Prokaryotic Cells Flashcards
Do bacterial cells have cell walls?
Yes, all bacterial cells have cell walls
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
What is a feature of all bacterial cell walls?
A layer of peptidoglycan made up of many paralell chains with short peptide cross links
What is a capsule?
A slime layer around cells that prevents them from being consumed in phagocytosis
What are pilli?
Thread-like protein projections found on the surface of some bacteria
What are flangella?
Proteins on the outside of the cell that move it around through rapid rotations
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
What are mesosomes?
Infoldings of the bacterial cell membrane
What are plasmids?
Circles of DNA that can reproduce independently of the cell
What kind of ribosomes are found?
70s
What is the purpose of gram-staining?
To distinguish between gram-positive and gram-negative bacteria
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
What colour are gram positive bacteria after gram staining?
Violet
What colour are gram negative bacteria after gram staining?
Red
Why is it important to know if a bacteria is gram positive or gram negative?
Different antibiotics only work on specific cell walls
What is a virus?
An intracellular paracite that reproduces in the cells of other living organisms
How do viruses attatch to their host cells?
Antigens that target proteins in the host cell surface membranes
What are the three types of virus?
DNA viruses
RNA viruses
RNA reteroviruses
What is a DNA reterovirus?
Where viral DNA acts directly as a template for both new DNA and the synthesis of viral proteins.
What are some examples of DNA reteroviruses?
Small pox
Lamdaphage
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.
What is an ssRNA virus?
RNA viruses that contain a single strand of RNA
What is a positive ssRNA virus?
RNA can act directly as mRNA and can be translated at the ribosomes
What are some examples of positive ssRNA viruses?
Polio
Hep C
What is a negative ssRNA virus?
The RNA must be transcribed before it is translated
What are some examples of negative ssRNA viruses?
Influenza
Ebola
Measles
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.
When a virus is inside the cell, what are the two routes to infection?
Lysogenic pathway
Lytic pathway
What is the lysogenic pathway of viral infection?
They don’t cause disease at first and they insert themselves into host DNA
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
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
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
How do RNA reteroviruses replicate?
Translated into DNA by viral enzyme and inserted into host DNA
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
When there is an epidemic, who are the first people to be vaccinated?
Health care workers
Children
The elderly
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
What phases must drugs do through before being put on the market?
Early research
Pre-clinical testing
Clinical trials
Regulatory review
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
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
