Microbiology

Question 1

Describe the DNA in a prokaryote

Answer 1

circular -free in cytoplasm- carries genetic code for proteins.

Question 2

describe the ribosomes in prokaryotes

Answer 2

-70s
-made of protein and rRNA and is site of protein synthesis/translation.

Question 3

describe the mesosomes in prokaryotes

Answer 3

folding of plasma membrane.
–site of respiration

Question 4

describe the cell wall in prokarotes

Answer 4

-made of peptidoglycan/murien- prevents osmostic lysis/bursting.

Question 5

what is the role of the slime capsule in prokarotes.

Answer 5

protection against drying out and some antibiotics.

Question 6

role of the plasmid-prokaryote

Answer 6

-circular DNA,
carries genes for antibiotic resistance.

Question 7

give 6 ways bacteria are identified.

Answer 7

-shape
size
-staining characteristics.
-genetic features
-antigenic features.
- metabolic features.

Question 8

what is the length of ecoli

Answer 8

3-8 micrometers

Question 9

why is shape distinguishable between bacteria

Answer 9

is determined by the rigid cell wall which has a unique 3D mesh of peptidoglycan molecules.

Question 10

why is metabolism distinguishable between bacteria

Answer 10

use different organic molecules as an energy source - some can use other inroganic molecules e.g nitrates.

Question 11

why is antigenic features distinguishable between bacteria

Answer 11

have unique surface proteins/glycoproteins.

Question 12

why is genetic features different in bacteria

Answer 12

different codes for different proteins.

Question 13

why are the staining characteristics between bacteria different

Answer 13

bacteria identified by their ability to take up stain, they are either describes as being gram negative or positive.

Question 14

what stain is used to stain bacteria

Answer 14

Grams stain e.g crystal violet stain

Question 15

describe the method for staining bacteria

Answer 15

1.stain cells with cvs (purple)
2.wash cells with solvent (ethanol)
3.gram +ve retain the stain in their thick peptidoglycan wall and appear purple.
4.gram -ve cells lose the stain as their lipopolysaccharide layer is dissolved by ethanol and stain red with safranin a counter stain

Question 16

name 6 factors that affect the growth of microorganisms

Answer 16

-nutrinets and water
-PH
-temperature
-oxygen abundance.
-type of growth medium
-mineral salts.

Question 17

how are nutrients supplied to bacteria

Answer 17

in nutrient rich agar or brothe.g a carbon source is supplied for glucose and co2. a nitrogen/ amino acid source is also needed for protein synthesis.

Question 18

what vitamins are required by bacteria

Answer 18

R, H

Question 19

what is the usual optimum PH of most bacteria

Answer 19

7.4

Question 20

what is the term given to bacteria living in acidic conditions

Answer 20

acidophiles.

Question 21

what are the type of bacteria that grow in high temperatures e.g hot springs

Answer 21

thermophiles

Question 22

what are the type of bacteria that grow in temperatures of 25-40 c

Answer 22

mesophiles

Question 23

what type of bacteria grow in very low temperatures

Answer 23

psychrophilic in arctic or Antarctic waters.

Question 24

what are the three categories for bacteria with different o2 requirements

Answer 24

-obligate aerobes
-obligate anaerobes
-facaultive anaerobes.

Question 25

what are obligate anaerobes-

Answer 25

cant survive in presence of oxygen. often produce toxins

Question 26

what are facaultive anaerobes

Answer 26

grow better in oxygen but can survive without but grow much slower e.g e-coli.