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reproduction - Coggle Diagram

- - - - RULES OF INHERITANCE: mendel worked out main rules for such inheritance
        
        only one of the parental traits
        was seen, not some mixture of the two.
        
        two copies of factor (genes) controlling traits are present in sexually reproducing animals. These two may be identical, or may be different, depending on the parentage.
        
        T: dominant traits
        
        t: recessive traits
        
        the tall/short trait and the round
        seed/wrinkled seed trait are independently inherited
      - How do traits get expressed?
        
        Cellular DNA: information source for making protein
        
        GENE: A section of DNA for making one protein
        
        Proteins control traits
        
        In a progeny, a gene set is present as 2 separate independent pieces called a chromosome.
        
        Every germcell will take one chromosome from each pair
        
        When two germ cells combine, they will restore the normal number of chromosomes in the progeny, ensuring the stability of the DNA of the species.
      - Sex determination
        
        Different species use very different strategies
        for this.
        
        in a few reptiles, temperature the egg is fertilised at determines if its male or female
        
        IN snails, individuals can change sex,
        indicating that sex is not genetically determined
        
        In human beings, the sex of the individual is largely
        genetically determined.
        
        WE HAVE 22 PAIRS OF CHROMOSOMES
        
        One of them is sex chromosome which is not always the perfect pair.
        
        women have perfect pair XX
        
        men have XY
        
        you sex is determined by what you inherit from your father
  - - - natural selection
      - genetic drift: accidents in small populations can change the frequency of some genes in a population, even if they give no survival advantage
      - acquired traits : change in non-re in non-reproductive tissues cannot be passed on to the DNA of the germ cells