Bacterial Genome

Question 1

How is bacterial shape determined

Answer 1

By genes

Question 2

Which gene in caulobacter causes a curved shape

Answer 2

Crescent in

Question 3

Name the 6 types of shapes bacteria can be

Answer 3

1- coccus (round)

2- rod (ecoli)

3- spirillum

4- spirochette (wavy)

5- stalk and hypha (budding and appendage)

6- filamentous (long and thin)

Question 4

What is dna in bacteria condensed into

Answer 4

A nucleoid

Question 5

How are genes switched on or off during rep

Answer 5

The dna unwinds from the nucleoid

Question 6

Explain the genome of an ecoli

Answer 6

Circular chromosome

Haploid 1 copy of each chromosome

No introns

No histones

1 oric site

Question 7

How many bp does ecoli have

Answer 7

4.6 million bp (4,300 genes)

Question 8

On the chromosome of bacteria, there are clusters of genes expressed on same mrna. What is this called and give example

Answer 8

Operons

Eg lac ZYA

Same sigma factor and stop codon

Question 9

Other than the lac operon, give another example

Answer 9

Trp operon

Produces tryptophan when needed to make amino acids
Contains 5 cluster genes

Question 10

What is in the middle of a chromosome inside genomic dna

Answer 10

The NOT1 restriction sites

Sequences dna is cleaved and recognised

Question 11

Why do plasmids on their genomic dna need to have replication functions

Answer 11

They replicate independently but coordinated to the chromosome to be passed onto daughter cells

Question 12

Explain what transposons are on plasmids and how they work

Answer 12

Transposons are genes which can be transferred elsewhere ie gene knockin

They contain insert sequences recognised by proteins

which cases them to be cleaved from plasmid or chromosomes

Question 13

What do transposons usually carry

Answer 13

Genes for antibiotic resistance

Question 14

What are tra genes found on plasmids

Answer 14

Transfer genes

They encode for things like sex pili which allows conjugation/ transfer

(F plasmid has tra genes)

Question 15

Other than plasmids , name 3 other mobile elements

Answer 15

1- bacteriophage transduction

2- transposons

3-integrons

Question 16

What’s the difference between lytic phage and lysogenic phage

Answer 16

Lytic - enzymes get degraded and phages reassemble killing cell

Lysogenic - the insertion of dna is stable and doesn’t kill cell

Question 17

What allows a phage to bind to a cell

Answer 17

Tail fibres

Question 18

What on a phage allows it to inject dna

Answer 18

Base plate

Question 19

What are integrons

Answer 19

Pickup genes which can carry resistance from a cell to another

Question 20

What is the difference between the pan genome and core genome

Answer 20

Pan genome contains extra genes inherited via transfer like pathogenicity islands, transposons, conjugative plasmids

Question 21

Explain briefly the steps of next gen sequencing (alternative to dideoxy)

Answer 21

Fragmented ss dna is hybridised with adaptors (nucleotides) then added to flow cell

On to flow cell when adapter binds this causes dna replication via dna pol and bridging occurs across flow cell

This copies the ss dna like a PCR reaction when multiple copies

When primers attach this allows for the comp labelled nucleotides to bind and it shows sequence

Question 22

What is bioinformatics

Answer 22

After sequencing where amino acids are determined and the structure of the gene appears

Eg identifying the start and stop codon on the ORF

Question 23

Name some impacts sequencing and bioinformatics has had

Answer 23

1- follow evolution of bacteria and mutations (comparative genetics)

2- allows all mutations to be seen from a small piece of dna responsible for mutation

3- screening for presence of infection and allowing treatment best for them

4- comparing genome with small section rather than full gene mapping