Genes and Chromosones

Genes and Chromosones

1. Genes are a set of microorganisms which forms part of a chromosone

   • Us humans produce sperm and eggs. In each egg or sperm there are 23 pairs of chromosomes.
   • There can be different amounts of genes per chromosome, and it mainly depends on the size of the chromosome.
   • Basic defenition : short sections of DNA
   • The DNA then contains a code/ instructions as to how to create a newborn animal
     • Some of the DNA features (e.g. small ears) can be passed on to the newborn animal
     • Some DNA is carried from father to baby, some from mother to baby or are based on enviromental facors
   • There are two types of genes, DOMINANT and RECESSIVE
     • Dominant is a type of gene which is more powerful
     • Reccesive is a type of gene which is less powerful
     • e.g mum = big eyes (dominant), dad = small eyes (recessive). Child will have big eyes

2. A chromosome is a set of DNA carrying genetic information from a male and female animal

   • 'XY' chromosone = male
   • 'XX' chromosone = female
   • The make up of chromosomes and genes
     • The writing in the gene in the picture is the basic code. It is made up of 4 letters, A C G T
       • They stand for the nucleotides in DNA
         • adenine
         • cytosine
         • guanine
         • thymine
   • Chromosomes are basically long strands of DNA which form up the codes to making a new animal
   • They are mainly made of proteins
   • 23 chromosomes from the egg meet with 23 chromosomes from the sperm
     • The genes then compare qualities
       • Physical traits are then incorporated into the newborn
   • Pairs of chromosomes in animals
     • Human :23 pairs
     • Fruit Fly :4 pairs
     • Rice plant :12 pairs
     • Dog :39 pairs

3. Selective breeding is when genes and chromosomes are extracted from an animal and replaced with another animal's gene or chromosome

   • This is usually to stop or help an animal in a characteristic or feature
   • Examples
     • e.g. a chicken has had some of its genes replaced to make it shyer and have smaller wings so they don't fly away
     • e.g. wheat is bred to have qualities such as it is easier to fertilise them and so they are less likely to catch a disease
   • Side Effects
     • Good Effects
       • More food
       • Better produce
       • Colour
       • Taste
     • Bad Effects
       • If a new disease comes along regarding an animal which has had genes extracted, the other animal will have the disease too
         • e.g. if chicken has a new disease and chicken genes have been inputted into a horse, the horse could have the dsease too
       • Health is mainly disregarded in selective breeding
       • Some people think that it is ethically wrong to do so

Images and files in the map