2A - Prokaryotic cells and viruses Flashcards
What are the organelles of a bacterial cell?
Pili Plasmid Genetic material in nucleoid region Capsule Cell wall Plasma cell membrane Flagellum Ribosomes
What is the function of the large DNA strand in bacterial cells?
Contains the genetic info in the cell.
Primary DNA structure.
What is the function of the plasmids in bacterial cells?
Secondary genetic info (smaller).
What is the function of the capsule in bacterial cells?
Provides protection.
Prevents desiccation and chemical attack.
What is the function of the cell wall in bacterial cells?
Made of murein.
Provides structure to the cell.
What is the function of the flagella in bacterial cells?
Used in motility of the cell movement.
What is the function of the plasma membrane in bacterial cells?
Controls what enters and exits the cell.
Exchange of substances with the environment.
What is the function of the ribosomes in bacterial cells?
Site of protein synthesis.
Smaller than eukaryotes (70s).
What is the function of the cytoplasm in bacterial cells?
Site of chemical reactions.
Contains enzymes.
What is the function of the pili in bacterial cells?
Attachment to surfaces.
What is the function of the attachment proteins in virus cells?
Used to attach to host cells.
What is the function of the lipid envelope in virus cells?
Derived from host cell membrane.
What is the function of the DNA/RNA in virus cells?
Encodes virus proteins.
What is the function of the capsids in virus cells?
Protein coat that encapsulates the DNA/RNA.
What is the function of the nucleoproteins in virus cells?
Accessory proteins e.g. enzymes.
What is the function of the matrix in virus cells?
Protein layer on the inside of the envelope.
How do virus’ replicate?
Use their attachment proteins to bind to complementary receptor proteins on the surface of host cells.
- Attach to host cell and injects its DNA material.
- Genetic material used as code to synthesise proteins.
- New virus particles are assembled.
- Virus’ burst out of, and destroy host cell.
How big are prokaryotic cells?
less than 10 um
What does prokaryote mean and why?
‘before the nucleus’ because they lack a membrane bound nucleus (or any other membrane bound organelles).
What are bigger: bacteria or virus’?
Bacteria are bigger.
How do prokaryotic cells replicate?
Binary fission.
Describe binary fission:
- The circular DNA and plasmid(s) replicate. The main DNA loop is only replicated once, but plasmids can be replicated loads of times.
- The cell gets bigger and the DNA loops move to opposite ‘poles’ (ends) of the cell.
- The cytoplasm begins to divide (and the new cell walls begin to form).
- The cytoplasm divides and two daughter cells are produced. Each daughter cell has one copy of the circular DNA, but can have a variable number of copies of the plasmid(s).
