OCR B1- YOU AND YOUR GENES

The entire B1 topic, no gaps

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  • Created by: Angel0900
  • Created on: 04-06-16 18:11
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  • OCR B1- YOU AND YOUR GENES
    • Genes, Chromosomesand DNA
      • Most cells in in a body have a nucleus
        • Nucleus- contains genetic material
          • The genetic material is arranged in chromosomes
            • The human body has 23 pairs of chromosomes  Pairs- one from each parent
            • Each chromosome has a long molecule of DNA
          • A gene is a short length of a chromosome
            • Genes control the development of different characteristics
              • Genes are instructions for cells
                • Each gene is a code for making a certain protein
                  • Proteins- build cells
                    • Structural Proteins- A part of things such as skin, hair, blood and cytoplasm
                    • Functional Proteins- Things that helps take part in things such as enzymes, the protein that helps digest food by breaking down food molecules
      • Nucleus- contains genetic material
        • The genetic material is arranged in chromosomes
          • The human body has 23 pairs of chromosomes  Pairs- one from each parent
          • Each chromosome has a long molecule of DNA
        • A gene is a short length of a chromosome
          • Genes control the development of different characteristics
            • Genes are instructions for cells
              • Each gene is a code for making a certain protein
                • Proteins- build cells
                  • Structural Proteins- A part of things such as skin, hair, blood and cytoplasm
                  • Functional Proteins- Things that helps take part in things such as enzymes, the protein that helps digest food by breaking down food molecules
      • Genotype- describes what genes an organism has
        • Gene controlled characteristics- characteristics given by the genes you have
          • ie Dimples, eye colour, attached/ detached earlobes
        • Environmental controlled characteristics- characters that have been given by the environment (where you live, lifestyle etc)
          • ie Scars
        • Characteristic controlled by genes and environmental factors- features that are impacted by the environment and genes
          • ie Hair Colour, weight, skin tone
    • Genes and variation
      • Sperm and egg cells have half the normal amount of DNA
        • They have 23 SINGLE chromosomes
        • when the sperm fertilises the egg during sexual reproduction it combines the 23 chromosomes of the egg with the sperms 23 chromosomes to make the pair of 23 chromosomes that we have in our body
        • Alleles- different versions of the same gene
      • Half a child's chromosomes come from each parent
        • Is the reasons why many children resemble their parents looks
        • Every child has a new unique set of alleles
      • Genes are shuffled together randomly to make eggs and sperm
        • The two chromosomes in a pair are never identical because they have different alleles
        • Each of the 23 chromosome pairs separate independently
          • Meaning the sex cells produced by one individual will all be genetically different
    • Inheritance and genetic diagrams
      • The combination of alleles determines the phenotype
        • Alleles - different versions of the same genes
      • Homozygous fro a trait- two alleles the same for that particular gene (ie BB)
      • Heterozygous for a trait- two different alleles for that particular gene (ie Bb)
        • Homozygous fro a trait- two alleles the same for that particular gene (ie BB)
      • Alleles can be dominant or recessive
        • if you have two dominant alleles or one dominant and one recessive allele the characteristics  only the characteristics caused by the dominant alleles are shown
          • Both alleles have to be recessive for characteristics caused by the recessive alleles to be shown
      • Genetic diagrams - Capital letters represent Dominant Alleles and lower case letters represent Recessive alleles
    • Chromosomes and genders
      • There are 23 chromosomes and the 23rd pair is labelled XY and are called sex chromosomes
        • Sex Chromosome- decides whether you're going to be male of female
      • Males- XY Females- XX
        • The Y causes the male characteristics
        • Sex is determined by a gene
        • Testes produce the male sex hormones that then make the res of the male reproductive system develop
          • Embryos that dont have the Y gene create ovaries and the res of the female reproductive system
      • The gene that makes the embryo into a male causes a specific protein to be produced
    • Genetic disorders
      • Caused by faulty alleles
      • Can be inherited- one or both parents carry the faulty allele
        • Huntington's and cystic fibrosis- caused by a single genes faulty allele
      • Some can be caused by recessive alleles
    • Stem Cells
      • Become ant types of cell
      • Most cells are specialised for a particular job
      • Most multicellular organisms become specialised at early stages of development
      • unspecialised cells: Develop into different cells depending on the instructions
      • Embryonic stem cells: unspecialised stem cells found in embryos
        • These are taken from the embryos and the embryos are destroyed
          • Some people see this as immoral and 'playing god'
            • these stem cells can be used to replace faulty cells of sick people
              • could make beating heart muscles for heart disease
                • could make Nerve cells fro paralyzed people with spinal injuries
                  • could make insulin producing cells for people with diabetes
              • embryonic stem cells are still being researched
      • Adult Stem Cells
        • Saftely extracted from adults, also unspecialised cells but can't become every cell type unlike embryonic stem cells
          • Medicine already use adult stem cells in medicine to cure illnesses
            • bone marrow contains adult stem cells that can turn into new blood cells to replace faulty ones

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