Asexual reproduction - no fusion of gametes and 1 PARENT. No mixing of genetic info so offspring are genetically identical. MITOSIS is involved.
MITOSIS - M (aking) I(identical) T(wo)
Sexual reproduction - joining of male and female gametes formed by MEOSIS which leads to non identical cells. Sperm and egg in animals or pollen and eggs in flowers or plants. There is mixing of genetic info so theres variation.
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B12.2 - Cell division in sexual reproduction...
Cells in the reproductive organs divide to form the gametes.
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Meiosis and how it works...
All gametes are genetically different from each other.
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B12.3 - DNA and the genome..
Genome = entire gentic material.
The genome can help,
the search for genes linked to diseases
treated inherited disorders
tracing past human migration patterns
DNA - genetic material in the nucleus. Also a polymer made up of 2 strands forming a double helix.
A gene - a small section of DNA in a chromosome which has a sequence to make amino acids.
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B12.4 - Inheritance in action....
An allele is a different form of a gene.
phenotype - physical appearance of charecterisitic.
genotype - genetic makeup determined by inherited allele
Homozygous - two same alleles.
Heterozygous - two different alleles.
Dominant allele - Always is a capital letter on punnet square and empowers reccesive.
Reccesive allele - Lower case letter on punnet square and is empowered by dominant allele.
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B12.5 - More about genetics and Punnet squares...
Human body - 23 pairs of chromosomes.
Females are represented by **
Male represented by XY
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Punnet squares...
25% chance or 1/4
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Example 2...
0% chance as there is always a dominant (non cystic fibrosis) that overpowers it.
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Inherited Disorders -
cystic fibrosis - recesive allele, must be inherited from both parents.
Polydactly - dominant allele, must be inherited from both parents.
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B12.7 - screening for genetic disorders...
Embreyo cells can be screened to detect inherited disorders.
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