Inheritance

• The genome is the entire DNA of an organism and a gene is a section of a molecule of DNA that codes for a specific protein
• The nucleus of a cell contains chromosomes on which genes are located
• An allele is a different form of the same gene
• Alleles determine the physical appearance of an organism, and are responsible for differences in appearance across species
• homozygous dominant means the genotype is two dominant alleles
• Homozygous recessive is when the genotype is two recessive alleles
• Heterozygous is when the genotype is one dominant and one recessive allele
• Genotype refers to the alleles an organism has
• Phenotype refers to physical appearance
• Recessive alleles need two copies to be the phenotyoe
• Dominant alleles only need one allele present to be the phenotype
• Most phenotypic features are the result of polygenic inheritance rather than single genes
• The sex if a person is controlled by one pair of chromosomes, XX in a female and XY in a male
• Cell division - Mitosis

  The division of a diploid cells to produce two genetically identical daughter cells
• Mitosis

  • Occurs during growth
  • Occurs during repair of tissues
  • Occurs during cloning
  • Occurs during asexual reproduction
• Diploid


  A cell with a full set of chromosomes (46)
• Mitosis

  1. DNA replication

  2. Chromosome replication (each chromosome made up of two identical sister chromatids)

  3. Chromosome condensation

  4. Spindle formation

  5. Chromosome alignment at equator

  6. Chromosome separation to opposite ends

  7. Cytoplasm splitting

  8. Formation of two genetically identical daughter cells
• Meiosis produces four cells with half the number of chromosomes, resulting in four genetically different haploid gametes
• random fertilisation produces genetic variation of offspring
• A haploid cell has 23 chromosomes
• Variation within a species can be genetic, environmental or a comvination
• Mutation is a rare random change in genetic material that can be inherited
• Resistance to antibiotics can increase bacterial populations, leading to difficulty in controlling infection rate
• Why is variation in characteristics important for organisms?


  It helps them compete for limited resources.
• What are the key concepts of Darwin's theory of evolution?

  • Species become better adapted over generations.
  • "Survival of the fittest" indicates that the best individuals survive.
  • Variation in characteristics is crucial for competition.
  • Resources for survival are limited, leading to competition among individuals.
• Key words to use when talking about natural selection:

  mutation

  variation

  competition

  survival

  reproduce

  pass on alleles