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Biology 1113 > Chapter 17: Gene Expression > Flashcards

Chapter 17: Gene Expression Flashcards

1
Q

3 steps of translation

A
  1. Initiation; req. E
  2. Elongation
  3. Termination
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2
Q

Introns

A

“nonsense” coding

may help regulate gene expression

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3
Q

Missense mutation

A

1 of 4 types of substitution mutations

when a nucleotide change still codes for an amino acid, but not the one you wanted

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4
Q

initiator tRNA

A

tRNA that carries the first amino acid [usually methionine (Met)] to the initiation complex so it can start translating protein

special factor that brings the bottom/small ribosomal sub-unit to the mRNA strand

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5
Q

Genetic disorders/hereditary dx

A

when a mutation has an adverse effect on phenotype

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6
Q

Frameshift mutation

A

when a single extra based gets inserted into a series of DNA’s codons, changing the triplet groups (reading frame) of the RNA

results in different amino acids being synthesized

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7
Q

Spliceosomes

A

protein/RNA complex that recognizes and removed introns

proteins and nuclear ribonucleoproteins (snRNPs) that recognize splice sites (for cutting out introns) and sometimes catalyzing splicing of introns

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8
Q

Substitution Mutations (4)

A
  1. nucleotide-repair substitution
  2. silent mutation
  3. missense mutation
  4. nonsenese mutation
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9
Q

template strand

A

the part of the unzipped DNA that RNA attaches to during transcription

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10
Q

Deletion mutations

A

LOSS of nucleotide pairs in a gene that may alter the reading frame can cause frameshift mutations

more disastrous than substitution mutations

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11
Q

(Beadle & Tatum’s) correct 1 gene: 1 polypeptide hypothesis

A

the idea that each gene dictates production of a specific polypeptide/protein

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12
Q

Transcription factors

A

mediate the binding of RNA polymerase and the initiation of transcription

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13
Q

Reading frames

A

correct groupings of codons required for polypeptide production

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14
Q

Initiation (translation)

A

complex of mRNA, tRNA, the first amino acid, small/bottom ribosomal sub-unit, and large/top ribosomal sub-unit come together

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15
Q

Anticodon

A

region in the tRNA whose triplet sequence matches that of the codons during translation

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16
Q

Signal peptides

A

markers on proteins that tell the proteins to go to the ER or to get secreted out of the cell

bind to Signal recognition particles (SRP)

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17
Q

RNA polymerase

A

binds to DNA (initiation), then untwists DNA to creates new RNA strand (elongation)

Works in the DNA’s 5 to 3 prime direction, adding bases to the RNA’s 3 to 5 prime direction

Multiple pols can be working on the gene at the same time

Usually transcribes 10-20 bases at a time, 40 per second in eukaryotes

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18
Q

Mutation

A

changes in the genetic material of a cell or virus

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19
Q

Wobble

A

flexible pairing of the third base of a codon

allows some tRNAs to bind to more than one codon; alternate version not ideal, but good enough

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20
Q

alternative RNA splicing

A

exon shuffling

(variability in the way) segments of DNA strands are treated as exons

may result in evolution of new proteins

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21
Q

Terminator

A

DNA sequence that tells RNA polymerase where to STOP working (in transcription)

Pol usually falls off about 10 to 35 bases later

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22
Q

codon/base triplet code

A

the 3-nucleotide segment of a DNA strand; one for each amino acid

64 three letter combos possible, enough to code for all 20 amino acids 61 codons) and stop signals (3 codons)

23
Q

Signal cleaving enzyme

A

cuts off a ribosome/polypeptide’s signal peptide once the complex has been delivered/bound to the ribosome

24
Q

Nucleotide-pair substitution

A

1 of 4 types of substitution mutations

when a nucleotide and its partner are replaced with another pair of nucleotides

25
Promotor
DNA sequence that tells RNA polymerase where to start working (in transcription)
26
RNA processing
Last step in transcription before translation 5 cap added, poly- A tail added (approx. 50-250 bases), introns removed, exons liked together This eases transport, protects mRNA from hydrolytic enzymes, help ribosomes attach to the 5 prime end
27
Where polypeptide synthesis happens
in the cytosol (except for when the ribosomes leave the cytosol and bind to the ER to make endomembrane system proteins).
28
Domains
regions of proteins that are coded for by different exons
29
Silent mutation
1 of 4 types of substitution mutations when the effect of a change has no effect on the amino acid produced because it is overshadowed by redundancy in the genetic code
30
Translocation complex
complex on the ER membrane where the signal recognition particles (SRP) can attach temporarily in order to bind the signal peptide and ribosome it was carrying
31
tRNA
houses the anticodons and carries the corresponding amino acids into ribosomes for translation about 80 bases long, takes 3D shape bc of Hydrogen bonding Runs 3 to 5 prime!
32
Polyribosome
aka polysome; looks a bit like a bead necklace When a bunch of ribosomes are working (still 5 to 3) on a single mRNA at the same time works very quickly
33
Gene expression
the process by which DNA directs transcription and translation
34
Insertion mutations
ADDITION of nucleotide pairs in a gene that may alter the reading frame can cause frameshift mutations more disastrous than substitution mutations
35
Transcription unit/region
Stretch of DNA being transcribed during transcription
36
Point mutation (2 types)
chemical changes in just one base pair of a gene 1. Nucleotide-pair substitutions 2. One or more nucleotide-pair insertions or deletions
37
TATA box
section of the promotor sequence that helps the polymerase know where to attach so it can start transcribing and so it can read in the right direction (but not all eukaryotes have it) Similar to -10 or -35 element in bacteria form the initiation complex by consisting of As and Ts that make the strand easier to unzip
38
Polyadenylation "stop" signal
tells pol to drop off???
39
Ribosome
made in the nucleus, excreted through pore complex organelle in cytosol or bound in the rough ER or nuclear envelope that synthesizes polypeptide chains from the codons on the mRNA chains made during transcription
40
How bacteria handles transcription and translation faster
transcription and translation are coupled together
41
Conformation
when a completed polypeptide chain folds into is 3D shape (bc of hydrogen attractions/bonds)
42
Central dogma
the idea that cells are governed by a cellular chain of command: DNA to RNA to Protein. Thanks, Sal!
43
Initiation factors
proteins that bring the large/top ribosomal sub-unit to the part for translation Req. GTP to GDP exergy
44
ribosomal RNA
What dreams and ribosome are made of
45
Signal recognition particles (SRP)
bind to signal peptides and brings them (and their ribosomes) to the ER After delivering signal peptides/ribosomes to ER, signal protein breaks off of ER
46
aminoacyl-tRNA synthetase
Enzyme that matches/binds tRNA triplet to the appropriate amino acid (w covalent bond) before it enters the ribosome requires ATP to AMP happens before the tRNA's anticodon is matched with the mRNA's codon triplet in the ribosome
47
Stop signals
DNA sequences that tell the RNA polymerase to stop coding
48
Primary transcript
the RNA strand you have (in transcription) before its 'processed'
49
(Beadle & Tatum's) debunked 1 gene: 1 enzyme hypothesis
the idea that each gene dictates production of a specific enzyme
50
3 binding sites of ribosome
E (exit) P (peptidyl tRNA binding site); peptide chain made A (aminoacyl tRNA binding site); tRNA enters ribosome
51
Redundancy
Phenomenon where multiple codons can code for the same amino acids (even though each codon can only code for 1 amino acid)
52
Ribozymes
RNAs that act as enzymes (by speeding up the binding of nucleic acids) catalytic RNA molecules can splice RNA function as enzymes (bc they can take on 3d structure, they have functional grps that can participate in catalysis, and they may hydrogen bond with other nucleic acid molecules)
53
Nonsense mutations
1 of 4 types of substitution mutations when a amino acid codon is changed into a stop codon proteins with this problem are nearly always nonfunctional
54
transcription initiation complex
completed assembly of transcription factors and RNA polymerase II (pol II) bound to a promoter

Biology 1113 (20 decks)

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