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Genetics > Chapter 13 - Translation of mRNA > Flashcards

Chapter 13 - Translation of mRNA Flashcards

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1
Q

The translation of the mRNA codons into __ ___ sequences that lead to what?

A
  1. amino acids
  2. synthesis of proteins
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2
Q

What are some important cellular component that play roles in translation?

A
  1. proteins
  2. RNAs
  3. small molecules
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3
Q

Genes that encode polypeptides are termed what?

A

protein encoding genes or structural genes

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4
Q

What are structural genes transcribed into?

A

mRNA

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5
Q

what is the main function of the genetic material?

A

to encode the production of cellular proteins

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6
Q

Who was the first to propose the idea of a relationship between genes and protein production?

A

Archibald Garrod

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7
Q

What was Garrod interested in? and what are the symptoms?

A
  • A disease called Alkaptonuria characterized by black urine & bluish black discoloration of cartilage and skin.
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8
Q

What was Garrod hypotheses on why alkaptonuria happened?

A

due to missing enzyme, homogentisic acid oxidase

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9
Q

Human diseases are caused by

A

mutations resulting in missing or defective enzymes

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10
Q

Who were the scientists that come up with the question “ Is it one-gene-one enzyme or one-gene-many enzymes?”

A

George Beadle and Edward Tatum

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11
Q

How did they test this question?

A

Using a wild type of Neurospora and four mutant strains were each streaked on minimal plates & supplemented plates with 4 different enzymes

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12
Q

What was the modification of the original question?

A

now “one-gene- one polypeptide”
- more accurate to say a structural gene encodes a polypeptide

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13
Q

What does translation involve?

A

an interpretation of one language into another…
nucleotide to Amino Acid

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14
Q

What does translation rely on?

A

Genetic code (which is universal from humans, bacteria, plants)

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15
Q

The genetic information is coded within mRNA in groups of three nucleotides called

A

codons

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16
Q

What are the 3 pockets in ribosomes and what do they do?

A

A - aminoacyl site -nucleotide to amino acid
P - peptidyl site - structure is formed
E- exit site - the polypeptide structure exits through here

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17
Q

What are the components of translation in tRNA & Ribosomes?

A
  1. Polarity (5’ to 3’ on opposite sides)
  2. 3 pockets
  3. MRNA is threaded between ribosomal subunits
  4. complimentary base pairing
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18
Q

What is Aminoacyl-tRNA synthetases?

A
  • enzymes that attach amino acids to specific tRNAs (20 of them)
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19
Q

What are the translation players?

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A
  1. mRNA
  2. tRNA
  3. ribosomes
  4. aminoacyl-tRNA synthetases
20
Q

What is the size of ribosomes in bacteria vs eukaryotes?

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A

Bacteria - 70s (50s & 30s)
Eukaryotes - 80s (60s & 40s)

21
Q

What are the 3 stages of translation/transcripation?

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A
  1. initiation
  2. elongation
  3. termination
22
Q

What is the start codon in Translation?

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A

AUG - methionine

23
Q

What is added, only in bacteria, to the methionine at the start of translation?

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A

a formyl group that is than removed at a later date

24
Q

5’UTR is essential in what but not this?

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A

essential in prokaryotes but NOT eukaryotes

25
what is 5'UTR?
untranslated region of mRNA that as as a buffer transcribed but not translated yet
26
the binding of mRNA to the 30S subunit is facilitated by a ___.
ribosomal-binding site or Shine-Dalgarno Sequence
27
Describe the Shine-Dalgarno Sequence
- complementary to a sequence in the 16S rRNA - interacts via hydrogen bonds
28
Why must initiation start at the P site?
the P site is where the sequence is put together, the polypeptide chain is where the start codon is. The A & E are blocked.
29
The elongation stage is the same in both prokaryotes & eukaryotes besides this.
the pockets are AUT in eukaroytes compared to APE in prokaryotes
30
Describe the Termination stage in Translation
1. Occurs when a stop codon is reached in the mRNA 2. most species have 3 stop or nonsense codons 3. these codons are not recognized by tRNAs but by proteins called release factors
31
What are the 3 stop or nonsense codons? where are they found?
1. UAG 2. UAA 3. UGA mRNA
32
What are release factors?
- 3D structure of release factors that mimics that of tRNAs
33
What is the start codon for eukaryotic translation?
AUG
34
Rules for optimal translation initiation are called
Kozak's rules
35
What are the release factors in bacteria vs Eukaryotes?
Bacteria have 3 1. RF1 recognizes UAA and UAG 2. RF2 recognizes UAA and UGA 3. RF3 does not recognize anything but required for the termination process vs Eukaryotes having 2 1. eRF1 recognizes all 3 stop codons 2. eRF3 required for termination process
36
How many levels of structure are their in proteins?
4 1. Primary 2. secondary 3. tertiary 4. quaternary
37
What is a protein's primary structure?
its amino acid sequence
38
While being translated, further folding will occur because (2)
1. its dictated by the amino acid sequence 2. can be aided by chaperones
39
What are chaperones?
a big protein complex that helps fold it
40
Describe how the 4 levels of protein structure look:
1. primary structure - just a sequence 2. secondary - alpha helix 3. 3D effect combines both Alpha + Beta 4. Quart - protein subunit which is two or more polypeptides
41
What are the 5 post-translational events?
1. Phosphorylation 2. Ubiquitination 3. Protein targeting 4. Proteolytic Cleavage 5. Polypeptide assembly 6. Chaperones
42
What is Phosphorylation?
- makes active or inactive enzymes - aka puts phosphate groups on (kinase) and takes phosphates off
43
what is Ubiquitination?
removes proteins if old or not needed anymore
44
what is protein targeting?
signal sequencing helps it get where it needs to go
45
what is proteolytic cleavage?
cutting things to make a functional polyprotein
46
what is polypeptide assembly? and give an example
two poylpeptides = one protein ex: hemoglobin
47
what are chaperones?
change shapes like a barrel

Genetics (12 decks)

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