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Biology 1113 > Chapter 17: Gene Expression > Flashcards

Chapter 17: Gene Expression Flashcards

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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
Q

Promotor

A

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

26
Q

RNA processing

A

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
Q

Where polypeptide synthesis happens

A

in the cytosol (except for when the ribosomes leave the cytosol and bind to the ER to make endomembrane system proteins).

28
Q

Domains

A

regions of proteins that are coded for by different exons

29
Q

Silent mutation

A

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
Q

Translocation complex

A

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
Q

tRNA

A

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
Q

Polyribosome

A

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
Q

Gene expression

A

the process by which DNA directs transcription and translation

34
Q

Insertion mutations

A

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

more disastrous than substitution mutations

35
Q

Transcription unit/region

A

Stretch of DNA being transcribed during transcription

36
Q

Point mutation (2 types)

A

chemical changes in just one base pair of a gene

  1. Nucleotide-pair substitutions
  2. One or more nucleotide-pair insertions or deletions
37
Q

TATA box

A

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
Q

Polyadenylation “stop” signal

A

tells pol to drop off???

39
Q

Ribosome

A

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
Q

How bacteria handles transcription and translation faster

A

transcription and translation are coupled together

41
Q

Conformation

A

when a completed polypeptide chain folds into is 3D shape (bc of hydrogen attractions/bonds)

42
Q

Central dogma

A

the idea that cells are governed by a cellular chain of command:

DNA to RNA to Protein. Thanks, Sal!

43
Q

Initiation factors

A

proteins that bring the large/top ribosomal sub-unit to the part for translation

Req. GTP to GDP exergy

44
Q

ribosomal RNA

A

What dreams and ribosome are made of

45
Q

Signal recognition particles (SRP)

A

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
Q

aminoacyl-tRNA synthetase

A

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
Q

Stop signals

A

DNA sequences that tell the RNA polymerase to stop coding

48
Q

Primary transcript

A

the RNA strand you have (in transcription) before its ‘processed’

49
Q

(Beadle & Tatum’s) debunked 1 gene: 1 enzyme hypothesis

A

the idea that each gene dictates production of a specific enzyme

50
Q

3 binding sites of ribosome

A

E (exit)
P (peptidyl tRNA binding site); peptide chain made
A (aminoacyl tRNA binding site); tRNA enters ribosome

51
Q

Redundancy

A

Phenomenon where multiple codons can code for the same amino acids (even though each codon can only code for 1 amino acid)

52
Q

Ribozymes

A

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
Q

Nonsense mutations

A

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
Q

transcription initiation complex

A

completed assembly of transcription factors and RNA polymerase II (pol II) bound to a promoter

Biology 1113 (20 decks)

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