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LF104 - MCO > Prokaryotic genetics > Flashcards

Prokaryotic genetics Flashcards

1
Q

What are the 4 reasons for studying prokaryotic genetics?

A
  • Provides a basic understanding of molecular biology + genomics and where research came from etc
  • Bacteria fundamental to human health + disease so understanding of genetics = important
  • Bacterial ecology; what bacteria are in environment, how do they interact etc.
  • Applications to biotechnology; manipulating bacteria for human uses.
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2
Q

History of genetics - who was involved and when?

A
  1. Lamarck, 1800 -> species aren’t fixed.
  2. Darwin, late 1800s -> “Origin of species”
  3. Beadle and Tatum 1941 -> “One gene, One enzyme”
  4. etc
    2003 = human genome project -> current = post genome era.
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3
Q

What is the definition of bacterial genetics?

A

Bacterial genetics = study of mechanisms of heritable information in bacteria.

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4
Q

What are the 4 mechanisms studied in bacterial genetics?

A

Studying:
- Chromosomes
- Plasmids
- Transposons
- Phages

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5
Q

What techniques can be used to study bacterial inheritance mechanisms?

A

Techniques:
- Culture in defined media
- Replica plating, mutagenesis, transformation, conjugation and transduction

ALL = methods of moving genes around.

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6
Q

What is the abundance of bacteria in the world?

A

30% of DNA on earth = bacterial
Vast majority of organisms = archaea or bacteria etc (single celled organisms)

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7
Q

Spread of cells in the body eukaryotic vs bacterial?

A

Aprx bacterial cells = eukaryotic cells in body.

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8
Q

What are the 6 factors that make bacteria model organisms ?

A
  1. Haploid = one gene for everything means easy study
  2. Asexual reproduction = cell division creates identical daughter cells meaning easy to workout reproduction
  3. Short generation time = useful in research
  4. Growth in defined media for some = full control of nutrients means defining metabolic pathways
  5. Easy to store
  6. Easy to genetically mutate
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9
Q

What does bacterial genome look like?

A
  • Single, circular double stranded DNA chromosome
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10
Q

What bacterium’s chromosome is the exception?

A

Borrelia burgdorfei (limes disease causer) -> Single linear chromosome.

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11
Q

What is a bacterial genome size?

A

Varies hugely - 0.58 mega base pairs => >10 mbp

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12
Q

What is special about the bacterial genome?

A
  • Little space in-between genes (more % overall are gene coding versus eukaryotic genomes)
  • Lack of introns (unlike eukaryotes)
  • Genes grouped into operons
  • Often carry plasmids
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13
Q

What are operons?

A

Genes with related functions grouped together under one promoter

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14
Q

What are plasmids?

A

Plasmids =
small circular DNA that replicates independently.
often w extra genes important for e.g. antibiotic resistance etc.

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15
Q

E. coli genome in detail - How big?

A

EC => DNA = 1mi long
Same thickness as spiderweb

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16
Q

How do bacteria reproduce?

A

Via asexual reproduction
Cell elongates and content volume is increased
The cell divides into two => creates identical daughter cells w copy of plasmids and DNA in each cell.

17
Q

3 essential steps in bacterial reproduction

A
  1. Cell grows to 2x length
  2. Septum then forms in middle
  3. Cell grows from either end then pinches to break cell into 2.
18
Q

Why is generation time important?

A
  • Many bacteria are fast to replenish and divide. (EC = 20mins)
  • Some are 1000s of years or unable to be cultured but vast majority are useful.
19
Q

What affects generation time?

A

Optimum conditions = fastest growth time.
Conditions:
Nutrients
pH
Temperature
etc

20
Q

What is needed to grow EC?

A

1940s = modern model organism
Synthesises all own cellular components using inorganic nutrient + carbon.
- Able to grow on really defined media. => useful for metabolism and growth studies

21
Q

EC minimal media with glucose - composition?

A

Phosphates -> pH control + phosphate source.
Nitrates -> source of nitrogen
Magnesium -> useful for nucleotides + proteins.
Calcium chloride -> useful for sensing + membrane transport
Trace metals -> important for protein function
Glucose -> a carbon source + used for energy

22
Q

What is the point of growing EC on minimal media?

A

Looking for mutants that won’t grow without certain nutrients.

23
Q

What is a prototroph?

A

Wild type EC = doesn’t need any nutrients. => can grow on minimal media

24
Q

What is an auxotroph?

A

Mutants of a wild type that now require certain nutrients to be able to grow => can no longer grow on minimal media.

25
Q

What is a biosynthetic auxotroph?

A

Need additional nutrients to be able to grow e.g. amino acids, nucleotides, vitamins etc.

26
Q

What is a catabolic auxotroph?

A

Mutants that can no longer catabolise certain carbon sources.
If using glucose as carbon = unaffected. (cannot break down glucose = death)

27
Q

What are housekeeping genes?

A

Genes essential for survival. (DNA replication, glycolysis etc)
Mutations = fatal

28
Q

What are conditional lethal mutants?

A

Mutant that is fatal under repressive conditions but not in permissive conditions.

(change environment = life or death)

29
Q

What are temperature sensitive mutants?

A

Mutants that only grow at a permissive temperature not at a restrictive temperature.

represented by “ts”

30
Q

How can we explain the reason for there being temperature sensitive mutants ?

A

Mutant protein will fold differently at different temperatures, e.g. in EC permissive = 30C , restrictive = 37C; proteins will fold better at 30 due to less energy in system.

Protein stability - depends on temp.

31
Q

What is the opposite to temperature sensitive mutants?

A

Cold sensitive mutants (may grow at higher temps but not at lower temps)

32
Q

Why are conditional lethal, temp and cold sensitive mutants important ?

A

These help to work out which genes are housekeeping genes.

33
Q

How to properly write gene annotation?

A

All in italics:
1. Three lowercase letters = biochem pathway gene product involved in.
2. Capital letter = denotes gene.
3. Maybe a number for which allele

34
Q

How to properly write protein nomenclature?

A

Proteins will be encoded by genes (NO ITALICS)
1. Capital letter start

Protein will always have a capital letter starting.

35
Q

How to properly write phenotypes?

A
  1. 3 letters total, first = capital
  2. 3 letters not italicised.
  3. If mutant -> phenotype shown by superscript +/-
36
Q
A

LF104 - MCO (9 decks)

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