Genetics Unit

• Cell Theory: 

  • All living things are made of 1 or more cells
  • Cells are the smallest units of living organisms
  • New cells come only from pre-existing cells by cell division
• Asexual Reproduction: Production of offspring form a single parent (bacteria, clones)

  
  

  Sexual Reproduction: Production of offspring from union of two sex cells, one from each different parent (hybrids)
• Cell Cycle involves reproduction, growth and repair

  • Stage between nuclear divisions in interphase
  • Rapid growth, chromosome replication, more growth, preparation for division
  • Genetic information found in DNA 
  • Contained in chromosomes (46 human)
  • Chromosomes are duplicated to make new daughter cells with the same DNA as the parent cell.
  • All cells in body have same DNA

  Two cells that divide continuously:

  • Spermatocytes (sperm producing cells)
  • Cells of a cancerous tumor
• Bases in DNA pair by forming hydrogen bonds between complementary nitrogenous molecules
• Autosomes: A chromosome that is not involved in determining the sex of an organism
• Sex Chromosomes: A chromosome that is involved in determining the sex of an organism
• Homologous Chromosomes: A chromosome that contains the same sequence of genes as another chromosome

  Why are they important:

  • Increase both the variety and stability of a species by carrying two copies of each chromosome.
  • Allow for the recombination and random segregation of genetic material from the mother and father into new cells.
  • Carry different versions of the same genes, called alleles.
  • Play an extremely important role in meiosis, allowing for the genetic variability that we see in offspring.
• Karyotype Charts: A photograph of pairs of homologous chromosomes in a cell, they are used to visualize abnormalities in chromosomes
• Prophase I - Nuclear membrane begins to dissolve

  Metaphase I - Homologous chromosomes attach to spindle fibers

  Anaphase I - Homologous chromosomes separate and move towards opposite poles

  Telophase I - Homologous chromosomes begin to uncoil and spindle fibers disappear
• Prophase II - Nuclear membrane dissolves and spindle fibers begin to form

  Metaphase II - Arrangement of chromosomes along equator of cell

  Anaphase II - Breaking of centromere and movement to opposite poles; nuclear membrane begins to form around chromosomes

  Telophase II - Second nuclear division complete, second division of cytoplasm occurs; product of four haploids (n number of chromosomes) daughter cells
• Independent Assortment: The number of variations in offspring that can happen. It is important because it contributes to genetic diversity.
• A mutation is any change to the nucleotide sequence of a DNA molecule, they can happen by deleting, duplicating, inversion and translocation which results in a change in the organism's traits.
• Monohybrid Cross: A cross that involves one alleles pair of contrasting traits

  
  

  Dihybrid Cross: Plants what were pure breed for two traits, and each parent differed in each trait
• Incomplete dominance: a condition in which neither allele for a gene completely conceals the presence of the other; it results in intermediate expression of a trait
• Complete dominance: when an allele from a parent is dominant over the recessive.
• Multiple Alleles: Many traits are the result of the interaction of more than two alleles for one gene, fruit fly example
• Pedigree Chart: Chart that shows the presence or absence of a trait within a family across generations

  
• Linked Genes: Are genes that are on the same chromosome and that tend to be inherited together
• Sex Linked Traits: Are taits that are controlled by genes located on the sex chromosomes