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Genetics Notes. Heredity:. The study of genetics started with observations made by GREGOR MENDEL , a monk who noticed that pea plants passed certain traits from one generation to the next.
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Heredity: • The study of genetics started with observations made by GREGOR MENDEL, a monk who noticed that pea plants passed certain traits from one generation to the next. • Heredityis the passing of genes from one generation to the next. We all inherit DNA from both our parents, and their parents and so on. • DNA contains genes that code for all of our characteristics.
Genes: • Provide genetic information, passed on from parents to offspring. • Genes provide traits • Ex:hair color, eye color, height, seed shape, etc.
Alleles • Allelesare different forms of a trait. We use letters to represent a particular trait. Example: HeightT= Tall t= Short • Dominant Allele: Fully Expressed • (Always in Capitalized letter) • Recessive Allele: Not shown when paired with a dominant allele; only noticeable when paired with another recessive allele (Always in lower case letter)
Genotype: • Is the combination of genes from each parent Homozygous = Same alleles. Ex: TT (Dominant) Same or tt(Recessive) purple PP homozygous dominant Heterozygous= Different alleles. Ex: Tt(Hybrid) different also called a CARRIER. purple Ppheterozygous
Phenotype: • Is the way an organism physically looks. • Ex: Blonde hair, brown eyes, tall, purple flowers, etc. • TT or Tt= Tall phenotype • tt = Short phenotype
RR Red feathers • What is the phenotype? What is the genotype?
Punnett Squares • Allow us to find the probability of the genotype and phenotype passed from parents to offspring • Letters OUTSIDE of the Punnett Square are from the parents • Letters INSIDE of the Punnett Square represent the probability of the parents’ offspring’s genotypes
Punnett Squares: Ex: Parents: Tt x tt (T=Tall, t=short) T tGenotype: t Tt=50% , tt= 50% Phenotype: t Tall=50%, Short=50%
Can you think of any traits that identify you and the rest of your family?