Topic 2A - Year 1 - Cell Structure and Division - Prokaryotic Cells and Viruses Flashcards
What is a prokaryote?
A prokaryote is a single celled organism
What is different about the organelles in a prokaryotic cell in comparison to a eukaryotic cell?
The organelles in a prokaryotic cell are not membrane bound.
What is different about the ribosomes in a prokaryotic cell when compared to ribosomes from a eukaryotic cell?
Ribosomes in a prokaryotic cell are smaller
What are the features of a prokaryotic cell ?
- Theres a cell surface membrane
- Theres a cell wall made of murein
- They are contained in a capsule
- They contain plasmids (small loops of DNA which contain genes for things like antibiotic resistance)
- There is no membrane bound nucleus DNA floats free in the cytoplasm and is present as a single long coiled up strand.
- The prokaryotic cell has a flagellum , which is a tail used to help the prokaryotic cel move
What is murein and where in the prokaryotic cell is it found?
Muiren is a glycoprotein ( a protein with carbohydrate attached ). Muiren makes up the cell wall in prokaryotic cells.
How is the capsule made and what is its purpose ?
The capsule is made up of secreted slime and it helps protect bacteria from attacks by cells of the immune system.
By which process do prokaryotic cells replicate?
Binary fission
What happens in binary fission (Prokaryotic Cell replication)
Firstly the plasmids in the prokaryotic cell replicate , this may happen several times. Then the The main DNA loop is replicate however this is only duplicated once.
The prokaryotic cell then gets bigger and the main DNA loop moves to opposite ends of the cell
The cytoplasm then begins to divide and new cell wall begins to form
Two daughter cells are produced each daughter cell has one copy of the circular DNA but can have variable number of copies of plasmids.
What does acellular mean?
Acellular means not a cell.
A virus is acellular (not a cell) what is it?
A virus is a nucleic acid surrounded by proteins.
Viruses have a protein coat , what is this protein coat referred to as?
A capsid
In a virus what sticks out from the capsid, and what is the purpose of this?
The protein coat of a virus (the capsid) has attachment proteins sticking out from its surface , the attachment proteins let the virus cling onto an appreciate host cell.
Where to viruses reproduce?
Viruses reproduce inside the cells of other organisms , the cells they reproduce in are known as host cells.
Viruses are not alive and consequently cannot undergo cell division , to reproduce they inject their nucleic acid (DNA) into the host cell , this hijacks the cell and that cells organelles begin to replicate the viral particles.
How do viruses inject their nucleic acid (DNA and RNA) into cells?
To inject their DNA and RNA the virus firstly has to attach to the host cells cell surface membrane , to do this they use their attachment proteins to bind to complimentary receptor proteins on the cell surface membrane of the host cell.
Different viruses have different attachment proteins and therefore attach to different host cells as they need a complimentary receptor protein to bind too.
