inheritance, variation and evolution

• a gene is a small part DNA found on a chromosome which codes for a particular protein
• how many cell devisions are the in meiosis?

  two
• in meiosis, four gametes are produced, each with only a single set of chromosomes. each of the gametes are genetically different from the others.
• give two examples of characteristics controlled by a single gene

  mouse fur colour, red-green colour-blindness in humans
• we have two alleles of each gene in the body- one on each chromosome in a pair
• what is it called when you have two of the same alleles for a particular gene?

  homozygous
• define genotype


  the combination of alleles you have
• define phenotype


  what characteristics you have as a result of your genetics
• define allele 


  an allele is a version of a gene that can code for different versions of a characteristic
• polydactyl


  baby is born with extra fingers or toes- caused by a dominant allele
• cystic fibrosis


  disorder of the cell membranes which releases sticky mucus into airways of lungs and pancreas- a recessive condition
• Charles Darwin’s Theory of Evolution states that all living species developed from simple life forms which first developed over 3 billion years ago
• how can you tell a new species has been formed?

  when the phenotypes become so different that they can no longer breed to produce fertile offspring
• how do we transfer the gene from one organism to another in genetic engineering?

  isolate the gene using an enzyme and insert into a vector (virus or bacterial plasmid) and then introduce it to another organism
• define genetic engineering


  the breeding of organisms so that the genes for particular useful or attractive characteristics stay in the population
• what is the Linnaean system?

  Carl Linnaeus‘s classification system composed of kingdom, phylum, class, order, family, genus, species
• what is Carl Woese‘s 3 domain system?

  organisms are split into 3 domains- archaea, bacteria and eukaryota
• what are archaea?


  organisms in this domain are primitive bacteria often found in hot springs and salt lakes
• what are bacteria in Woese’s domain system?

  contains true bacteria such as E.coli
• what are eukaryota?


  organisms such as fungi, plants, animals and protists