Lecture 12-Phenotype
Page 1: Introduction
Title: BIS10 - Genotype to Phenotype
Page 2: Reminders
Unit 2 Quiz: Due Thursday night by midnight
PSA Written Principle: Due Friday
Midterm Exam: In class on Wednesday, Feb. 12 (2:10-3:00 pm)
Page 3: Variation within Species
Key Concept: Individuals within species vary
Page 4: Genetic Variation
Similarity: All humans are about 99.9% similar in their DNA.
Difference: The 0.1% difference accounts for variations in traits such as:
Skin color
Hair color
Height and weight
Behavior
Health
Significance of Genetic Variation: This small percentage influences a wide range of traits.
Page 5: GATTACA
Quote: "There is no gene for the human spirit" indicating the limitations of genetic determinism.
Page 6: Genetic vs. Environmental Variation
Genetic Similarity: All humans share about 99.9% of their DNA, with 0.1% accounting for variations.
Types of Variation: Some variations are genetic while others arise from environmental influences.
Page 7: Inquiry on Genetic Phenotypes
Question: What kinds of phenotypes have you heard that there are genes for?
Page 8: Genetic Traits - Eye Color
List of Eye Color Traits:
Jet Black
Darkest Brown/Black
Medium Brown with Dark Chocolate Brown Base
Light Golden Brown
Honey Blonde
Medium Auburn
Page 9: Genetic Traits - Height
Context: Discussion includes star athletes highlighting the impact of genetics and environment on physical traits.
Star Athletes Mentioned: Joel Embiid, Jose Altuve, J.J. Watt, etc.
Page 10: Genetic Traits - Bitter Taste Perception
Context: Variation in taste perception due to genetic factors.
Page 11: Mechanism of Trait Control
Question on Mechanism: How do genes control traits?
Page 12: Definition of a Gene
Definition: A gene is often described as a recipe for a protein.
Page 13: Gene Construction and Function
Gene Making Process: DNA encodes signals for:
Transcription Start & Stop
Translation Start & Stop
Page 14: Heredity
Definition of Heredity: The passing of genetic traits from parents to offspring.
Visual Representation: Illustrates original DNA and new identical strands.
Page 15: Understanding Phenotype
Definition of Phenotype: A phenotype is a trait that results from the interaction of genotype and environment.
Page 16: Genotype Description
Example of Genotype Sequence: GGATGCG... (Illustration of DNA sequence changes and their implications)
Page 17: Interaction of Phenotype and Genotype
Concept: Phenotype = genotype + environment + interactions
Page 18: Types of DNA Differences
Inquiry: What types of differences in DNA cause changes in phenotypes?
Page 19: Genetic Factors
Example: Presence of specific genes, not mutations, may influence traits.
Page 20: Mendel's Rules
Importance: Mendel's rules allow predictions of phenotypes in offspring based on parental genotypes.
Page 21: Monogenic Traits
Definition: A monogenic trait is associated with a single gene, e.g., bitterness in broccoli (PTC gene).
Page 22: Taste Bud Anatomy
Structure Description: Tongue covered with papillae containing taste buds and gustatory cells.
Function: Gustatory cells perceive tastes including bitterness.
Page 23: PTC Receptor Gene
Details: PTC = Phenylthiocarbamide; its receptors are proteins involved in taste perception.
Page 24: Alleles
Definition: Alleles are different forms or versions of a gene.
Inheritance: Each parent contributes one allele.
Notation: Different alleles denoted by capital and lowercase letters, e.g., T or t.
Page 25: Allele Numbers in Cells
Somatic Cell Alleles: 2 copies of each gene.
Sperm/Egg Cell Alleles: 1 copy of each gene.
Choices: A) 2 in somatic cell, 2 in egg/sperm B) 1 in somatic cell, 1 in egg/sperm C) 2 in somatic cell, 1 in egg/sperm D) 1 in somatic cell, 2 in egg/sperm
Page 26: Chromosome Basics
Inheritance Structure: Two copies of a chromosome from each parent. Somatic cells are diploid, while sperm and eggs are haploid.
Page 27: Dominance in Alleles
Dominant vs Recessive:
Homozygous vs. heterozygous traits.
Implications of dominant (T) vs recessive (t) combinations on traits.
Page 28: Punnett Square
Tool for Predicting Traits: Visual representation of dominance and recessive traits through allele combinations.
Example: TT, Tt combinations illustrating homozygous and heterozygous traits.
Page 29: Autosomal Recessive Inheritance
Punnett Square Example of Inheritance: Results in probabilities of affected vs. unaffected offspring.
Page 30: Bitter Taster vs Non-Taster
Genetic Outcomes: TT or Tt genotype = "taster"; tt genotype = "non-taster".
Key Question: Is tasting a dominant trait? Why?
Page 31: Are You a Taster?
Interactive Question: Personal assessment of taste perception in bitterness of broccoli.
Page 32: First Nucleotide
Nucleotide Sequences: Explaining the sequence construction is intrinsic to protein synthesis.
Stop Codons: Critical for RNA interpretation.
Page 33: Mutations and Variations
Missense Mutation: Variation causing differences in protein structure and function.
Page 34: Genetics of Eye Color
Inheritance: Melanin production leads to variations in eye color.
Multiple Genes Involved: Eye color determination relies on at least 3 genes, complicating traditional models.
Page 35: Color Hierarchy and Genes
Hierarchy of Color Dominance: B (brown) > G (green) > b (blue).
Traits Explained: Dominance relationships among different alleles affecting eye color.
Page 36: Gene Interactions in Eye Color
Melanin Production Factors: Activation of genes controlling melanin leads to diverse eye colors.
Page 37: Importance of Melanin
Function of Melanin Beyond Eye Color: Influence on hair color and other phenotypic traits due to genetic mutations affecting expression.