The Nature of Heredity

Brainstorm

Genetics

How do we get the traits we get? Why do I have green eyes, you have brown, blue, green eyes etc.? Why do we all look so different?

What is heredity? How do we get the traits that we do?

Genetics: the scientific study of heredity and variation or inherited characteristics

Heredity: the passing of traits from parent to offspring

Genetic Material

Gene

A sequence of nucleotides forming a section of a chromosome

Codes for a specific protein

“packets” of hereditary info that is passed from generation to generation

Locus

The specific location of a gene on a chromosome

Allele

A specific form of a gene

Chromosomes

Carry info for traits

Each species has a characteristic # of chromosomes per body cell

Body cells (somatic) and gametes (sex cells) have different number of chromosomes

Haploid: a cell containing half the usual # of chromosomes (n)

Diploid: a cell containing two copies of each chromosome (2n)

Asexual Reproduction

Almost always involves cell division

Results in offspring that are genetically identical to single parent

Advantages

No mate needed

Nothing left to chance

Disadvantages

Lack of variability and adaptation

Sexual Reproduction

Results in offspring that are genetically variable

Offspring inherit half of their genetic info from each of two parents

Disadvantages

Need a partner

Need specialized organs

Genetic info may be passed that makes organism weak

Advantages

Variability/adaptation

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P141 #1,2,5,6,7,8,10