Prokaryotic Cells and Viruses Flashcards
What is the structure and function of the plasma membrane in a prokaryotic cell?
The plasma membrane is mainly made of lipids and proteins. It controls the movement of substances in and out of the cell
What is the structure and function of the cell wall in a prokaryotic cell?
The cell wall supports the cell and prevents it from changing shape. It’s made of a polymer called murein. Murein is a glycoprotein (a protein with a carbohydrate attached)
What is the structure and function of the capsule in a prokaryotic cell?
Some prokaryotes have a capsule made up of secreted slime. It helps to protect the cell from attack by cells of the immune system
What is the structure and function of plasmids in a prokaryotic cell?
Plasmids are small loops of DNA that aren’t part of the main circular DNA molecule. Plasmids contain genes for things like antibiotic resistance, and can be passed between prokaryotes. Plasmids are not always present in prokaryotes where some have several
What is the structure and function of DNA in a prokaryotic cell?
Prokaryotic cells don’t have a nucleus, the DNA floats free in the cytoplasm. DNA is circular, present as one long coiled up strand. There are no histone proteins attached to it
What is the structure and function of the flagellum in a prokaryotic cell?
The flagellum (plural flagella) is a long, hair-like structure that rotates to make the prokaryotic cell move. Not all prokaryotes. have a flagellum where some have more than one
What is the structure and function of the cytoplasm in a prokaryotic cell?
The cytoplasm of a prokaryotic cell has no membrane-bound organelles. It has ribosomes but they’re smaller than those in a eukaryotic cell
Are viruses cells?
Viruses are acellular - they’re not cells. Viruses are just nucleic acids surrounded by a protein
Are viruses smaller or bigger than bacteria?
Smaller
Where do viruses replicate?
All viruses invade and reproduce inside the cells of other organisms. These cells are known as host cells
Describe the structure of a virus
Viruses contain a core of genetic material - either DNA or RNA. The protein coat around the core is called the capsid. Attachment proteins stick out from the edge of the capsid. These allow the virus to cling on to a suitable host cell
What is the process called for prokaryotic cells replicating?
Binary fission
Explain the process of binary fission
- The circular DNA and plasmid(s) replicate. The main DNA loop is only replicated once, but plasmids can be replicated more than once
- The cell gets bigger and the DNA loops move to opposite poles of the cell
- The cytoplasm begins to divide and a new cell wall begins to form
- The cytoplasm divides and two daughter cells are produced. Each daughter cell has one copy of each circular DNA, but can have variable number of copies of the plasmid(s)
Explain the process of viruses replicating
- Viruses use their proteins to bind to complimentary receptor proteins on the surface of host cells
- Viruses don’t undergo cell division - they inject their DNA or RNA into the host cell. The host cell then uses it’s own organelles to replicate the viral particles
Do different viruses have the same attachment proteins?
Different viruses have different attachment proteins and therefore require different receptor proteins on host cells. As a result, some viruses can only infect one type of cell where others can infect lots of different cells
