Brainscape's Knowledge GenomeTM

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


See full index

MGD > Session 5 > Flashcards

Session 5 Flashcards

0
Q

What is needed in transcription?

A
  • Enzyme: RNA polymerase
  • Activated substrates: NTPs
  • Template: DNA
  • 3 stage process: initiation; elongation; termination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What is needed in DNA replication?

A
  • Enzyme: DNA polymerase
  • Activated substrates: dNTPs
  • Template: DNA
  • 3 stage process: initiation; elongation; termination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is needed in translation?

A
  • Enzyme: ribosome
  • Activated substrates: amino acids
  • Template: mRNA
  • 3 stage process: initiation; elongation; termination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the 3 stages of initiation, elongation and termination in DNA replication

A
  • Initiation: recognition of origin of replication; initiation proteins; DNA polymerase
  • Elongation: 5’ to 3’ chain growth
  • Termination: replication forks meet
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the 3 stage process of initiation, elongation and termination in transcription

A
  • Initiation: promoter recognition; transcription initiation factors; RNA polymerase
  • Elongation: 5’ to 3’ chain growth
  • Termination: sequence dependent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens during initiation of transcription?

A
  • Transcription factors bind to the initiation code - 5’ TATA 3’ ie promoter region are upstream to the Open reading frame
  • Binding of transcription factors to DNA attracts RNA a polymerase to start mRNA production
  • RNA polymerase separates the DNA strands so the RNA nucleotides can bind along the template strand
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens during the elongation stage of transcription?

A
  • RNA polymerase travels along the template strand reading it from 3’ to 5’
  • Picks up base pairs and copies them onto a complementary RNA sequence forming an mRNA sequence
  • The mRNA transcript has nucleoside triphosphates (NTPs) added to the 3’ end (so is made from 5’ to 3’)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a promoter sequence?

A
  • Area of gene upstream of the open reading frame that regulates transcription
  • Includes sequences for the binding of transcription factors, RNA polymerase and regulatory factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens during the termination stage of transcription?

A
  • A methyl-guanine ‘cap’ is added to the 5’ end by a 5’ - 5’ triphosphate linkage
  • Stabilises the mRNA
  • A stop codon at the 3’ end activates the cleavage of the mRNA (AAUAA)
  • 3’ end is then polyadenylated - called tailing (polyAtail)
  • Both protect against degradation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens during the splicing stage of transcription?

A
  • Pre-mRNA (with introns and exons) is converted to mature mRNA (exons only)
  • Introns are removed by endonucleases (breaks within the polynucleotide) and exonucleases (degrades polynucleotide from 5’ or 3’ end)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe mRNA

A
  • Made by RNA polymerase II
  • ~2%
  • 100,000 of kinds
  • A few copies of each present
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe rRNA

A
  • Made by RNA polymerase I
  • > 80%
  • Few kinds
  • Many copies of each
  • Eukaryotes: 80s (60s and 40s subunits)
  • Prokaryotes: 70s (50s and 30s subunits)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe tRNA

A
  • Made by RNA polymerase III
  • ~15%
  • ~100 kinds
  • Very many copies of each
  • Is uncharged without a bound amino acid, becomes charged and is known as an aminoacyl-tRNA when an amino acid is bound
  • Has an anticodon which is completely to the codon on mRNA
  • Is single stranded RNA molecule that form a clover shape by hydrogen bonding between complementary anti-parallel bases
  • Goes from 5’ to 3’ - 3’ end bonds to amino acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the features of the genetic code?

A
  • Changes from a 4 letter ‘DNA language’ to a 20 letter ‘protein language
  • Triplet code
  • Degenerate
  • Non-overlapping and ‘comma-less’ (no gaps)
  • Adaptor molecule is tRNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the initiation triplet code?

A
  • AUG (codes for methionine - is at the beginning of every protein until it is spliced off)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the termination triplet codes?

A
  • UAA
  • UAG
  • UGA
  • Are all stop codons
16
Q

What is the ‘wobble’ position?

A
  • 5’ base of anticodon and 3’ base of codon
  • Allows a single tRNA species to recognise more that one codon
  • Contains Ionoside nucleotide which is aspecific
17
Q

What happens during the initiation stage of translation?

A
  • The 40s subunit of a rRNA binds with Met-tRNA to the 5’ cap of the mRNA
  • Starting codon 5’ AUG is recognised and is specific to Methionine only (has the anticodon 5’ CAU
  • 60s subunit binds
18
Q

What happens during the elongation stage of translation?

A
  • rRNA has two sites for tRNA to bind: P site (holds peptide chain); A site (accepting tRNA)
  • Met-tRNA occupies the P site and then another aminoacyl-tRNA enters the ribosome to occupy the A site (requires GTP)
  • Methionine forms a peptide bind with the adjacent aminoacyl-tRNA (requires peptidyl transferase) making the tRNA in the P site now uncharged
  • This tRNA leaves the ribosome, which moves along the mRNA to the next codon leaving the A site unoccupied again (translocation)
  • mRNA is read from 5’ to 3’, and the polypeptide chain grows from amino (N-) to carboxy (C-) terminus
19
Q

What happens during the termination stage of translation?

A
  • Requires a stop codon to be read on the mRNA
  • Are no tRNA molecules with a complementary anticodon that can bind
  • Peptide and tRNA are hydrolysed to release the protein into the cytoplasm
20
Q

Define the term gene

A
  • A unit of hereditary
  • A transcription unit (ie a length of DNA on a chromosome that contains the code for a protein (or RNA) as well as sequences necessary for its expression, such as promoter and terminator sequences and introns)
21
Q

What are the reactions that occur in the the maturation of mRNA A?

A
  • Capping
  • Polyadenylation
  • Splicing
22
Q

What do bacteria in regards to gene expression?

A
  • Simpler promoters
  • Different transcription factors
  • Single RNA polymerase
  • Coupled transcription-translation
  • No post-transcriptional processing
  • Short-lived mRNAs
  • Simpler ribosomes (can be exploited by drugs targeting 30s subunit so it only affects bacteria)
  • Distinctive translation inhibition mechanism
  • Different translation factors
23
Q

How can the effects of various mutations in a gene be predicted?

A
  • Severity of mutation depends on the amount of difference in a protein
  • If an amino acid is swapped for one with similar properties there will not be a large effect
  • Effects may be profound however if amino acids have different properties
  • Premature or delayed stop codons cause truncated/elongated proteins that may not function correctly or at all
24
Q

How can mutations outside the coding region affect gene expression?

A
  • Mutations to promoter regions where transcription factors bind can activate or deactivate gene expression

MGD (9 decks)

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