inheritance, variation and evolution

• sexual reproduction includes the fusion of male and female gametes
• DNA is a polymer made up of 2 strands that form a double helix
• a gene is a sequence of amino acids that code for a protein
• a genome is a entire set of genetic material in an organism
• why is it important we understand the human genome?

  1. we can search for genes that are linked to specific diseases
  2. finding the treatment for inherited disorders
  3. so that we can identify human migration patterns
• DNA

  • 4 different nucleotides A, T, C, G
  • a phosphate group
  • a sugar
• dna has different patterns of nucleotides that code for a specific characteristic and fold up in a specific shape for its role
• the main uses of proteins are

  • enzymes
  • hormones
  • structural proteins
• a gamete is a sex cell
• a chromosome is a dna molecule that carries genetic information
• an allele is a different version of a gene
• a dominant allele is always expressed even if there is one
• a recessive allele will not be expressed unless there is 2
• two identical alleles are homozygous
• two different alleles are heterozygous
• a genotype is an individuals genetic make up
• a phenotype is the way the allele is expressed (what you can observe)
• what is a genetic mutation?

  a change in DNA
• what increases the risk of mutations?

  • carcinogens
  • radiation
• what is a substitution?

  when one of the bases changes for another so the protein that is codes for changes
• what is insertion?

  • when an extra base is added
  • one of the bases gets pushed along and it continues
  • alters the triplets
  • amino acid chain would be completely different
• what is deletion?

  • when one of the bases is removed from the sequence
  • when one of the bases is removed all the bases to the right move to the left
• pros of asexual reproduction

  • only one parent is needed
  • process is quick
• cons of asexual reproduction

  • no genetic variation
  • if one of the organisms have a disease they will all get it which causes a wipe out
• pros of sexual reproduction

  • genetic variation
  • population is less likely to wipe out
  • organisms can adapt
• cons of sexual reproduction

  • time consuming and requires energy
• capital letter → dominant

  small letter → recessive
• cystic fibrosis

  • recessive inherited disorder
  • if you have 1 allele you are a carrier
• polydactyly

  • when a baby is born with extra fingers or toes
  • caused by one dominant allele
• embryo screening

  • during IVF we can look at an embryo before implanting it to look for diseases
  • if it carries a genetic disorder we can get rid of the embryo and use another
• advantages of embryonic screening

  • reduces overall suffering
  • save money
• disadvantages of embryonic screening

  • suggests that people with disorders are undesirable
  • people might use screening for specific traits
  • destroying life by getting rid of unwanted embryos
• female chromosomes are XX
• male chromosomes are XY
• what is variation?

  • different types of phenotype
  • relies on genes and the environment
• charles darwin

  • believed in "survival of the fittest" only organisms with specific characteristics will survive
  • noticed that certain traits were being passed onto offspring
  • believed in natural selection where individuals that are best adapted to the environment can out compete others and produce offspring
• what is evolution?

  inheritance of certain characteristics over generations change and could create new species
• speciation

  a phenotype of an individual could change so much that a new species will be created and it will no longer be able to interbreed and produce fertile offspring
• what is selective breeding?

  when we take the best plants or animals and breed them together to get specific characteristics
• how does selective breeding work?

  1. choose parents with desired characteristics
  2. breed them together
  3. breed the offspring with the desired characteristics
  4. continue this over generations until the population is how you want it