Prokaryotic cells and viruses Flashcards
What is the description and function of the plasma membrane?
It is made of lipids and proteins and controls the movement of substances into and out of the cell.
What is the description and function of the cell wall?
Made of a glycoprotein called murein, it supports the cell and prevents it changing shape.
What is the description and function of the slime capsule?
It helps to protect the bacteria from attack by cells of the immune system.
What is the description and function of the plasmids?
They are small loops of DNA that contain different genes to the main DNA and can be passed between prokaryotes.
What is the description and function of the circular DNA?
DNA that floats free in the cytoplasm, it is circular and forms one long coiled up strand that doesn’t attach to any histone proteins.
What is the description and function of the flagellum?
It rotates to allow the cell to move.
What is the description and function of the cytoplasm?
It contains no membrane bound organelles. It contains ribosomes but they are smaller than eukaryotic cells. It is the site of chemical reactions.
What is the process of bacterial cell division and how does it work?
Binary fission, the circular DNA and plasmids replicate, but plasmids can be replicated multiple times. The cells get bigger and the DNA moves to opposite poles. The cytoplasm divides and tow daughter cells are produced. Each daughter cell contains a single copy of the circular DNA molecule and a variable number of plasmids.
Describe the structure of a virus?
They have a nucleic acids core of either DNA or RNA. A protein coat called a capsid surrounds the core and attachment proteins stick out from the capsid and these let viruses cling to a suitable host cell.
How do viruses replicate?
They use attachment proteins to bind to the complementary receptor proteins on the surface of the host cell. The virus then injects its DNA or RNA into the host cell. The cell will then use its nucleic acid and protein building machinery to produce new viral particles. Eventually, the new viral particles are released, when the host cell bursts.
