ANSCI 1100- Genetics

• Genetics


  Science that deals with the study of heredity and variations
• Animal Breeding


  Application of principles of genetics to select the best animals based on human needs
• Gregor Mendel


  • Postulated that traits are carried by genetic material, which is now known as "gene"
  • Discovered that genes exist in different forms, "allele"
  • Discovered that alleles of different genes are inherited differently
• James Watson and Francis Crick


  • Discovered that DNA exists as a double helix

  
• Gene


  The basic physical and functional unit of heredity, made up of DNA (Deoxyribonucleic acid)
• DNA


  The hereditary material in almost all living organisms, a biological compound consisting of a chain of nucleotides called polynucleotides
• Nucleotides


  • Adenine (A)
  • Thymine (T)
  • Guanine (G)
  • Cytosine (C)
• The coding system of the gene is based on the arrangement of the 4 bases: Guanine (G), Adenine (A), Thymine (T) and Cytosine (C)
• Structural Gene


  Responsible for the synthesis of certain biochemical products (hormones & enzymes) during cell metabolism
• Regulatory Gene


  Control and regulate the functions of other genes (on/off)
• Ribonucleic acid (RNA)


  Functional molecules that translate DNA code
• DNA Replication


  DNA Polymerase reads new template DNA strand and stitches together the complementary new strand

  
• Mutation


  Error in gene sequence that can lead to incorrect protein, no protein, or not all are harmful (e.g. brown eyes)
• Mutation


  • Natural mutation in myostatin gene in beef cattle led to the development of Belgian Blue breed that has double-muscling trait
• Homologous Chromosomes


  Chromosome pairs that are similar in length, gene position, and centromere location
• Heterologous Chromosomes


  Chromosomes that differ in type, function, or size
• Chromosome Number


  • Man: 46
  • Sheep: 54
  • Horse: 64
  • Goat: 60
  • Donkey: 62
  • Pig: 40
  • Mule: 63
  • Dog: 78
  • Cattle: 60
  • Cat: 38
  • Domestic Buffalo: 48
  • Rabbit: 44
  • Murrah Buffalo: 50
  • Mouse: 40
  • Cross (N x B): 49
  • Rat: 42
  • Reindeer: 70
  • Chicken: 78
  • Llama: 74
  • Duck: 80
  • Turkey: 82
• Autosome


  Body cells, diploid (2 sets of chromosomes), cell division: mitosis
• Sex Cells


  Gametes: egg and sperm cell, haploid (1 set of chromosomes), cell division: mitosis and meiosis
• The manner by which the genetic information is transmitted from cell to cell is made possible through somatic cell division (mitosis), and the transmission of the genetic materials from parent to offspring is through reduction division of the germinal cells (meiosis) and subsequent union of the gametes
• Locus


  Location of a gene in a chromosome
• Allele


  Genes that occupy corresponding loci in homologous chromosomes but affect the same characteristics in a different way (e.g. height)
• Homozygous Gene


  Genes that correspond to each other
• Heterozygous Gene


  Genes that contrast in response
• Dominant Allele


  Gene that overpowers/dominates the expression of the other, symbolized by capital letter
• Recessive Allele


  Allele whose expression is suppressed
• Phenotype


  Characteristics that can be perceived by the naked eye
• Genotype


  Actual genetic make-up
• Phenotype and Genotype Examples

  • Height: Tall, Dwarf - TT, tt, Tt
  • Color: Black, Red, Roan - BB, bb, Bb