Structure of prokaryotic cells and viruses Flashcards
What is a prokaryotic cell?
Prokaryotic cells are unicellular that lack a nucleus and membrane-bound organelles
Where are prokaryotic cells found?
- Bacteria
- Archaea
Are prokaryotic cells smaller or bigger than eukaryotic cells?
Smaller
What is the structure of prokaryotic cells?
- Cell-surface membrane
- Cytoplasm
- Cell wall made of murein
- 70S ribosomes
- Circular DNA
- Plasmids
- Some have a capsule
- Some have flagella
- Some have pili
Do prokaryotic cells have membrane-bound organelles?
No
What type of ribosomes do prokaryotic cells have?
70S ribosomes
Do prokaryotic cells have a nucleus?
No
- They have a single circular DNA molecule that is free in the cytoplasm and is not associated with proteins
Do prokaryotic cells have a cell wall?
Yes
- Made of murein which is a glycoprotein
Do prokaryotic cells contain plasmids?
Yes but not always
- Can contain one or more
Describe the function of plasmids
Plasmids carry genes that can be passed between prokaryotes
Some prokaryotic cells may have an extra layer around the cell wall. What is this called?
A capsule
Describe the function of a capsule around the cell wall
Protective slimey layer which helps the cell to retain moisture
Do prokaryotic cells have flagella?
Yes but not always
- Can contain one or more
Describe the function of flagella
It rotates to enable the cell to move
What are the similarities between eukaryotic and prokaryotic cells?
- Both have DNA
- Both have a cell membrane
- Both contain cytoplasm
- Both have ribosomes
What are differences between eukaryotic and prokaryotic cells?
- Eukaryotic cells have a nucleus, prokaryotic cells don’t
- Eukaryotic cells have linear DNA, prokaryotic cells have circular DNA
- Prokaryotic cells don’t have membrane-bound organelles, eukaryotic cells do
- Eukaryotic cells have 80S ribosomes, prokaryotic cells have 70S ribosomes
- Prokaryotic cells have cell wall made of murein, eukaryotic cells have cell walls made of either cellulose (plants) or chitin (fungi)
- Prokaryotic cells may have a capsule, eukaryotic cells don’t
How do prokaryotic cells replicate?
Binary fission
Describe the process of binary fission
- Circular DNA and plasmids replicate (circular DNA replicates once, plasmids can replicate many times)
- Cell gets bigger and DNA loops move to opposite poles
- Cytoplasm begins to divide and a new cell wall begins to form
- Cytoplasm divides and 2 daughter cells are produced
What is a virus?
An acellular non-living particle
Describe the structure of a virus
- Protein capsid
- Attachment proteins on capsid
- DNA or RNA core
How do viruses replicate?
By infecting host cells
Describe the process of viral replication
- Virus uses attachment proteins on its surface to attach to complementary receptor proteins of a host cell
- Virus inject their DNA or RNA into host cell
- Host cell uses its nucleic acid and protein-building machinery to produce new viral particles
