Cell Division Flashcards
Cell continuity
Means that all cells develop from pre-existing cells
Chromatin
Chromosomes that are not dividing ( during interphase)
Chromosomes
Threads of DNA and protein that become visible in the nucleus at cell division
Haploid cell
One set of chromosomes
Diploid cell
Two sets of chromosomes
What are body cells also called
Somatic cells
What human cells contain 23 chromosomes
Sperm and egg cells
What does the cell cycle contain
90% Interphase mitosis 10%
Interphase
Phase in the cell cycle when the cell is not dividing
What is interphase used for
Processes like respiration,photosynthesis and protein synthesis
Mitosis
A form of nuclear division which one nucleus divises to form two nuclei, each with identical gene in somatic cells (body cell)
What is Mitosis used for
Multicellular growth and repair
Unicellular - reproduction
What are the stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
Describe prophase
Chromatin contract and chromosomes become visible.
Nucleolus disappears and spindle fibres appear in the cytoplasm.
The nuclear membrane starts to break down
Describe Metaphase
The nuclear membrane disappears completely.
A spindle fibre from each pole attaches to the centrometers of all the chromosomes. Chromosomes line up across the middle of the cell
Describe Anaphase
Spindle fibres contract and pull chromosomes to opposite poles of the cells
Describe Telophase in plant cells
Chromosomes lengthened and turn into chromatin. Spindle fibres breakdown and the nucleoli reform
Cytokineses from immediately after mitosis.
In Plants, cleavage cannot occur due to cell walls, a cell plate forms, the region between the cell walls is called the middle lamella
Describe Telophase in Animals
Chromosomes lengthened and turn into. Spindle fibres breakdown and the nucleoli reform
Cytokineses from immediately after mitosis.
A cleavage furrow forms
What is cancer
When cells lose their ability to control both the rate of mitosis and the number of times mitosis takes place
What are tumours
Masses of cancerous cells
What are benign tumours
Benign tumours do not spread to other tissue
Malignant tumours
Malignant tumours spread and are life threatening
What is cancer caused by (with examples)
Cancer is caused by carcinogens
( radiation, cigarette smoke)
Examples of Cancer treatment
Surgery to remove tumours , radiation to kill cancer cells, chemotherapy (stops cell division)
What is Meiosis
Nuclear division which the daughter nuclei contain half the chromosome number of their parent nucleus
Functions of Meiosis
Allows for sexual reproduction while maintaining the chromosome number.
Allows for variation among organisms
Differences between Mitosis and Meiosis
Mitosis
Chromosome number maintained
1 parent 2 daughter cells
Daughter cells identical to parent
Meiosis
Chromosome number halted
1Parent 4 daughter cells
Gametes different to parent genes
