Prokaryotic Cells Flashcards Preview

A Level Biology: Topic 2 (Edexcel) > Prokaryotic Cells > Flashcards

Flashcards in Prokaryotic Cells Deck (39)
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1
Q

Do bacterial cells have cell walls?

A

Yes, all bacterial cells have cell walls

2
Q

Are the contents of bacterial cells hypertonic or hypotonic to the surrounding medium?

A

Hypertonic so water moves into the cell by osmosis and the cell wall stopps it from bursting

3
Q

What is a feature of all bacterial cell walls?

A

A layer of peptidoglycan made up of many paralell chains with short peptide cross links

4
Q

What is a capsule?

A

A slime layer around cells that prevents them from being consumed in phagocytosis

5
Q

What are pilli?

A

Thread-like protein projections found on the surface of some bacteria

6
Q

What are flangella?

A

Proteins on the outside of the cell that move it around through rapid rotations

7
Q

What is the difference between the cell membrane in eukaryotic and prokaryotic cells?

A

Eurakyotic cells have mitochondria but in prokaryotic cells the membrane has some respiratory enzymes

8
Q

What are mesosomes?

A

Infoldings of the bacterial cell membrane

9
Q

What are plasmids?

A

Circles of DNA that can reproduce independently of the cell

10
Q

What kind of ribosomes are found?

A

70s

11
Q

What is the purpose of gram-staining?

A

To distinguish between gram-positive and gram-negative bacteria

12
Q

What is the difference between gram positive and gram negative bacteria?

A

In the cell wall
Gram positive has a think layer of peptidoglycan
Gram negative has a thin layer without teichoic acid and an outer layer of lipopolycaccharides

13
Q

What colour are gram positive bacteria after gram staining?

A

Violet

14
Q

What colour are gram negative bacteria after gram staining?

A

Red

15
Q

Why is it important to know if a bacteria is gram positive or gram negative?

A

Different antibiotics only work on specific cell walls

16
Q

What is a virus?

A

An intracellular paracite that reproduces in the cells of other living organisms

17
Q

How do viruses attatch to their host cells?

A

Antigens that target proteins in the host cell surface membranes

18
Q

What are the three types of virus?

A

DNA viruses
RNA viruses
RNA reteroviruses

19
Q

What is a DNA reterovirus?

A

Where viral DNA acts directly as a template for both new DNA and the synthesis of viral proteins.

20
Q

What are some examples of DNA reteroviruses?

A

Small pox

Lamdaphage

21
Q

What is an RNA virus?

A

They have RNA as 70% of their genetic material and are more likely to mutate
Don’t produce viral DNA.

22
Q

What is an ssRNA virus?

A

RNA viruses that contain a single strand of RNA

23
Q

What is a positive ssRNA virus?

A

RNA can act directly as mRNA and can be translated at the ribosomes

24
Q

What are some examples of positive ssRNA viruses?

A

Polio

Hep C

25
Q

What is a negative ssRNA virus?

A

The RNA must be transcribed before it is translated

26
Q

What are some examples of negative ssRNA viruses?

A

Influenza
Ebola
Measles

27
Q

What is a RNA reterovirus?

A

They have a protein capsid and lipid envelope. The RNA strand makes reverse transcriptase so makes DNA with the viral genome that can be incorperated into host DNA.

28
Q

When a virus is inside the cell, what are the two routes to infection?

A

Lysogenic pathway

Lytic pathway

29
Q

What is the lysogenic pathway of viral infection?

A

They don’t cause disease at first and they insert themselves into host DNA

30
Q

What is the lytic pathway of viral infection?

A

Viral DNA is replicated independantly of the host cell and the cell then bursts with viral DNA and produces symptoms

31
Q

How do positive ssRNA viruses replicate?

A

The strand of RNA is used directly as the sense strand of mRNA and is translated into viral proteins

32
Q

How do negative ssRNA viruses replicate?

A

The viral RNA must be transcribed onto a sense strand by using RNA replicase and then coding for viral proteins

33
Q

How do RNA reteroviruses replicate?

A

Translated into DNA by viral enzyme and inserted into host DNA

34
Q

What ways do antivirals work?

A

They target the receptors of the virus that recognise host cells
They target the enzymes that help to translate or replicate DNA or RNA
They inhibit protease enzymes

35
Q

When there is an epidemic, who are the first people to be vaccinated?

A

Health care workers
Children
The elderly

36
Q

What are the ways to control the spread of disease?

A
Rapid identification
Nursing in iscolation
Preventing transmission
Steralising and disposing of equiptment after use
Wearing protective clothing
37
Q

What phases must drugs do through before being put on the market?

A

Early research
Pre-clinical testing
Clinical trials
Regulatory review

38
Q

What are the considerations when fast-tracking vaccines through clinical testing?

A

Severity of the disease
Avaliability of other treatments
Effectiveness of disease control
Freedom over participation

39
Q

What are the reasons against using untested drugs?

A

Not ethical
May make the situation worse if side effects
Difficult to decide who gets the drug
Informed consent could be an issue