Introduction to Microbiology

Question 1

Features of viruses?

Answer 1

No cells
DNA or RNA
no nucleus
no ribosomes
no membrane bound organelles
Protein capsid or envelope is on the outside layer
replicate via host machinery

Question 2

Features of bacteria?

Answer 2

Has cells
DNA or RNA
prokaryotic nucleus
70s ribosomes
no membrane bound organelles
has rigid peptidoglycan cell wall
replicates by binary fission

Question 3

Features of fungi?

Answer 3

has cells
DNA or RNA
eukaryotic nucleus
80s ribosomes
has membrane bound organelles
rigid cell wall containing chitin
replicates by budding or mitosis

Question 4

Features of protozoa and helminths?

Answer 4

Has cells
DNA or RNA
eukaryotic nucleus
80s ribosomes
has membrane bound organelles
has a flexible membranes
mitosis replication

Question 5

What are the morphological and biochemical characteristics of bacteria?

Answer 5

Morphological - nature of the cell wall, staining, shape and spore forming abilities
Biochemical - metabolism, production of specific enzymes or toxins

Question 6

Characteristics of viruses used for classification?

Answer 6

Type of nucleic acid
number of strands of nucleic acid
polarity of viral genome
symmetry of nucleocapsid
lipid envelope

Question 7

How do parasitic helminths transmit?

Answer 7

Through direct swallowing or by larvae penetrating the skin

helminths are multicellular worms

Question 8

Parasitic protozoa?

Answer 8

Single celled organism

has metabolically active stage and dormant stage

Question 9

What are the features of gram positive bacteria?

Answer 9

Thick, multilayered
no outer membrane
no lipopolysaccharide
low lipid and lipoprotein content
Teichoic and lipoteichoic acids are present
no porins

Question 10

What are the features of gram negative bacteria?

Answer 10

Thin, single layer
has outer membrane
has lipopolysaccharide
high lipid and lipoprotein content
no Teichoic and lipoteichoic acids
Porins

Question 11

Structures of the bacteria?

Answer 11

Has a capsule
flagella
pili
plasmids
spores (gram positive only)

Question 12

what is the basic structure of virus?

Answer 12

DNA or RNA genome
capsid core
polymerase protein
envelope

Question 13

What are the two types of viral capsids?

Answer 13

Icosahedral capsid - closed

Helical capsid - open

Question 14

What are the importance of viral surface proteins?

Answer 14

Attach to membrane proteins in the host cell
target for antibodies
determinants of antibody specificity

Question 15

Steps of viral replication?

Answer 15

1) target cells surface proteins of the virus interact with specific receptors and bind
2) viruses enter the cells
3) viruses uncoated so nucleic acid available for transcription
4) viral proteins and viral genome produced and replicated
5) virion assembly brings together newly formed nucleic acid
6) release and dissemination

Question 16

What are retroviruses?

Answer 16

Uses reverse transcriptase to copy a positive ssRNA genome into dsDNA which is the template for new genome synthesis