Biodiversity (4-6)

• Heredity: passing on of traits from parents to offspring
• Genetics: is the branch of science that deals with heredity
• Heritable Traits: passed on from one generation to the next. (eg. eye colour, hair colour, skin colour).
• Non-Heritable (Acquired) Traits: not passed on from generation to generation. Acquired through experience in life. (eg. dyed hair, scar, ability to play instrument).
• Continuous Variation

  • there is a range of possibilities
  • strongly influenced by the environment
  • (eg. height, hair colour, mass)
• Discrete Variation

  • when there are only a few options to choose from (either/or).
  • unaffected by the environment
  • (eg. blood type, attached or detached earlobes, ability to roll tongue)
• Dominant traits will always show up in the offspring, if present
• Recessive traits will not show up if a dominant trait is present
• Gene: segments of DNA that code for a specific characteristics or trait
• Allele: Different versions of the same gene (eg. blue eyes vs brown eyes)
• Genotype: types of genes inherited (eg. BB/Bb/bb).
• Phenotype: what is expressed (traits you can see).
• Homozygous Dominant: both alleles passed onto offspring are dominant (BB).
• Heterozygous: one allele is dominant and one is recessive. The recessive allele is masked. (Bb)
• Homozygous Recessive: both alleles passed onto offspring are recessive (bb).
• Punnett Squares: a tool to see the results of genetic crosses
• DNA stands for deoxyribonucleic acid
• DNA is the inherited material responsible for variation.
• DNA is found in all living things + found in the nucleus of each cell
• DNA needs to reproduce itself and must move from the parent to offspring
• DNA controls all the structures and functions of the cells
• A = sugar

  B = Phosphate

  C = Nitrogen Base (Adenine, Guanine, Thymine, Cytosine)

  D = Nucleotide

  
• The nucleotide is made up of one base, one sugar, and one phosphate
• The arrangement of the 4 bases in the rungs of the ladder form the entire genetic code
• The structure is similar to a ladder that has been twisted into a spiral known as double helix
• James Watson and Francis Crick were the scientists who discovered the structure of DNA
• Chromosomes:

  • packages of DNA
  • each human cell nucleus contains 46 chromosomes
  • chromosomes are organized into pairs (23 pairs, one from mom and one from dad)
• Genes:

  • segments of DNA
  • located on the chromosomes
  • come in pairs that both code for the same trait (eg. eye colour, leg length)
• Alleles:

  • possible forms of a gene
  • organisms have 2 alleles for each trait
  • arrangement of those alleles will determine what trait will be expressed
• body cells of the human body are called somatic cells. These cells often need to grow or be replaced.
• The process of somatic cells dividing to replace themselves or for an organism to grow is called Mitosis
• sex cells of the human body are called gametes. Produced through the process of meiosis. These new cells only have half the DNA of the parent cell.
• If the chromosomes do not separate during Meiosis, one will end up with an extra and one with a missing chromosome. (Nondisjunction). However, it is not a problem with Mitosis.
• Changes to the DNA are called mutations

  Causes (mutagen - generates mutation)

  • x-rays
  • chemicals
  • UV rays

  Results:

  • can cause changes in the structure of the DNA. Individual bases could be mixed up
  • one mutated cell that could turn into a tumour that spreads throughout the body
  • not all mutated cells are harmful
• Incomplete Dominance: both traits are shown, neither is dominant or recessive (in a blended form)
• Codominance: both traits are shown in the heterozygote form =, dominance is shared but NOT blended
• Natural Selection

  Main Contributor: Charles Darwin

  • all organisms produce more offspring that can possibly survive
  • there is incredible variation within each species
  • some of those variations increases the chances of an organism surviving to reproduce
  • over time, variations that are passed on lead to changes in the genetic characteristics of a species
• Selecting Desirable Traits

  Artificial Selection

  • process of selecting and breeding individuals with desirable traits to produce offspring that have these desired traits (eg. vegetables, livestock, flowers).
• Cloning

  Clone: a genetically identical copy of an entire organism or its cell or gene (eg. cutting from a plant, budding).
• Artificial Reproductive Technology

  Artificial Insemination (AI): Sperm are harvested from a desirable male and injected into a female.

  In Vitro Fertilization (IVF): Fertilization that happens outside the body, usually in a petri dish (embryo is placed in female).

  Uses:

  • treat infertility
  • choosing desirable traits in livestock
  • maximize pregnancy rates in livestock
  • bring back extinct or endangered species