B1 (you and your genes)

• Cells


  The building blocks of every organism on the planet
• Eukaryotic cells


  • Complex, include all animal and plant cells
• Prokaryotic cells


  • Smaller and simpler, bacterial cells
• Both eukaryotic and prokaryotic cells contain genetic material in the form of the chemical DNA
• Genetic material is stored differently in eukaryotic and prokaryotic cells
• Eukaryotic cells


  • Contain a nucleus
• Subcellular structures in a typical animal cell

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• Additional subcellular structures in plant cells

  • Rigid cell wall
  • Large vacuole
  • Chloroplasts
• Prokaryotic cells


  • Do not have a nucleus
  • Store genetic material as a circular chromosome and plasmids
• Prokaryotic cells do not contain mitochondria or chloroplasts
• Microscopes allow us to see cells and subcellular structures
• Using a light microscope to view cells

  1. Prepare thin specimen

  2. Place on slide with water/mountant

  3. Add cover slip

  4. Adjust focus and magnification
• Chromosomes are long molecules of DNA
• Chromosomes


  • Come in pairs
  • Contain very long DNA molecules coiled up
• DNA


  Made up of smaller, repeating units called nucleotides
• Gene


  Short length of DNA on a chromosome that codes for a particular protein
• Alleles


  Different versions of the same gene
• Genotype


  The combination of alleles an organism has for each gene
• Phenotype


  The characteristics the organism displays
• Phenotype is influenced by both genotype and the environment
• Nucleotides


  Consist of a sugar, phosphate group, and one of four bases: adenine, thymine, cytosine, guanine
• Complementary base pairing


  A pairs with T, and C pairs with G
• Triplet


  A sequence of three bases in a gene that codes for a specific amino acid
• Protein synthesis


  1. DNA in nucleus used as template to make mRNA

  2. mRNA moves to cytoplasm and attaches to ribosome

  3. Ribosome joins amino acids in correct order to form protein
• Mutation


  A random change in the DNA base sequence
• Types of mutations


  • Insertions
  • Deletions
  • Substitutions
• Mutations that change the amino acid sequence

  Can affect the structure and function of the resulting protein
• Mutations in non-coding DNA can also affect phenotype by controlling gene expression
• Inheritance of alleles


  1. Parents produce gametes with one copy of each gene

  2. Gametes fuse to form offspring with pairs of chromosomes and genes
• Many regions of DNA are non-coding
• Non-coding parts of DNA

  They switch genes on and off, so they control whether or not a gene is expressed (used to make a protein)
• Mutations in non-coding DNA may prevent protein from being produced, which may in turn affect the organism's phenotype
• Alleles are different versions of the same gene
• Producing an offspring


  1. Chromosomes from male and female gametes get mixed together

  2. Offspring ends up with pairs of chromosomes and alleles for each gene
• Dominant allele


  The version of the characteristic that appears
• Recessive allele


  The characteristic caused by the recessive allele only appears if both alleles are recessive
• Homozygous


  Having two alleles the same for a particular gene
• Heterozygous


  Having two different alleles for a particular gene
• Genotype


  The alleles an organism has
• Phenotype


  The characteristics an organism displays