Structure Of Prokaryotic Cells And Of Viruses Flashcards
Differences between prokaryotic cells and eukaryotic cells
- prokaryotic cells are smaller whereas eukaryotic cells are larger
- prokaryotic cells are not membrane bound organelles whereas eukaryotic cells are membrane bound organelles
- prokaryotic cells have smaller 70s ribosomes whereas eukaryotic cells have larger 80s ribosomes
- prokaryotic cells have no nucleus whereas eukaryotic cells have nucleus
- prokaryotic cells have a cell wall made of murein whereas eukaryotic cells have cell walls made of cellulose
What may a prokaryotic cell contain?
- plasmids
- a capsule around the cell
- flagella
What organelles do prokaryotic cells have compared to eukaryotic cells?
- prokaryotic cells have ribosomes whereas eukaryotic cells have ribosomes, mitochondria, chloroplast, endoplasmic reticulum, Golgi and nucleus
- no membrane bound organelles
Which ribosomes do prokaryotic cells contain compared to eukaryotic cells?
- prokaryotic cells contain 70s smaller ribosomes found in prokaryotes, mitochondria and chloroplasts whereas eukaryotic cells contain 80s larger ribosomes (25nm)
Compare the nucleus is eukaryotic cells with prokaryotic cells
- prokaryotic cells do not have a nucleus, they have a singular circular DNA molecule free in the cytoplasm which is not protein bound whereas eukaryotic cells contain nucleus with nuclear envelope, pores, nucleoplasm, chromosomes and nucleolus
Compare the cell walls of prokaryotic cells and eukaryotic cells (plants and fungi)
- prokaryotic cell walls contain murein a glycoprotein whereas plants contain cellulose and fungi contain chitin which is a nitrogen containing polysaccharide
Plasmid
- small loops of DNA which only carry a few genes
Capsule
- slimy layer made of protein which prevents the bacteria from desiccating (drying out) and protects the bacteria against the hosts immune system
Flagella
- flagella rotates to enable the bacteria to move
What are viruses?
- acellular and non living organisms
What are the features of viruses?
- nucleic acids (RNA or DNA)
- capsid
- attachment protein
What do some viruses have?
- external envelope derived from host plasma membrane
- if present, contains exposed glycoproteins forming spikes allowing attachment to host
What is an example of an attachment protein?
- glycoproteins
What is the function of capsid?
- protects nucleic acids from enzymes when outside host
- binds to host cell surface
- assists in penetration of host and introduction of nucleic acid
What is tobacco mosaic virus characterised by?
- yellow blotches/ spots on leaves of plants; first discovered in Tobacco
Why is tobacco mosaic virus transmitted by?
- aphids
What type of virus is tobacco mosaic virus?
- non enveloped (naked) RNA virus
What shape does tobacco mosaic virus have?
- helical shape
What is (lambda) phage characterised by?
- lysing of bacterial cells around initial infection point; shows as clear areas in bacterial colony
What type of virus is (lambda) phage?
- non enveloped (naked) DNA virus
What shape does (Lambda) phage have?
- complex: polyhedral head and helical tail
Describe the process of binary fission
- Circular DNA and plasmids replicates
- Division of the cytoplasm to produce to daughter cells
What is the formula to find the number of cells after generation?
- N= N0 (initial number) X 2^n (n= number of divisions or generations)
What do logarithm scales show?
- orders of magnitude in a linear fashion
Why is it better to use a log scale?
- larger range of values as numbers increase rapidly
Why do viruses not undergo cell division?
- they are acellular and non living
Describe the steps of virus replication
- Virus attaches to host cell and injects genetic material
- Genetic material used as code to synthesise more nucleic acids and proteins using the host cell
- New virus particles are assembled
- Viruses burst out of, and destroy, host cell
