Lecture 3: Gene Expression: Translation / Protein Synthesis Flashcards

1
Q

Transcription + Translation =

A

Gene Expression

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2
Q

Section of DNA (a gene) being transcribed & translated to produce a protein.

A

gene expression

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3
Q

Genes can be turned on and off (called ___________) by various mechanisms.

Occur at any point during gene expression, but most commonly occurs at the
level of ___________.

A

gene regulation

transcription

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4
Q

Gene regulation:

Signals from the environment or from other cells activate proteins called
_____________ factors which control the level of transcription.

A

transcription

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5
Q

What are regulatory elements in transcription process?

A

Enhancers and suppressors

-Genes are turned on and off in different patterns during development stages

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6
Q

There are the 20 biologically active amino acids in humans. They are
encoded directly by the codons of the universal genetic code are called
__________ or ____________ amino acids.

A

standard, canonical

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7
Q

There are _____ Essential amino acids (indispensable) amino acid , which
cannot be synthesized de novo ), and have to get them from diet.

A

9

– histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine,
tryptophan, and valine.

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8
Q

Basic amino acid structure:

a central alpha carbon covalently bonded to…

A

-a carboxyl group
-an amine group
-a hydrogen
-a variable R group

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9
Q

a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule, and the genetic information is translated into proteins by living cells.

A

Codon

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10
Q

Amino acids are the structural units (monomers) that make up

A

proteins.

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11
Q

There are the 20 biologically active amino acids in

A

Humans

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12
Q

They are
encoded directly by the codons of the universal genetic code are called

A

standard or canonical amino acids

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13
Q

There are _________ Essential amino acids (indispensable) amino acid , which
cannot be synthesized de novo ), and have to get them from __________

A

There are nine Essential amino acids (indispensable) amino acid , which
cannot be synthesized de novo ), and have to get them from diet

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14
Q

nine essential AA

A

histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine,
tryptophan, and valine

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15
Q

Amino Acids join together to form short polymer chains called _____________
or longer chains called either __________ or __________.
*

A

peptides
or longer chains called either polypeptides or proteins.
*

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16
Q

Basic Amino Acid Structure

a central alpha carbon covalently linked to:

A

a central alpha carbon covalently linked to:

  • Carboxyl group
  • an amine group
  • a hydrogen
  • a variable R group
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17
Q

The Genetic Code

Codon

A

– a sequence of three nucleotides that together form a unit of genetic code in a DNA
or RNA molecule, and the genetic information is translated into proteins by living
cells.

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18
Q

The Genetic Code

Nonoverlapping and universal in

A

plant and animal kingdoms (ex. Mitochondrial code)

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19
Q

The Genetic Code

Degenerate (wobble base codon

A

– The first two positions of the mRNA codon observe Watson-Crick base pairing rules
(A-U, C-G) The third position exhibits wobble

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20
Q

The genetic code

codon read by

A

Read by complementary tRNA linked to aa

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21
Q

Initiation codon

A

AUG (met)

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22
Q

Stop codons

A

UAA, UGA, UAG

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23
Q

Translation

Information what

high what

A
  • Information decoding
  • High energy consuming process
    – consumes 90% of cells energy
    – 4 ATP / aa
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24
Q

Protein Synthesis Players

A
  • Ribosome / rough ER / rER (rRNA + protein)
  • tRNA = anticodon with aa
  • mRNA = codon
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25
Q

Protein Synthesis Players

Ribosome has 2 sites which associate with mRNA

A

– P site (initaition)
– A site (elongation)

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26
Q

Protein Synthesis Steps

Initiation

A

– 1st aa always methionine (Met) at P site
– Template = mRNA
– mRNA moves down in register (A site) and codon is read by
anticodon of tRNA

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27
Q

Protein Synthesis Steps

Elongation

A

– new aa brought in to match new codons and peptide bonds formed

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28
Q

Protein Synthesis Steps

Termination

A

Stop codon (UGA,UAA,UAG)

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29
Q

Massager RNA (mRNA)

Carries instructions from DNA to where

tells the ribosome what

A
  • Carries instructions from DNA to the rest of the ribosome.
  • Tells the ribosome what kind of protein to make
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30
Q

Transfer RNA (tRNA)

A

A go-getter.
Gets the right
parts to make the
right protein
according to
mRNA instructions

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31
Q

Ribosomal RNA (rRNA)

Part of the _____

helps in ______

A
  • Part of the structure of a ribosome
  • Helps in protein production
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32
Q

Ribosomal RNA (rRNA)

Ribosomes contain two ______ and 50 or more ________

rRNA sequences are widely used for ________

A
  • Ribosomes contain two major rRNAs and 50 or more
    proteins
  • rRNA sequences are widely used for working out
    evolutionary relationships among organisms
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33
Q

Ribosomal RNA (rRNA)

Prokaryotic rRNA

A

size 70s

large subunits- 50s and 23s

small subunits: 30s

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34
Q

Ribosomal RNA (rRNA)

eukaryotic rRNA size

A

size: 80s

large subunits- 60s and 28s

small subunit- 40s

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35
Q

End Product of protein synthesis

A
  • The end products of protein synthesis is a primary structure of a
    protein.
  • A sequence of amino acid bonded together by peptide bonds.
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36
Q

Post Translational Modification and Regulation

Recognition of

A

Signal Peptide

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37
Q

Post Translational Modification and Regulation

Glycosylation

O linked

N linked

A

addition of sugars to proteins destined to be membrane or
secreted
– “O” linked- serine/threonine in golgi
– “N” linked - asparagine in ER

38
Q

Post Translational Modification and Regulation

Proteolysis cleavage-

A

Truncation

39
Q

Post Translational Modification and Regulation

_______ bonds bridges

Attachment or binding of groups _________

A

Disulfide bonds bridge

NAD,Zn,Mg,FAD

40
Q

Post Translational Modification and Regulation

Assembly of ______

A

multiple subunits

41
Q

Post Translational Modification and Regulation

______ group modifications

A

R

42
Q

R -Group Modifications

A
  • Phosphorylation (via kinase on -OH group of
    serine/threonine/ tyrosine)
  • Methylation
  • Acetylation (palmitylation C16 via thioester with
    cysteine, myristication C14 at amino-terminal
    glycine)
  • Isoprenation (farnesyl,guanosyl groups)
  • Hydroxylation
43
Q

Phosphorylation via

A

kinase on -OH group of
serine/threonine/ tyrosine)

44
Q

Acetylation

A

palmitylation C16 via thioester with
cysteine, myristication C14 at amino-terminal
glycine)

45
Q

Isoprenation

A

arnesyl,guanosyl groups

46
Q

Maturation of Human Pre-Pro-insulin

Pre-pro-protein

A protein precursor that contains a ______________

A

a protein precursor that contains a signal peptide
sequence; it is a nonpolar sequence at the head of the
growing polypeptide chain and contains many
hydrophobic amino acids residues.

47
Q
A
48
Q

Maturation of Human Pre-Pro-insulin

Pre-pro-protein

required for its transfer into the ________ of the
______________; the signal sequence is then
cleaved to form the protein or proprotein.

A

required for its transfer into the cistern of the
endoplasmic reticulum; the signal sequence is then
cleaved to form the protein or proprotein.

49
Q

Insulin Protein Precursors: Pro-Insulin

Pre-pro-sequence

About ___ non polar aa guide the protien to be

A

– About 30 non-polar aa guide the
protein to be secreted out of cells or
into different compartment of the cell
sub-organells

50
Q

Insulin Protein Precursors: Pro-Insulin

Pro-sequences

Areas where

Usually in the transition of

May be involved In

A

– areas in the protein that are essential
for its correct folding
– usually in the transition of a protein
from an inactive to an active state.
– Pro-sequences may also be involved in
pro-protein transport and secretion

51
Q

Clinical Usage of C peptide Measurement

  • Patients with ________ may have their C-peptide levels measured as a means of
    distinguishing type ________ from type _________ or __________
A
  • Patients with diabetes may have their C-peptide levels measured as a means of
    distinguishing type 1 diabetes from type 2 diabetes or Maturity onset diabetes of
    the young (MODY).
52
Q

Clinical Usage of C peptide Measurement

  • Measuring __-peptide can help to determine how much of their own natural
    insulin a person is producing as C-peptide is secreted in ________ amounts to
    _________.
A
  • Measuring C-peptide can help to determine how much of their own natural
    insulin a person is producing as C-peptide is secreted in equimolar amounts to
    insulin.
53
Q

Clinical Usage of C peptide Measurement

C-peptide levels are measured instead of _________ because C-peptide can
assess a person’s own _________ even if they receive _________ injections

A

C-peptide levels are measured instead of insulin levels because C-peptide can
assess a person’s own insulin secretion even if they receive insulin injections

54
Q

Clinical Usage of C peptide Measurement

  • Because the liver does not metabolize ____-peptide, meaning blood C-peptide may
    be a better measure of ______ _______ secretion than insulin itself.
A
  • Because the liver does not metabolize C-peptide, meaning blood C-peptide may
    be a better measure of portal insulin secretion than insulin itself.
55
Q

Clinical Usage of C peptide Measurement

A very low C-peptide confirms Type ____ diabetes and insulin ___________ and is
associated with high glucose variability, hyperglycaemia and increased
complications.

A

A very low C-peptide confirms Type 1 diabetes and insulin dependence and is
associated with high glucose variability, hyperglycaemia and increased
complications.

Hyperglycemia- recent increase in sugar levels not due to a underlying condition

56
Q

Genetic Codon Change Causes Mutation in
Proteins

Point mutation

missense and nonsense mutation

A
  • Point Mutations
    – No change-silent due to alteration in 3rd base of
    codon, wobble or degenerate base
    – Missense- change in base leads to change in aa
    – Nonsense-formation or modification of termination
    codon
57
Q

Genetic Codon Change Causes Mutation in
Proteins

Frameshift mutation

A

insertion or deletion of a nucleotide

58
Q

Diseases Related to Mutations

a-thalassemia (Nonsense)

– normally 142 aa long
– If stop codon at 142 mutates get a 172 aa version including these
variants:

A
  • Constant Spring: glutamine @ 142
  • Icaria: lysine @ 142
  • Seal Roe: glutamate @ 142
  • Koya Dora: serine @ 142
59
Q
  • Thalassemia- Frameshift Mutation

Abnormal Hemoglobin Wayne

A

everything after 138 is incorrect (goes to 147
before stop)

60
Q

Inhibitors of Protein Synthesis

Streptomycin and erythromycin

A

Streptomycin / Gentamycin: 30S prok. initiation
* Erythromycin: Target 50S prok. Elongation, both Gram + and Gram -
bacteria

61
Q

Inhibitors of Protein Synthesis

Chloramphenicol and cyclohexamide

A
  • Chloramphenicol: 70S ribosomal subunit in prok, elongation, broad
    spectrum, bone marrow suppression
  • Cyclohexamide: 80S euk translocation step, and fungus etc
62
Q

Inhibitors of Protein Synthesis

Tetracycline and Puromycin

A
  • Tetracycline: Inhibits incoming tRNA to A site at 30S subunit in
    prokaryotes
  • Puromycin: Premature terminator both prok and euk, mimic tRNA
    binds at A site, resistant to hydrolysis
63
Q

Inhibitors of Protein Synthesis

Diphtheria toxin

A

Euk elongation factor II inhibitor

64
Q

Antibiotics Bind to Ribosome

The following antibiotics bind to the 30S subunit of the
ribosome:

A

– Aminoglycosides
– Tetracyclines

65
Q

Antibiotics Bind to Ribosome

The following antibiotics bind to the 50S ribosomal subunit:

A

– Chloramphenicol
– Erythromycin
– Streptogramins- a group of cyclic peptide antibiotics that inhibit,
like macrolides and lincosamides, the synthesis of bacterial
proteins.

66
Q

Streptogramins

A

a group of cyclic peptide antibiotics that inhibit,
like macrolides and lincosamides, the synthesis of bacterial
proteins.

67
Q

Hemaglobulin Constant springs

A

Mutation at the stop codon at 142aa and gets elongated to a 172aa chain.

Glutamine @ 142

68
Q

C peptide can be release in the blood and then

A

Get measured for a marker for Diabetic patients

69
Q

Pre-pro- insulin sequence

Pre sequence

A

Has a lot of + charges of a single peptide sequence so it can go through the lipid bilayer

once it passes the bilayer the Pre sequence is removed

70
Q

Pre-pro- insulin sequence

Pro sequence

A

This is where digestions and endonuclease cleavage happens into active insulin

71
Q

Glycosylations of what molecular is common

A

Immunoglobulins

72
Q

30s what does the S stand for

A

Size

73
Q

Nonoverlapping

A

When mRNA is synthesized, it will read every three nucleotides without jumping

74
Q

How two Aminoacids are linked

A

Carboxyl chain is linked to the N terminal with the removal of water

75
Q

+ charged Amino acids

A

Lysine
Histidine
Arginine

76
Q

Negative Charged Amino acids

A

Aspartic acid
Glutamic acid

77
Q

AZT is used for patients with

A

AIDS and is where H-N-H binds to promotor regions and inhibits it

78
Q

Rifampin is used to treat

A

Tuberculosis

79
Q

Prokaryotes have almost no

A

modifications such as G-cap

80
Q

Alternate splicing is where what is removed

A

Exons

81
Q

Pre-mRNA is what

A

Introns and extrons but introns get removed

82
Q

Splicing is

A

where introns are removed

83
Q

Specific enzymes cut the primary transcript of mRNA, tRNA, and rRNA to make individual RNAs

A

Endonucleases

84
Q

The promotor sequence is recognized by

A

RNA polymerase

85
Q

The CAAT, GC, and TATA box are all located where

A

Upstream and are part of the promotor region and is toward the left side

86
Q

Upstream of RNA

A

does not directly transcribe RNA but may regulate it

87
Q

RNA is synthesized with only one strand of

A

DNA

88
Q

Polymerase 3 is the main

A

Processive enzyme

89
Q

P= Rho factor=

A

Stops synthesis= Rho dependent

90
Q

SIgma subunit

A

Recognizes sequence in DNA template= promotor region

91
Q

Cofactors for RNA synthesis

A

Mg2+, Fe2+, and Zn2+

92
Q

RNA can be self folded into many shapes such as

A

Hair pin and step loop shaped