Genetics

?
View mindmap
  • Section 3 - Genetics
    • Sexual Reproduction and Meiosis
      • produces genetically different cells
        • gametes are haploid
          • fuse to produce zygote (diploid)
            • mitosis and develops into embryo
      • gametes are produced by meiosis
        • 1st division
          • duplicates DNA, chromosomes line up and pulled apart, each cell has mixture from mother and father - genetic variation
        • 2nd division
          • chromosomes line up, arms pulled apart - 4 haploid daughter cells
    • DNA
      • Made up of nucleotides
        • double helix structure
        • DNA strands are polymers with repeating units - nucleotides
          • sugar molecule, phosphate molecule, base
            • ATCG (adenine, thymine, cytosine, guanine)
            • complementary base pairing A+T C+G (weak hydrogen bonds)
      • stored as chromosomes and contains genes
        • long coiled molecules of DNA
        • DNA makes up genome
        • gene codes for particular protein
    • Genetic Diagrams
      • Alleles are different versions of the same gene
        • inherited genes control characterisitics
        • 2 versions of every gene in your body
        • Dominant capital C recessive smaller c
          • dominant alleles overule
        • homozygous - two alleles
        • heterozygous - two different
        • to be a recessive characteristic, both must be recessive
      • genetic diagrams can show the influence of a single characterisitic
        • monohybrid inheritence
          • can be shown in a monohybrid cross or a punnett square
    • More Genetic Diagrams
      • a genetic diagram can show how sex is determined in humans
        • 23rd pair of chromosomes ** or XY determine the sex
        • males XY females ** - equal chance of a boy or a girl
        • All eggs have an X chromosome, but sperm can have X or Y
      • Family Pedigrees can also show monohybrid inheritance
        • family tree of genetic disorders
        • e.g. cystic fibrosis
          • for children to inherit the disorder, both parents must have it or be carriers
          • recessive allele
    • Variation
      • organisms of the same species have differences
        • genetic or environmental
          • genetic variation caused by different alleles, which can lead to differences in the phenotype
          • new alleles through mutations
          • sexual reproduction causes alleles to be combined in offspring
        • e.g. different breeds of dog
      • Alleles arise due to genetic mutations
        • changes to base sequence of DNA
        • little or no effect on the phenotype
        • new combinations of alleles may interact to produce new phenotypes
    • Human Genome Project
      • researchers managed to map over 20000 human genes
        • started 1993
        • complete map of human genome (20500 genes) completed 2003
        • 1800 genes related to disease
      • medical applications
        • prediction and prevention of diseases
        • testing and treatment for inherited disorders
        • new and better medicines

Comments

No comments have yet been made

Similar Science resources:

See all Science resources »See all Genetic variation resources »