Bacterial Lecture

Question 1

What is a chromosome?

Answer 1

Main genetic element in prokaryotes, most bacteria have a single circular chromosome carrying all/most genes

Question 2

What are plasmids?

Answer 2

Circular or linear double-stranded DNA that replicate separately from chromosome

Question 3

Give 2 examples of reproduction within bacteria?

Answer 3

-bionary fission
-E.Coli can divide every 20 mins

Question 4

What is the cell size range for prokaryotes?

Answer 4

0.2um to >700 um in diameter

Question 5

What is the size range for eukaryotes?

Answer 5

10um to >600um

Question 6

What are 3 major cell morphology’s?

Answer 6

Coccus- spherical

Bacillus - rod/cylinder shape

Spirillum - spiral shape

Question 7

What type of cells have unusual shapes?

Answer 7

• filamentous bacteria
• appendaged bacteria

Question 8

What is the bacterial cell wall ?

Answer 8

Peptidoglycan
- rigid layer that provides strength to the cell wall

Question 9

What are 4 things polysaccharides are composed of?

Answer 9

• NAG/NAM
• amino acids

-lysine or diaminopineoic acid (DAP)

• cross linked differently in gram-negative bacteria and gram-positive bacteria

Question 10

Give an overview of the gram-positive cell wall (peptidoglycan)

Answer 10

• up to 90% peptidoglycan
• common to have teichoic acid covalently bound to peptidoglycan
  -bind diavlent metal ions prior to transport

Question 11

What is the outer membrane of the bacterial cell?

Answer 11

• small amount of total cell contains peptidoglycan
  -most of cell wall composed of outer membrane or the lipopolysaccharide layer (LPS)

Question 12

What is the lipopolysaccharide layer?

Answer 12

Barrier against antibiotics and other harmful agents

Question 13

What does the LPS consist of?

Answer 13

Core polysaccharide and lipid A

Question 14

What does LPS replace?

Answer 14

Most of phospholipids in outer half of the outer membrane

Question 15

Outline 3 improvement contrasts in light microscopy;

Answer 15

(1) different kinds of cells are different colours

(2) bacteria can be divided into 2 major groups -positive/negative

(3) gram positive appear purple, gram negative appear pink

Question 16

What is the consistency of the polysaccharide layer?

Answer 16

Thick / thin

Or

Rigid / flexible

Question 17

What is the function of slime layers?

Answer 17

• assist in attachment to surfaces
• protect against phagocytosis

-resist desiccation

Question 18

What is the function of fimbriae?

Answer 18

Enable organisms to stick to surfaces or form pellicles

Question 19

How do pili appear?

Answer 19

Longer and fewer found per cell than fimbriae

Question 20

When are endospores formed?

Answer 20

During endosporulation or sporulation

When growth ceases due to lack of essential nutrients I.E carbon/nitrogen

Question 21

What are endospores?

Answer 21

Highly differentiated cells resistant to heat, harsh chemicals and radiation

Question 22

Why are endospores described as “survival structures” ?

Answer 22

To endure unfavourable growth conditions

Question 23

When are endospores present?

Answer 23

In some gram-positive Bactria

Question 24

What is the flagella?

Answer 24

Structure that assists in swimming bacteria

Question 25

What is the function of the flagella?

Answer 25

Increase/decrease rotational speed relative to strength of proton motive force