Variation and Genetics | One Shot Video

Mendelian Genetics
Gregor Mendel is known as the "father of genetics" for his work with pea plants, where he discovered the fundamental laws of inheritance.

Mendel’s Laws:
Law of Segregation:
Each individual has two alleles for each gene, one from each parent. These alleles segregate during the formation of gametes, so each gamete carries only one allele for each gene.

Law of Independent Assortment:
Genes for different traits are inherited independently of each other, provided they are on different chromosomes or far apart on the same chromosome.

Law of Dominance:
In a pair of alleles, one is dominant and masks the effect of the other (recessive) allele.

Multiple Alleles
Definition: While Mendel worked with traits controlled by a single pair of alleles, many genes exist in multiple forms (alleles). However, an individual can have only two alleles for a given gene (one from each parent).
Example in Humans:
ABO Blood Group System:

Sex-Linked Inheritance
Definition: Traits that are linked to genes located on the sex chromosomes (X or Y).

Sex Chromosomes:
Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).

X-Linked Traits:
Recessive: Traits are more common in males because they have only one X chromosome. If they inherit the recessive allele, it will be expressed.
Examples:
Hemophilia: A condition where blood doesn't clot properly. The gene for hemophilia is located on the X chromosome.
Color Blindness: Inability to distinguish certain colors, often red and green. The gene is also located on the X chromosome.

Y-Linked Traits:
Traits passed directly from father to son since only males have a Y chromosome.
Example: Male infertility can be linked to certain mutations on the Y chromosome.
These concepts are fundamental in understanding how traits are inherited and can help explain genetic patterns in families.

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