GENETICS

• Humans typically have 3 billion base pairs
• Genetics


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


  DNA sequence that contains instructions for building proteins
• Genes


  A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses)
• Genome


  Sum total of all of an organism's DNA
• Genome


  The complete genetic material of an organism along with its non-coding nucleic acid sequence
• Chromosome


  A cellular structure consisting of one DNA molecule and associated protein molecules
• Allele


  Alternative version of a DNA
• Genotype


  All the set of alleles, an individual's complete set of alleles
• Phenotype


  Observable physical and functional traits. These are the characteristics that are expressed from the genes like physical and biochemical characteristics
• Humans have 46 chromosomes, 23 pairs
• Chromosome pairs


  • First 22 pairs - Autosomes
  • Last 1 pair- Allosome
• XX- female , XY- Male
• Karyotype


  Identify and evaluate the size, shape , and number of chromosomes
• Karyotype


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


  • You can find out if you have alterations and mutations that you could possibly pass down to your offsprings
  • You can find out are the ones causing you to have difficulties in having a baby; knowing if you're sterile
  • If a fetus has a chromosomal defect
• Autosome


  Each autosome carries the same genes at the locus. Each chromosome carries a specific characteristic
• Gene Locus


  The location of a specific pair of genes
• Alleles


  Alternative versions of the same gene pair. Arise from mutations. Not all mutations are bad, bad only if they can cause illnesses. Like one could be tall, but one could also be short. Yet, they are the same characteristics as they both are heights
• Homozygous Pairs


  Two identical alleles at a particular locus
• Heterozygous


  Two different alleles at a particular locus
• Homologous Chromosomes


  One member of each pair
• Dominant Alleles


  • Masks or suppresses the expression of its complementary allele
  • Always expressed, even if heterozygous
  • Are not always more common than recessive ones; sometimes they may be rare in a population
• Dominant Alleles


  • Polydactyly- it is a condition wherein you have extra fingers , trait is being controlled/ expressed by a dominant allele but it is not common
• Recessive Alleles


  • Will not be expressed if paired with a dominant allele (heterozygous)
  • Will only be expressed if the individual is homozygous for the recessive allele
• Gregor Mendel


  • Father of Modern genetics
  • Worked with pea plants in the 1850s in Austria
  • Did multiple genetic experiments to develop basic rules of inheritance
• Law of Segregation


  • Suggests that gametes carry only one allele of each gene
• Law of Independent Assortment


  • Genes for different traits are separated from each other independently during meiosis. This applies only if the two genes in question are in different chromosomes
  • Genes do not influence each other with regard to the sorting of alleles into gametes
• Law of Dominance


  • Complete Dominance: Dominant alleles are expressed
  • Incomplete Dominance: Both alleles are partially expressed, comes up with a new phenotype like a mix
  • Co-Dominance: No dominant alleles, but alleles are expressed equally
• Punnett square analysis


  1. Monohybrid - one set of characteristic only

  2. Dihybrid - two sets
• Polygenic Inheritance


  • Inheritance of phenotypic traits that depend on many genes
  • Examples: eye color, skin color, height and body size
  • Polygenic traits are usually distributed within a population as a continuous range of values
• Linked Allele


  • Physically located on the same chromosome
  • May be inherited together
  • May be shuffled during crossing over during meiosis
• Nearer alleles have lower chance of being inherited separately, farther alleles have higher chance
• Sex-Linked Inheritance


  • Sex chromosomes are the 23rd pair
  • Not homologous, X and Y chromosomes carry different genes
  • Males have one X and one Y chromosome; females have two X chromosomes
  • refers to inheritance patterns that depend on genes located on the sex chromosomes.
• Genes


  • Code for proteins, not specific for behavior
  • Encode specific proteins
  • Proteins have specific function leading to phenotypes
• Non-disjunction


  When the sister chromatids fail to separate during the meiosis/mitosis. Kapag di sila nagseparate then it could result to amioploydy then there is an abnormal number of chromosomes
• Monosomy


  • All or part of one X chromosome is absent
  • Short stature, webbed neck, rudimentary ovaries, underdeveloped breasts, broad shield like chest
• Pedigree Analysis


  • A very important tool for studying the inherited diseases
  • These diagrams make it easier to visualize relationships with families, particularly
• Autosomal Recessive Pedigree

  • Possible diseases include: Cystic fibrosis, Sickle cell anemia, Phenylketonuria (PKU), Tay Sachs disease