Genetics

• all genetic information is found in the nucleus of every living cell
• all genetic information is stored in the form of genes
• genes code for particular characteristics
• genes make up chromosomes
• chromosomes are long molecules of DNA
• somatic cells->body cells
• gametes->sex cells
• there are two gametes:

  • egg cells
  • sperm cells
• somatic cells have 46 chromosomes, while gametes have 23 chromosomes
• chromosomes are found in pairs (one from each parent)
• the pair of chromosomes together are called homologous chromosomes
• homologous chromosomes have the same kind of genes with some differences
• there are two types of cell division:

  • Mitosis
  • Meiosis
• Mitosis purpose is to produce new cells identical to the parent cell
• diploid: 2 sets of chromosomes

  haploid: 1 set of chromosomes
• Mitosis happens in the skin and hair follicles (human)
• Mitosis happens in the roots, leaves, stem and flowers (flowers)
• in mitosis two genetically identical diploid daughter cells are produced from one parent cell
• Meiosis happens during the formation of gametes
• the number of chromosomes produced is half than in mitosis
• while the parent cell is diploid the daughter cells are haploid (meiosis)
• meiosis is a reduction division
• meiosis happens in the (human)

  • testicleles (male)
  • ovaries (female)
• meiosis happens in the (plants)

  • anther (male)
  • ovaries (female)
• zygote: diploid cell formed by fusion of 2 haploid gametes
• meiosis purpose is to produce gametes and to increase genetic variation
• allele: different versions of a gene
• 2 identical alleles=a homozygous characteristic
• 2 different alleles=a heterozygous characteristic
• the allele that shows in the phenotype is the dominant out of the two different alleles
• phenotype: the physical expression of a gene
• genotype: the genetic makeup of an organism
• recessive allele only have an effect of the phenotype if the organism is homozygous
• when an organism is heterozygous only the dominant allele is expressed
• DNA: Deoxyribonucleic acid
• DNA is a chemical/molecule that contains the genetic information of an organism
• DNA has a double helix structure, which is a spiral of two strands of nucleotides.
• DNA has an organic base made up of adenine, thymine, cytosine and guanine
• in the organic base thymine is always paired with adenine and cytosine with guanine
• the bases are held together by hydrogen bonds