Cytogenetics

• Genome


  Complete set of genetic instructions characteristic of an organism, including protein-encoding genes and other DNA sequences
• A baby is born
• Genome sequencing


  1. Drops of blood from heel placed into device

  2. Device deciphers entire DNA sequence of white blood cell
• Emma's genome indicates overall good genetic health
• Cystic fibrosis (CF)


  Inherited disease caused by mutation in CFTR gene that alters protein function, thickening secretions
• Emma has inherited a mutation in a gene


  Greatly raises her risk of developing certain types of cancers
• Emma has inherited genes


  Predict a healthy heart, but she might develop diabetes unless she exercises regularly and limits carbohydrates
• Many traits are difficult to predict because of environmental influences, including experiences
• Emma is the beautiful consequence of a mix of her parents' genomes, receiving half of her genetic material from each
• Genetics


  Study of inherited traits and their variation
• Heredity


  Transmission of traits and biological information between generations
• Cytogenetics


  Science that combines cytology and genetics, allowing investigation of heredity at the cellular level
• Chromosome


  Structure composed of double-stranded DNA complex with histone and nonhistone proteins
• Inherited traits range from obvious physical characteristics to many aspects of health, including disease
• Attributing some traits to genetics, such as sense of humor or whether or not one votes, are oversimplifications
• Over the past decade, genetics has exploded from a mostly academic discipline and a minor medical specialty dealing with rare diseases, to the new basis of some fields, such as oncology (cancer care)
• Gene


  Biochemical instructions that tell cells how to manufacture certain proteins
• DNA


  Molecule that transmits information in its sequence of four types of building blocks (nucleotides), which function like an alphabet
• Scientists are still analyzing what all of our genes do, and how genes interact and respond to environmental stimuli
• Genomics


  Scientific field that analyzes and compares genomes, and reveals how closely related we are to each other and to other species
• Levels of organization


  • Individuals
  • Family
  • Population
• DNA


  • Resembles a spiral staircase or double helix
  • The "rails" consist of alternating chemical groups (sugars and phosphates)
  • The two strands are oriented in opposite directions
  • The "steps" are pairs of four types of building blocks (A, T, C, G)
• DNA information


  Sequences of A, T, C, and G
• DNA


  • Can perpetuate itself when the cell divides
  • Can provide information to manufacture specific proteins
• Central dogma of molecular biology

  1. Replication of DNA

  2. Transcription of RNA from DNA

  3. Translation of protein from RNA
• DNA replication


  1. Chains of double helix untwist and separate

  2. Each half builds a new partner chain from free DNA bases

  3. A and T attract each other

  4. C and G attract each other
• Transcription


  Copies sequence of part of one DNA strand into messenger RNA
• Translation


  1. Three RNA bases in a row attract transfer RNA that brings in a particular amino acid

  2. Amino acids align and link to form a protein
• Cystic fibrosis (CF)


  Inherited disease caused by abnormal CFTR protein that thickens secretions
• Mutation can alter a protein, causing symptoms
• Exome


  DNA sequences that encode proteins, accounting for 85% of known genetic diseases
• Allele


  Gene variant with slightly different DNA base sequence from person to person
• Mutations can also help, like making cells unable to bind HIV
• Chromosome


  23 structures that DNA sequences of human genome are dispersed among
• Somatic cell


  Non-sex cell with 23 pairs of chromosomes
• A human somatic cell has two complete sets of genetic information (genomes)
• Mendelian trait


  Trait caused predominantly by a single gene
• Multifactorial trait


  Trait determined by one or more genes and environmental factors
• The more factors that contribute to a trait or illness, the more difficult it is to predict the risk of occurrence in a particular family member
• The environmental effects on gene action counter the idea of "genetic determinism," that "we are our genes"