reproduction t16

• Bacterias reproduce asexually 

  Plants can reproduce sexually or asexually
• Sexual reproduction is the fusion of male and female gametes involving 2 parents which is called fertilisation
• The offspring contain a mixture of the parents genes and so it is genetically different which is why you inherit characteristics from both parents and introduces lots of variation
• Gametes are cells like sperm and eggs in animals or pollen and eggs in plants
• Gametes only have half of the genetic material of a normal cell
• A normal human cell has 46 chromosomes
• A human gamete only have 23 chromosomes
• When the 2 gametes fuse together the resulting cell has 46 chromosomes again
• We mate gametes through a process known as meiosis
• asexual reproduction only takes place with one parent and doesn’t involve any gametes meaning there is no mixing of genetic material  meaning there I son genetic variation
•  With asexual reproduction all of the offsprings are identical clones
• For eukaryotic organisms ,such as plants, fungi and some animals, asxual reproduction is achieved through mitosis
• For prokaryotic organisms, such as bacteria, do it by binary fission
• Binary fission involves the bacterium dividing into two new cells which contain exact copies of its DNA
• Haploid cells are cells that have half the chromosomes of normal cells
• A diploid cell is 2 haploid cells that make a normal cell with 2 sets of genetic information one from each parent (46 chromosomes)
• Chromosomes are in the nucleus of a cell and contain genetic information
• Plants can reproduce asexually using bulbs and tubers; these are food storage organs from which budding can occur, producing new plants which are genetically identical to the parent plant
• In mitosis one cell is copied into two identical cells
• In humans the gametes are sperm cells and egg cells
• In gametes the chromosomes are single not paired
• Gametes are made by meiosis
• Meiosis produces non identical cells. Every sperm cell and egg cell is different. Meiosis also takes place in flowering plants
• In plants the gametes are pollen and egg cells
• Animals and flowering plants carry out sexual reproduction 
• fertilisation: 

  
  

  sexual reproduction involves the fusion of male and female gametes
• In sexual reproduction, there is mixing of genetic information
• As every gamete is different due to meiosis, each offspring is 


  genetically variated ( different)
• Asexual reproduction does not involve gametes
• Because there is only one parent in asexual reproduction, there is no mixing of genetic information. Making the offspring all genetically identical which makes these offspring clones
• In asexual reproduction meiosis does not take place since it does not involve gametes
• Asexual reproduction only involves mitosis 
• mitosis is the process of cell division that results in two identical daughter cells
• Plants reproduces by forming tiny buds which drop off and grow into new plants
• selective breeding is the process of breeding animals or plants to produce offspring with desirable characteristics
• genetic variation is the differences in alleles that are passed from parents to offspring
• Offspring plants are genetically identical to the parent 
• Meiosis only takes place in reproductive organs. In humans that is the testes in the males and the ovaries in the females
• 1. In the first stage of meiosis, all of the chromosomes are copied
  2. The cell then divides into 2
  3. Both of these cells divide one more time forming the gametes. In the gametes, the chromosomes are now single, not paired
  4. Meiosis has halved the number of chromosomes and produces 4 gametes from one cell
  5. Each of these four gametes are genetically different from each other
  6. Each gamete has different alleles
• the disadvantage of asexual reproduction is lack of variation because there is no mixing of genes between parents