Mendel and Meiosis Chapter 10 p. 258 - 285. Chapter Outline Mendel’s Laws of Heredity Meiosis.
Introduction to Genetics Heredity and Mendel’s Peas Mrs. Stewart Honors Biology Central Magnet...
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Transcript of Introduction to Genetics Heredity and Mendel’s Peas Mrs. Stewart Honors Biology Central Magnet...
Introduction to Genetics
Heredity and Mendel’s Peas
Mrs. Stewart
Honors Biology
Central Magnet School
Standards:
CLE 3210.4.1 Investigate how genetic information is encoded in nucleic acids.
CLE 3210.4.2 Describe the relationships among genes, chromosomes, proteins, and hereditary traits.
CLE 3210.4.3 Predict the outcome of monohybrid and dihybrid crosses.
Objectives:
Differentiate between characteristics and traits
Analyze Mendal’s principle of dominance
Predict genotype based on phenotype Analyze characteristics and traits in
this classroom
Decide with your partner
What is heredity?
Why do family’s look alike?
Heredity & Genetics
Heredity - The transmission of characteristics from parents to offspring
Genetics – the study of heredity
Genes – Segments of DNA that code for a characteristic
Characteristics vs. Traits
Characteristic – a heritable feature Example: flower color, plant height
Trait – a genetically determined variant of a characteristic Example: purple flower color vs white Now referred to as “Alleles”
Dogs Tell your cats two examples of
characteristics that can be inherited from human parents to offspring.
Cats Give your dogs an example of
traits/alleles (variations) for the characteristics he/she listed.
Gregor Mendel (1822-1884)
“Father of Genetics”
Austrian Monk
Studied characteristics & traits in pea plants Have only 7 chromosomes Can cross pollinate or self pollinate
Gregor Mendel’s Peas• “Self pollination”-
Pollen from the plant fertilizes its own eggs• Similar to asexual
reproduction. • “True-breeding” -
produce identical new plants.• “Purebreds”
Mendel’s Peas• “Cross-pollination”• Remove male parts
from true breeding plant, pollinate it with pollen from a plant with different traits.
• Produce “hybrids”• Genetically
different
Mendel’s Observations
Characteristics
Seed shape
Seed color
Seed coat color
Pod shape
Pod color
Flower position
Plant height
Traits/Alleles
wrinkled or smooth
yellow or green
white or grey
smooth or constricted
green or yellow
axial or terminal
tall or short
Alleles
We use letters to represent the different variations
Capital Letters = Dominant allele Lowercase letters = recessive allele Example: T = tall plant, t = short plant Most genes have two or more variations
(alleles)
Important Vocabulary Terms HETEROzygous:
(DIFFERENT) have different alleles Example: Tt
HOMOzygous : (SAME) have the same
alleles. Example: TT or tt
HYBRID = offspring of heterozygous parents
PUREBRED (true-breeding) = offspring of homozygous parents – will produce offspring identical to parent traits
Generations• The parent
generation
• The first generation
• The second generation
Dominance
• Tall height “masks” the effects of short height.• Tall is “dominant”; Short is “recessive”.
(P) – Purebred Tall x Purebred Short
F1 – All tall (hybrids)
F2 – 3:1 ratio tall:short
Principle of Dominance
some variations (traits/alleles) are dominant over others
Dominant traits will mask or hide the presence of a recessive trait
Recessive traits are hidden/masked by a dominant allele
Principle of Dominance – UFC style
Only one can win
•Matt Hughes = Recessive
•BJ Penn = Dominant
Genotype VS. Phenotype
GENOTYPE: actual combination of alleles (genes) inherited from parents. (One from MOM, and one from DAD.) Example: Tt, TT or tt
PHENOTYPE: physical appearance/expression of the trait. Example: Tall plant or short plant
Cats and Dogs (think – pair – share)
Phenotype Widows Peak or straight
hair line
Genotype Ww, WW or ww
Cats And Dogs
The dominant trait is “gray” fur, and the recessive trait is “white” fur. Lets use the following alleles: Gray is G. White is g.
If a bunny is heterozygous gray: What is the genotype? ______________
If a bunny is homozygous white: What is the genotype? ______________
If a plant is homozygous gray: What is the genotype? ______________
Gg
gg
GG
Principles of Dominance
Predictable patterns of dominant and recessive only apply to single gene traits
Example: gene for hairline has 2 alleles – widow’s peak (W) or straight hairline (w) Possible Genotypes: WW, Ww or ww
Dominance VS. Commonality
Does dominant mean most commonly occurring?
No Examples:
Polydactyl – having 6 fingers Achondroplasia – Dwarfism O blood type (recessive)
Group Activity
Inventory of Traits
Dogs and Cats
Predict you and your partners possible genotypes for the phenotypes listed in traits activity.
Objectives:
Differentiate between characteristics and traits
Analyze Mendal’s principle of dominance
Predict genotype based on phenotype Analyze characteristics and traits in
this classroom