OBJECTIVES
1. Describe Gregor Mendel’s experiment on peas
2. Differentiate dominant and recessive alleles
3. Differentiate genotype and phenotype
4. Describe Mendel’s Law of Inheritance
a. Law of Segregation
b. Law of Dominance
c. Law of Independent Assortment
5. Predict the genetic percentages (genotype, phenotype
through a Punnett square
VOCABULARIES
1. Genetics
2. gene
3. allele
4. homozygous ex. AA, aa, BB, cc,
5. heterozygous ex. Aa, Bb, Cc
6. genotype ex. AA, aa, Bb, AABB
7. phenotype ex. Skin color, height
8. dominant gene ex. AA, BB
9. recessive gene ex. aa, bb, cc
10. Punnett square
11. F1, F2
Differentiate homozygous allele
and heterozygous allele
Differentiate genotype
and phenotype
Johann Gregor Mendel (1822-1884)
Father of Genetics
Gregor Mendel, through his work on pea plants, discovered the fundamental laws of
inheritance. He deduced that genes come in pairs and are inherited as distinct units, one from
each parent. He tracked the segregation of parental genes and their appearance in the
offspring as dominant or recessive traits, recognized the mathematical patterns of inheritance
from one generation to the next. Mendel's Laws of Heredity are usually stated as:
1) The Law of Segregation: Each inherited trait is defined by a gene pair. Parental genes are
randomly separated to the sex cells so that sex cells contain only one gene of the pair.
Offspring inherit one genetic allele from each parent when sex cells unite in fertilization.
2) The Law of Independent Assortment: Genes for different traits are sorted separately from
one another so that the inheritance of one trait is not dependent on the inheritance of
another.
3) The Law of Dominance: An organism with alternate forms of a gene will express the form
that is dominant.
The genetic experiments Mendel did with pea plants took him eight years (1856-1863) and he
published his results in 1865. During this time, Mendel grew over 10,000 pea plants, keeping
track of progeny number and type. Mendel's work and his Laws of Inheritance were not
appreciated in his time. It wasn't until 1900, after the rediscovery of his Laws, that his
experimental results were understood.
Give your insight about Gregor Mendel’
experiment
Mendel's First Law, also called The Law of Equal
Segregation, which states: during gamete formation,
the two alleles at a gene locus segregate from
each other; each gamete has an equal probability
of containing either allele.Apr 9, 2022
A Punnett square can be used to predict genotypes (allele combinations) and
phenotypes (observable traits) of offspring from genetic crosses. A test cross can be used to
determine whether an organism with a dominant phenotype is homozygous or heterozygous.
Mendel's law of segregation | Genetics (article) | Khan Academy
https://www.khanacademy.org › ... › Mendelian genetics
PUNNETT Square Practice Monohybrid cross
Create a Punnett square then identify the genotypes, genotypic,
phenotypes and phenotypic ratio
1. male parent AA X female parent AA (A- brown eyes)
GENOTYPES:
Genotypic ratio:
PHENOTYPES:
Phenotypic ratio:
PUNNETT Square Practice Monohybrid cross
Create a Punnett square then identify the genotypes, genotypic ratio,
phenotypes and phenotypic ratio
2. male parent Aa X female parent Aa
(A – curly hair, a – straight hair)
GENOTYPES:
Genotypic ratio:
PHENOTYPES:
Phenotypic ratio:
PUNNETT Square Practice dihybrid cross
Create a Punnett square then identify the genotypes, genotypic ration,
phenotypes and phenotypic ratio
3. Male parent AABB. X female parent aabb
( A- brown complexion, a- fair complexion)
(B – tall, b – short)
GENOTYPES:
Genotypic ratio:
PHENOTYPES:
Phenotypic ratio:
PUNNETT Square Practice dihybrid cross
Create a Punnett square then identify the genotypes, genotypic ration,
phenotypes and phenotypic ratio
4. Male parent AaBb. X female parent AaBb
( A- black, a- albino). (B – big, b – small)
GENOTYPES:
Genotypic ratio:
PHENOTYPES:
Phenotypic ratio:
What does law of dominance
in the genetics mean?
How does the law of dominance
shown in the picture?
The Principle of Independent Assortment describes how different genes
independently separate from one another when reproductive cells
develop. Independent assortment of genes and their corresponding traits
was first observed by Gregor Mendel in 1865 during his studies of genetics
in pea plants.
Principle of independent assortment - Nature
What does Law of Independent
Assortment mean?
How do phenotypes and genotypes
show the Law of Independent
Assortment?
What is the genotypic ratio?
What is the phenotypic ratio?
CHROMOSOME - a threadlike structure of
nucleic acids and protein found in the
nucleus of most living cells, carrying genetic
information in the form of genes.
Autosome –not a sex chromosome
Sex chromosome-chromosomes that
determine the gender of organism
HUMAN has 46 or 23 pairs of chromosomes
Autosomes = 44 or 22 pairs
Sex chromosome = 2 0r 1 pair = XY
gene from the other parent is normal.
The abnormal gene dominates. Most of
sex link traits/ diseases are carried by X
chromosome Jan 28, 2020
Sex-linked traits/diseases are passed
down through families through one of
the X or Y (sex) chromosomes.
Sex-linked recessive: MedlinePlus Medical
Encyclopedia
Dominant inheritance occurs when an
abnormal gene from one parent causes Three types of Sex Linked Inheritance
trait/disease, even though the matching
⮚X - linked dominant
⮚X - linked recessive
⮚Y - linked
Examples of X-linked dominant disorders
1. Rett syndrome (female- mental retardation, microcephaly, autism) 2. X-linked
Lissencephaly “smooth brain”(male-abnormal development of brain and
genitalia)
3. double-cortex syndrome (female- epilepsy, mental dis abilty)
4. incontinentia pigmenti type 1, characterized by dermatological, ocular, dental,
and neurological abnormalities.
X-Linked Dominant Disorders - an overview - ScienceDirect.com
https://www.sciencedirect.com › topics › neuroscience › x...
X-linked recessive inheritance refers to genetic conditions associated with mutations in
genes on the X chromosome. A male carrying such a mutation will be affected, because he carries
only one X chromosome. A female carrying a mutation in one gene, with a normal gene on the other X
chromosome, is generally unaffected.
Definition of X-linked recessive inheritance - NCI Dictionary of ...
https://www.cancer.gov › genetics-dictionary › def › x-lin...
X-Linked Recessive Disorders
•Red-green color blindness (male)
•Hemophilia A.
•Duchenne Muscular dystrophy/DMD (male- muscle pain, stiffness, learning disability
Y- Linked inheritance
Hypertrichosis of the ears, webbed
toes, and porcupine man(excessive
dry skin) are examples of Y-linked
inheritance in humans. Hypertrichosis
of the ears
(or hairy ears) is a condition wherein
there is a conspicuous growth of hair
on the outside rim of the ear.Jun 28,
2021
Y-linked inheritance - Definition and Examples Biology Online
http
FAMILY PEDIGREE
A diagram of family history that uses
standardized symbols. A pedigree shows
relationships between family members and
indicates which individuals have certain genetic
pathogenic variants, traits, and diseases within a
family as well as vital status and health condition
through generations of a family.
Pedigrees are normally used to represent simple
dominant and recessive traits. For example, having a
widow's peak hairline is dominant. If an individual has
that trait, their symbol on the pedigree will be shaded
in.
Break out room activity:
⮚ watch the video
https://www.youtube.com/watch?v=uhK
qmNOiPR8
⮚ Create a family pedigree using a hypothetical trait
legend for the pedigree chart
Individual activity (Gdocs)
⮚ Create a family pedigree for 3 generations ( your grand parents, your parents and you
and siblings)
⮚ Explain the family pedigree your created, consider dominance or recessive,
affected or carrier