ocr 21st century science B1
- Created by: Amber-Jade
- Created on: 21-11-12 16:52
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- B1-You and your genes
- Variation
- Order of size (large to small): Cell, nucleus, chromosomes, DNA, gene, base
- Nucleus, DNA and proteins provide instructions. Your diet is the ingredients.
- Functional Proteins: enzymes - anylase, protease
- Nucleus, DNA and proteins provide instructions. Your diet is the ingredients.
- Structural proteins: e.g. hair, skin, blood, cytoplasm
- Functional Proteins: enzymes - anylase, protease
- Functional Proteins: enzymes - anylase, protease
- Gender and the rule of genes
- Normal cells contain 23 pairs of chromosomes. Sex cells contain 23 single chromosomes. Pair 23 determines the gender. Women = **, Men = XY.
- Genotype = genetic make up, e.g. Ff, FF, ff. Phenotype = physical expression of a gene, e.g. brown hair
- Homozygous = same two identical alleles, e.g. FF, ff. Heterozygous = different alleles for an inherited characteristic, e.g. Ff
- allele = different versions of the same gene on a chromosome
- Inherited disorders
- Dominant disorders - need only one copy
- Huntington's disorder - no carriers because of dominance
- affects nervous system - causes involuntary movement, dementia
- Huntington's disorder - no carriers because of dominance
- Recessive genes - weak, need 2 copies
- Cystic Fibrosis - can have carriers
- affects cells membrane - causes thick, sticky mucas in lungs, gut, pancreas
- Cystic Fibrosis - can have carriers
- Dominant disorders - need only one copy
- Embryo Selection
- PGD - preimplantation genetic diagnosis. Take fertility drug; doctor collects egg; sperm fertilise in petri dish (in vitro fertilisation); at eight cells, one cell is removed; tested for disorders; healthy embryos returned to womb
- not 100% accurate (false negative and false positive)
- Cloning
- Stem cells - unspecialised, found in marrow and embryos; can grow into any type of cell
- Natural clone = identical twins as the fertilised cell splits
- not always identical because of the evironment
- unicellular = one celled organism
- asexual reproduction
- Variation
- Ethics
- Embryo Selection
- PGD - preimplantation genetic diagnosis. Take fertility drug; doctor collects egg; sperm fertilise in petri dish (in vitro fertilisation); at eight cells, one cell is removed; tested for disorders; healthy embryos returned to womb
- not 100% accurate (false negative and false positive)
- HFEA - a regulating body.
- Scientists - framework, for the greater good population
- Politicians - rights
- Indervidual's consent
- Choices: adopt, test (chance of miscarriage), abortion, no tests (could have disorder)
- Embryo Selection
- Egg cell = X, Sperm cell = X or Y. 50% chance of each gender, Sperm decide.
- Normal cells contain 23 pairs of chromosomes. Sex cells contain 23 single chromosomes. Pair 23 determines the gender. Women = **, Men = XY.
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