Primary Metabolites Flashcards
What is the bacterial cell wall made out of?
Peptidoglycan
Do bacteria have mitochondria?
No. It also only has a single chromosome
What is primary metabolism?
Occurs during balanced growth of the organism - tropophase (nutrient excess)
What is secondary metabolism?
Occurs in the absence of growth - idiophase (nutrient limitation)
How can a strain be improved by the use of mutagenesis?
Mutagen can cause a DNA mutation which is random. This can act on the contaminant gene and remove it.
What are the three types of mutagenesis?
Point = single base change
Transversion = purine (A, G) to pyrimidine (C, T)
Transition = purine to purine, pyrimidine to pyrimidine
What can act as mutagens?
UV / Gamma / X rays (cause deletions and frame-shifts too). Chemicals like alkylating agents and Biologicals like transposons and genetic crossing.
What is a forward mutation?
Mutations which inactivate a gene
What is a reversal?
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.
What would be a required enhancement from mutagenesis? (3)
- Enhanced product yield
- Lower contaminant yield
- Lower substrate requirement
How can genetic material be exchanged across different strains?
Genome shuffling
How does this occur?
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.
What are three uses of producing a cloned gene?
- Determine its sequence and predict its functionality
- Introduce extra copies of the gene into the organism (e.g - provide increased enzyme synthesis)
- Deletion of that gene (e.g - by double crossover)
What is the first step in a double crossover event?
- Two chromosomes with different alleles are present on them. There is a break at the first allele.
Second step?
- The first and third allele will crossover to the other chromosome and vice-versa.
What is the characteristic of this event?
Only the central allele remains in the same place, signifying a double crossover
What method/technology is used for gene editing?
CRISPR-Cas9
What are the two components of it?
RNA guide which searches for the DNA. Cas9 cleaves the DNA by acting as a endonuclease.
Some strains can cut its own DNA which is not desired. How is DNA introduced into gram -ve bacteria?
Use of Ca2+ and heat shock in strains deficient in restriction/modification
How is DNA introduced into gram +ve bacteria?
Production of protoplasts
How are genes introduced into fungi?
Protoplasts + DNA + Ca2+ + polyethylene glycol
Disruption of membrane = electroporation / metal ions / agrobacterium / shooting
What is a primary metabolite?
A primary metabolite is a kind of metabolite that is directly involved in normal growth, development, and reproduction
What is a secondary metabolite?
Secondary Metabolites are compounds that are not directly engaged in normal growth and development but do have some ecological functions within the cell
Which enzyme makes fatty acids up to 16C in length?
Fatty Acid Synthase (FAS)
Which enzyme extends the 16C by two carbons?
Elongase
What is the role of the desaturases?
They introduce double bonds at specific points along the carbon chain.
Where are fatty acids synthesised?
Cytosol
Where does FAS gather 2 carbon units from?
Acetyl-CoA
Why is it important that we get essential fatty acids from our diet?
We cannot produce them ourselves because we lack certain desaturases (e.g - 18:2 and 18:3)
What cannot we produce then?
Eicosanoids = these are lipid-based signalling molecules that play a unique role in innate immune responses (hormones)
We consume fish for fatty acids, but where do the fish get the fatty acids from?
Microorganisms
What are two commercial interests for the microbial fatty acids?
- Not easily obtained from another source
- Be easy to extract and purify
What about the organism itself? (3)
- To be generally regarded as safe (GRAS)
- Growth on cheap growth media
- Produce good yield
