Exam 2 Flashcards

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1
Q

What is a codon?

A

3 Nucleotides

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2
Q

Central Dogma?

A

DNA(Transcription in Nucleus)->RNA(Translation in Cytoplasm)->Protein

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3
Q

What does tRNA do?

A
  • Carry Amino Acids

- Work with ribosomes to produce polypeptides

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4
Q

What is an Anticodon?

A

3 nucleotide sequence that is complementary to mRNA codon.

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5
Q

What is Translation?

A
  • mRNA to Protein
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6
Q

What are the Translation Components?

A
  • Ribosome
  • Initiation factors
  • Elongation Factors
  • Anticodon
    • Initiator tRNA
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7
Q

What is Charging?

A
  • Chemically linking amino acids to tRNAs
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8
Q

What is Aminoacyl tRNA synthetases?

A
  • Recognize specific tRNAs

- One for each Amino acid

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9
Q

Primary Functions of the Ribosome?

A
  • Decode the mRNA

- Form peptide bonds

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10
Q

What is Peptidyl Transferase?

A
  • Enzomatyic component a ribosome.

- Forms peptide bonds between amino acids.

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11
Q

What is the P-Site?

A
  • Binds the tRNA attached to the growing peptide chain
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12
Q

What is the A-site?

A
  • Binds the tRNA carrying the next amino acid
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13
Q

What is the E-site?

A
  • Binds the tRNA that carried the last amino acid.
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14
Q

In prokaryotes, initiation complex includes?

A
  • Initiator tRNA charged with N-formylmethionine
  • Small ribosomal subunit
  • mRNA strand
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15
Q

What are the 3 steps of Prokaryotic translation?

A
  • Initiation
    • Initiator tRNA – formylmethionine
    • Initiation factors
  • Elongation
    • Addition of tRNA/A.A.
  • Termination
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16
Q

What happens during Prokaryotic Elongation in Translation?

A
  • Elongation adds amino acids
    • 2nd charged tRNA can bind to empty A site
    • Requires elongation factors
    • A peptide bond can then form
    • Addition of successive amino acids occurs as a cycle
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17
Q

When does Elongation Stop In Prokaryotic Translation?

A
  • Elongation continues until the ribosome encounters a stop codon.
  • The stop codons are recognized by release factors.
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18
Q

What are the differences between prokaryotic and eukaryotic translation?

A
  • Eukaryotic mRNA is more stable

- Transcription and translation are separate processes.

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19
Q

Charging a tRNA depends on which enzyme?

A
  • Aminoacyl tRNA synthetases
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20
Q

During translation, what molecule bears the anticodon? The codon?

A
  • tRNA

- mRNA

21
Q

What is a base substitution?

A
  • Substitute one base for another
22
Q

What is Silent mutation?

A
  • Same amino acid inserted
23
Q

What is a Missense Mutation?

A
  • Changes amino acid inserted
24
Q

What is a Nonsense Mutation?

A
  • Changes to a stop Codon
25
Q

What is a frameshift Mutation?

A
  • Addition or deletion of a single base

- Alter reading frame downstream

26
Q

how is gene expression controlled?

A

-Gene expression is often controlled by regulatory proteins binding to specific DNA sequences.

27
Q

What are the DNA motifs?

A
  • Helix-turn-helix motif
  • Homeodomain motif
  • Zinc finger motif
  • Leucine zipper motif
28
Q

What is Induction?

A
  • Enzymes for a certain pathway are produced in response to a substrate
29
Q

What is Repression?

A
  • Capable of making an enzyme but does not
30
Q

What is Prokaryotic Regulation?

A
  • Prokaryotic cells often respond to their environment by changes in gene expression
31
Q

What is an operon?

A
  • A genetic unit consisting of structural genes and regulatory elements
32
Q

Constitutively Definition?

A
  • Constantly Expressed
33
Q

What is Inducer exclusion?

A
  • Presence of glucose inhibits the transport of lactose into the cell
34
Q

Preferential use of glucose in the presence of other sugars?

A
  • Mechanism involves activator protein that stimulates transcription
  • Catabolite activator protein (CAP) is an allosteric protein with cAMP as effector
  • Level of cAMP in cells is reduced in the presence of glucose so that no stimulation of transcription from –CAP-responsive operons takes place
35
Q

When lactose is high?

A
  • Glucose is scarce
  • cAMP is high
  • Abundant lac mRNA synthesized
36
Q

When lactose is low?

A
  • Glucose is high
  • cAMP is low
  • Little lac mRNA synthesized
37
Q

A mutation in the P region of the lac operon would most likely result in?

A
  • Reduced expression of lac
38
Q

The lac operon is normally expressed when?

A
  • in the presence of lactose and the absence of glucose.
39
Q

Major differences between eukaryotic and prokaryotic regulation?

A

-Eukaryotes have DNA organized into chromatin which complicates protein-DNA interaction

40
Q

What is Basal Expression?

A
  • Low Expression
41
Q

What are General transcription factors in eukaryotic transcription?

A

-Necessary for the assembly of a transcription apparatus and recruitment of RNA polymerase II to a promoter, basal level of transcription

42
Q

What are the Specific transcription factors in eukaryotes?

A
  • Increase the level of transcription in certain cell types or in response to signals
  • Cell type specific
  • Condition specific
43
Q

Why are Restriction enzymes significant?

A
  • Allow a form of physical mapping that was previously impossible
  • Allow the creation of recombinant DNA molecules (from two different sources)
44
Q

Restriction Enzymes?

A
  • Recognize specific DNA sequences
  • Cleave at a specific site within the sequence
  • Can lead to “sticky ends” that can be joined
  • Palindromic sequences
  • Same sequence in both directions
45
Q

What is DNA ligase?

A
  • Joins the two fragments forming a stable DNA molecule
  • Catalyzes formation of a phosphodiester bond between adjacent phosphate and hydroxyl groups of DNA nucleotides
  • The same enzyme joins Okazaki fragments on lagging strand in replication
46
Q

What is Gel Electrophoresis?

A

-Separate DNA fragments based on size
-The gel made of agarose or polyacrylamide
-Subjected to an electrical field
-Negatively-charged DNA migrates towards the positive pole
-Larger fragments move slower, smaller move faster
-DNA is visualized using fluorescent dyes
Ethidium bromide

47
Q

What is the sense strand?

A
  • It’s the original strand that goes from 5’-> 3’
48
Q

What is molecular cloning?

A
  • Isolation and expansion of a specific DNA sequence
49
Q

What is a DNA Library?

A
  • A collection of DNAs in a vector that taken together represent the complex mixture of DNA