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molecular genetics (the complete set of genetic information of a organism…

- - - - a sperm cell fuses with an
        egg cell to form a
        zygote, this is a new cell (gametes/sex cells)
        
        the gametes are haploid cells made from meiosis, they then fuse during fertilization to make a zygote witch is a diploid cell. after this the zygote grows and repairs itself using mitosis
      - fertilization is a random event - so witch male and female gametes fuse together is random
      - the zygote is the first stage of life= it contains all the instructions for growth and development of the entire organism.
    - - meiosis =
        makes 4 unique cells for reproduction
        
        to make sex cells/gametes,
        for sexual reproduction
        (haploid cells -23 chromosomes)
        
        2 different types for each species ( e.g. egg & sperm)
        
        - has 2 stages
        
        How it happens:
        (once the DNA replicates it forms 2 new diploid cells, then these cells divide in half to form 4 haploid cells/gametes)
        
        chromosomes are rearanged, to form new combinations of alleles every time a new gamete is made
        = genetic recombination , important as a sourse of gentic variation
        
        because the same alleles don't devide into the 4 haploid cells every time. (it is the same ingredients just mixed and matched in different orders)
        
        during meiosis/gamete formation:
        
        the homologous chromosomes separate
        
        gametes inherit 1 of each pair
        (witch one they get is just random),
        this is so the chromosome number stays the same through the generations
        
        this is due to the prossess of independent assortment during meiosis
      - mitosis =
        makes 2 identical daughter cells ( idnetical to the parent)
        for an organism to grow, repair and replace
        
        makes body/somatic cells (diploid cells - 46 chromosomes)
        
        every cell in your body does mitosis (even the sex organs)
        
        each cell has identical chromosomes/genes
        
        e.g. replace old cells, repair damaged tissue & make us grow
        - has 1 stage
    - - through mitosis a cell always divides into 2 cells
      - through meiosis a cell always divides into 4 cells
      - (DNA = a semi-conservative process
        this is because the 2 new DNA molecules that have been replicated each have 1 old strand and 1 new strand)
      - How the chromosome/DNA replicates:
        1) the DNA strands unwind from its twisted double helix.
        2) the enzyme (helicase) causes the 2 strands/sides of the chromosome molecule to unzip/separate
        3) the unzipped bases ( on both sides) become exposed to other contents of the nucleus ( in the nucleus sap, there are free nucleotides)
        4) the free nucleotides in the nucleus sap join with the now separates strands, and form bonds with the complementary bases on the DNA strands.
        5) once the new bases are complete( bonded) you have to new DNA molecules formed ( identical to the original unless there was a mistake / mutation