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BIO 1A03 > T2- M3&4 > Flashcards

T2- M3&4 Flashcards

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1
Q

What happens to mRNA during translation

A

It is read and translated into the specific primary amino acids

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2
Q

What does translation require and consist of

A
  • initiation
  • elongation
  • termination
  • release factors
  • synthetase enzymes
  • transfer RNA
  • rRNA and ribosomal proteins
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3
Q

What does tRNA do

A

Translate amino acids from a pool of cataclysmically situated amino acids into a growing polypeptide strand in ribosome

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4
Q

Is each tRNA identical

A

No

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5
Q

How long is each tRNA molecule

A

70-90 nucleotides

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6
Q

What type of bonding does tRNA have

A

Hydrogen bonding between nucleotide bases

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7
Q

What does tRNA allow the formation of

A

4 double helical segments and 3 characteristic loops

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8
Q

What shape does tRNA fold onto itself in

A

L shape 3D structure

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9
Q

What does the anticodon region of tRNA compliment

A

mRNA codon sequence

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10
Q

Direction of anticodons written

A

3’ to 5’

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11
Q

Direction of written mRNA

A

5’ to 3’

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12
Q

What is at the 3’ end of tRNA molecule

A

Amino acid attachment site made of single stranded CCA nucleotide

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13
Q

What is the point of attachment to amino acids in tRNA

A

Terminal A for molecule activation

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14
Q

What protein is tRNA activation carried out by

A

aminoacyl tRNA synthetases

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15
Q

What does the tRNA active site recognize

A

anticodon end and attachment site

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16
Q

How many aminoacyl synthetases for each amino acid

A

20

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17
Q

What happens when aminoacyl synthetases bind to active site of tRNA

A

Can catalyze covalent attachment of tRNA to amino acid using ATP hydrolysis

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18
Q

What is the result of aminoacyl attachment to tRNA

A

charged tRNA molecule and amino acid joins polypeptide

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19
Q

How many codons and amino acids does mRNA code for

A

64 codons and 20 amino acids

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20
Q

How many tRNA molecules are there and why

A

45 due to nature of pairing interactions
- can bind to more than one mRNA

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21
Q

Define wobble

A

Explains the redundancy of the genetic code
- great flexibility in pairing third nucleotide of codon to its tRNA anticodon

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22
Q

Where is translation in eukaryotes

A

In the ribosome in the cytoplasm

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23
Q

Where is translation in prokaryotes

A

Cytosol

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24
Q

When does initiation begin in eukaryotes

A

When the initiation complex forms towards the 5’ end cap of mRNA and scans for AUG

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25
Q

What type of mRNA do eukaryotes have

A

Single stranded monocistronic mRNA

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26
Q

Describe initiation in prokaryotes

A

Located at ribosome sites called “shine dalgarno sequences” located upstream of AUG
- because they do not have 5’ cap

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27
Q

What type of mRNA do prokaryotes have

A

Polycistronic- code for several polypeptides along open reading frames

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28
Q

Why can prokaryotes have open polycistronic mRNA

A

Have functionally similar genes grouped together- transcribed from one promoter

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29
Q

How is a functional ribosome formed

A

Small and large subunits attach to mRNA molecule

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30
Q

What is the first amino acid

A

Methionine

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31
Q

What recruits the small ribosomal subunit

A

The initiation factor binding to 5’ cap

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32
Q

When does the large subunit bind

A

When the AUG is encountered

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33
Q

What energy does initiation use

A

GTP hydrolysis

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34
Q

When are initiation factors released

A

Once the ribosomal initiation complex are complete

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35
Q

How are amino acids synthesized

A

Amino end to carboxyl end

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36
Q

What site is methionine in

A

P site of large ribosomal subunit

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37
Q

Where does charged tRNA enter and bind

A

A site

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38
Q

How many nucleotides are read at once

A

3

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39
Q

What happens once correct pairing is made

A

GTP is hydrolyzed and aminoacyl end of tRNA released

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40
Q

Why is there a change in ribosome after tRNA binds

A

Allows for peptidyl transferase reaction to occur

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41
Q

What is a peptidyl transferase reaction

A

Condensation reaction of peptide bond
- transfer of polypeptide chain onto tRNA in A site

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42
Q

what allows translocation of tRNA

A

GTP bound elongation factors

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43
Q

What happens once GTP reaches stop codon

A

GTP bound release factors bind to A site and catalyze hydrolysis of bond between terminal amino acid in polypeptide and tRNA in P site

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44
Q

What will enable the dissociation of translation complex

A

GTP hydrolysis

45
Q

What did the work on “neurospora crassa” by Beadle and Tatum establish

A

The one gene, one enzyme hypothesis based on the fact that fungus can grow well on minimal medium

46
Q

What were Beadle and Tatum interesting in finding

A

They wanted to know if genes were mutated and disrupted, if they could still produce arginine

47
Q

What did Beadle and Tatum hypothesis

A

One gene codes for one enzyme responsible for a part of the metabolic pathway

48
Q

How was the one gene one enzyme tested

A

Srb and Horowitz put radiation on fungus to see which of the three enzymes are needed for arginine synthesis

49
Q

What did Srb and Horowitz conclude

A

For a mutant to grow on either ornithine or citrulline, it must be able to make arginine from either compound

50
Q

What is a better name for one gene, one enzyme

A

One gene, one polypeptide

51
Q

Describe the human genome

A

Represents the full number of proteins expressed by all the info in our DNA

52
Q

How many protein encoding genes did the project determine

A

20-25 000

53
Q

Why can a single gene code for multiple proteins

A

Due to RNA processing and post translational modifications

54
Q

Where does information split in eukaroytes

A

Double membrane nuclear envelope

55
Q

Where did the nuclear membrane evolve from

A

Single membrane ER

56
Q

What does compartmentalization allow

A

Intricate control in cell respiration regulation

57
Q

Where are translation prepared mRNA sent and why

A

From nucleus to cytosol for free or ER bound proteins to facilitate translation

58
Q

How can our proteome change

A

Depending on developmental stages and in response to internal and external signals

59
Q

How are signals detected in blood glucose increase

A

Beta cells in pancreas sensory responses

60
Q

How will the pancreas respond to high blood glucose levels

A

Release insulin to produce response on target cells

61
Q

Where can glucose be absorbed in the bloodstream

A
  • In the mouth across epithelial surfaces (with small microvilli and capillaries)
  • in microvilli of small intestines
62
Q

Where is insulin regulated

A

At transcriptional and translational levels

63
Q

Where is insulin produced

A

Dense ER of pancreas cells

64
Q

How many coded polypeptide amino acids in insulin

A

110

65
Q

How many functional insulin amino acids coded

A

51

66
Q

How many alpha and beta amino acids in insulin

A

21 alpha, 30 beta

67
Q

Who determined structure of functional insulin and how

A

Dorothy Hodgkin using x ray crystallography

68
Q

Define preproinsulin

A

110 amino acid precursor of mature insulin gene

69
Q

What does preproinsulin contain

A

N terminal sequence that interacts with SRP particles to move to lumen of ER

70
Q

What happens to preproinsulin

A

It is cleaved and yields proinsulin

71
Q

What does proinsulin do

A

Undergoes folding in addition to formation of 3 disulfide bonds

72
Q

What does proinsulin require to form bonds

A

Chaperon proteins

73
Q

Where does proinsulin go

A

From RER to Golgi

74
Q

What is formed after proinsulin

A

Insulin dimers (with beta and alpha chains) and releases c chain

75
Q

What happens to c and n chains after modifications

A

They can bind to insulin receptors of target cells

76
Q

What are two types of modifications

A

Covalent attachment and degregation of other proteins

77
Q

What are the three types of covalent attachment

A

Phosphorylation, methylation, acetylation

78
Q

Define phosphorylation

A

Involves a phosphate group to serine, threonine or tyrosine amino acid residues
- reversible

79
Q

Describe methylation

A

covalent addition of methyl group

80
Q

Describe acetylation

A

Covalent addition of acetyl group

81
Q

What happens once beta cells release insulin

A

Insulin effector molecules bind to receptors that are expressed on specific target tissues

82
Q

What are receptors

A

Proteins that receive and interpret info from signaling molecules

83
Q

What does the insulin protein bind to

A

Insulin receptors called “receptor kinases”

84
Q

In what form do receptor kinases exist

A

Monomeric form

85
Q

Why is there a conformational change in insulin receptor

A

Insulin signaling molecules bind to receptor which pair up and dimerize

86
Q

What does insulin receptor activate

A

Cytoplasmic domains of receptor which act like kinase receptors

87
Q

What do kinase proteins engage in

A

Phosphorylation of amino acids

88
Q

What activates an intracellular response

A

Due to intracellular signal amplification, the extracellular insulin signal causes cytoplasmic proteins to activte

89
Q

What does intracellular signal activate

A

Glucose transporter proteins at cell surface- abosorbs glucose

90
Q

When are intracellular signals induced in insulin

A

Once insulin is bound to receptor and phosphorylation occurs

91
Q

What proteins are needed for intracellular signals in insulin

A

transducer and amplifier proteins

92
Q

What type of feedback is signal induction

A

Positive feedback

93
Q

What type of feedback is signal termination

A

Negative

94
Q

Why is double negative feedback important

A

As an inhibitor, provides fine control

95
Q

which cells take up glucose and fatty acids and where is extra stored

A

fat cells take up glucose and fatty acids and extra is stored in form of triglycerides

96
Q

Do skeletal muscle or liver cells store more glucose?

A

Skeletal muscle

97
Q

are exons included or removed

A

included

98
Q

are introns included or removed

A

removed

99
Q

what happens if exons are removed

A

creates isoforms or different types of RNA from same transcript

100
Q

How many exons in insulin gene

A

22

101
Q

what do skeletal muscle have removed

A

exon 11 and introns

102
Q

how is the affinity of insulin receptor in skeletal cell

A

higher due to the isoform
- higher response of glucose uptake

103
Q

what is removed in liver cells

A

only the introns, exon 11 present

104
Q

How is the affinity of insulin receptors in liver cells

A

low affinity to insulin

105
Q

what type of signal does insulin act as?

A

effector

106
Q

Is insulin process positive or negative feedback?

A

Negative

107
Q

What happens if insulin protein incorrectly processed after translation

A

Cannot bind to receptor of sensor tissues

108
Q

What happens if insulin protein incorrectly spliced

A

No ability to transport glucose proteins

109
Q

What does deficiencies in insulin protein and receptor cause

A

Hyperglycemia and diabetes

BIO 1A03 (10 decks)

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