Prokaryotic Cells + Viruses Flashcards
Prokaryotic cells
Single celled organisms that does not contain a nucleus. They’re much smaller than eukaryotic cells as well as much simpler.
An example is bacterial cells.
What organelles does a prokaryotic cell contain
Cytoplasm Flagellum Circular DNA Plasma membrane Plasmids Cell wall Capsule
Cytoplasm
No membrane bound organelles. It has tiny ribosomes
Flagellum/ flagella
Rotates to move cell. Don’t all have one
Plasma membrane
Mainly made of proteins and lipids. Controls movement of substances in and out of cell.
Circular DNA
No nucleus. DNA floats free in cytoplasm. Not attached to histone proteins.
Plasmids
Small hoops of DNA that aren’t part of main circular DNA molecule. Plasmids contain genes for things like antibiotic resistance and can be passed between prokaryotic cells. They’re not always present, but some have several.
Cell wall - prokaryotic
Supports cells and prevents it from changing shape. It’s made of a polymer called murein. Murein is a glycoprotein.
Capsule
Secreted slime that protects bacteria from attack by cells of immune system.
What are viruses
Acellular. Not cells. Nucleic acids surrounded by protein. Smaller than bacteria. No plasma membrane. No cytoplasm. No ribosomes. Invade and reproduce in host cells.
Viruses use host cells to replicate themselves. How
- Attachment proteins bind to complementary receptor proteins on the surface of host cells.
- Some viruses only infect one type of cell.
- Don’t cell divide (not alive) so inject DNA or RNA into host cell and the host cell replicates viral particles.
How do prokaryotic cells replicate
By binary fission
Explain binary fission
- Circular DNA and plasmids replicate. The main DNA is copied once and the plasmids are copied loads.
- Cell enlarges and DNA loops move to opposite poles.
- Cytoplasm divides and new cell wall forms.
- Cytoplasm divides and 2 daughter cells are produced. Each cell is one copy of circular DNA but have a variable number of plasmid copied.
