B12 - Reproduction

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B12 - Reproduction

B12 - Reproduction 

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B12. 1 - Types of reproduction...

  • 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...

chromosomes divide, similar chromosomes pair up, sections of DNA get swapped, pairs of chromosomes divide, chromosomes divide  (http://www.bbc.co.uk/staticarchive/b899469e2e9c542b546c6b8606499133ce34097c.gif)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...

f is the cystic fibrosis allele. Mother and father both have one F and one f allele. The four combinations of allele are: FF, Ff, Ff, ff.  (http://www.bbc.co.uk/staticarchive/229258ad0480868953b60abd723d99a9df9aefbd.gif)25% chance or 1/4

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Example 2...

f is the cystic fibrosis allele. Mother has two F alleles, father has one F and one f allele. The four combinations of allele are: FF, FF, Ff, Ff.  (http://www.bbc.co.uk/staticarchive/f19d189da8b1f2c053e437c72cc59076eddbc437.gif)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.
  • It has social economic and environmental issues
  • May not be reliable. 
  • Risk of miscarrige. 
  • Very emotional. 
  • Religious restrictions. 
  • expensive. 
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Comments

Clare Jones

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Spelling errors and definitions of dominant and recessive not worded well.

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