The Language of Heredity

In asexual reproduction, an organism gets ALL of its genetic material or DNA from ONE parent.

Fission : bacteria divide to form two identical bacteria (copy the DNA first!)

Budding : a hydra grows a miniature exact copy of itself. The copy later breaks off to become a new organism.

Regeneration: a sea star breaks into pieces and each piece becomes a new sea star.

In sexual reproduction, an organism gets ½ of its genetic material or DNA from its mother and ½ of its genetic material or DNA from its father.

sperm are the male sex cells; eggs are the female sex cells. Sex cells: gametes.

Fertilization is when an egg and a sperm join to form a new organism.

A zygote is the cell that forms when a sperm fertilizes an egg.p. 126

Heredity is the passing of traits from parents to offspring (children). How traits are inherited is a HUGE issue in sexual reproduction because this type

of reproduction results in so much variation. Do brothers and sisters who have the same mom and dad look exactly alike? Do they act alike? Why?

Gene: a section of DNA on a chromosome that contains the instructions (code) for making a specific protein.

Genes can exist in more than one form. For example, the gene for hair texture may have straight hair form and a curly hair form. The gene for facial dimples may have a “with dimples” form and a “without dimples” form.

You may have inherited a “with dimples” gene from your mom and a “without dimples” gene from your dad. Will you have dimples?*ALLELES are the different forms of a gene that control a particular trait. For every gene, we have two alleles, one from our mom and one from our dad.

*GENETICS is the study of how traits are inherited through the interactions of alleles.

GREGOR MENDEL: The Father of Genetics

He combined his interest in mathematics, science, and gardening. He studied pea plants. He studied ONE trait at a time through several generations and used the mathematics of probability to explain his observations.

PURE BRED: an organism that ALWAYS produces the same trait, generation after generation after generation….. (e. g.,both alleles are in the same form)

*HOMOZYGOUS (homo=same)

HYBRID: an organism that received two different alleles from its parents

*HETEROZYGOUS (hetero=different)

*DOMINANT ALLELE: a form of allele that dominates or “covers up” other forms

*RECESSIVE ALLELE: a form of allele that seems to disappear, if paired with a dominant allele.