Module 8- Genetics
Genetic Terminology Related to Inheritance
Video 1 Notes:
• Alleles & Genes
• Tastebuds cannot taste PTC (Phenylthiocarbamide)
o Chemical sold on paper strips- “PTC paper”, some people taste PTC, others don’t
o The trait of being able to taste PTC or not is based on genetics
▪ Ability to taste PTC or not is impacted by a specific gene
• Gene: portion of DNA that codes for a trait, made of nucleotides, each gene is at a different location
(gene locus), each gene is a different size or length (# of nucleotides dependent on size)
• Many traits are coded for by interactions of more than one gene (eye color- many genes)
• Humans have 46 chromosomes (made up of DNA & protein, condensed unit of DNA, represents
genetic code)
• 23 pairs total (one from mom one from dad on each)
• Gene Locus on chromosomes (area where specific gene codes for a trait (ability to taste PTC))
o Gene is involved with coding for taste receptors on your tongue. The receptors you have can
make a difference for whether you taste PTC or not
• Inherit 23 chromosomes from your mother and 23 chromosomes from your father, each parent
contributes an allele
o Allele: versions of a gene, can be same form of gene or different (PTC taster, non-PTC taster),
represented by letters
o Together, the two alleles you inherit (forms of the gene) determine the trait of tasting or not
tasting PTC
o Since its about tasting, use letter T, but capitalization matters
▪ Capital letter- dominant allele
• If one or both are dominant, then it will be expressed
▪ Lowercase letter- recessive allele
• Typically, not expressed if no dominant is present
o 2 allele copies, so the genotypes (genetic makeup) could be: TT, Tt, tt
• Genotypes help determine a phenotype (physical characteristic)
o When writing genotypes, you write the capital letters first
o Ability to taste PTC is a dominant trait so the phenotype (a PTC taster) is due to a genotype that
includes at least one dominant allele
▪ So which genotypes can taste PTC then? TT (both dominant) & Tt (at least one
dominant)
▪ If child is tt, both parents must be Tt
• Punnett Square: can be used to determine the probability of offspring’s genotypes, which can
determine phenotypes
• Polydactyl: can result in having extra fingers or toes, presence of at least one dominant allele (may not
be as common in the population)
Video 2 Notes:
• Genetic Terminology & Notations
o Genetics & how genetic information is passed down, how individuals differ in terms of their
characteristics & how that affects DNA
• Genes in terms of function: each gene provides information to produce ONE polypeptide (polypeptide
In hemoglobin, etc.)
o Can refer to genes using different letter (A, B, C)
Genetic Terminology Related to Inheritance
Video 1 Notes:
• Alleles & Genes
• Tastebuds cannot taste PTC (Phenylthiocarbamide)
o Chemical sold on paper strips- “PTC paper”, some people taste PTC, others don’t
o The trait of being able to taste PTC or not is based on genetics
▪ Ability to taste PTC or not is impacted by a specific gene
• Gene: portion of DNA that codes for a trait, made of nucleotides, each gene is at a different location
(gene locus), each gene is a different size or length (# of nucleotides dependent on size)
• Many traits are coded for by interactions of more than one gene (eye color- many genes)
• Humans have 46 chromosomes (made up of DNA & protein, condensed unit of DNA, represents
genetic code)
• 23 pairs total (one from mom one from dad on each)
• Gene Locus on chromosomes (area where specific gene codes for a trait (ability to taste PTC))
o Gene is involved with coding for taste receptors on your tongue. The receptors you have can
make a difference for whether you taste PTC or not
• Inherit 23 chromosomes from your mother and 23 chromosomes from your father, each parent
contributes an allele
o Allele: versions of a gene, can be same form of gene or different (PTC taster, non-PTC taster),
represented by letters
o Together, the two alleles you inherit (forms of the gene) determine the trait of tasting or not
tasting PTC
o Since its about tasting, use letter T, but capitalization matters
▪ Capital letter- dominant allele
• If one or both are dominant, then it will be expressed
▪ Lowercase letter- recessive allele
• Typically, not expressed if no dominant is present
o 2 allele copies, so the genotypes (genetic makeup) could be: TT, Tt, tt
• Genotypes help determine a phenotype (physical characteristic)
o When writing genotypes, you write the capital letters first
o Ability to taste PTC is a dominant trait so the phenotype (a PTC taster) is due to a genotype that
includes at least one dominant allele
▪ So which genotypes can taste PTC then? TT (both dominant) & Tt (at least one
dominant)
▪ If child is tt, both parents must be Tt
• Punnett Square: can be used to determine the probability of offspring’s genotypes, which can
determine phenotypes
• Polydactyl: can result in having extra fingers or toes, presence of at least one dominant allele (may not
be as common in the population)
Video 2 Notes:
• Genetic Terminology & Notations
o Genetics & how genetic information is passed down, how individuals differ in terms of their
characteristics & how that affects DNA
• Genes in terms of function: each gene provides information to produce ONE polypeptide (polypeptide
In hemoglobin, etc.)
o Can refer to genes using different letter (A, B, C)
