Genetics & Inheritance

• The gene pool is the total number of alleles present within a population.
• Stage 1 of Mitosis: Interphase

  • organelles duplicate
  • genetic material doubles
  • cell continues to carry out normal function
• Stage 2 of Mitosis: Mitosis

  • chromosomes are pulled to opposite ends of the cell.
  • 2 genetically identical nuclei in 1 cell.
  • genetic material is separated
  • organelles are separated
• Stage 3 of Mitosis: Cytokinesis

  • cell fully divides, leaving a cell scar
  • producing 2 genetically identical daughter cells
• Bacteria carry out asexual reproduction which is known as binary fission.
• Mitosis produces cells for the purpose of growth and repair
• Meiosis produces gametes (eggs/sperm)
• In every cell, there are 46 chromosomes and 23 pairs.
• Chromosomes are made up of tightly coiled DNA which codes for a characteristic in the body.
• A gene is a section of DNA that codes for a protein that will express a certain characteristic
• Diploid: any cell with 23 pairs or 46 chromosomes.
• Haploid: any cell with half the number of chromosomes [23 single chromosomes] - gametes.
• Meiosis Stage 1: Interphase

  • each chromosome undergoes DNA replication
  • each chromosome now has 2 chromatid arms
  • we have NOT doubled the chromosome number
  • 'crossing over' occurs which creates new genetic combinations
• Meiosis Stage 2: Meiosis

  • the homologous chromosome pairs are pulled apart and separated into 2 cells.
• Meiosis Stage 3:

  • the chromatid arms are pulled apart and separated.
• Meiosis results in the formation of 4 unique haploid gametes compared to the original diploid cell.
• Random alignment of chromosomes increases variation.
• An advantage of asexual reproduction: it is quick and only 1 parent is required.
• A disadvantage of asexual reproduction: there is less genetic diversity which means they are more susceptible to disease and extinction.
• An advantage of sexual reproduction: there is more variation [less likely to die out]
• A disadvantage of sexual reproduction: requires 2 parents and is time consuming.
• An allele is a different form or variation of a gene.
• Genotype is an individual's combination of alleles
• Phenotype is the trait expressed due to a genotype.
• Homozygous refers to having two identical alleles (either both dominant or recessive)
• Heterozygous refers to having one dominant and one recessive allele.
• A female has XX chromosomes.
• A male has XY chromosomes.