Prokaryotic Cells Flashcards Preview

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

Flashcards in Prokaryotic Cells Deck (39):
1

Do bacterial cells have cell walls?

Yes, all bacterial cells have cell walls

2

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

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

3

What is a feature of all bacterial cell walls?

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

4

What is a capsule?

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

5

What are pilli?

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

6

What are flangella?

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

7

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

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

8

What are mesosomes?

Infoldings of the bacterial cell membrane

9

What are plasmids?

Circles of DNA that can reproduce independently of the cell

10

What kind of ribosomes are found?

70s

11

What is the purpose of gram-staining?

To distinguish between gram-positive and gram-negative bacteria

12

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

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

What colour are gram positive bacteria after gram staining?

Violet

14

What colour are gram negative bacteria after gram staining?

Red

15

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

Different antibiotics only work on specific cell walls

16

What is a virus?

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

17

How do viruses attatch to their host cells?

Antigens that target proteins in the host cell surface membranes

18

What are the three types of virus?

DNA viruses
RNA viruses
RNA reteroviruses

19

What is a DNA reterovirus?

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

20

What are some examples of DNA reteroviruses?

Small pox
Lamdaphage

21

What is an RNA virus?

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

22

What is an ssRNA virus?

RNA viruses that contain a single strand of RNA

23

What is a positive ssRNA virus?

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

24

What are some examples of positive ssRNA viruses?

Polio
Hep C

25

What is a negative ssRNA virus?

The RNA must be transcribed before it is translated

26

What are some examples of negative ssRNA viruses?

Influenza
Ebola
Measles

27

What is a RNA reterovirus?

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

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

Lysogenic pathway
Lytic pathway

29

What is the lysogenic pathway of viral infection?

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

30

What is the lytic pathway of viral infection?

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

31

How do positive ssRNA viruses replicate?

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

32

How do negative ssRNA viruses replicate?

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

33

How do RNA reteroviruses replicate?

Translated into DNA by viral enzyme and inserted into host DNA

34

What ways do antivirals work?

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

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

Health care workers
Children
The elderly

36

What are the ways to control the spread of disease?

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

37

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

Early research
Pre-clinical testing
Clinical trials
Regulatory review

38

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

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

39

What are the reasons against using untested drugs?

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