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MICROBIO Lecture > Lecture 12 Translation and Horizontal Gene Transfer > Flashcards

Lecture 12 Translation and Horizontal Gene Transfer Flashcards

1
Q

Describe tRNA Molecules

A
  • Convert the language of RNA into that of proteins
  • Clover leaf shape
  • Two functional regions
  • Synthetase enzyme attaches an amino acid here
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2
Q

What are the Three Stages of Translation

A
  • Initiation
  • Elongation
  • Terminationa
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3
Q

Describe the Initiation step of translation

A
  1. ) 16S rRNA in the ribosome hybridizes with Shine-Dalgarno sequence
  2. ) tRNA with formylmethionine binds start codon in P site
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4
Q

What is the purpose of the Shine-Dalgarno sequence

A

Aligns mRNA with the ribosome

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5
Q

Describe the Elongation step of translation

A
  1. ) tRNA+AA binds A site
    - Requires energy - GTP
    - Antibiotic tetracycline inhibits binding
  2. ) Peptide bond joins amino acids - catalyzed by 23S rRNA
  3. ) Ribosome moves 1 codon along mRNA
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6
Q

Describe the Termination step of translation

A
  • Any one of 3 stop codons
  • UAA, UAG, and UGA
  • no tRNAs with corresponding anticodons

Fig 13.30

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7
Q

What do release factors do?

A

cleave, release polypeptide

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8
Q

What is a Mutation?

A
  • Heritable change in DNA sequence
  • Can generate alleles (alternate forms of genes)
  • Can give rise to new phenotypes
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9
Q

What is Vertical gene transfer (Eukarya)

A
  • Sexual reproduction

- New combinations of genes when gametes from parents fuse

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10
Q

How to Bacteria and Archaea create genetic variability.

A

Horizontal gene transfer a

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11
Q

What are the three mechanisms of Horizontal gene transfer

A
  • Transformation
  • Transduction
  • Conjugation
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12
Q

Horizontal Gene Transfer
Transformation
What are the examples from lecture?

A

Uptake of free DNA from environment

Only a few bacterial genera known to be naturally competent

Gram + Streptococcus, Bacillus

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13
Q

What are the two techniques of artificial transformation

A
  • CaCl2 - makes cells more permeable

- Electroporation - pulses high voltage, temporary holes - cell wall, plasma membrane

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14
Q

DNA Transformation

A

Bacterial RecA protein Integrates DNA by homologous recombination

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15
Q

Membrane-bound protein complexes bring DNA into the cell how?

A

using a nuclease ?

Fig 16.26

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16
Q

Horizonal Gene Transfer

Conjugation

A
  • DNA transfer by direct cell contact
  • Requires pili, plasmids
  • Major mode of spreading antibiotic resistance genes
17
Q

Describe Plasmids

A
  • double-stranded, circular DNA
  • Extrachromosomal
  • carry genes that confer advantage
  • can be transferred by conjugation
  • are replicons - have their own ori
18
Q

What is an episome?

A

plasmids that exist with or without integrating into chromosome

19
Q

What is a well-studied example of conjugative plasmid

A

The F (Fertility) Factor of Escherichia coli

20
Q

Run through the steps of Conjugation: F+ x F- Mating

A
  1. ) Pilus from the donor F+ extends toward the Recipient F-
  2. ) Pilus Retracts and F factor beings replication
  3. ) Plasmid-encoded enzyme nicks one strand of F factor , Single strand enters recipient
  4. ) A new complementary strand made via Rolling circle replication
21
Q

What is a High Frequency of Recombination (Hfr) cell?

A

Can transfer integrated F factor and part of chromosome to F- cell

22
Q

What can happen when there is conjugation across biological domains.

A

Causes crown gall disease
Tumor-inducing plasmid (Ti)

Piece of Ti, called T DNA, transferred by conjugation from bacterium into plant cell

Piece integrates into plant genome

Agrobacterium tumefaciens

23
Q

What are the two functions o the T DNA transferred by Agrobacterium?

A
  1. ) Directs plant cells to overproduce phytohormones
    - Uncontrolled growth forms tumor
  2. ) Stimulates plant cells to make opines a C and N source for bacterium
24
Q

What does the term “mobile DNA” mean?

A

refers to segments of DNA that can move from one site to another within other DNA molecules

25
Q

What is the process that transposable elements move?

A

Transposition

MICROBIO Lecture (9 decks)

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