12. Cell Division Flashcards
Cell continuity def
Means all cells develop from pre existing cells.
3 steps to form a new cell
- Produce new materials.
- Grows larger
- Reproducing to form a new cell
When (not) dividing what shape is the chromosomes in?
When not dividing chromosomes are long thin threads called chromatin.
When dividing the chromatin forms a number of clearly distinguishable chromosomes.
Chromosome def. and how many in each cell
A coiled thread of DNA and protein found in the nucleus.
23 pairs in each cell, 46 single chromosomes
Role of genes and what they are
Responsible for inheritance and characteristics.
Sections of DNA on the chromosome.
This DNA has the info for forming proteins
Difference between haploid and diploid
Haploid: has one of each set of chromosomes. Symbolised by ‘n’. No. of chromosomes = 23. Eg. Egg and Sperm
Diploid: has two of each set of chromosomes. Symbolised by ‘2n’. No. of chromosomes= 46. Eg. Every cell in the body.
Cell cycle def.
Changes that occur in a cell between one cell division and the next.
Parts of the cell cycle
Interphase: The phase when the cell is not dividing.
Mitosis/Meiosis: when cell is dividing.
What happens during interphase
Is an active stage. Cell is not dividing. Chromosomes appear as chromatin. 1. New cell organelles formed. 2. Forms enzymes needed for growth and division. 3. Chromosomes become visible as single strands. 4. They replicate 5. They then duplicate.
Replication
When chromosomes make identical copies.
Duplication
When cells pair up
Stages of mitosis
Prophase, Metaphase, Anaphase, Telophase.
Party Monday and Tuesday
Prophase
Nuclear membrane disassembles.
Nucleolus disappears.
Spindle fibres form in the cell
Metaphase
Chromosomes line up in the equator of the cell.
Spindle fibres go to poles.
Spindle fibres attach to the chromosomes at the centromere.
(Metaphase:Middle)
Anaphase
Spindle fibres contract and pulls the chromosome to the pole.
(Anas dad the builder pulls apart, he’s a contractor)