Structure Of Prokaryotic Cells And Of Viruses (3.2.1.2) Flashcards
Part of Cell Structure (3.2.1)
1
Q
What are prokaryotic cells?
A
- Small, single-celled organisms that lack a nucleus and membrane-bound organelles
2
Q
What organelles are found in prokaryotic cells?
A
- Cell wall
- Cell-surface membrane
- A circular DNA molecule
- Ribosomes
- Cytoplasm
3
Q
Describe the structure and function of the cell wall (prokaryotic)
A
- Made of murein, a glycoprotein
- Provides structural support and protection
4
Q
Describe the structure and function of the cell-surface membrane (prokaryotic)
A
- A phospholipid bilayer
- Controls the entry and exit of substances
5
Q
Describe the structure and function of a circular DNA molecule (prokaryotic)
A
- Free in the cytoplasm, not membrane-bound
- Carries the genetic information
6
Q
Describe the structure and function of the ribosomes (prokaryotic)
A
- 70S ribosomes, which are smaller than the 80S ribosomes found in eukaryotic cells
- Site of protein synthesis
7
Q
Describe the structure and function of the cytoplasm (prokaryotic)
A
- Lacks membrane-bound organelles
- Contains enzymes and structures needed for cellular processes
8
Q
What structures may be present in a prokaryotic cell?
A
- A capsule surrounding the cell wall
- Plasmids
- Flagella
9
Q
Describe the function of structures that may be present in a prokaryotic cell?
A
- Capsule → slimy layer of protein, prevents the bacteria from drying out and protects the bacteria against the host’s immune system
- Plasmids → small loops of DNA that carry additional genes
- Flagella → rotates to enable the bacteria to move
10
Q
What are the differences between eukaryotic and prokaryotic cells?
A
- Nucleus present / No nucleus present
- Membrane-bound organelles present / No membrane-bound organelles present
- Larger 80S ribosomes / Smaller 70S ribosomes
- Linear DNA / Circular DNA
- If the cell wall is present, does not contain murein / Cell wall contains murein
- No plasmid DNA present / May have plasmid DNA present
11
Q
What are viruses?
A
- Acellular and non-living particles containing no nucleus, no organelles, no cell-surface membrane and no cytoplasm
- Are much smaller than bacteria
12
Q
What do all viruses contain?
A
- Genetic material
- A capsid, consisting of protein
- Attachment proteins on the outside
13
Q
What may some viruses contain?
A
- An envelope
14
Q
How do viruses work?
A
- Attach using their attachment proteins, which are complementary to receptors on the host’s cell surface membrane
- Once attached they infect host cells, replicate and often cause the host cell to burst
- Some viruses also produce toxins that harm the host
