Biology

• Genetics


  The field of study that deals with heredity
• Heredity


  Passing on of characteristics from parent to offspring
• Trait


  An inherited characteristic, such as eye colour or hair colour
• Gregor Mendel


  Austrian monk who lived in the 1800's, first person to conduct carefully planned experiments on heredity
• Pea plants


  • Grow quickly – can study several generations in a short time period
  • Mendel studied 7 different traits: seed shape, seed colour, pod shape, pod colour, flower position, height, and flower colour
• All the traits that Mendel selected to study had only two different alleles
• Allele


  Different forms of a trait
• Mendel's experiments


  1. Crossed plants with two different alleles to produce offspring (first generation, F1)

  2. Allowed the first generation to self-pollinate to produce offspring in the second generation (F2)
• Dominant allele


  An allele that is always expressed whenever it is present
• Recessive allele


  An allele that is only expressed when the dominant form is NOT present
• Genotype


  The combination of alleles an organism has
• Phenotype


  The outward appearance of a trait
• Homozygous


  Both alleles are the same
• Heterozygous


  The two alleles are different
• Most of our traits do not follow the simple inheritance pattern that Mendel observed
• DNA mutations produce genetic diversity within a population
• Mutations


  • A permanent change in the genetic material of an organism
  • Can be harmful, beneficial, or have no effect
• Natural selection


  The process by which characteristics of a population change over many generations as organisms with heritable traits survive and reproduce, passing their traits to offspring
• Selective advantage


  A genetic advantage that improves an organism's chance of survival, usually in a changing environment
• Adaptation


  Structural or behavioural feature or physiological process that improves the organism's chance of surviving in its environment to reproduce
• Speciation


  The formation of new species
• Adaptive radiation


  The diversification of a common ancestral species into a variety of differently adapted species
• Extinction


  Occurs when a species completely disappears from Earth
• Artificial selection


  Selective pressure exerted by humans on populations in order to improve or modify desirable traits
• Monoculture


  Repeated planting of the same varieties of a species over large expanses of land
• Gene


  A sequence of nucleotides in a DNA molecule that determines heredity information, such as coding for a protein
• Recombinant DNA


  A DNA molecule carrying a new combination of genes from different organisms
• Restriction enzymes


  Enzymes that can cut the double-stranded DNA molecules at very precise sequences of four to eight base pairs called recognition sites
• Sticky ends


  Ends with exposed nucleotide bases at each end of a DNA fragment after being cut by a restriction enzyme
• Ligation


  The process of joining DNA fragments using the enzyme DNA ligase
• Gene cloning


  The process of making large quantities of a desired segment of DNA once it has been isolated
• Steps in gene cloning using recombinant DNA technology


  1. Extract DNA from a donor organism

  2. Use restriction enzymes to remove the required gene from the DNA

  3. Use a vector (e.g. plasmid) to introduce the foreign gene into a host cell

  4. Recombination occurs when the donor DNA bonds to the vector DNA

  5. The recombinant DNA is mixed with bacteria, allowing the bacteria to take up the recombinant DNA and multiply
• Uses of recombinant DNA


  • Producing insulin in bacteria
  • Producing growth hormone in bacteria
• Gene cloning


  The production of many identical copies of a single gene
• Uses of gene cloning

  • To produce large quantities of a protein
  • To alter phenotypes of other organisms in a beneficial way
• Transgenic organisms


  Organisms with foreign DNA or genes inserted into them
• Scientists first began experimenting with genetic engineering in the 1970's
• Recombinant DNA


  Contains DNA from 2 or more different organisms
• Restriction enzymes


  Enzymes that cleave DNA at specific nucleotide sequences in order to insert foreign DNA into it
• Sticky ends


  DNA that is single stranded and overhanging at each end of a DNA molecule (unpaired nucleotides)