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Microbial Biotechnology > Primary Metabolites > Flashcards

Primary Metabolites Flashcards

1
Q

What is the bacterial cell wall made out of?

A

Peptidoglycan

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2
Q

Do bacteria have mitochondria?

A

No. It also only has a single chromosome

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3
Q

What is primary metabolism?

A

Occurs during balanced growth of the organism - tropophase (nutrient excess)

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4
Q

What is secondary metabolism?

A

Occurs in the absence of growth - idiophase (nutrient limitation)

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5
Q

How can a strain be improved by the use of mutagenesis?

A

Mutagen can cause a DNA mutation which is random. This can act on the contaminant gene and remove it.

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6
Q

What are the three types of mutagenesis?

A

Point = single base change
Transversion = purine (A, G) to pyrimidine (C, T)
Transition = purine to purine, pyrimidine to pyrimidine

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7
Q

What can act as mutagens?

A

UV / Gamma / X rays (cause deletions and frame-shifts too). Chemicals like alkylating agents and Biologicals like transposons and genetic crossing.

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8
Q

What is a forward mutation?

A

Mutations which inactivate a gene

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9
Q

What is a reversal?

A

Another mutation at the second amino acid change can overcome the effect of the first amino acid. May revert back to its original function, reversing the first mutation.

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10
Q

What would be a required enhancement from mutagenesis? (3)

A
  1. Enhanced product yield
  2. Lower contaminant yield
  3. Lower substrate requirement
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11
Q

How can genetic material be exchanged across different strains?

A

Genome shuffling

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12
Q

How does this occur?

A

Selected strains of the same or closely-related strains undergo protoplast fusion. Both cell walls are degraded and this produces two protoplasts which can merge and form recombinations of DNA.

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13
Q

What are three uses of producing a cloned gene?

A
  1. Determine its sequence and predict its functionality
  2. Introduce extra copies of the gene into the organism (e.g - provide increased enzyme synthesis)
  3. Deletion of that gene (e.g - by double crossover)
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14
Q

What is the first step in a double crossover event?

A
  1. Two chromosomes with different alleles are present on them. There is a break at the first allele.
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15
Q

Second step?

A
  1. The first and third allele will crossover to the other chromosome and vice-versa.
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16
Q

What is the characteristic of this event?

A

Only the central allele remains in the same place, signifying a double crossover

17
Q

What method/technology is used for gene editing?

A

CRISPR-Cas9

18
Q

What are the two components of it?

A

RNA guide which searches for the DNA. Cas9 cleaves the DNA by acting as a endonuclease.

19
Q

Some strains can cut its own DNA which is not desired. How is DNA introduced into gram -ve bacteria?

A

Use of Ca2+ and heat shock in strains deficient in restriction/modification

20
Q

How is DNA introduced into gram +ve bacteria?

A

Production of protoplasts

21
Q

How are genes introduced into fungi?

A

Protoplasts + DNA + Ca2+ + polyethylene glycol
Disruption of membrane = electroporation / metal ions / agrobacterium / shooting

22
Q

What is a primary metabolite?

A

A primary metabolite is a kind of metabolite that is directly involved in normal growth, development, and reproduction

23
Q

What is a secondary metabolite?

A

Secondary Metabolites are compounds that are not directly engaged in normal growth and development but do have some ecological functions within the cell

24
Q

Which enzyme makes fatty acids up to 16C in length?

A

Fatty Acid Synthase (FAS)

25
Q

Which enzyme extends the 16C by two carbons?

A

Elongase

26
Q

What is the role of the desaturases?

A

They introduce double bonds at specific points along the carbon chain.

27
Q

Where are fatty acids synthesised?

A

Cytosol

28
Q

Where does FAS gather 2 carbon units from?

A

Acetyl-CoA

29
Q

Why is it important that we get essential fatty acids from our diet?

A

We cannot produce them ourselves because we lack certain desaturases (e.g - 18:2 and 18:3)

30
Q

What cannot we produce then?

A

Eicosanoids = these are lipid-based signalling molecules that play a unique role in innate immune responses (hormones)

31
Q

We consume fish for fatty acids, but where do the fish get the fatty acids from?

A

Microorganisms

32
Q

What are two commercial interests for the microbial fatty acids?

A
  1. Not easily obtained from another source
  2. Be easy to extract and purify
33
Q

What about the organism itself? (3)

A
  1. To be generally regarded as safe (GRAS)
  2. Growth on cheap growth media
  3. Produce good yield

Microbial Biotechnology (4 decks)

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