA used in translation? (5)

A

Reads a nucleic word (the mRNA codon) and interprets it as a protein word (the amino acids)

bears a specific amino acid at one end

bears a nucleotide triplet that can base-pair with the complementary codon on mRNA

consists of a single RNA strand, smaller than mRNA

Can fold itself and form a 3d structure, and twists into an L shape

45
Q

What is an anticodon? (4)

A

A nucleotide triplet that base-pairs to a specific mRNA codon

example- mRNA codon 5’-GGC-3’ (code for glycine)

tRNA base-pairs with 3’-CCG-5’ as its anticodon

carries glycine at the other end

46
Q

Where is tRNA transcribed? (3)

A

From DNA templates

made in the. nucleus and travels to the cytoplasm

used repeatedly

47
Q

What is molecular recognition?

A

tRNA that binds to an mRNA codon must carry that amino acid, carried out by aminoacyl-tRNA synthetases

Pairing of tRNA anticodon with the appropriate mRNA codon

some tRNA are able to bind to more than one codon

48
Q

What are aminoacyl0tRNA synthetases? (2)

A

Enzyme that only fits a specific combination of amino acid and tRNA

catalyzes covalent attachment of amino acid to its tRNA

49
Q

What is wobble? (2)

A

flexible base pairing at specific codon positions

YOU at the 5’ end of tRNA can pair with A or G in the 3’ end

50
Q

What are ribosomes used for? (2)

A

facilitates the specific coupling of tRNA anticodons with mRNA codons during protein synthesis

Holds the tRNA and mRNA close together and catalyzes the formation of peptide bonds

51
Q

What are ribosomes made up of? (2)

A

A large and small subunit that joins when attached to an mRNA molecule

subunits are made up of ribosomal RNA

1/3 is made up of proteins found in the exterior

52
Q

Ribosomal RNA (2)

A

made in the nucleolus

most abundant type of RNA

53
Q

What do proteins on ribosomes do?

A

Support shape changes

54
Q

How do bacterial and eukaryotic ribosomes differ? (2)

A

Eukaryotic ribosomes are larger

some drugs can inactivate bacterial ribosomes without affecting eukaryotic ribosomes

55
Q

What is the ribosome structure? (2)

A

a binding site for mRNA and three sites for tRNA

an exit site in the large subunit where the polypeptide leaves

56
Q

What are the three binding sites for tRNA in ribosomes?

A

P site holds the tRNA carrying the growing polypeptide chain

A site holds the tRNA carrying the next amino acid after the P site

E site is where discharged tRNA leaves the ribosomes

57
Q

What occurs during translation initiation?

A

mRNA, tRNA with the first amino acid, and subunits come together

ribosomal subunit binds to both mRNA and a specific initiator tRNA (carries methionine)

58
Q

How does the translation stage differ in eukaryotes?

A

small subunits is bound to the tRNA and binds to the 5’ cap f mRNA. Moves downstream until it reaches the start codon

59
Q

What is the translation initiation complex? (2)

A

union of all the RNA and ribosomes

formed by GTP hydrolysis

60
Q

What are initiation factors?

A

proteins required to bring all the components together

61
Q

What occurs during translation elongtaion?

A

Amino acids are added one by one

codon recognition occurs

peptide bond formation occurs

translocation occurs

62
Q

What is codon recognition? (2)

A

Anticodon of an incoming tRNA pairs with the complementary mRNA in the A site

GTP increases accuracy and efficiency

63
Q

What is peptide bond formation? (2)

A

rRNA in the large subunit catalyzes formation of a peptide bond between amino groups of the A site and P site

removes polypeptide from the tRNA in the P site

64
Q

What is translocation?

A

ribosomes translocates the tRNA in the A site to the P site, P site to the E site where it is removed

65
Q

What occurs during termination translation? (3)

A

When ribosomes reach a stop codon on mRNA, A site accepts a release factor

release factor promotes hydrolysis of the bond between the tRNA in the P site and the last amino acid of the polypeptide

two ribosomal subunits and other components dissociate

66
Q

How do proteins fold?

A

gene determines primary structure, folding proteins

67
Q

What is post translational modification? (3)

A

certain amino acids being chemically modified by the addition of sugars, lipids, phosphate groups, and more

enzymes removes amino acids from the leading end

can also cleave

68
Q

What is the difference between free and bound ribosomes? (2)

A

Free ribosomes synthesize proteins that stay in the cytosol

bound ribosomes are attached to the ER< and makes proteins of the endomembrane system and proteins secreted from the cell

69
Q

How are polypeptides synthesized? (9)

A

Growing polypeptide either completes in the cytosol or cues the ribosome to attach to the ER

Polypeptides for attached RNA are marked by signal peptide

Recognized by a signal-recognition particle (SRP)

SRP brings the ribosome to a receptor protein built into the ER Membrane

SRP then binds to a receptor protein in the ER

forms a protein complex that forms a pore and ahs a signal-cleaving enzyme

SRP leaves, polypeptide synthesis resumes, and translocates across the membrane

signal cleaving enzymes cuts off the signal peptide

rest of the completed polypeptide leaves the ribosome and fold into its final conformation

70
Q

How are signal proteins for organelles apart from the endomembrane system formed?

A

Translation is completed in the cytosol before being imported to said organelles

71
Q

How are multiple polypeptides made? (3)

A

Multiple ribosomes translate an mRNA at the same time

a single mRNA can be used to simultaneously make many copies (forms polyribosomes/ polysomes)

72
Q

What is a mutation? (2)

A

Changes to the genetic information of a cell

responsible for the diversity of genes

73
Q

What is point mutation? (2)

A

changes in a single nucleotide pairs of a gene

if it occurs in the gamete, it may be transmitted to offspring and future generation

74
Q

What is a genetic disorder? (2)

A

a point mutation producing an adverse effect

example- sickle cell disease

75
Q

What is nucleotide-pair substitution? (2)

A

Replacement of one nucleotide and its partner with another pair of nucleotides

some can have no effect due to the redundancy of genetic code

76
Q

What is silent mutation? (2)

A

Mutation with no observable effect on phenotype

example- change in nucleotide pair changes codon but translates into the same amino acids

77
Q

Missense mutation

A

substitutions that changes one amino acid to anther

78
Q

What is nonsense mutation? (2)

A

mutation that changes a codon for an amino acid into a stop codon

terminates translation prematurely and produces a short polypeptide

79
Q

What is an insertion?

A

Additions of nucleotide pairs in a gene

80
Q

What is a deletion?

A

Loss of nucleotide pairs in a gnene

81
Q

What is the consequence of deletion and insertions? (2)

A

Bothe produces a more disastrous effect compared to substitution

may alter the reading frame of the genetic message

82
Q

What is a frameshift mutation? (2)

A

whenever the number of nucleotides inserted or deleted is not a multiple of three

all downstream nucleotides are improperly grouped

83
Q

What is spontaneous mutation?

A

When a mismatched nucleotide strand is used as a template in the next round of replciation

84
Q

What is a mutagen? (2)

A

Interacts with DNA and causes mutation

example- radiation

85
Q

What are chemical mutagens? (3)

A

Can be similar to DNA nucleotide, pairs incorrectly

can interfere with correct DNA replication and distorts the DNA double helix

can change pairing properties of bases

86
Q

What is a gene?

A

a region of DNA that can be expressed to produce a final functional product that is either a polypeptide or an RNA molecule

BI157 (21 decks)

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