Prokaryotic cells

Question 1

Components of a bacterial cell

Answer 1

Cell wall
Pili
Flagellae
Cell surface membrane
Plasmid
Nucleoid
70S ribosomes

Question 2

Bacterial cell walls

Answer 2

Contents are usually hypertonic to medium around them so water tends to move into cells
Prevents cell swelling and bursting
Maintains shape of bacterium
Has a layer of peptidoglycan

Question 3

Pili

Answer 3

Used for attachment to host cell for sexual reproduction
Make bacteria more vulnerable to virus infections as bacteriophage use pili as an entrance point

Question 4

Flagellae

Answer 4

Moves the bacterium by rapid rotations

Question 5

Cell surface membrane

Answer 5

Similar to in eukaryotes however bacteria have no mitochondria so membrane is site of some of the respiratory enzymes
Membrane has infoldings known as mesosomes

Question 6

Plasmid

Answer 6

Small circle of DNA
Codes for bacterial phenotype in addition to the genetic information in the nucleoid
Can reproduce themselves independently of the nucleoid
Can be transferred from one bacterium to another through sexual reproduction using pili

Question 7

Nucleoid

Answer 7

Where a single length of DNA that is folded and coiled is found

Question 8

70S ribosome

Answer 8

Smaller than 80S ribosomes
Have two subunits (30S and 50S)
Involved in protein synthesis

Question 9

What is gram staining

Answer 9

A technique used to distinguish types of bacteria using their cell wall

Question 10

Gram positive bacteria

Answer 10

Have a thicker layer of peptidoglycan in their cell walls with teichoic acid
The crystal violet is trapped in the peptidoglycan layer so stays purple

Question 11

Gram negative bacteria

Answer 11

Thin layer of peptidoglycan in cells walls with no teichoic acid
Takes up red safranin as no peptidoglycan to trap crystal violet, so turns red

Question 12

Which antibiotics for which bacteria

Answer 12

Beta lactam antibiotics for gram positive as it inhibits formation of the peptidoglycan layer
Glycopeptide antibiotics for gram negative as they cant penetrate gram positive wall

Question 13

Other ways of classifying bacteria

Answer 13

By shape
By respiratory requirements

Question 14

Bacterial shapes

Answer 14

Spherical (cocci)
Rod shaped (bacilli)
Twisted (spirilla)
Comma shaped (vibrios)

Question 15

Bacteria respiratory requirements

Answer 15

Obligate anaerobes - need oxygen for respiration
Facultative anaerobes - use oxygen if it is available
Obligate anaerobes - can only respire without oxygen

Question 16

Virus attachment proteins

Answer 16

Specific proteins that target proteins in the host cells cell surface membrane

Question 17

Virus forms

Answer 17

DNA viruses
RNA viruses
RNA retroviruses

Question 18

DNA viruses

Answer 18

Genetic material is DNA
Viral DNA acts as a template for new viral DNA and mRNA needed for synthesis of proteins

Question 19

RNA viruses

Answer 19

Genetic material is RNA
Much more likely to mutate than DNA viruses
Single strand of RNA (ssRNA)

Question 20

Positive and negative ssRNA viruses

Answer 20

Positive ssRNA - have RNA that can act directly as mRNA and be translated at ribosomes
Negative ssRNA - cannot be directly translated so must be transcribed first

Question 21

Virus pathways

Answer 21

Lysogenic (latency)
Lytic

Question 22

Lysogenic pathway

Answer 22

Viral DNA is incorporated into host cell but stays dormant and only reproduces when host cell does
Then joins lytic pathway

Question 23

Lytic pathway

Answer 23

Viral DNA is inserted into cell and takes over biochemistry
Replicates genetic material
New phage particles are assembled
Cell lysis occurs and phages are released

Question 24

RNA retroviruses

Answer 24

Have viral RNA as their genetic material
This cant be used as RNA but is translated into DNA using reverse transcriptase
Viral DNA moves into host cell nucleus

Question 25

How are viruses spread

Answer 25

Infected mucus Droplets of saliva Infected blood or faeces Contact between infected organisms

Question 26

How to treat viral diseases

Answer 26

Antiviral treatment - targets receptors by which viruses recognise host cells, target enzymes that help translate DNA or RNA, inhibit protease so new virus particles cant bud from host membranes

Question 27

Ways of virus prevention

Answer 27

Vaccinations Disease control

Question 28

Ways of controlling the spread of a disease

Answer 28

Rapid identification of the disease Nursing in isolation Preventing transmission between individuals Sterilising or disposing of equipment after use Health workers wearing protective clothing Identifying contacts

Question 29

Development of medicine stages

Answer 29

Early phase research Preclinical testing Clinical trials Regulatory review Scale up to manufacturing Post market surveillance

Question 30

Factors affecting whether a drug should be fast tracked

Answer 30

Severity of the disease Availability of any other treatments fir the disease Effectiveness of standard disease control methods Transparency about the process and consent forms Freedom of choice over participation

Question 31

Reasons against using untested drugs

Answer 31

People think it is unethical Unexpected side effects can make the situation worse Deciding who gets the drug can be difficult Informed consent can be difficult due to less understanding about the drug Issue of trust between individuals and heath workers