Introduction to bacteria Flashcards Preview

Medicine Term One > Introduction to bacteria > Flashcards

Flashcards in Introduction to bacteria Deck (35):
1

What colour do gram positive cells stain

Purple

2

What colour do gram negative cells stain

red

3

What 3 shapes do bacteria exist as

Coccus
Bacillus
Spiral

4

What is a coccus shape bacteria

Spherical

5

What is a Bacillus shape bacteria

Rod

6

What size is bacteria

Most bacteria range from 0.2–2.0 µm

7

How do bacteria replicate

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

8

Why do gram negative cells loose colour when stained

as lipopolysaccharide dissolves crystal violet stain, so bacterium remain red

9

What is bacteria conjugation

Bacteria direct exchange of plasmids (genes)

10

What bacteria have plasmids

resisting bacteria

11

What layer does gram negative have

lipopolysaccharide

12

What causes genetic variation

spontaneous mutation
transfer of DNA

13

Main function of peptidoglycan

Shape and strength

14

main function of lipopolysaccharide

Strong immune response

15

When does spore forming occur

when conditions become adverts and nutrient run out

16

What happens in spore forming

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

17

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

To survive in adverse environmental conditions

18

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

F+ cells and both contain identical copies of plasmids

19

What is a bacteriophage

Virus that parasites a bacterium, injecting and reproducing in it

20

What is the lysogenic cycle

when material is injected with the DNA from the bacteriophage

21

What are the three ways bacteria exchange DNA

transformation
transduction
Conjugating

22

What is bacterial transduction

viruses carry bacterial genes from one bacterium to another

23

What is bacterial transformation

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

24

What is MacConkeys Agar

Specialised bacterial growth medium selective for gram negative

25

Why is MacCokeys agar selective and differential

Inhibits growth of Gram positive
and differentiates between which Gram negative bacteria are lactose fermentors

26

What does MacCokeys agar contain

Bile salts and crystal violet
Lactose and neutral red ph indicator

27

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

pink

28

What do you find on the cell surface of bacteria

Plasma membrane
penicillin binding site
peptidoglycan
lipopolysaccharides

29

Function of peptidoglycan (murein)

Strength and shape
(counteracts high osmotic pressure)

30

What is frimbraie

thread like projections used for adherence

31

What is used to identify strains within a species

DNA typing techniques

32

What do strains of species have

similar characteristics

33

Naming bacteria follows what principle

Genus is mentioned then the species

34

whats the genus and whats the species Staphylococcus aureus

Staphylococcus - genus
aureus - species

35

How does bacteria conjugation occur aka function of plasmids

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