mendel & inheritance - weeblybiologywithmsgeorge.weebly.com/uploads/2/2/4/3/22439118/...1....
Post on 18-Jul-2020
2 Views
Preview:
TRANSCRIPT
Mendel & Inheritance
SC.912.L.16.1 Use Mendel’s laws of segregation and
independent assortment to analyze patterns of inheritance.
1. Students will use Mendel’s laws of
segregation and independent assortment
to analyze patterns of inheritance.
Mendel’s Law of Segregation: gene pairs separate when
gametes (sex cells) are formed; each gamete as only one
allele of each gene pairReview:
• Heterozygous = the
two alleles are
different (hybrid) Aa or
Bb
• Homozygous = the
two alleles are the
same (AA or aa)
1. Students will use Mendel’s laws of
segregation and independent assortment
to analyze patterns of inheritance.
Mendel’s Law of Independent Assortment: different pairs
of genes separate independently of each other when
gametes are formed
This means when chromosomes line up in homologous
pairs during Metaphase I of meiosis that not ALL of moms
chromosomes are on one side and not ALL of dads
chromosomes are on one side – THEY ARE INTERMIXED!
1. Students will use Mendel’s laws of
segregation and independent assortment
to analyze patterns of inheritance.
Dominant Traits: shown with capital letters; controlling trait
Example: Brown hair over blonde hair; Huntington’s disease
Recessive Traits: shown with lowercase letters; hidden allele
Examples: Cystic fibrosis and Tay Sach’s – can be a carrier OR must have two recessives for it be expressed
1. Students will use Mendel’s laws of
segregation and independent assortment
to analyze patterns of inheritance.
Inheritance can be predicted using a
Punnett square
Results show the probability of an
offspring receiving that trait, and may be
expressed in percent, ratios, or fractions
Genotype
probability (genetic
makeup of the organism):
TT – 25%, ¼ , or 1:4
Tt – 50%, ½, or 2:4 (1:2)
Tt – 25%, ¼ , or 1:4
1. Students will use Mendel’s laws of
segregation and independent assortment
to analyze patterns of inheritance.
Practice predicting Punnett square results. Express results for both genotype and phenotype (physical appearance of an organism)
1. Students will use Mendel’s laws of
segregation and independent assortment
to analyze patterns of inheritance.
Two Types of Crosses:
Monohybrid: Contains four boxes; a cross between two
heterozygous would produce a 1:2:1 genotype ratio and
a 3:1 phenotype ratio
Dihybrid: Contains sixteen boxes; a dihybrid cross involves
two traits for each parent and a cross between two
heterozygous parents would produce a 9:3:3:1 phenotype
ratio
1. Students will use Mendel’s laws of
segregation and independent assortment
to analyze patterns of inheritance.
Dihybrid Cross:
2. Student’s will identify, analyze, and/or
predict inheritance patterns cause by
various models of inheritance.
Patterns of Inheritance:
Sex Chromosomes: 23 pairs, XY = males, XX = females
Sex-Linked Traits: traits linked with particular sexes, X-linked traits are
on inherited on X chromosome from mother (examples: hemophilia,
color-blindness, baldness)
Multiple Alleles: presence of more than two alleles for a trait (eye
color)
Polygenic Trait: one trait controlled by many genes (hair color, skin
color); genes may be on the same chromosome or different
chromosomes
2. Student’s will identify, analyze, and/or
predict inheritance patterns cause by
various models of inheritance.
Patterns of Inheritance (Continued):
Codominance: phenotypes of both homozygous parents are
produced in heterozygous offspring so both alleles are expressed
(black + white chickens = checkered chicken; sickle cell anemia)
Incomplete Dominance: phenotype of a heterozygote is a mix of the
two homozygous parents; neither allele is dominant, but combine to
display both traits (white flower + red flower = pink flower)
2. Student’s will identify, analyze, and/or
predict inheritance patterns cause by
various models of inheritance.
A pedigree may be used to
show patterns of
inheritance
squares = males and circles
= females
shaded = affected, half-
shaded = carrier
top related