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genetics > L2 Introduction to Bacterial Genetics > Flashcards

L2 Introduction to Bacterial Genetics Flashcards

Understand basic concepts, techniques and key terms in bacterial genetics.

1
Q

DNA is arranged in a double helix structure, with the two strands ? to one another.

A

Antiparallel (parallel, but going in opposite directions)

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2
Q

Define: Wildtype

A

An unmodified natural isolate of a species (e.g. that which is used for comparative experimental purposes)

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3
Q

Define: Mutant

A

A variant from the wild type as a result of a specific change in the DNA sequence (see Mutation)

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4
Q

Define: Mutation

A

A specific change in the DNA sequence of an organism (such that the sequence differs from the wildtype)

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5
Q

Define: Allele

A

One copy of a gene

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6
Q

Define: Phenotype

A

An observable trait that may be altered by genetic mutation

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7
Q

Define: Genotype

A

The defined nucleotide sequence of an organism, usually expressed in terms of alleles of its genes

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8
Q

Define: Haploid

A

Possessing a single copy of each gene

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9
Q

Define: Diploid

A

Possessing two copies of each gene

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10
Q

Define: Polyploid

A

Possessing multiple (more than 2) copies of each gene

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11
Q

When a cell is ‘competent’, this means ? is able to occur

A

Transformation (genetic alteration of a cell resulting from uptake of exogenous genetic material)

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12
Q

The transfer of genes by direct cell-to-cell contact is known as…

A

Conjugation

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13
Q

Conjugation involves a donor and a recipient. It is usually mediated by…

A

Conjugative plasmids

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14
Q

In the lab, the Hfr strain allows conjugation to transfer part of the…

A

Chromosome itself (not just the plasmid)

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15
Q

Non-conjugative plasmids lack which gene?

A

mob gene

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16
Q

Transduction involves the use of a ? to introduce exogenous DNA

A

Bacteriophage (phage)

17
Q

Describe the polarity of dsDNA and the group present at each end

A

5’ and 3’ ends are reversed between strands. PO4 at 5’, OH at 3’

18
Q

The ‘Central Dogma’ of genetics states that…

A

Information, once encoded in a protein, cannot be decoded back into RNA or DNA ⏮

19
Q

Transcription can be described in 3 stages…

A
  1. Initiation
  2. Elongation
  3. Termination
20
Q

DNA synthesis is…

A

Semi-Conservative ½

21
Q

DNA synthesis in bacteria requires an…

A

RNA (or DNA) primer

22
Q

dNTP is the DNA precursor, more specifically the 4 types (corresponding to the different bases) are…

A
  1. dATP (adenine)
  2. dGTP (guanine)
  3. dCTP (cytosine)
  4. dTTP (thymine)
23
Q

Bacterial chromosomes are ? shaped

A

Circle ⃝

24
Q

When DNA is synthesised from the bacterial chromosome, there are two…

A

Replication forks

25
Q

When DNA synthesis occurs, there are key differences between the two strands, which are known as the…

A

Leading and lagging strands

26
Q

Mutations are sometimes detectable by phenotype. If not, we can use…

A

Sequence analysis

27
Q

A transition mutation results in a change from one type of base…

A

to another base of the same type (e.g. Pyrimidine to Pyrimidine ( C ⃡ T ) / Purine to Purine ( A ⃡ G )

28
Q

A transversion mutation results in a change from one type of base…

A

to another base of a different type (e.g. Pyrimidine (C or T) to Purine (A or G) and vice versa)

29
Q

Mutations can be (4 types)…

A
  1. Silent
  2. Missense
  3. Nonsense
  4. Frameshift
30
Q

A change in the base on position 3 often causes a ? mutation

A

Silent

31
Q

The more genes are required for a particular phenotype…

A

The more likely a mutation is to occur (and to have an observable effect)

32
Q

Spontaneous mutations are very rare, partly due to the…

A

Powerful repair systems in cells

33
Q

Mutagens can be used to artificially overload cell repair mechanisms. This is known as…

A

Induced Mutation

34
Q

Selection of mutations from cultures is either…

A

General or specific

35
Q

Describe 3 ways of selecting mutant bacteria…

A
  1. ❌ Negative selection (select for mutants which have lost certain capabilities, uses the velvet pad)
  2. 💊Enrichment (prevent growth of mutants, eliminate growing wildtypes with antibiotics)
  3. ✅ Positive selection (provide conditions where only the mutants will grow)

genetics (19 decks)

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