Variation are fewer.
Occurs due to small inaccuracies in DNA
Variation are large.
Occurs due to crossing over, separations of
chromosomes.
The biological science, which deals with the mechanism
of heredity and causes variation called genetics.
"genetics" was coined by English biologist William
Bateson
Acquired Traits
Inherited Traits
a) Do not change germ cells
Bring changes in germ cells
b) Cannot be passed on to
future generations
Can be passed on to their
progeny
c) Do not lead to evolution
May lead to evolution
Example: Losing limbs due to
an accident
Example: Deformed limbs at
birth due to a genetic defect
Heredity
Heredity the process of passing down traits and characteristics
from parents to their offspring through genes
Variation The difference between individuals in a species or
group of organisms
Environment variation
Genetic Variation
Importance of Variation
Variation helps organisms adapt to changing environments.
It drives the evolution of new, better-adapted species.
Accumulation of Variation During Reproduction
Asexually
Sexually
Father of Genetics (Gregor Johann Mendel)
DNA: deoxyribonucleic acid, is a molecule that contains
genetic information for the development and functioning
of an organism.
Chromatin: refers to a mixture of DNA and proteins that
form the chromosomes found in the cells of humans and
other higher organisms
Chromosomes: is a DNA molecule that consists of a part
or all of the genetic material of an organism
Genes: a segment of DNA that is the basic unit of heredity and
is passed from parent to child, is a molecule that contains
genetic information for the development and functioning of an
organism.
Alleles: a pair of genes that occupy a specific location on a
particular chromosome and control the same trait
Rules of inheritance
The dominant allele is the stronger of the two alleles.
Represented by a capital letter, it determines the dominant
traits.
Dominant traits manifest in both homozygous and
heterozygous conditions.
Dominant allele
The recessive allele is the weaker of the two alleles.
Represented by a lowercase letter, it remains suppressed in
the presence of a dominant allele.
Recessive traits are expressed only in the homozygous
condition.
Recessive allele
-Genotype: The unique DNA sequence or allele combination
inherited from parents.
- Phenotype: Observable traits like appearance and behavior,
influenced by genotype and environment.
Homozygous Condition:
Inherits identical alleles of a
gene from both parents
Heterozygous Condition:
Inherits different alleles of
a gene from each parent
Gregor Mendel's experiment
Plant selected by Mendel: Pisum sativum( garden pea) .
used a number of contrasting characters for garden pea
Mendel's rules for the inheritance of traits.
Law of Dominance: In heterozygous pairs, the dominant
allele masks the recessive one.
Law of Segregation: Traits have two alleles that separate
during gamete formation; one from each parent combines
during fertilization.
Law of Independent Assortment: Alleles of different genes
assort independently into gametes
Why only pea
plant?
Annual Plant
Short Life Cycle
Large no. of offsprings
7 pairs of allelic
characteristics
Cross between two pea plants with
one pair of contrasting characters
Monohybrid Cross
Characters/traits like T are called dominant trait ( because it
express itself ) and t are recessive traits.
A cross between two plants having two pairs
of contrasting characters.
Dihybrid Cross
Round, yellow :9
Round, green : 3
Wrinkled , yellow: 3
Wrinkled, green :1
Phenotypic Ratio
Haploid cells contain a single set of chromosomes (n) and are
formed through meiosis. They are primarily involved in sexual
reproduction, with examples including sperm and egg cells.
Diploid cells, on the other hand, have two sets of chromosomes
(2n) and divide through mitosis. These cells make up most of
the body’s tissues, such as nerve and muscle cells.
Parents-> Round green × wrinkled yellow
Self-pollination of F1 plants resulted in parental
phenotypes and two new mixtures.
Round and yellow seeds are dominant traits.
New phenotype combinations indicate that genes for
round and yellow seeds are inherited independently.
PRASHANT KIRAD
PRASHANT KIRAD
ABHISHEK VIYAS
