Introduction to bacteria

Question 1

What colour do gram positive cells stain

Answer 1

Purple

Question 2

What colour do gram negative cells stain

Answer 2

red

Question 3

What 3 shapes do bacteria exist as

Answer 3

Coccus
Bacillus
Spiral

Question 4

What is a coccus shape bacteria

Answer 4

Spherical

Question 5

What is a Bacillus shape bacteria

Answer 5

Rod

Question 6

What size is bacteria

Answer 6

Most bacteria range from 0.2–2.0 µm

Question 7

How do bacteria replicate

Answer 7

Binary fission, 
Asexual replication (DNA doubles and cell divides)

Question 8

Why do gram negative cells loose colour when stained

Answer 8

as lipopolysaccharide dissolves crystal violet stain, so bacterium remain red

Question 9

What is bacteria conjugation

Answer 9

Bacteria direct exchange of plasmids (genes)

Question 10

What bacteria have plasmids

Answer 10

resisting bacteria

Question 11

What layer does gram negative have

Answer 11

lipopolysaccharide

Question 12

What causes genetic variation

Answer 12

spontaneous mutation

transfer of DNA

Question 13

Main function of peptidoglycan

Answer 13

Shape and strength

Question 14

main function of lipopolysaccharide

Answer 14

Strong immune response

Question 15

When does spore forming occur

Answer 15

when conditions become adverts and nutrient run out

Question 16

What happens in spore forming

Answer 16

DNA divided into two copies 
developing spore engulfed 
Peptidoglycan forms a cortex around developing spore 
lytic enzymes destroy mother cell 
Mature spore cell released

Question 17

In spore forming bacteria change from once cell to another why?

Answer 17

To survive in adverse environmental conditions

Question 18

After conjugation what are both bacteria called and what is present in both

Answer 18

F+ cells and both contain identical copies of plasmids

Question 19

What is a bacteriophage

Answer 19

Virus that parasites a bacterium, injecting and reproducing in it

Question 20

What is the lysogenic cycle

Answer 20

when material is injected with the DNA from the bacteriophage

Question 21

What are the three ways bacteria exchange DNA

Answer 21

transformation
transduction
Conjugating

Question 22

What is bacterial transduction

Answer 22

viruses carry bacterial genes from one bacterium to another

Question 23

What is bacterial transformation

Answer 23

the bacterium takes up of foreign DNA from its surroundings i.e. dead bacterias DNA

Question 24

What is MacConkeys Agar

Answer 24

Specialised bacterial growth medium selective for gram negative

Question 25

Why is MacCokeys agar selective and differential

Answer 25

Inhibits growth of Gram positive

and differentiates between which Gram negative bacteria are lactose fermentors

Question 26

What does MacCokeys agar contain

Answer 26

Bile salts and crystal violet

Lactose and neutral red ph indicator

Question 27

What colour does agar turn in the presence of gram negative lactose fermentor

Answer 27

pink

Question 28

What do you find on the cell surface of bacteria

Answer 28

Plasma membrane
penicillin binding site
peptidoglycan
lipopolysaccharides

Question 29

Function of peptidoglycan (murein)

Answer 29

Strength and shape

counteracts high osmotic pressure

Question 30

What is frimbraie

Answer 30

thread like projections used for adherence

Question 31

What is used to identify strains within a species

Answer 31

DNA typing techniques

Question 32

What do strains of species have

Answer 32

similar characteristics

Question 33

Naming bacteria follows what principle

Answer 33

Genus is mentioned then the species

Question 34

whats the genus and whats the species Staphylococcus aureus

Answer 34

Staphylococcus - genus

aureus - species

Question 35

How does bacteria conjugation occur aka function of plasmids

Answer 35

transfer resistance from one bacteria to another via the formation of a PILUS; a bridge between two bacterial cells that is used for communication