Transcript Patterns of Inheritance

Patterns of Inheritance
Heredity and the Environment
• Organisms are products of their heredity and
of their surroundings.
• Ex: Your height and built are probably similar
to you parents, but they are also influenced by
environmental factors like nutrition and
exercise.
Heredity and the Environment (cont.)
Heredity and the Environment (cont.)
• A once popular theory was “blending”, an
individuals genetic makeup was formed when the
parents’ genes mixed at fertilization.
• Resulting in a sort of averaging of parent’s genes.
• Genetics no longer includes this theory.
Who is this?
Who is this?
• Gregor Mendel was a monk, gardener, high
school science teacher, mathematician, and
scientist.
Mendel & the Idea of Alleles
• In the 1860’s, Gregor Mendel used garden peas to
study heredity.
• Peas are very easy to grow, are self-fertilizing, and
he could study many generations during his 8 yrs.
of experiments.
Mendel & the Idea of Alleles (cont.)
• Mendel concentrated
on traits that did not fit
the blending theory.
• He found several
different
characteristics of pea
plants that he could
study in an either or
form.
Mendel & the Idea of Alleles (cont.)
• Mendel classified and isolated true-breeding
plants which produced offspring identical to
themselves generation after generation.
Mendel & the Idea of Alleles (cont.)
• He then crossbred his plants, classified all the
offspring, and looked for patterns of
inheritance
Mendel & the Idea of Alleles (cont.)
• He demonstrated with pea plants that both parents
pass on to their offspring genetic factors that
remain separate generation after generation.
• Today the concept of genes has replaced Mendel’s
vague idea of factors.
• Gene: is a segment of DNA whose sequence of
nucleotides codes for a specific functional product.
Mendel & the Idea of Alleles (cont.)
• Most genes exist in more than one form, or allele.
• Each allele of a particular gene has a different base
sequence.
• All organisms have genes that exist as several
different alleles.
Mendel & the Idea of Alleles (cont.)
• Most traits – such as hair color, skin color, nose
shape, and handedness – result from the complex
interactions of several genes with each other and
the environment.
Genes and Chromosomes
• Homologous chromosomes carry the same
genes, although their genes may be present as
different alleles.
• Stains help identify homologous chromosomes
by binding to specific regions to create unique
banding patterns.
When we have 46 chromosomes lined up by
size and shape, it is called karyotype.