inheritance variation and evolution

• DNA is the chemical that all of the genetic material in a cell is made up from
• genes code for a sequence of amino acids that make up a specific protein
• genome is the entire set of genetic material in an organism
• mutation is a random change in the organisms DNA
• increase in chance of mutation when exposed to certain substances or types of radiation
• mutations to a gene can lead to changes in the protein it codes for, which can lead to a change in the function of the protein
• most mutations have very little or no effect on a protein
• sexual reproduction:

  • produces genetically unidentical cells
  • genetic information from 2 organisms (mother father)
  • mother and father produce gametes by meiosis
  • each gamete contains 23 chromosomes
  • egg cell and sperm cell fuse together in fertilisation to form a cell with full number of chromosomes
• gamete has 23 chromosomes half a set
• asexual reproduction:

  • produces genetically identical cells
  • only 1 parent
  • happens by mitosis
  • new cell has exacly the same genetic material as parent (clone)
• to make gametes cells divide by meiosis
• meiosis makes 4 gametes
• meiosis happens in the reproducive ograns like ovaries and testes
• mitosis make 2 identical daughter cells
• meiosis:

  • 1 human body cell with full set of chromosomes(46)
  • cell duplicates its genetic material so you have double chromosomes(92)
  • 1st division you get 2 cell each with 46 chromosomes
  • 2nd division you get 4 cell each with 23 chromosomes and they are called gametes
• natural selection is the process by which individuals with traits that are better suited to their environment survive and pass on these good genetics to their offspring
• selective breeding is the process where humans breed animals or plants to produce offspring with desirable characteristics
• genetic engineering is when scientists change an organisms DNA using biotechnology
• asexual reproduction is faster and uses less energy as the organism doesnt need to find a mate
• the zygote has all the information needed to develop into a new individual
• male chromosomes are XY
• female chromosomes are XX
• alleles are a different version of a gene
• the genes you inherit determine what characteristics you develop
• there is a 50 percent change your offspring is male or female
• if an organism has two allels for a gene that are the same its homozygous
• if an organism has two alleles for a gene but the two alleles are different its heterozygous
• capital letters are used for dominant alleles, while lower case letters are used for recessive alleles
• if two alleles are different only one can determine the characteristic and this allele is dominant
• for an organism to show a recessive characteristic both alleles must be recessive
• genotype is combination of alleles
• phenotype is the physical characteristics like eye colour
• cystic vibrosis is a genetic disorder of the cell memberane in which the body creates thick mucus in air ways and pancreas
• for cystic fibrosis the people with the recessive allele f may not have the disorder but carry it and in order for a child to get it they need to have both alleles f either from both their parents carrying a recessive f or having it themselves
• polydactyly is a genetic disorder when someone has an extra finger of toe and isnt life threatening
• polydactyly can be caused by one parent as the allele is a dominat D
• embryo screening can be used to detect genetic disorders by removing the cell from the embryo to analyse its genes and see if it has a genetic disorder
• embryo screening has many ethical issues as some people think it implies genetic disorders are undesierable or screening can be expensive some people think it will help prevent suffering