Genetics

Genetics

Heredirty
1. The set of characteristics that you inherit from your parents e.g. hair colour
The study of hereditry
True-breeding
1. plants are those that constantly produce offspring the same as the parents for a particular trait
Mendel
1. The Father of Genetics
2. Dominant Trait
  1. the trait that appeared in the F1 generation
  2. Recessive Trait
    1. trait that was masked in F1 and appeared in F2 generation
3. Gamates
  1. Reproductive cells e.g ova in females, sperm in males
  2. Only have half the NUMBER of chromosomes
  3. Also called haploid cells
Genes
1. a hereditry unit that controls a particular characteristic
2. made up of Deoxyribonuclei Acid (DNA)
Chromosomes
1. genes are found on them
2. found in the nucleus of body cells
3. long and coiled thread like structure made of DNA and protein
4. many thousand genes along its length
Diploid Cells
1. all cells in your body
2. the chromosomes exist in pairs based on size and shape
3. contain the full set of chromosomes (46)
Homologous pair
1. one pair from your mum one from your dad
2. homo = same
Environment
1. the set of factors that have acted on you throughout your entire life
Zygote
1. a new cell formed when a egg and sperm cell meet
2. have the full number of chromosomes as half came from the father and half came from the mother
Males
1. XY
2. half the sperm carry X and the other carry Y
Females
1. XX
Mitosis
1. when each cells divides and the resulting daughter cell each recieves a copy of the parent cells chromosomes
2. each daughter cell is an exact copy of the parent cell
3. e.g. hair growing, fingernails growing
Meiosis
1. cells seperate randomly to produce different types of gamates
2. cell division to produce gamates with half the number of the parent cell
Alleles
1. different forms of the same gene
2. Dominant Allele
  1. will always be expressed by showing its physical appearance and by using a capital letter
  2. you only need one dominant allele to show the appearnace
  3. we use a capital letter
  4. e.g.Green pea ( GG or Gg)
3. Recessive Allele
  1. will always be masked or hidden by the dominant allele
  2. we use a lower case letter
  3. if a recessive trait shows up then there will be 2 recessive alleles present
  4. e.g. Yellow pea (gg)
Genotype
1. the different combinations of the parents genes
Phenotype
1. The physical appearance produced by a genotype
  1. e.g. the physical characteristic is green (phenotype) thus the possible genotype is GG or Gg
Punnet Squares
1. can be used to predict the results of reproduction (crossing) between different organisms
Co-Dominance
1. the phenotype of the heterozygous organism is a COMBINATION of the phenotypes of the heterozygous organisms
Homozygous
1. both genes or alleles are the SAME
2. homo = same
Heterozygous
1. both genes or alleles are DIFFERENT
  1. hetero = different
Incomplete Dominance
1. a cross between organisms with two different phenotypes produce offspring with a third phenotype that is a BLENDING of the parental traitrs
Blood type
1. controlled by genes
2. A type
  1. AA or AO
3. B type
  1. BB or BO
4. AB type
  1. AB
    1. co dominance
5. O type
  1. OO
    1. recessive
Pedigrees / Family Trees
1. show the phenotypes of related individuals over a number of generations
  1. Female is a circle
    1. Male is a square
Sex-linked inheritance
1. only occurs on the sex chromosomes
  1. NO GENES ON THE Y CHROMOSOME
  2. carrier is not counted as healthy
    1. e.g. is a female has a gene for Haemophilia and a gene for a normal gene on the other she will have no blood issue but will be able to pass it onto offspring
DNA
1. a long molecule with two strands twisted together to make a double helix
  1. the ladder uprights have a chain of alternating sugar and phosphate units
    1. The ladder rungs have pairs of special molecules called nitrogen bases
      1. there are 4 different nitrogen bases
        A = adenine
        T = thymine
        C = cytosine
        G = guanine
        C and G can ONLY pair with each other
        A and T can ONLY pair with each other
2. when a piece of DNA is copied EXACTLY it is called replication
  1. the strands first unzip
    1. an exact copy is then made by matching each base with its complementary base
      1. once a section is copied, one old and one new strand are zipped together to produce a duplicate DNA

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