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Meiosis
Read Pg. 98 and 99 and complete a Venn Diagram comparing sexual and asexual reproduction. Make a list of all vocabulary words that are important.
Asexual reproduction (mitosis)
Sexual reproduction(meiosis)
Read Pg. 98 and 99 and complete a Venn Diagram comparing sexual and asexual reproduction. Make a list of all vocabulary words that are important.
Asexual reproduction (mitosis)
Sexual reproduction(meiosis)
• 1 parent
• Exact copies of
the parent cell
• Somatic cells
• Types of
reproduction
in living things
• Pass DNA
• 2 parent
• Daughter cells
are diverse
• Traits from each
parent
• Sperm and egg
CHROMOSOMES
In the nucleus of each cell, the DNA molecule is packaged into structures called chromosomes.
CHROMOSOMES
Each chromosome is made up of DNA tightly coiled.
CHROMOSOMES
Do all living things have the same types of chromosomes?
Cat 38 Cotton 26
Chicken 78
Chimpanzee 48
CHROMOSOMES
Humans Chromosomes
SOMATIC VS SEX CELLS
SOMATIC CELLS
Each one contains 46 chromosomes (23 pairs).
Chromosomes that carry the same set of genes are called
homologous (like a pair of shoes).
Diploid (2n) cells
Skin cells Eye cells Liver cells
SEX CELLS (gametes)
Each one contains 23 chromosomes, half of the usual.
Each sex cell (sperm and egg) has only one of the
chromosomes from each homologous pair.
Haploid (n) cells:
Egg Sperm
SOMATIC VS SEX CELLS
MITOISIS
Somatic cells clone themselves with the process of mitosis. Mitosis replicates a cell with a complete set of 23 chromosomes identical to each other.
MEIOSIS
Specialized diploid cells split in half twice to create four separated cells each one genetically different.
♂Male - Germ-line cell
Diploid (2n)
♀ Female - Germ-line cell
Diploid (2n)
↓Meiosis↓
Sperm Haploid (n)
Egg Haploid (n)
↓Fertilization↓
OffspringDiploid (2n)
MEIOSIS
The stages of meiosisReplication 1 Each chromosome make an exact copy of itself (Idem mitosis)
Meiosis IResult in two diploid cells
2 Arrenging: each chromosome (now made of two identical chromatids) pair with its homologous chromosomes at the equator of the cell.
3 Chromosomes separate and move to opposite ends of the cell.4 Nuclear membrane is formed.
Meiosis IIResult in four haploid cells
5 Each cell contains one member of each homologus chromosome pair.6 Arrenging II: line up at the equator.
7He chromatids pull appart and move to opposite ends of the cell. Nuclear membrane forms
MEIOSIS
During synapsis, sometimes there is an exchange of homologous parts between non-sister chromatids. This exchange is called crossing over.
MEIOSIS
Complete the following chard with the differences between mitosis and meiosis:
Mitosis Meiosis
DNA Replication
Number of divisions
Crossing over
Number of daughter cells
Chromosome number of products
Functions
MEIOSIS
Complete the following chard with the differences between mitosis and meiosis:
Mitosis Meiosis
DNA Replication
Number of divisions 1 2
Crossing over X
Number of daughter cells 2 4
Chromosome number of products 2n n
Functions Somatic Reproduction