genetics study of inheritance. reproduction asexual – cell divides, creating an identical daughter...
TRANSCRIPT
Genetics
Study of Inheritance
Reproduction
• Asexual – Cell divides, creating an
identical daughter cell
• Sexual– Exchange of genetic
material, both parents contribute to fertilization of egg/ovary
– Increases diversity – In Animals Egg & Sperm– In Plants Pollen & Ovary
Heredity
• We share many similarities with our parents & siblings, but we are not genetically identical due to the mixing of genes
Chromosomes
• A chromosome is a rod-shaped bundle of DNA
• In sexual reproduction, each “parent” contributes ½ of the offspring’s genetic info– ½ from “mom’s egg” & ½ from
“dad’s sperm”
• The physical characteristics that show are due to “genetics”
Genes vs Alleles
• A gene is a section of a chromosome that codes for a specific trait– EX: Eye Color
• An allele is a variation of that instruction– EX: Brown vs blue eyes
• Every gene has 2 alleles, which we represent with a single letter (capital or lowercase)– BB or Bb or bb
Genotype vs Phenotype
• Genotype the Genetic code – BB
• Phenotype the Physical trait – Brown eyes
Dominant vs Recessive Alleles
• A dominant allele (represented by a capital letter), if present, shows that specific trait– BB or Bb = Brown Eyes
• A recessive allele (represented by a lowercase letter), must have both alleles to show a trait– bb = Blue eyes
• If both letters are the same, BB or bb, we say it is HOMOZYGOUS (dominant or recessive)
• If both letters are different, Bb, we say it is HETEROZYGOUS
Look at this…
• HH = Does not have trait
• Hh = Does not show trait, but is a carrier
• hh = shows trait
Trait could be anything inheritable, such as baldness or albinism
Let’s watch this video…
• https://www.youtube.com/watch?v=CBezq1fFUEA
Punnett Squares
• We can predict the outcome of offspring by using a PUNNETT SQUARE
Let’s Practice…