1.4 - Cell Division Flashcards
Why do all Multicellular Organisms require a continuous supply of new Cells?
- Growth
- Development
- Repair
What are the 3 Stages of the Cell Cycle?
- Growth
- DNA Replication + Mitosis
- Division (Cytokinesis)
What happens in the Growth stage of The Cell Cycle?
- The Cell Grows in Size.
- The number of sub-cellular structures (e.g. Mitochondria & Ribosomes) Increase.
What happens in the DNA Replication Stage? (M)
- The DNA is Duplicated
- So each new cell has a full set of DNA.
How is the DNA placed in a Cell that is not Dividing?
- Spread out into Long Strings.
When a Cell starts to Prepare for Division, what happens to the DNA?
- DNA Condenses into Chromosomes.
What are Chromosomes?
- Coiled up packets of DNA.
What does the DNA in Chromosomes contain?
- A large number of Genes.
- These control the Development of different Characteristics.
What are the two copies of Chromosomes called?
- A ‘Pair’.
- One copy is from mother, other copy is from father.
How many Chromosomes do Humans have?
- 23 Pairs
- 46 Singular
When each Chromosome is Duplicated what happens?
- Each Duplicate stays attached to the original, forming an X Shape.
What is each half of the Duplicated Chromosome called?
- An Arm
What happens when a Cell is ready to Divide?
1 ) All of the Cell’s Chromosomes line up along the centre of the Cell.
2 ) Cell fibres from both sides of the cell attach to their respective half of each Chromosome.
3 ) Cell fibres pull the arms of the Chromosomes to opposite sides of the cell (Poles).
4 ) The Chromosomes are broken in half into two separate arms.
What happens during the final stage of The Cell Cycle (Cytokinesis)?
- The Cell Membrane and Cytoplasm pull apart forming two genetically identical Daughter Cells.
What is the Definition of Binary Fission?
The Process by which Prokaryotic Organisms Divide and Reproduce.
What kind of Division/Reproduction is Binary Fission?
Asexual Reproduction
What does a Bacterial Cell need to do before it can Divide?
- Grow
- Replicate Genetic Material
What does a Bacterial Cell do after Replicating it’s DNA?
- The Nucleoids move to either side of the cell.
- The Plasmids are arranged randomly.
What does a Bacterial Cell do when it’s ready to Divide?
- It grows a new Cell Wall down the middle of the Cell.
- When this Cell Wall is complete the two halves pull apart.
What is the Mean Division Time of a Cell?
How long it takes to divide on average.
What are the Optimal Conditions for Bacteria to grow in?
- Warm
- Moist
- Plenty of Nutrients
