Lectures 8 & 9 - Bacterial Genetics Flashcards Preview

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Flashcards in Lectures 8 & 9 - Bacterial Genetics Deck (29):
0

Give a brief overview of what defines a prokayote

Nucleoid
Condensed 'free' DNA
One circular chromosome
Unique DNA
Continuous genes
No introns
Co-transcribed groups of genes -operons
Chromosome segregation
Directional gene transfer
Unequal parental contribution of merozygote
Normally recover only one product from cross over

1

What are the processes of horizontal gene transfer in bacteria?

Conjugation
Transformation
Transduction

2

How do bacteria reproduce?

Binary fission

3

What are the technical advantages of using bacteria in genetic technology?

There numbers make it easier to identify rare events
They have rapid growth
They have powerful detection systems
Clonal growth means that reproduction of one particular genome is easy

4

What is the smallest bacteria?

Mycoplasma genitalium - 580kbp

5

What is the largest bacteria?

Streptomyces coelicor - 8.67Mbp

6

What is oriC?

The origin of replication

7

What is terC?

The termination point

8

What is it called when there is one replication per cell division?

Slow growth

9

What is it called when there are multiple replication forks?

Rapid growth

10

How come E. coli can replicate in 20 minutes if it takes 40 minutes to replicate the genome?

Multiple replication forks

11

What is the gene density of the bacterial chromosome?

90%

12

What is an operon?

A cluster of genes under the control of a single promoter

13

What is a plasmid?

A circular piece of DNA separate to the chromosome, which usually contains genes not essential for host growth.

14

What are the possible roles for plasmids?

Adaptation
Pathogenesis
Evolution
Antibiotic resistance
Fertility
Tumour induction

15

What do Agrobacterium Ti plasmids do?

Induce tumours

16

Outline the process of conjugation

Binds to bacteria which does not contain the plasmid
Pore forms between them through which DNA is transferred
Only one strand of the plasmid is transferred

17

Describe the normal life cycle of a bacteriophage

Adsoption to cell
Injection of DNA
DNA replication and gene expression
Assembly of new phage particles
Cell lysis and release

18

What is a transposon?

A jumping gene

19

What is an insertion sequence?

A short DNA sequence that acts as a single transposable element

20

What is the traditional method of mapping a bacterial genome?

Mapping by co-inheritance

21

What is the modern method of mapping a bacterial genome?

Genome sequencing

22

What is a mutant?

A variant where a characteristic is heritably modified

23

What is an auxotroph?

A mutant which is unable to produce a certain metabolite

24

What is the idea behind mapping by co-inheritance?

That the closer two genes are the more likely they are to be co-inherited

25

What is bacterial transformation?

Gene exchange by the uptake of DNA

26

Describe the process that led to DNA being discovered as the transforming principle

In 1928 griffiths discovered there was a transforming principle due to the transformation of rough streptococcus pneumonia by dead smooth S. pneumonia in vivo.
Avery then found this principle was DNA

27

How is mapping by transduction carried out?

Use a phage lysate to infect with three different auxotrophic genes. Use the proportion of auxotrophs. E.g. Arg-, pur- and met- would measure proportion of arg+,pur+ to arg+, met+

28

How do you map by conjugation?

Measured by minutes. So say it takes 100 minutes for the whole chromosome to transfer. Interrupt after 20 minutes, only arg present that means Arg is 20 minutes or less, interrupt after 40 minutes now Arg and Met present etc.