Microbiology Block A- Lecture 1

Front 1

What is binary fission?

Back 1

When two cells arise from one cell

Front 2

What is DNA replication?

Back 2

It is when one chromosome forms two daughter chromosomes

Front 3

What is cell elongation?

Back 3

When a cell becomes longer e.g. E. Coli becomes twice the original length

Front 4

What are the steps to binary fission?

Back 4

DNA replication

Cell elongation

Septum formation

Completion of septum with formation of distinct walls

Cell separation

Front 5

What does relaxed DNA have a number of?

Back 5

DNA has a number of turns in the helix predicted by the length of the molecule

Front 6

What does higher order structure imposed by supercoiling result in?

Back 6

It can allow the compaction of DNA

Front 7

What is negative supercoiling?

Back 7

When turns are removed from the helix

Front 8

What is positive supercoiling?

Back 8

When turns are added to the helix

Front 9

What enzyme carries out supercoiling?

Back 9

Topoisomerase’s

Front 10

What is topoisomerase II?

Back 10

It is the enzyme that creates the negative supercoils also called DNA gyrase

Front 11

What does topisinerase IV do?

Back 11

It relaxes the DNA and introduces positive supercoils

Front 12

What does supehelicity of DNA have an affect on?

Back 12

Gene expression and DNA replication

Front 13

What are some properties of DNA?

Back 13

Double helix

Double stranded molecules

Complementary base sequences

Two strands that run anti parallel 5’ to 3’ and 3’ to 5’

Protein interact mainly with the major groove

Front 14

What does semi conservative mean in terms of DNA?

Back 14

There is one new strand and one old pre-existing strand in DNA replication

Front 15

What direction does DNA polymerase synthesise DNA in?

Back 15

It goes in the 5’ to 3’ direction

Front 16

What is the short RNA primer always required to provide?

Back 16

3’- OH group to initiate DNA synthesis

Front 17

Does the leading strand replicate continuously or discontinuously?

Back 17

Continuously

Front 18

Is the lagging strand replicated continuously or discontinuously?

Back 18

Discontinuously

Front 19

What does the lagging strand in DNA need to replicate?

Back 19

Polymerase I

Front 20

What direction does DNA polymerase III in?

Back 20

5’ to 3’

Front 21

What is the enzyme called that proofreads for mistakes in DNA replication?

Back 21

DNA polymerase III

Front 22

What are the stages of proofreading in DNA replication?

Back 22

1. Proofreading begins at the time of the nucleotide insertion

2. Mismatched nucleotide is excised from growing DNA strand

3. Correct nucleotide is inserted into the growing DNA strand

Front 23

How many replication forks do bacteria have?

Back 23

Bacteria have dual replication forks

Front 24

At what rate are nucleotides added to DNA?

Back 24

1kbps

Front 25

How long does chromosome replication take?

Back 25

~ 40 minutes

Front 26

How long can E. Coli double in?

Back 26

~20 minutes

Front 27

How many daughter chromosomes are made after replication in a bacteria ?

Back 27

Two daughter chromosomes

Front 28

What are the steps of DNA replication and cell division in E. Coli?

Back 28

1. Origin and terminus at opposite poles of cell

2. Origin moves to mid cell, replication factory forms at the mid cell (primary cellular positioning system)

3. Chromosome replicated, daughter origins move to 1/4 & 3/4 positions of the cell. Stationary replication factory.

4. Segregation complete

5.ftsZ ring forms at the mid cell before separation

Front 29

What is the location of FtsZ ring facilitated by ?

Back 29

Min proteins MinC (Z ring formation inhibitor), MinD, MinE

Front 30

What does FrsZ do in cell division?

Back 30

Initiates cell division by forming contractile ring

Front 31

What does FtsA do in bacterial cell division?

Back 31

ATP hydrolysing protein and proved energy for divisome assembly

Front 32

What does ZipA do I bacterial cell division?

Back 32

Anchors Z- ring to cell membrane

Front 33

What does Ftsl do in bacterial cell division?

Back 33

Penicillin binding protein, synthesis septal peptidoglycan

Front 34

What does FtsK do in bacterial cell division?

Back 34

DNA translocase, pumps daughter chromosomes into appropriate daughter cell

Front 35

What is the enzyme called that proofreads in DNA replication

Back 35

DNA polymerase