Chapter 13 - Translation Flashcards

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1
Q

The ___ of the mRNA codons into amino acid sequences leads to proteins

A

Translation

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2
Q

Genes that encode polypeptides

A

Structural Genes

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3
Q

What was the genetic model that Beadle and Tatum used?

A

Neurospora crossa (a common bread mold)

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4
Q

A single gene controlled the synthesis of a single enzyme

A

One gene - one enzyme hypothesis

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5
Q

Reasons the one gene - one enzyme hypothesis was modified

A
  1. Enzymes are only one category of proteins
  2. Some protein complexes are composed of two or more different polypeptides
  3. Many genes have been identified that do not encode polypeptides
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6
Q

Translation relies on the ___

A

Genetic Code

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7
Q

What is the genetic information coded within mRNA in groups of three nucleotides called?

A

Codons

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8
Q

What does the AUG (specifies methionine) codon do?

A

Start codon

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9
Q

What do the UAA, UAG, and UGA codons do?

A

Stop codons

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10
Q

If the third base is a variable base, what else can it be called?

A

Wobble base

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11
Q

The first amino acid has an exposed amino group

A

N-terminal or amino terminal end

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12
Q

The last amino acid has an exposed carboxyl group

A

C-terminal or carboxy terminal end

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13
Q

What does each amino acid that may be found in polypeptides have?

A

Side chain or R group

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14
Q

Nonpolar amino acids are ___

A

Hydrophobic

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15
Q

Polar and charged amino acids are ___

A

Hydrophilic

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16
Q
  1. Glycine (Gly) G
  2. Alanine (Ala) A
  3. Valine (Val) V
  4. Leucine (Leu) L
  5. Isoleucine (Ile) I
  6. Proline (Pro) P
  7. Cysteine (Cys) C
  8. Methionine (Met) M
A

Nonpolar, Aliphatic Amino Acids

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17
Q
  1. Phenylalanine (Phe) F
  2. Tyrosine (Tyr) Y
  3. Tryptophan (Trp) W
A

Aromatic Amino Acids

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18
Q
  1. Serine (Ser) S
  2. Threonine (Thr) T
  3. Asparagine (Asn) N
  4. Glutamic Acid (Glu) E
A

Polar, Neutral Amino Acids

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19
Q
  1. Aspartic Acid (Asp) D
  2. Glutamic Acid (Glu) E
A

Polar Acidic Amino Acids

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20
Q
  1. Histidine (His) H
  2. Lysine (Lys) K
  3. Arginine (Arg) R
A

Polar, Basic Amino Acids

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21
Q
  1. Primary
  2. Secondary
  3. Tertiary
    4.Quaternary
A

The Four Levels of Structure in Proteins

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22
Q

A protein’s ___ is its amino acid sequence

A

Primary structure

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23
Q

What is it called when the primary structure of a protein folds to form regular, repeating shapes?

A

Secondary structures

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24
Q

What are these?
α helix
β sheet

A

The two types of secondary structures

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25
Q

Secondary structures are stabilized by the formation of ___

A

Hydrogen bonds

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26
Q

Where do the hydrogen bonds form?

A

The polypeptide backbone

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27
Q

What is it called when the short regions of secondary structure in a protein fold into a three-dimensional structure?

A

A tertiary structure

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28
Q

What is the tertiary structure determined by?

A
  1. Hydrophobic and Ionic interactions
  2. Hydrogen Bonds and Van der Waals interactions
29
Q

Proteins made up of two or more polypeptides have a ___

A

Quaternary Structure

30
Q

A key category of proteins

A

Enzymes

31
Q

What accelerates chemical reactions within a cell?

A

Catalysts

32
Q

Synthesize molecules and macromolecules

A

Anabolic Enzymes

33
Q

Break down large molecules into small ones

A

Catabolic Enzymes

34
Q

Who proposed the Adaptor Hypothesis

A

Francis Crick and Mahon Hoagland

35
Q

tRNAs play a direct role in the recognition of codons in the mRNA

A

Adaptor Hypothesis

36
Q

The Adaptor Hypothesis proposed that tRNA has two functions

A
  1. Recognizing a 3-base codon in mRNA
  2. Carrying an amino acid that is specific for that codon
37
Q

What are the enzymes that attach amino acids to tRNAs?

A

Aminoacyl-tRNA Synthetases

38
Q

What are the aminoacyl-tRNA synthetases responsible for?

A

The Second Genetic Code

39
Q

Who proposed the Wobble Hypothesis?

A

Francis Crick

40
Q

What is the location called where translation occurs on the surface of a large macromolecular complex?

A

Ribosome

41
Q

Segments of a Ribosome

A
  1. Small Subunit
  2. Large Subunit
  3. Assembled Ribosome
42
Q

Where is the Bacterial Ribosome found?

A

The Cytoplasm

43
Q

Where are the two Eukaryotic Ribosomes found?

A

Cytoplasm and Organelles (ie. Mitochondria and Chloroplasts)

44
Q

Where does the mRNA lie on the surface of during bacterial translation?

A

The 30S subunit

45
Q

Where does the mRNA exit through as the polypeptide is being synthesized?

A

The 50S subunit

46
Q

What are the three discrete sites of a Ribosome?

A
  1. Aminoacyl site (A site)
  2. Peptidyl site (P site)
  3. Exit site (E site)
47
Q

What are the three components of an Initiation Complex

A
  1. The mRNA
  2. Initiator tRNA
  3. Ribosomal subunits
48
Q

What is the binding of mRNA to the 30S subunit started by?

A

A ribosomal-binding site or the Shine-Dalgarno Sequence

49
Q

What is this sequence?
1. IF1 (Initiation Factor 1) and IF3 bind to the 30S subunit
2. The mRNA binds to the 30S subunit
3. IF2, which uses GTP, promotes the binding of the initiator tRNA to the start codon in the P site
4. IF1 and IF3 are released
5. IF2 hydrolyzes its GTP and is released
6. The 50S subunit associates. This marks the end of the initiation stage

A

The Shine-Dalgarno Sequence

50
Q

What is the difference in Eukaryotic tRNA vs Bacterial tRNA?

A

Eukaryotic tRNA carries methionine and Bacteria tRNA carries formylmethionine

51
Q

What is this sequence, used for optimal start codon recognition, called:
G C C (A/G) C C A U G G

A

Kozak Sequence

52
Q

Where is the start codon for Eukaryotic translation located?

A

At the first AUG after the 5’ cap

53
Q

During which stage are amino acids added to the polypeptide chain (one at a time)?

A

The Translation Elongation Stage

54
Q

How fast can bacteria process amino acids in the Translation Elongation Stage?

A

15-20 amino acids per second

55
Q

How fast can eukaryotes process amino acids in the Translation Elongation Stage?

A

2-6 amino acids per second

56
Q

What is this process called?
1. A charged tRNA binds to the A site. EF-Tu facilitates tRNA binding and hydrolyzes GTP
2. Peptidyltransferase, which is a component of the 50S subunit, catalyzes peptide bond formation between the polypeptide and the amino acid in the A site.
3. The ribosome translocated 1 codon to the right. This translocation is promoted by EF-G, which hydrolyzes from the E site.
4. This process is repeated, again and again, until a stop codon is reached

A

Translation Elongation

57
Q

What stage occurs when a stop codon in reached in the mRNA?

A

The Translation Termination Stage

58
Q

What are the three stop/nonsense codons?

A
  1. UAG
  2. UAA
  3. UGA
59
Q

What proteins recognize the stop/nonsense codons?

A

Release Factors

60
Q

Which bacterial release factor recognizes UAA and UAG?

A

RF1

61
Q

Which bacterial release factor recognizes UAA and UGA?

A

RF2

62
Q

Which bacterial release factor does not recognize any of the three codons?

A

RF3

63
Q

What does RF3 do?

A

It binds to GTP and helps facilitate the termination process

64
Q

What is the Eukaryotic Release Factor that recognizes all three stop codons?

A

eRF

65
Q

What is this process called?
1. tRNA in P site carries completed polypeptide
2. A release factor (RF) binds to the A site
3. The polypeptide is cleaved from the tRNA in the P site. The tRNA is then released
4. The ribosomal subunits, mRNA, and release factor dissociate

A

Translation Termination

66
Q

Where do both transcription and translation occur in bacteria?

A

In the cytoplasm

67
Q

What is the term called when an mRNA strand is long enough, a ribosome will attach to its 5’ end?

A

Coupling

68
Q

What is an mRNA transcript that has many bound ribosomes in the act of translation?

A

A polyribosome or polysome