genes and variation test

  • Created by: tia5sos
  • Created on: 22-11-20 13:38
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  • genes and variation
    • chromosomes are really long molecules of DNA
      • the genome is the entire genetic material of an organism
      • the genetic material is stored in the nucleus and is arranged into chromosomes
      • each chromosome is one very long molecule of DNA that is coiled up
      • a gene is a short length is a short length of a chromosome
      • Genes determine the production of proteins. The sequence of bases in the gene determines the type of protein which is produced. The production of different proteins controls the development of different characteristics, e.g. dimples, and how an organism functions.
      • Genes can exist in different versions. Each version gives a different form of a characteristic, like blue or brown eyes. The different versions of the same gene are called alleles or variants.
    • organisms of the same species have differences
      • organisms of the same species will usually look at least slightly different - e.g. in a room full of people you'll see different color hair, individually shaped noses and a variety of heights etc.
      • These differences are called variation within a species.
      • Variation can be genetic - this means it is caused by differences in the genotype. Genotype is all of the genes and alleles that an organism has. An organism's genotype affects it's phenotype - the characteristics that it displays (appearance).
      • an organism's genes are inherited from it's parents.
      • it's not only genotype that affects an organisms phenotype though - interactions with its environment can also influence phenotype. For example, a plant grown in sunlight could grow luscious and green. The same plant grown in darkness would grow tall and spindly and its leaves would turn yellow - these are environmental variations.
      • most variation in phenotype is determined by a mixture of genetic and environmental factors.
        • for example, the maximum height that an animal or plant could grow to is determined by its genes. But whether it actually grows that tall depends on its environment (e.g. how much food it gets).


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