Cytogenetics

• Heritable features that vary among individuals

  Variants for each character
• Loci


  Specific position on a chromosome where a particular gene is located
• Alleles


  Variations of a gene from a given locus from which we derive our traits
• Homozygous


  Pair of identical alleles
• Heterozygous


  Pair of different alleles
• Hybridization


  Mating or crossing of two genetically different parents
• Parental


  True breeding parents
• F1 generation


  Offspring of the parental cross
• F2 generation


  Offspring of the F1 gen. cross
• Genotype


  Genetic composition of the organism
• Phenotype

  Visible expression of traits
• Cell as the basic unit of plant structure

  1838
• Cell as the basic unit of animal structure (Robert Remak)

  1839
• Cell


  Basic unit of life, smallest unit of protoplasm capable of independent existence
• Major parts of the cell

  • Form
  • Nucleus
  • DNA
  • Organelles
  • Reproduction
  • Ribosome size
• Differences between prokaryotic and eukaryotic cells

  • Unicellular vs multicellular
  • No true nucleus vs has true nucleus
  • Naked, circular DNA vs protein-bound, linear DNA
  • Not membrane-bound vs membrane-bound
  • Binary fission vs mitosis, meiosis
  • 70s ribosomes vs 80s ribosomes
• Cell components

  • Cell membrane
  • Cytosol
  • Cytoplasmic organelles
  • Cytoplasmic inclusion bodies
  • Nucleus
• Cell membrane


  Outermost component, phospholipid bilayer and proteins, selective barrier, undergoes changes during cell division
• Cytosol


  Platform where organelles are bound, divides during cell division to give rise to two new daughter cells
• Mitochondria


  Site of aerobic respiration, major site of ATP production
• Endoplasmic reticulum


  Collects, modifies, packages, and distributes proteins and lipids manufactures
• Golgi apparatus


  Vesicles formed by the Golgi apparatus
• Lysosomes

  Intracellular digestive enzymes, phagocytosis
• Peroxisomes

  Break down fatty acids, amino acids, and H2O2
• Cytoskeleton

  Form the framework of the cell, internal support to hold the organelles in place, composition: microfilaments, microtubules, intermediate filaments, facilitate chromosome movement during cell division
• Endoplasmic reticulum


  Series of membranes forming sacs and tubules extending from the outer nuclear membrane into the cytoplasm, may be with or without ribosomes, Smooth ER: lipid synthesis, Rough ER: protein synthesis
• Ribosomes

  Site of protein synthesis, assembles nucleotides in groups of three called codon to synthesize amino acids, may be free or bound
• Nucleus

  Carries the genetic material embedded in the DNA, the nuclear envelope consists of two separate membranes that form nuclear pores at the surface of the nucleus, DNA and associated proteins are found inside the nucleus as chromatin
• Chromosomes

  Highly compacted, densely coiled DNA material, pairs of autosomes, pair of sex chromosomes, genetic information
• Gene

  Portion of the DNA that codes for a particular trait
• Genome

  The entire sequence of genetic material of an organism
• Cell cycle

  • Interphase
  • Mitosis
• Interphase

  1. Accounts for 90% of the cell cycle

  2. Cell is not yet actively dividing

  3. Newly produced cells grow by imbibing water and producing more proteins in anticipation for DNA synthesis

  4. Cell doubles the number of chromosomes by replicating DNA

  5. Cell continues to grow and checks for errors that may be present in the duplicated chromosomes
• Mitosis

  1. Cell is actively dividing

  2. Increased condensation of chromosomes

  3. Nuclear envelope still present

  4. Appearance of the centromere

  5. Appearance of the mitotic spindle

  6. Nuclear envelope disintegrates

  7. Chromosomes align at the mitotic plate

  8. Kinetochores retract sister chromatids to opposite poles

  9. Cell begins to elongate

  10. Sister chromatids reach opposite poles

  11. Nuclear envelope reappears

  12. Chromosomes de-condense

  13. Two nuclei are created in one cell

  14. Cleavage furrow appears

  15. Nuclear envelope developed