Download Patterns of Inheritance Chapter 13

Ch. 13 Mendel and Heredity
•When we think of how
offspring resemble or
differ from their parents,
we refer to specific traits.
• Traits are distinguishing
characteristics
• Such as:
Mendel and Heredity
• What
differences
among these
people do you
see?
• Genetics is the
branch of
biology that
seeks to explain
inherited
variation.
Variations make each
individual unique
• Inherited features are the
building blocks of evolution.
• Remember that crossing over
adds to the genetic variety of
the gametes.
• Environment also plays a role
in shaping variation.
– Nutrition
– Temperature
– Sun exposure
•The search for explanations
lies within:
chromosomes, genes &
nucleic acids.
Heredity and Environment
• Studying twins has helped separate the
effects of inheritance and the environment.
• Ex: weight and intelligence are affected by
environment also coat color in certain
mammals
• Explanations of Heredity
Old Theory
* Blending
New Theory
* Genetics
Could not explain why
some individuals resemble
other relatives.
How do we know that all traits do not come
from the blending of our parents traits?
Gregor Mendel
He was a monk, gardener, science
teacher, mathematician
Experiment
• Gregor Mendel used garden peas.
• He developed the fundamental
principles of heredity that became the
foundation of modern genetics
• Why did he choose peas?
A
B
Effects of environment on
Twins
Twin on right spent decades sunbathing
and smoking while sister did not.
Heredity and Environment
Siamese cats have a gene
for dark fur, but the enzyme
produced by the gene
functions best at low
temperatures. The cat’s
extremities—its ears, paws,
and tail—are cooler than the
rest of its body.
1)Easy to grow
2)Reproduce quickly
3)Study many generations
4)Both male and female parts
5)Control how they mate
(Self-fertilizing)
6)Can make a purebred line