bio review pt 2

• DNA


  organism's genetic material/blueprint
• Structure of DNA


  • Double helix

  
• Nucleotide


  Sequences of nucleotides & complementary nucleotides|>Phosphate|>Sugar|>4 nitrogen bases
• Nitrogenous Bases (4)


  • Adenine (A)
  • Cytosine (C)
  • Thymine (T)
  • Guanine (G)
• Adenine (A) bonds to


  Thymine (T)
• Cytosine (C) bonds to

  Guanine (G)
• Amino acids


  • 20 different amino acids
• Proteins


  Made from amino acids<|>Polypeptides -> Protein
• Functions of Proteins


  • Enzyme (speed up chemical reactions)
  • Structural (provide support and framework)
  • Transport (move materials around body)
  • Hormone (coordinate and regulate activities)
  • Defensive (protect body against disease)
  • Energy (source of chemical energy)
• Enzyme


  Speeds up a chemical reaction
• DNA Replication


  1. Unzip DNA at nitrogen base
  2. New complementary strand attaches to old strand
  3. DNA is rezipped into new strands
• Mutations


  Spontaneous changes that occur in cells

  Can be passed on to offspring
• Types of Mutations


  • Frameshift (addition or deletion of nitrogen base)

  Point (one nitrogen base substituted for another)
• Mutagens


  • Physical (gamma rays, X-rays, UV-rays)

  Chemical (benzene)
• Genetic Disease


  Mutation that occurs in egg or sperm cell and is passed on
• Genome


  Entire set/collection of DNA instructions found within a cell
• Chromosomes


  • Coiled DNA

  Homologous pairs (1-22 somatic, 23=sex)

  X is bigger than Y, XX=female, XY=male

  
• Genes


  Small sections of a chromosome that code for a specific trait
• Alleles


  Different variations of genes
• Cell Division


  Mitosis (diploid->diploid, 2n->2n)

  Meiosis (diploid->haploid, 2n->n)
• Fertilization


  Sperm + egg = zygote (23 chrom. + 23 chrom. = 46 chrom.)
• Genetics


  Study of inheritance
• Heredity


  Passing on of physical or mental characteristics from one generation to another
• Gregor Mendel


  Monk that studied inheritance through pea plants
• Dominant Allele


  The one that "presents" itself, masks recessive allele
• Recessive Allele


  Only "presents" when there is no dominant allele, must have 2 copies

  
• Homozygous


  A pair of identical alleles of a gene
• Heterozygous


  Two different alleles for a gene, "carriers"
• Phenotype


  Expressed/visible trait
• Genotype


  Organism's genetic makeup
• Homozygous dominant tall pea plant crosses with short pea plant


  • TT x tt
• Mendel crosses two heterozygous pea plants

  • Tt x Tt
• Brown eyes dominant over blue eyes, heterozygous brown-eyed person crosses with blue-eyed person


  • Bb x bb
• Sex-linked (X-linked) inheritance


  Traits carried on the X chromosome

  
• Female carrier of hemophilia allele has child with non-carrier

  • Females with hemophilia: 50%

  Males with hemophilia: 0%
• Unaffected mother, affected father, male offspring

  • Huntington's disease: 100% affected
• Pedigree Charts


  Trace traits back several generations (family tree)

  
• Pedigree Chart Symbols


  • Unaffected male

  Affected male

  Unaffected female

  Affected female

  Carrier female
• Autosomal Dominant Pedigree


  Every affected has at least 1 affected parent

  Unaffected individuals will not have an affected child
• Autosomal Recessive Pedigree


  All children of affected parents are affected