Prokaryotic cells and viruses Flashcards
How are prokaryotes different to eukaryotes?
Eukaryotes are larger and have a nucleus bounded by a nuclear membrane (the nuclear membrane) whereas prokaryotes either have no nucleus or no envelope.
All bacteria have a cell wall, what is it made of?
Murein, this is a polymer of polysaccharides and peptides.
How do many bacteria protect themselves?
By secreting a capsule of mucilaginous slime around the wall.
Within the cytoplasm which ribosomes do bacteria cells have?
70s (smaller than those in eukaryotes but still synthesise proteins).
What does bacteria store food reserves as?
Glycogen granules and oil droplets.
In what form is the genetic material in a bacteria?
Circular strands of DNA, separate from this are smaller circular pieces of DNA (plasmids)
What can plasmids do?
Reproduce themselves independently and may give the bacterium resistance to harmful chemicals such as antibiotics.
Role of cell wall for bacteria cell?
Physical barrier that excludes certain substances and protects against mechanical damage and osmotic lysis.
Role of capsule in bacterium?
Protects bacterium from other cells and helps groups of bacteria to stick together for further protection.
Role of cell-surface membrane in bacterium?
Acts as a differential permeable layer, which controls the entry and exit of chemicals.
Role of circular DNA in bacterium?
Possesses the genetic information for the replication of bacterial cells.
What is the role of plasmids in a bacterium?
Possesses genes that may aid the survival of bacteria in adverse conditions e.g. produces enzymes that may break down antibiotics.
I’m prokaryotes, is DNA associated with proteins?
No.
Prokaryotes don’t have chloroplasts but what do some bacteria have?
Bacterial chlorophyll associated with the cell-surface membrane.
What are viruses?
Acellular, non-living particles.
