CP 12 Gene Structure Flashcards

1
Q

Which direction is RNA made

A

5’ –> 3’, uses 3’–>5’ dna strand as template

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2
Q

the DNA bases are:
the RNA bases are:

A

ATCG
AUCG

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3
Q

what are the differences between DNA replication and Transcription

A
  • Only 1/2 DNA nucleotide strands acts as template for synthesis
  • Relatively small part of DNA molecule serves as template
  • RNA polymerases catalyze assembly of RNA nucleotides into RNA strand
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4
Q

what are the 2 main parts of a gene

A
  • regulatory region
  • Coding region
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5
Q

what is the regulatory region of a gene

A

a promoter (control sequence for transcription)

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6
Q

what is the coding region of a gene

A

a transcription unit (section of the gene that is
copied into an RNA molecule)

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7
Q

what is the basic structure of a prokaryotic coding gene from left to right

A
  • promoter
  • 5’ UTR
  • start codon
  • DNA being coded
  • stop codon
  • 3’ UTR
  • terminator signal
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8
Q

what is the basic structure of a eukaryotic coding gene from left to right

A
  • promoter
  • 5’ UTR
  • start codon
  • DNA being coded (Exon 1, Intron, Exon 2) separated by splice signals
  • Stop codon
  • 3’ UTR
  • Poly(A) Signal
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9
Q

TF Eukaryotes have a termination sequence

A

F

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10
Q

what are the 3 steps to transcription

A
  • Initiation
  • Elongation
  • Termination
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11
Q

what are the steps to initiation

A
  • promoter binds (TATA Box)
  • Transcription factors (TF) bind
  • RNA polymerase 2 binds
  • additional TFs bind to form “transcription initiation complex”
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12
Q

what are the steps to elongation

A
  • RNA polymerase moves along the DNA, it untwists double helix
  • gene can be transcribed simultaneously by several RNA polymerases
  • Nucleotides are added to the 3’ end of growing RNA molecule
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13
Q

what are the steps to termination

A
  • Complete RNA is released
  • RNA polymerase leaves
  • dbl helix reforms
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14
Q

In eukaryotes the RNA polymerase 2 is responsible for ____ while RNA polymerase 1 is responsible for ___

A
  • tRNA, 1/4 rRNAs, protein coding genes
  • the three other rRNAs
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15
Q

Whats the difference between transcription in prok and euk cells

A
  • prokaryotes, mRNA produced by transcription is immediately translated without more processing
  • In eukaryotes, nuclear envelope separates
    transcription from translation
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16
Q

what is pre-mRNA

A
  • beginning RNA template in euk cells that are modified through RNA processing to yield
    finished mRNA
  • Must be processed in nucleus to produce translatable mRNA
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17
Q

what is the 5’ cap on mRNA

A
  • Site where ribosome attaches to mRNA
  • Connected by 3 phosphate groups
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18
Q

what is the Poly(A) Tail in pre-mRNA

A
  • substitute for terminator sequence
  • Signals RNA polymerase to stop transcription
  • Protects mRNA from RNA-digesting enzymes
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19
Q

what are the Introns and exons of pre-mRNA

A
  • Introns = Non–protein-coding intervening sequences in the pre-mRNA
  • Exons = Amino acid-coding sequences retained in finished mRNAs
20
Q

TF Exons have to be removed before translation

A

F, Exons are expressed

21
Q

how many variations of genetic code can be made with a 3 letter codon

A

64

22
Q

TF Each codon specified same amino acid in all living organisms

A

T

23
Q

How many sense codons and how many stop/start codons are there

A
  • 61 sense codons
  • 3 stop/start
24
Q

what is the “Wobble Hypothesis”

A

First two nucleotides of anticodon and codon must match exactly, Third nucleotide has more flexibility

25
Q

what is aminoacylation

A

the process of adding the AAs to a tRNA

26
Q

what are the 2 types of ribosomes

A
  • Prokaryotic 705 Ribosome (505 top, 305 bottom)
  • Eukaryotic 805 Ribosome (605 top, 405 bottom)
27
Q

what are the sites of a Ribsosome (in order)

A

-A (aminoacyl site)
-P (peptidyl site)
-E (exit site)

28
Q

what does the A site in a ribosome do

A

accepts the tRNA with the AA

29
Q

What does the P site on the ribosome do

A

Base pairing between codon (mRNA) and anticodon (tRNA), binds their AA to the growing polypeptide chain

30
Q

What does the E site of the ribosome do

A

Releases the tRNA without the AA attached

31
Q

what happens in termination in translation

A
  • A site reaches stop codon
  • Release factor (RF) binds to A site
  • Peptide chain released from P site
  • Ribosome disassembled
32
Q

what is a polysome

A

Multiple ribosomes simultaneously translate single mRNA

33
Q

what is polypeptide processing (3 steps)

A

Processing convert polypeptides into finished form
- Removal of one or more amino acids from the protein chains
- Addition of organic groups
- Folding to get correct 3D structures

34
Q

TF polypeptides can be inactive and activated at certain locations

A

T, (Pepsin inactive form pepsinogen activated by stomach acid removal of amino acids)

35
Q

what are sorting signals

A

sort proteins to cellular locations where they function

36
Q

TF cells cant adapt

A

F, cells need to adapt

37
Q

what is one way that cells adapt

A

gene regulation

38
Q

what is gene regulation

A

Ability of cells to control levels of gene expression
eg) Proteins produced at the correct time in the correct amounts

39
Q

why is eukaryotic gene regulation necessary

A
  • cell differentiation
  • to turn certain genes on and off as organism matures (embryo –> adult)
40
Q

what is the most common level of gene regulation if prokaryotic cells

A

transcription, sometimes translation, minimally at protein/post-translational level

41
Q

what is a missense mutation

A

Sense codon changed to different sense codon

42
Q

what is a nonsense mutation

A

Sense codon changed to nonsense (stop) codon

43
Q

what is a silent mutation

A

Sense codon changed to different sense codon that specifies the same AA

44
Q

what is a frameshift mutation

A

Single base-pair deletion or insertion in coding region of gene

45
Q
A