Lecture 1 - The Nature of Heredity

• What does DNA stand for?

  • Deoxyribonucleic Acid 
• What is DNA?

  • The material in the nucleus of a cell that contains all of the cell’s genetic information.
• The field of biology that involves the study of how genetic information is passed from one generation of organisms or cells to the next is called Genetics.
• Every cell in your body is controlled by your unique DNA
• DNA will tell the cell exactly what it needs to do 

  It contains the information which makes you unique
• Our DNA Determines:

  If you will be a boy or a girl

  How many limbs we have

  What color eyes, hair, or skin

  Which species we belong to
• Chromosomes

  Every cell in your body has a nucleus

  Inside each nucleus, you will have 46 chromosomes

  ½ of these came from your dad and ½ came from your mom, that would be 23 from each parent. 
• Chromosomes

  
• DNA

  
• When we zoom into one chromosome we find a long stranded molecule

  This molecule is called DNA

  This DNA is extremely long and looks like a twisted ladder
• DNA Samples

  • DNA is typically collected from:
  • Cell Swabs ~ cheek, skin etc.
  • Blood Samples
  • Hair Fibers
• Francis Crick and James Watson are credited with discovering structure of DNA
• Largely work of Rosalind Franklin that led to this discovery

  • If we were to look at a distinct set of chemicals on the DNA molecule for instructions this is called a gene
  • Each one of these genes will be located at a specific location called a locus on a chromosome
  • One chromosome can carry hundreds or thousands of genes.
  • The complete set of an organism’s hereditary information is called its Genome
• The Chemical Composition of DNA

  • DNA has 3 main components:
  • A deoxyribose sugar (cyclic 5-carbon sugar)
  • A phosphate group that has a negative charge
  • A nitrogenous base
  • These three components together are called nucleotides
• There are 4 possible bases for nucleotides of DNA

  1. Adenine
  2. Cytosine
  3. Thymine
  4. Guanine
• • These 4 nitrogenous bases have a key relationship
• The bases of one strand are paired with the bases in the other strand
• Adenine (A) always bonds with Thymine (T)
• Cytosine (C) always bonds with Guanine (G)
• Adenine (A) and Guanine (G) are double-ringed structures known as purines.
• Thymine (T) and Cytosine (C) are single-ringed structures known as pyrimidines.