Transcript Ch09

Chapter 9
Patterns of Inheritance
PowerPoint Lectures for
Biology: Concepts and Connections, Fifth Edition
– Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
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9.0 Genetics
- the science of
A common genetic
- will produce offspring with similar
Purebred dogs
- show less
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9.1 Gregor Mendel
- hypothesized that there are alternative
- experimental genetics
- Mendel crossed pea plants that differed in
- traced traits from generation to
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9.2 Mendel's law of segregation
- the inheritance of
- there are alternative forms
- accounts for variation in
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For each characteristic, an organism inherits:
- two
– Homozygous: two
– Heterozygous: two
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If the two alleles of an inherited pair differ:
• The dominant allele
- determines the
• The recessive allele
- has no noticeable effect on the
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The law of segregation
- a sperm or egg carries only one
9.3 Phenotype
- expressed
Genotype
- actual
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9.4 Homologous chromosomes
- bear the two alleles for
- alternative forms of a gene
- are located at
- on homologous
9.5 Genetic traits in humans
- can be tracked through
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CONNECTION
9.6
Some human genetic disorders follow simple
Mendelian
- Recessive disorders
- can be carried unnoticed by
- range in
- from mild (
- to severe (
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Dominant disorders
- some serious, but
- lethal conditions
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CONNECTION
9.7 New genetic technologies
- Identifying
tests can distinguish parental carriers of
Fetal testing
1. Amniocentesis
- removal of ___________________ to test
for genetic
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2. Fetal imaging
- Ultrasound imaging uses sound waves to
produce
Ethical consideration:
How will genetic testing
Video: Ultrasound of Human Fetus 1
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9.8 Complete dominance
- dominant allele has same phenotypic effect
whether
Incomplete dominance
- heterozygote exhibits characteristics
intermediate between
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9.9 Many genes have more than
Ex: human ABO
– involves
– AB blood group
• an example of
• both alleles are expressed in
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9.10 Polygenic inheritance
- the additive effects of two or more genes
- Ex: human
- controlled by at least
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SEX CHROMOSOMES AND SEX-LINKED GENES
9.11 Many animals have a pair of chromosomes to
determine sex
- human male is
- the Y chromosome has genes for
- human female is
- absence of a Y chromosome allows
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9.12 Sex-linked genes
- for characteristics (
- located on either sex
- in humans, refers to a gene on
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
CONNECTION
9.13 Sex-linked disorders
In humans, recessive sex-linked traits:
- expressed much more frequently in
Most known sex-linked traits are caused by
genes (alleles) on
Examples: Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings