Binary Fission and Viral Replication Flashcards
What types of organism undergoes either cell cycle or binary fission or viral replication?
Eukaryotes undergo cell cycle.
Prokaryotes undergo binary fission.
Viruses undergo viral replication.
What are the ideal conditions for prokaryotes to replicate rapidly?
Warm temperatures
Lots of nutrients.
What is the formula for working out how many bacterial cells were produced in a certain time?
2ⁿ
n = number of divisions
number of divisions = total time / time it takes for cell to divide once.
A bacterial cell has a mean division time of 30 minutes. How many cells would it produce after 3 hours?
3 hours = 180 minutes
180 / 30 = 6 (number of divisions)
2⁶ = 64
Describe how binary fission is carried out [4 marks]
1# Plasmids and circular DNA makes copies of itself.
2# The 2 copies of DNA move to polar sides of cell and the cell ELONGATES.
3# The plasmids divide RANDOMLY between the 2 sides, and the organelles grow.
4# Cytoplasm SPLITS and membrane folds in.
5# 2 new cells produced with different number of plasmids.
Describe how viral replication is carried out [4 marks]
1# Virus ATTACHES to the protein markers on a host cell using attachment proteins.
2# Virus INJECTS its genetic material into the HOST cell.
3# Host cell transcribes / translates the viral genes.
4# Protein forms NEW virus particles.
5# Virus particles BURST out of host cells and the host cell is destroyed.
Comparing virus replication to binary fission…
Requires host cells
Produces only 2 daughter cells
Cytoplasm is divided
Daughter cell always have
exactly the same amount of
nucleic acid as their parent cell
Involves the replication of
genetic information
Requires host cells ✓
Produces only 2 daughter cells ✓
Cytoplasm is divided ✓
Daughter cell always have
exactly the same amount of ✓
nucleic acid as their parent cell
Involves the replication of ✓ ✓
genetic information
What property determines whether something is alive?
The ability for it to replicate INDIVIDUALLY.
Describe the structure and function of a virus. [4 marks]
A virus consists of…
Genetic material =
ALL viruses contain DNA / RNA.
Capsid =
Protein structure which contains the genetic material.
Attachment proteins =
Allow virus particles to attach and enter host cell.
Lipid envelope =
SOME viruses are surrounded by a lipid envelope formed from the host cell membrane.
What does it mean by viruses are ‘acellular’
Lacking the components of a cell (e.g. ribosomes, membranes, mitochondria…etc)
They are non-living - cannot replicate without a host.
Are bacteria and viruses alive or not?
Bacteria are alive.
Viruses are not alive.
