Genetic

• Genetics


  The study of how genes bring about characteristics, or traits, in living things and how those characteristics are inherited
• Genes


  Specific sequences of nucleotides that code for particular proteins
• Meiosis


  The process where the diploid number of chromosomes is reduced to a haploid number
• Sexual reproduction


  The process where haploid gametes come together to reestablish the diploid condition
• Gregor Mendel


  Augustinian monk who developed the science of genetics
• Mendel performed his experiments in the 1860s and 1870s, but the scientific community did not accept his work until early in the twentieth century
• Mendelian genetics


  The science of genetics based on the principles established by Mendel
• Molecular genetics


  Another branch of biology distinct from classical Mendelian genetics
• Diploid cells


  Cells that have a double set of chromosomes, one from each parent
• Haploid cells


  Cells that have a single set of chromosomes, formed through meiosis
• Gametes


  Haploid sex cells formed through meiosis
• Alleles


  The different forms of a gene
• Genome


  The set of all genes that specify an organism's traits
• Genotype


  The gene composition of a living organism
• Phenotype


  The expression of the genes
• Homozygous


  When two identical alleles are present for a particular characteristic
• Heterozygous


  When two different alleles are present for a particular characteristic
• Dominant allele


  The allele that expresses itself when present with a recessive allele
• Recessive allele


  The allele that is "overshadowed" and only expresses itself when two recessive alleles exist together
• Pure lines


  Populations of homozygous individuals for particular characteristics
• Parent generation


  Pure-line pea plants that are cross-pollinated
• F1 generation


  The offspring of the parent generation cross
• F2 generation


  The offspring of the F1 generation cross
• Mendel's laws of genetics

  • Law of dominance

  2. Law of segregation

  3. Law of independent assortment
• Genetic cross


  Also called a Mendelian cross, a way to predict the probability of inherited traits in offspring
• Punnett square


  A boxed figure used to determine the probability of genotypes and phenotypes in the offspring of a genetic cross
• Incomplete dominance


  When two characteristics are equally expressed, rather than one dominating the other
• Multiple alleles


  When more than two alleles exist for a particular characteristic in a population
• Polygenic inheritance


  When a characteristic is determined by an interaction of genes on several chromosomes or at several places on one chromosome
• Gene linkage


  When genes that are located close together on a chromosome are inherited together
• Sex linkage


  When a gene occurs on a sex chromosome, usually the X chromosome
• DNA


  Deoxyribonucleic acid, consisting of two long nucleotide chains in a double helix structure
• Colorblindness


  Expresses itself in the male
• Hemophilia


  Blood disease where blood does not clot normally because an important blood-clotting protein is missing
• The gene for hemophilia occurs on the X chromosome
• Females


  May be a carrier of hemophilia but normally do not express it
• Males


  Have no offsetting gene on the Y chromosome, so the gene for hemophilia expresses itself
• Most cases of hemophilia occur in males
• DNA


  Consists of two long nucleotide chains that twist around one another to form a double helix
• Nucleotide


  Consists of a nitrogenous base, a phosphate group, and a molecule of deoxyribose