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Cmb > Microbial Genetic/ Biotech > Flashcards

Microbial Genetic/ Biotech Flashcards

1
Q

What are mutations ?

A

Random, inheritable alterations in the sequence of the genome
They can change the phenotype

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2
Q

What are selectable mutations ?

A

Could be selected after placing organisms under conditions where their growth will be favoured (eg: mutations of resistance
Mutations converting an auxotrophy to phototrophy (inability/ability to synthesise metabolites)

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3
Q

What are non selectable mutations ?

A

Can only be identified after testing the whole population of an organism (eg- mutations of auxotrophy, mutations of sensitivity like temp sensitive mutants

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4
Q

What are mutagens?

A

Physical or chemical factors that increase the rate of mutations

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5
Q

The most important processes contributing to genetic variation include ?

A

Mutations
Recombination
Transpositions

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6
Q

What is a point mutation?

A

It involves a single base pair change

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7
Q

What types of point mutations are there?

A

-base pair substitution: a single base pair/nucleotide is substituted with another

Base pair insertion/deletion: nucleotide is added or deleted

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8
Q

What May base pair substitutions lead to?

A

Silent, missense or nonsense mutations

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9
Q

What do insertions and deletions cause ?

A

Have a more dramatic effect: getting rid of a base pair changes the amino acid therfore can result in a non functional protein

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10
Q

What is a silent mutation?

A

Something that has no effect on the encoded protein (as genetic code is redundant: different triplets can code for the same amino acid)

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11
Q

What is a missense mutation?

A

If the altered codon causes encoding for a different amino acid (doesn’t really make sense)

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12
Q

What is a nonsense mutation?

A

If a codon for an amino acid is converted into a stop codon.

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13
Q

How do you detect mutagenic compounds ?

A

By an ames test.

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14
Q

Explain an Ames Test

A

Plate (his-) strain of salmonella typhimurium ( a mutant that requires the amino acid histidine for growth) in the medium without histidine

  1. The mutant (his-) cells don’t grow on the medium. The only (his+) cells could grow
  2. If the testes compound (soaked into the disk) is a mutagen it causes reversion of many his- cells into his+ cells due to mutations. The mutants grow around the disk.
  3. The more colonies grow, the more strong the mutagen is. Many strong mutagens are also carcinogens
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15
Q

What’s recombination ?

A

The process by which parts or all of the DNA molecules from 2 seperate sources are exchanged or brought together into a single DNA molecule

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16
Q

What’s homologous recombination ?

A

Exchanging DNA fragments from 2 different DNA molecules that have identity in some regions

This process involves an endonuclease, single strand binding protein and RecA protein

17
Q

Examples of plasmid born resistance to metals?

A

Enterobacteria

Pseudomonas

Ralstonia metallidurans

18
Q

What is enterobacteria resistant to?

A

Ions of arsenic, copper mercury zinc

19
Q

What is pseudomonas resistant to?

A

Chromium Mercury tellurium

20
Q

What is ralstonia metallidurans resistant to?

A

High content of heavy metals, possesses 2 large plasmids: pMOL28 and pMOL30

21
Q

What is the main tool for genetic engineering ?

A

Bacterial plasmids

22
Q

What kind of adaptive mechanisms do bacterial plasmids include ?

A 
Antibiotic resistance 
Toxin production 
Metal resistance 
Degradation of organic compounds 
Utilisation of metabolic pathways
23
Q

What’s transduction ?

A

Gene transfer in bacteria mediated by phages (bacterial viruses)

24
Q

What’s generalised transduction ?

A

Potentially any donor bacterial gene could be transferred

25
Q

Specialised transduction ?

A

Only certain donor genes could be transferred

26
Q

How does generalised transduction work?

A

Phages carry random fragments of the donors bacterial chromosomes to another bacterium. Transferred DNA can be integrated into new DNA by recombination.

27
Q

Transposition takes places where?

A

Between plasmids and chromosomes

Within and among chromosomes

28
Q

The action of a transposon is based on what

A

Transposition (a frameshift insertion)

29
Q

What’s the main advantage of biomedical research?

A

Easily and rapidly cultivable in lab by using microbiological techniques

30
Q

Bacteria have what?

A
  • small haploid genome

- universal genetic code

31
Q

Most eukaryotic organisms have a diploid state but can be propagated as haploids. How is this good?

A

This is an advantage for genetic research since most mutations are expressed phenotypically

Cmb (6 decks)

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