Genes

• Part of a cell that contains chromosomes

  The nucleus
• DNA structure


  • The structure of DNA is a double-helix
• Chromosomes

  Where genes are located
• Zygote


  A zygote is a fertilized egg cell that is formed when a sperm and egg fuse during fertilization.The zygote contains all the genetic information (DNA) needed to develop into a baby
• Human eggs and sperm only contain 23 chromosomes each
• Gene mutation


  A gene mutation is a change in the DNA sequence of a gene, which can make it different from most people's.Mutations can be caused by errors during cell division
• Chromosome mutation

  • Down syndrome
• Characteristics that are inherited:

  Hair colour

  Eye colour

  Skin colour
• Characteristics that are environmental

  • Language: The language someone speaks
  • Music: A person's favorite music
  • Mental and psychological characteristics: Such as intelligence and extraversion
  • Behaviors: Such as parenting and aggression
• Characteristics influenced by genes and environment:

  Intelligence

  Weight
• Variation


  Genetic variation is the difference in DNA sequences between individuals within a species or population. There are 2 types of variation: Genetic and Enviromental. These variations can be discreet or continuous
• Why do identical twins have the same DNA:

  They originated from the same zygote
• Distinguish between an allele and a gene:

  Alleles are different versions of the same gene. For example, the gene for eye colour has an allele for blue and an allele for brown
• Recessive allele


  Is only expressed if the individual has two copies of it and doesn't have the dominant
• Dominant allele:

  Only needs one copy to be expressed
• The four DNA bases:

  The four bases in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T). These bases form specific pairs (A with T, and G with C).
• Discrete variation:

  Is controlled by a single gene
• Continuous variations:

  Characteristics that are controlled by more than one gene
• Genotype


  Genetic makeup of an organism
• Phenotype


  Observable characteristics of an organism
• Process of natural selection

  1. Variation in traits within a population

  2. Individuals with advantageous traits survive and reproduce more

  3. Passing on of advantageous traits to offspring

  4. Over time, population changes to be better adapted
• Evolution


  The gradual change in the characteristics of a population of organisms over successive generations
• Biodiversity:

  Is a measure how many types of organisms or species that are found within a habitat
• Endangered


  An organism at risk of extinction in the wild
• Gene banks


  Facilities that store genetic material from various species for conservation purposes
• Genetic cross diagram to show probability of child inheriting cystic fibrosis if both parents are carriers


  
• Competition 


  The competition between organisms for food and shelter
• Population 


  This refers to all the members of the same species that live in an habitat
• Three causes of extinction:

  Natural disasters

  Habitat loss

  Global warming