Download CH # 3C

CHAPTER 3C
Section 1
• HEREDITY – The passing of traits from
parent to offspring
FATHER OF GENETICS…
• Gregor Mendel--born 1822
*Austrian monk
*(21)bad test taker
*returned to work in
lab
Unraveling the Mystery…
• Why did he choose to work with the Pea Plant?
• Fast Growing
• Self-Pollinating – can fertilized it’s own eggs
Eggs- produced by an ovule on
Stigma
Sperm-produced by Anther
Cross-Pollinating – can fertilize another plant
Mendel only worked with ONE characteristic at a time
• Characteristicfeature that has
different forms in a
population
• Trait – different
forms of a
characteristic
Mendel’s
st
1
Experiment…..
• Work with all 7 characteristics, but did
them separately
• Cross True-breeding dominant plants with
true-breeding recessive plants for the same
characteristic
• Ex) Pure Purple Flowers x Pure White Flowers
• First generation had all one color
(PURPLE)
• Dominant – one that appears most often
• Recessive – on that appears least often
Mendel’s Second Experiment…..
• He then self-pollinated these 1st generation
plants
• Results - some had PURPLE
(DOMINANT) and some were
recessive (white)
• Ratio – 3:1 in second generation
Section 2
• Genes – instructions for an inherited trait
• Alleles – different forms of a gene
– Dominant (capital letters)
– Recessive (lowercase letters)
Genotypes…..
Types of genes that are present
• PP
• Pp
• pp
Phenotype…..
The physical appearance of the
organism
• Ex)
PP-----Purple
Pp-----Purple
pp-----white
• PP -
Pure Purple
Pure Dominant
True Purple
True Dominant
Homozygous Purple
Homozygous Dominant
• Pp - Heterozygous
• pp -
- Pure White
- Pure Recessive
- True White
- True Recessive
- Homozygous White
- Homozygous Recessive
Punnett Squares…..
• Used to organize all the possible outcomes
of the offspring from a particular set of
parents
Probability….
• The chance that something will occur
Ex) Flip of a coin
Boy or girl
Roll of the die
Paper/rock/scissors
Genotype Probability…..
Rr
rr
• PP x PP
100% PP
• PP x Pp
50% PP, 50% Pp
• PP x pp
100% Pp
• Pp x Pp
25% PP, 50% Pp, 25% pp
• Pp x pp
50% Pp, 50% pp
• pp x pp
100% pp
Incomplete Dominance…..
• Snapdragons- Red x white = Pink
• Both show their affect
One Gene….Many Traits
Many Genes, One Trait…..
Section 3
• Meiosis…..process used to make the sex
cells
• Male Sex Cell – Sperm
• Female Sex Cell - Egg
Sperm…..
Egg…..
•
Meiosis….
• REDUCTION
• DIVISION
• Process to make sex cells
Meiosis Video:
60131.mov
Sex Chromosomes…..
Sex-Linked Disorders…..
• Carried on the Xchromosome
• Males are more
likely to get this
disease
Pedigrees…..
Selective Breeding…..
• WHY ????
• Examples:
Horses
Dogs
Humans