Mitosis and meiosis

Note by , created about 6 years ago

Biology Note on Mitosis and meiosis, created by Tomsie on 06/07/2013.

Created by Tomsie about 6 years ago
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Mitosis Growth and repair Produces diploid cells identical to each other and the parent cell  Meiosis  Sexual reproduction Produces haploid cells different to each other and the parent cell

GrowthHumans are made up of millions of cells, benefits: Can be specialized to do  particular tasks Groups of cells can function as organs making a more efficient organism  Organism can grow very large  Cell division  New cells needed throughout life For growth; replace damaged cells and worn down tissues   Normal human body cells are diploid that have two of each chromosome   When new cells are made the 46 chromosomes are copied exactly  by mitosis  Mitosis Type of cell division used for growth, repair and asexual reproduction Occurs whenever new cells are created  Produces two cells the exact same and the parent cells  In mitosis each chromosome is copied then new chromosomes moved to opposite side of the cell before the cell divides, leaving on set of 46 chromosomes in two new cells


Formation of Sex Cells All human reproduction is sexual Joining together haploid gamete cells from each parent half the normal number of chromosomes  This makes a new cell with both the parents genetic material  This is called a diploid zygote  Male gamete is sperm and females is the egg  When the sperm and egg join they create a zygote cell Sperm contains 23 chromosomes and egg contains 23, when together they make a human zygote with 46 chromosomes containing genetic material from both parents  This is called meiosis that's used to produce cells for repair and asexual reproduction  Gametes contain different genetic material to each other and to the parent cell Meiosis responsible for genetic variation

Process of fertilisation

Helpful terms: Gamete – cell with half the normal number of chromosomes, and only used for sexual reproduction Zygote – cell formed when two gametes combine Fertilisation – term to describe the joining of two gametes Haploid – having half the normal number of chromosomes Diploid – having the normal number of chromosomes

Gametes Are all haploid Other adaptions to increase chances of fertilization and development in the embryo  Sperm cells have a tail to propel them to the egg; more mitochondria to provide more energy and enzymes at the front to digest the eggs membrane Egg cells contain large food stores to support the zygote before it can feed from the placenta  

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