B13 - Reproduction

• Types of Reproduction:

  • Sexual
  • Produces offspring that are genetically different
  • Most animals produce sexually
  • Asexual
  • Produces offspring that are genetically the same
  • Tends to happen with bacteria
• Advantages and Disadvantages of Asexual reproduction:

  • Advantages
  • Happens very quickly
  • Do not need to find a mate
  • Disadvantages
  • Disease can affect you as you can pass on undesirable traits
• Advantages and Disadvantages of Sexual Reproduction:

  • Advantages
  • Genetic variation
  • Desirable traits are passed on
  • Disadvantages
  • Long process
  • Requires 2 mates
• Gametes:

  • Types include
  • Egg cell
  • Sperm cell
  • Pollen
  • Meiosis
  • Occurs when there is a cell with 46 chromosomes
  • Produces 4 daughter cells
  • Different sections of the chromosomes are swapped around which leads to genetic variation
• DNA:

  • Contains base pairs
  • A matches up to T
  • C matches up to G
  • 3 Billion base pairs
  • Genome produces 21,000 proteins
• Dominant genes are always shown with a capital letter
• • Homozygous alleles are when both alleles are the same
  • Heterozygous alleles are when they are different
  • Can be heterozygous dominant or heterozygous recessive
• Punnet Square:

  A) TT

  B) Tt

  C) Tt

  D) tt

  
• Genetic diseases

  • Cystic fibrosis
  • Recessive allele
  • Both genes needed to show trait
  • May be a carrier of the gene unknowingly
  • Produces too much mucus in your lungs making it hard to breath
  • Polydactyly
  • Too many fingers or toes
  • Caused by a dominant gene
  • Only need one gene to show trait
• Genetic Screening:

  • Adults
  • Checking what genotypes they have
  • Embryos
  • Checking the amniotic fluid or the placenta to see if the baby has one of the diseases
  • IVF
  • Embryo is formed
• Ethical concerns for genetic screening:

  • Goes against religious views
  • IVF leads to creation of 'designer' babies meaning they are no longer natural
  • Lead to an increase in abortions if there is a high chance of the baby having a genetic disease
  • Not always accurate meaning people terminate a perfectly healthy pregnancy