Topic 6 - LQC 3A And 3B

Question 1

How do bacteria reproduce?

Answer 1

Binary fission, asexual reproduction

Question 2

What do they not make in this process that animal cells do?

Answer 2

Spindle fibres

Question 3

B VS V: Where is a mesosome found? What is it?

Answer 3

Bacterial cell, Inner folding of the membrane

Question 4

B VS V: Where is a slime capsule found? What is it?

Answer 4

Bacterial cell.
Protective outer layer, prevents dehydration

Question 5

B VS V: Where is a flagella found? What is it?

Answer 5

Bacterial cell.
Movement

Question 6

B VS V: Where is main circular DNA found?

Answer 6

Bacterial cell

Question 7

B VS V: Where is a cell membrane found?

Answer 7

Bacterial cell

Question 8

B VS V: Where is ribosome found? What is it? What size are they?

Answer 8

Bacterial cell
small 70S
site of translation

Question 9

B VS V: Where are pilli found? 3 functions?

Answer 9

Aid movement
allow bacteria to attach to surfaces
involved in conjugation (cell to cell contact)

Question 10

B VS V: Where is a plasmid found? What is it?

Answer 10

Bacterial cell
Small loop of DNA

Question 11

B VS V: Where is a cell wall found? What is it made of? What does that determine?

Answer 11

Bacterial cell
Made of peptidoglycan
It’s composition makes bacteria either gram-positive or gram-negative

Question 12

B VS V: Where is a capsid found? What is it?

Answer 12

Virus
Repeating protein sub units, to protect the nucleic acid (RNA or DNA)

Question 13

B VS V: Where are enzymes found? What are they used for?

Answer 13

Virus, contain enzymes for replication processes

Question 14

B VS V: Where are nucleic acid found? What are they?

Answer 14

Virus
RNA - single stranded
DNA - Double or single stranded

Question 15

B VS V: Where is the envelope found? What is it?

Answer 15

Virus
Taken from host cell surface membrane, contains lipids and proteins.
Helps virus to attach to host cell and penetrate the cell surface membrane.

Question 16

B VS V: Where are glycoproteins found? What are they?

Answer 16

Virus
Recognise by host immune system as non-self
Act as antigens

Question 17

What do viruses require for reproduction?

Answer 17

HOST CELL - they lack the internal structures for growth and reproduction

Question 18

What is cell lysis?

Answer 18

Cells swelling and bursting, releasing virus particles

Question 19

Describe process of how viral particles are released?

Answer 19

• virus attaches
• virus inserts nucleic acid
• viral nucleic acids replicate
• viral protein coats synthesised
• new virus particles formed
• virus particles released due to cell lysis

Question 20

Bacterial cells have no…. And no ….

Answer 20

Nucleus and other membrane bound organelles

Question 21

What are the two classes of Bacteria, based on their cell walls?

Answer 21

Gram positive and gram negative

Question 22

What happens to gram positive bacteria in presence of the stain?

Answer 22

Take up the stain, turn purple

Question 23

What happens to gram negative bacteria in presence of the stain?

Answer 23

Reject the stain, pink

Question 24

Why do gram positive bacteria retain the stain?

Answer 24

Only made up of cell wall and inner membrane
They have more peptidoglycan in their cell walls

Question 25

Why does gram negative bacteria not retain the stain?

Answer 25

- more complex cell wall (containing lipopolysaccharides) - thinner layer of peptidoglycan - lipopolysaccharides is an endotoxin, which blocks dyes, detergents and antibiotics - periplasmic space between cell wall and cell membrane

Question 26

Describe the process of binary fission (7)

Answer 26

- DNA is replicated - old cell wall begins to break down around the middle of the cell - DNA is associated with the cell membrane - cell pinches forming septum - two identical daughter cells formed - plasmids often divide at the same time Time between divisions is generation time

Question 27

Bacteria can reproduce by …

Answer 27

Binary fission and sexual reproduction

Question 28

What are the three types of sexual reproduction bacteria can reproduce by?

Answer 28

- transformation - transduction - conjugation

Question 29

Describe the process of transformation

Answer 29

– A bacterium takes in DNA from environment (shed by other bacteria / introduced to in lab) – DNA is in form of circular DNA called plasmid – it can be copied in the receiving cell and passed onto its descendants

Question 30

Describe the process of transduction

Answer 30

– Virus transfers bacterial DNA from one bacterium to another – viruses called bacteriophages are able to infect bacterial cells and use them as hosts – after multiplying viruses assemble and remove portion of the host cells bacterial DNA – when bacteriophage later infects new host cell, a piece of bacterial DNA is incorporated into genome of new host

Question 31

Describe the process of conjugation

Answer 31

– DNA is transferred from one bacterium to another – pilus allows donor to pull itself close to recipient, DNA is transferred between cells – in most cases DNA is in form of a plasmid

Question 32

Viral envelope contains …

Answer 32

- host protein and lipids - viral proteins (glycoproteins, called antigens) - VAPs, virus attachment particles

Question 33

Two adaptations of a virus

Answer 33

- extremely small, easily get into body - simple structure of protein coat and genetic material, withstand harsh conditions and retain infectivity

Question 34

What are the six major transmission routes?

Answer 34

Inoculation, inhalation, fomites, direct contact, vectors, ingestion

Question 35

Describe inhalation

Answer 35

Breathing in leopard drop which contains pathogen through airways. These were expelled from more respiratory tract of individual. E.g. flu, cold

Question 36

Describe Direct contact

Answer 36

Transfer of pathogen directly onto skin/physical barrier, due to close contact with infected person

Question 37

Describe inoculation

Answer 37

Pathogen enters directly into body through a break in the skin, e.g. dog bite, tattoo

Question 38

Describe vector

Answer 38

Another organism transferring the pathogen to another organism, e.g. mosquitoes and malaria

Question 39

Describe ingestion

Answer 39

Contaminated food or drink bleeding to vomiting and diarrhoea, greatest risk from raw/undercooked food e.g. E. coli, salmonella

Question 40

Describe fomites

Answer 40

Inanimate objects that carry pathogens from one host to another e.g

Question 41

Four major barriers to entry of pathogens

Answer 41

Skin, mucosal membrane, gut flora, stomach acid

Question 42

Describe how skin provide provides a barrier to pathogen entry

Answer 42

– Hard protein keratin outer layer preventing microorganism entry – skin flora outcompetes and prevents colonisation by other bacteria, as microbes live on the skin – skin can be breached by wounds, blood clotting helps prevent this

Question 43

Describe how mucosal membranes provide a barrier to pathogen entry

Answer 43

- Mucus lines airways and gut, goblet cells produce mucus - Mucus traps microbes and other particles, cilia beats mucus to throat where it swallowed or coughed up - secretions from eyes and nose contain the enzyme lysozyme, it breaks down bacterial cell walls causing them to burst

Question 44

Describe how stomach acid provides a barrier to entry of pathogens

Answer 44

- Contains hydrochloric acid, giving a pH of less than 2.0, optimum pH for the enzyme Pepsin - This kills most bacteria enter with food or drink

Question 45

Describe how gut flow provides a barrier to the entry of pathogens

Answer 45

– intestines contain friendly bacteria which we have mutualistic relationship with – they aid digestion and outcompete pathogenic bacteria, for food and space – bacteria also secrete chemicals to aid defence against pathogens