GENES

• Genetics


  Study of genes and their transmission from our generation to the next
• Genes


  DNA that contains instructions for building proteins
• Genome


  Sum total of all of an organism's DNA, including the complete genetic material and noncoding nucleic acid sequence
• Genotype


  Genes in our DNA that tells us what will be expressed, an individual's complete set of alleles (heterozygous or homozygous)

  
• Phenotype


  Physical traits and appearances that we see, observable physical and functional traits

  
• Karyotype


  • A composite visual display of all 23 pairs of chromosomes of an individual lined up side-by-side

  
• Mutations


  Structural and Numerical
• Dominant


  A gene that is being expressed, represented by a capital letter
• Recessive


  A gene that is being hidden, represented by a small letter
• Homozygous


  Having two identical alleles of a particular gene or genes
• Heterozygous


  Having two different alleles of a particular gene or genes
• Genotypic Ratio


  Numerical comparison of how many offspring will have one phenotype versus another

  
• Phenotypic Ratio


  Numerical comparison of the allele combinations the offspring will have, such as homozygous dominant, heterozygous, or homozygous recessive

  
• Gregor Mendel 1822-1884 was the Father of Modern Genetics, who worked with pea plants in the 1850's in Austria and developed the basic rules of inheritance
• Reasons for Mendel's success

  • The pea plant can be easily grown and maintained, they are naturally self-pollinating but can also be cross-pollinated, it is an annual plant so many generations can be studied within a short period, and it has several contrasting characters
• Inheritance


  The process of how an offspring receives genetic information from parents, which is the reason offspring are similar to their parents
• Law of Dominance


  Hybrid offspring will only inherit the dominant trait in the phenotype, while the suppressed alleles are the recessive traits
• Law of Segregation


  Gametes carry only one allele of each gene, and allele pairs segregate during gamete formation and re-unite randomly during fertilization
• Law of Independent Assortment


  A pair of traits segregates independently of another pair during gamete formation, so different traits get equal opportunity to occur together
• Punnett Square


  A diagram used to predict probabilities of traits passed on to offspring, for monohybrid (one trait) or dihybrid (two traits) crosses

  
• Chromosomal Mutations


  Changes in the DNA sequence that manifest as genetic disorders
• Karyotyping


  A laboratory technique that produces an image of an individual's chromosomes to look for abnormal numbers or structure

  
• Nondisjunction


  The failure of a pair of homologous chromosomes or sister chromatids to separate during meiosis, resulting in numerical mutations
• Aneuploidy


  A condition where there is an addition or deletion of one or more chromosomes, such as trisomy (2N+1) or monosomy (2N-1)
• Genetic Disorders

  • Down Syndrome (Trisomy 21), Patau Syndrome (Trisomy 13), Klinefelter Syndrome (XXY), Turner Syndrome (XO), Jacob Syndrome (47,XYY)
• Structural Mutations


  Alterations that affect whole chromosomes or genes, resulting from errors in cell division that cause a section to break off, be duplicated, or move onto another chromosome
• Translocation


  The transfer of genetic material between two non-homologous chromosomes
• Inversion


  Two breaks occur in one chromosome, and the region between the breaks rotates 180 degrees before rejoining
• Deletion


  Breaks in a chromosome resulting in the loss of one or more genes
• Genetic Disorders


  • CRIDUCHUT (loss of segment of chromosome 5), Pallister Killian Syndrome (part of chromosome 12 duplicated)
• Polygenic Inheritance


  Inheritance of phenotypic traits that depend on many genes, such as eye color, skin color, height, and body size

  
• Genes and environment are both important factors that shape who and what we are
• Linked Alleles


  Alleles physically located on the same chromosome, which may be inherited together or "shuffled" during crossing over in meiosis
• Sex-linked Inheritance


  Inheritance involving the sex chromosomes (X and Y), where males have one X and one Y, and females have two X chromosomes
• Genes code for proteins, not specific for behavior
• Protein Functions


  • Hormones, Enzymes, Structural, Neurotransmitters, Intracellular messengers