Genetics

• Do animals usually reproduce via sexual or asexual reproduction? 

  Sexual reproduction
• Which process is used to create gametes?

  Meiosis 
• What do we call the fusion of male of female gametes? 

  Fertilisation
• Sexual reproduction involves the combination of DNA from two different parents. This means that the offspring will be genetically different to either of their parents. 
• Sperm and egg cells are haploid cells and only have 23 chromosomes. When a sperm fertilises the egg though, they form a diploid cell that has 46 chromosomes.
• During sexual reproduction in plants, which two gametes fuse together? 

  Pollen and egg
• How many parents are involved in asexual reproduction? 

  1
• As a result of asexual reproduction, are the offspring genetically identical or genetically unique?

  Genetically identical
• When fungi and plants reproduce asexually, which process do they use?

  Mitosis
• Do bacteria reproduce via sexual or asexual reproduction? 

  Asexual reproduction 
• When bacteria reproduce asexually, which process do they use?


  Binary fission
• Sexual reproduction involves the joining of male and female gametes, each containing genetic information from the mother or father.
• Asexual reproduction involves one parent with no gametes joining. It happens using the process of mitosis, where two identical cells are formed from one cell.
• Asexual reproduction

  Uses mitosis to form an identical clone of the parent organism
• Sexual reproduction

  Involves the fusion of two gametes like a sperm and an egg, leading to genetically different offspring
• Advantages of asexual reproduction

  • Only one parent is needed
  • The process is very quick
• A single organism reproduces asexually, so it can quickly colonize an entire new area
• Asexual reproduction can happen within just a couple of days in the right conditions -> fast
• Asexual reproduction leads to no genetic variation in the offspring
• If a new disease comes along and one of the asexual offspring is susceptible

  Chances are that all of them will be susceptible and it could wipe out the whole population
• Asexual reproduction leads to no genetic variation


  Organisms will have less chance of adapting to new conditions like changes in the climate or a new competitor
• Sexual reproduction

  • Leads to loads of genetic variation within the population
  • In the short term, the population is less likely to get wiped out by a single event like a new disease because some individuals will be more resistant to it than others
  • In the longer term, it allows for evolution to take place and the most favorable traits are most likely to be passed on each generation
• Disadvantages of sexual reproduction

  • It takes a lot more time and energy than asexual reproduction
  • Animals have to first of all find their potential mates, which can be time-consuming
  • Animals also need to impress their mate
• Sexual reproduction


  Involves the fusion of male and female gametes (fertilization)
• Asexual reproduction


  Takes place with only one parent and doesn't involve any gametes
• Organisms that can reproduce through sexual or asexual reproduction

  • Plants (a)
  • Animals (s)
  • Bacteria (a)
• Sexual reproduction

  • Offspring contain a mixture of their parents' genes
  • Introduces lots of variation as each offspring is different
• Gametes

  Cells like sperm and eggs in animals, or pollen and eggs in flowering plants, that only have half the normal genetic material
• Meiosis


  The process by which gametes are formed with half the normal genetic material
• Sexual reproduction doesn't have to involve sex or intercourse, it just refers to the fusion of male and female gametes
• Asexual reproduction

  • No mixing of genetic material
  • All offspring are identical clones
• Mitosis


  The process by which eukaryotic organisms like plants and fungi reproduce asexually
• Meiosis is the formation of four non-identical cells from one cell.
• meiosis

  • The cell makes copies of its chromosomes, so it has double the amount of genetic information.
  • The cell divides into two cells, each with half the amount of chromosomes (46).
  • The cell divides again producing four cells, each with a quarter the amount of chromosomes (23).
  • These cells are called gametes and they are all genetically different from each other because the chromosomes are shuffled during the process, resulting in random chromosomes ending up in each of the four cells.
• meiosis

  These gametes with 23 chromosomes join at fertilisation to produce a cell with 46 chromosomes, the normal number. This cell divides by mitosis to produce many copies. More and more cells are produced, and an embryo forms. The cells begin to take on different roles after this stage (differentiation).
• While mitosis is used for the division of ordinary body cells to produce diploid (2n) daughter cells, meiosis is used to produce haploid gametes (sperm and egg cells). Gametes only have one copy of each chromosome.
• Meiosis

  The process that forms gametes (sex cells) with half the genetic material of a normal cell
• Gametes

  Sex cells like sperm and egg cells that contain half the genetic material of a normal cell (haploid)
• Diploid cells

  Cells with two sets of genetic information, one from each parent
• Meiosis

  1. Replication of cell's DNA

  2. Chromosomes line up in pairs

  3. Chromosome pairs pulled apart and cell splits in two

  4. Cell splits in two again resulting in 4 genetically unique cells