Cells: Structure of prokaryotic cells and viruses Flashcards
Name the process which bacteria divides by:
Binary fission
Describe binary fission in bacteria:
- Circular DNA and plasmids replicate
- Cytoplasm divides
- Cell wall reforms
Describe how HIV is replicated:
- HIV’s attachment proteins bind to receptors on membranes of T-helper cells
- Capsid is injected into host cell, containing genetic material
- Genetic material is incorporated into host DNA where reverse transcriptase makes RNA into DNA
- Protein synthesis makes viral proteins
- They assemble and burst out of the cell
Why aren’t viruses alive?
They do not possess the division machinery to divide, so they can no divide outside of host cells.
Give three features of a prokaryotic cell that are not found in a eukaryotic cell:
- Capsule
- No nucleus
- Smaller ribosomes
Eukaryotic cells have a nucleus. What do prokaryotic cells have instead?
- A circular, coiled DNA strand that floats freely in the cytoplasm
- Some have plasmids
Why do some bacteria cells have a capsule made up of secreted slime?
Helps protect the bacteria from attack by immune system cells.
Why do viruses have attachment proteins?
Allow the virus to attach onto a host cell
What is the ELISA test used for?
Detecting antigens associated with specific diseases, like HIV
Explain how the ELISA test works:
1) Antibodies complementary to the antigen are bound to the bottom of a reaction vessel
2) When the patient sample is added, target antigens present bind to the antibody
3) A second complementary antibody is added with an enzyme attached
4) A substrate is added which reacts with the enzyme
5) If the target antigen is present, a colour change occurs.
Prokaryotes are _____ celled organisms.
Single
Role of cell wall in bacterial cell:
Support and strengthens the cell
Prevents it from changing shape.
What is a bacterial cell’s cell wall made up of?
Murein
What type of molecule is murein?
A glycoprotein
Role of flagellum in bacterial cell:
Rotates to make the cell move
