Heredity Notes - Madison County Schools

Heredity Notes
 DNA- (Deoxyribonucleic
acid)- genetic material that
carries the information
about an organism and is
passed from parent to
 Humans contain 23 pairs
of chromosomes- a total
of 46 chromosomes (23
from mom and 23 from
 Heredity-the passing of traits from parents
to offspring.
Back to Nucleus
 DNA is loose strands in the nucleus
(chromatin), but once a cell gets ready to
divide, it produces condensed strands
 Chromosomes must replicate before they
can divide. Why? You don’t want to lose
half of yourself do you?
 DNA are made up four different nitrogen
bases pairs. Adenine (A), Thymine (T),
Guanine (G), Cytosine (C) are the
nitrogen bases.
 Adenine always pairs with Thymine and
Guanine always pairs with Cytosine.
 With these four base pairs, there are
8,000,000 possible outcomes between two
parents and the arrangement of
Heredity Vocabulary
 Gene- a set of information that controls a
trait; a segment of DNA on a chromosome
that codes for a specific trait (hair color,
eye color, ear lobes).
 Traits- characteristics that an organism
can be pass on to its offspring through its
Heredity Vocab Continued
 Alleles- the different forms of a gene.
 Homozygous trait- having two identical
alleles for a trait.
 Heterozygous trait- having different
alleles for a trait.
 Genotype- genetic make up.
 Phenotype- physical appearance or
visible trait.
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