Introduction to Genetics

TEKS 7.14A define heredity as the passage of genetic instructions from one generation to the next

TEKS 7.14B recognize that inherited traits of individuals are governed in the genetic material found in the genes within chromosomes in the nucleus

Gregor Mendelis often called the “Father of Genetics”.

He identified dominant & recessive traits by studying the heredity of pea plants.

The process in which characteristics or traits are passed from parents to offspring is called heredity.

The scientific study of heredity, or how genes are passed to offspring, is called genetics.

Traits are an organism’s physicalcharacteristics (phenotype), like nose shape, eye color, blood type or eyelash length.

These traits are controlled by genes that are passed to us from our parents.

Human cells contain rod-shaped structures called chromosomes.

Chromosomes are found in the nucleus of a cell & are made up of strands of DNA (deoxyribonucleic acid).

Long sections of DNA make up genes. Genes carry the genetic information that controls our traits.

DNA is made up

of the same basic chemicals that everything else is make up of-CHONPS… Remember

Cell Theory and Organic Molecules

Chromosomesexist in pairs, each chromosome having the same genes; therefore genes also exist in pairs (genotype).

Offspring receive one set from the

mother & one from the father.

Each offspringwill receive a different combination of genes from its parents.

Sexual reproductionresults in more diversity due to the large number of gene combinations that may occur.

Each member of a gene pair is called an allele.

Alleles are different forms of the same gene, for example on allele may be for dimples & the other for no dimples.

Alleles may be dominant

or recessive.

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A dominant allele is a strong form of a gene whose traits always show up, or is expressed in the organism.

The recessive allele on the other hand is a weak form of a gene that can be hidden or covered up if the dominant allele is present.