Cell division Flashcards
Where are all cells derived from?
Pre existing cells
What are new cells produced for?
For growth and to replace damaged or old cells
What must happen to DNA before cell division?
Must be copied or replicated, so that each new cell will have an identical copy of the DNA
What form is the DNA of prokaryotes (bacteria) ?
One circular chromosome attached to the inside of the cell membrane
How do eukaryotic cells store genetic information?
In Chromosomes
How many chromosomes do eukaryotes have in their body cells?
Between 10-50
How many chromosomes do humans have?
46 or 23 identical pairs
What form are eukaryotic chromosomes in?
Each chromosome is composed of a single tightly coiled DNA molecule. Chromosomes can’t be seen when cells aren’t dividing and are called chromatin
How is DNA compacted into chromosomes?
DNA is tightly coiled around proteins called histones
What are chromosomes in dividing cells called?
Duplicated chromosomes are called chromatids and are held together by the centromere.
What are the first 22 pairs of chromosomes called?
Autosomes
What are the last pair of chromosomes?
The last pair are sex chromosomes, XX female and XY male
What does asexual reproduction involve?
One single cell dividing to make 2 new identical daughter cells. ( examples are mitosis and binary fission)
What does sexual reproduction involve?
Two cells (egg and sperm) joining to make a new cell (zygote) that is not identical to the original cells. Meiosis is an example
Cell division in prokaryotes?
- Prokaryotes such as bacteria divide into two identical cells by the process of binary fission.
- Single chromosome makes a copy of itself
- Cell wall forms between the chromosomes dividing the cell
What is G1 in the Cell cycle?
Primary growth phase
What is S in the cell cycle?
Synthesis- DNA replication
What is G2 in the cell cycle?
Secondary growth phase
What is interphase in the cell cycle?
G1, S, and G2
What is M in the cell cycle?
Mitosis
What is C in the cell cycle?
cytokinesis
What order do the five phases of the cell cycle happen?
G1, S, G2, M, and C
What happens in G1?
The first growth stage after cell division. Cells mature by making more cytoplasm and organelles.The cell carries on its normal metabolic activities during this stage
What happens in S in the cell cycle?
Synthesis stage, DNA is copied or replicated two produce two identical copies
What happens in G2 in the cell cycle?
The second growth stage, occurs after DNA has been copied. All cell structures needed for cell division are made (eg centrioles). Both organelles and proteins are synthesised
What happens in interphase in the cell cycle?
DNA replicates, centrioles if present replicate, cell prepares for division
What happens in Mitosis?
- Division of the nucleus
- Also called karyokinesis
- Only occurs in eukaryotes
- Has four stages
- Doesn’t occur in some cells such as brain cells
