genetics

• Diploid


  Nuclei possessing pairs of homologous chromosomes (2n)
• Haploid


  Nuclei possessing only one set of chromosomes (n)
• Sexually reproducing organisms inherit their genetic sequences from both parents
• Organisms with diploid cells will possess two copies of each chromosome (one of maternal origin, one of paternal origin)
• Homologous chromosomes


  Chromosomes that share the same structural features and the same genes at the same loci positions
• Genetics


  Branch of biology that deals with heredity and variation of organisms
• Chromosomes carry the hereditary information (genes)
• Genetic information flow


  DNA -> RNA -> Proteins

  
• Chromosomes (and genes) occur in pairs
• New combinations of genes occur in sexual reproduction
• Mendel's Principles of Inheritance

  • Principle of Dominance
  • Principle of Segregation
  • Principle of Independent Assortment
• Monohybrid cross


  1. Determine parent genotypes

  2. Write down cross

  3. Draw Punnett square

  4. Determine offspring genotypes and phenotypes

  
• Punnett square


  A useful tool to do genetic crosses and predict the genotypes and phenotypes of the offspring

  
• Mendel's Principles of Heredity apply universally to all organisms
• Cystic Fibrosis


  A lethal genetic disease affecting Caucasians, caused by a mutant recessive gene
• Incomplete dominance


  When the heterozygous phenotype is intermediate between the two homozygous phenotypes

  
• Codominance


  When both alleles are fully expressed in the heterozygous phenotype

  
• Karyotype


  The complete set of chromosomes in a cell, including 23 homologous pairs
• Autosome


  The first 22 homologous pairs of human chromosomes that do not influence the sex of an individual
• Sex chromosome


  The 23rd pair of chromosomes that determine the sex of an individual
• Autosomal recessive trait


  A trait that requires two recessive alleles to be expressed

  
• Autosomal dominant trait


  A trait that is expressed when the dominant allele is present
• Sex-linked trait


  A trait produced by genes only on the X chromosome, can be dominant or recessive
• Pedigree


  A diagram that shows the relationship between parents and children over generations and how a trait is passed down

  
• Nucleic acid


  The two types are RNA and DNA, found in cells and involved in the transmission of hereditary information

  
• Nucleotide


  The building block of nucleic acids, composed of a base, sugar, and phosphate

  
• Pentose sugar


  The structural difference between ribose (in RNA) and 2'-deoxyribose (in DNA) is the presence or absence of a hydroxyl group at the 2' carbon

  
• Nitrogen-containing heterocyclic bases


  The five bases are adenine, guanine, cytosine, thymine (in DNA), and uracil (in RNA)

  
• Phosphate


  The third component of a nucleotide, derived from phosphoric acid
• e


  Present in RNA
• 2′-deoxyribose


  Present in DNA

  
• Bonding


  1. Between C-1 of the monosaccharide and N-9 of the purine base

  2. Pyrimidine bases linked to the C-1 of the monosaccharide through the N-1 nitrogen

  
• Bonding


  1. glycosidic bond

  
• Nitrogen-Containing Heterocyclic Bases


  • Thymine (T)
  • Cytosine (C)
  • Uracil (U)
  • Adenine (A)
  • Guanine (G)

  
• Adenine, guanine, and cytosine are found in both DNA and RNA

  
• Uracil is found only in RNA
• Thymine is found only in DNA
• Phosphate


  The third component of a nucleotide
• Nucleotide formation


  1. Nucleoside formation

  2. Nucleoside reacts with phosphate group
• Nucleoside


  A two-subunit molecule in which a pentose sugar is bonded to a nitrogen-containing heterocyclic base