Microbiology

Question 1

•viruses:

• they are acellular
• no organelles or chromosomes
• no cytoplasm
• core of nuclei acid (DNA or RNA), surrounded by a protein coat

•bacteria (prokaryotes):

• no nucleus
• no membrane bound organelles
• gram (+) and (-)
• peptidoglycan cell wall

Answer 1

•eukaryotes:

• membrane bound organelles
• DNA in chromosomes
• have nucleus

•fungi:

• eukaryotic structure
• can be uni or multicellular
• chitin in cell walls

•protozoa:

• eukaryotic cellular organism
• no cell wall
• ingest solid particles

Question 2

CLASSIFICATION:

species=genus
genera= family
families= orders

genus name= capital letter, in italics

species name= lower case letter, in italics

Answer 2

BACTERIA AND ARCHAEA:

• morphological characteristics: visual
• microscopic observations:
• gram stain
• size + shape
• arrangement

Question 3

• gram stain- divides bacteria into (+) and (-)
• catalyse test- allows microorganisms to breakdown H2O2 (lets off gas)
• oxidase test- looks for presence of cytochrome c oxidase

Answer 3

CULTURE MEDIA:

•medium- nutrient solution for growing microorganisms

•agar- polysaccharide extracted from seeweed
melts at 100deg

3 domains which all living things are classified into: Bacteria, Archaea and Eukaryotes

Question 4

BACTERIAL CELLWALL:
•rod or circular shape
•cell envelope=plasma membrane + cell wall
•cytoplasm
•flagellum

Cell wall made from peptidoglycan (rigid structure lies outside cell membrane)

Answer 4

• gram positive- purple (thick peptidoglycan cell wall)
• gram negative- red (thin peptidoglycan cell wall)

Lysozyme breaks down peptidoglycan (good for gram positive bacteria)

Question 5

•nucleoid:
not a nucleus
location of chromosome
usually 1 closed circular double-stranded DNA molecule

•plasmids:
bacteria contain these
small circular bits of DNA that exist and replicate independently of chromosome

Answer 5

•ribosomes:
slightly smaller than eukaryotic ribosomes

•external structures:
flagella (motility)
pili (hair like structures which help it attach to cells)

Question 6

ARCHAEA:
•live in extreme environments
•similar shapes to bacteria (rods + cocci are common)
•ether linkages in membrane, adds strength + resistance for environments they live in

Answer 6

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