Lecture 1
Ancient world: Parents pass on characteristics to offspring
Pythagoras suggested that the father supplies the essential characteristics (“form”) and the
mother supplies the material building blocks
Aristotle thought children were made from “purified blood from the testes” (semen) and
menstrual blood
Antonie van Leeuwenhoek (1632 – 1723) and Nicolaas Hartsoeker (1656 –1725)
Invented the microscope and started the field of microbiology
They developed/refined the Theory of Preformationism: we all come from miniature
versions of ourselves. Sperm contain complete preformed individuals called “homunculus"
What are the flaws with that theory? (And a benefit?)
- No influence of new environments
- If only men provided the offspring and the mother only functioned to provide nutrition, how
could females then be born?
- It should already have a little homunculus in it already, and one in him etc
- Benefit: at the time is provided evidence that the nature of humans were in line with the
bible (Adam and Eva)
Francis Galton (1822-1911): founded psychometrics, differential psychology, and behavior genetics
He studied twins and family trees (pedigree) to understand hereditary (genetic influences)
E.g. Eminent status was more likely to appear in close relatives, with the likelihood of
eminence decreasing as the degree of relationship became more remote
“Nature prevails enormously over nurture.” that parents also pass on the environment
and not only genes
Darwin: Voyage of the Beagle most important trip for science
The idea of “blending inheritance” Though Darwin was on the
right track about many things, he was terribly off track about the
mechanism behind inheritance. As were everyone else before
Mendel!!
Charles Darwin’s Theory of Pangenesis: contributions to egg or
sperm from every part of the body. Also implied blending
inheritance
What is the problem with these “blending” theories of
inheritance? How does it affect the Theory of Natural Selection?
- No variety if everything is blended! consequence: there
is nothing to be selected every variation will be
averaged out
- If you blend elements, you can never get it’s origin back
Gregor Mendel (1822-1884) Mendel concluded that there are:
two “elements” of heredity for each trait in each individual (dominant and recessive)
these two elements separate, or segregate, during reproduction.
Offspring receive one of the two elements from each parent.
These conclusions are the essence of Mendel’s first law The
Law of Segregation
The Punnett square: a diagram used to predict the
genotypes of a cross or breeding experiment. Useful to
determine the probability of an offspring having a
particular genotype
, - Dominant Allele (Upper case “S”) An allele that expresses its phenotypic effect even when
heterozygous with a recessive allele. So, if S is dominant over s, then SS and Ss have the same
phenotype
- Recessive Allele (Lower case “s” or any other letter) An allele whose phenotypic effect is not
expressed in a heterozygote. It is only expressed when
homozygous, like if s is recessive over S, only ss would
show the recessive phenotype.
saved the theory of selection and vanished away the theory of
blending
What happened when Mendel looked at two or more traits at
the same time?
Mendel’s 2nd law The Law of Independent Assortment:
The inheritance pattern of one trait will not affect the
inheritance pattern of another (inheritance of one traits is
independent of the inheritance of other traits) so
independent of each other, but dependent on the
segregation of the trait itself
Humans have two genomes: one from the father and one from the mother
Mendelian Disorders: Controlled by one gene and therefor easy to predict
Huntington’s Disease:
Brain disorder causing progressive deterioration of the physical, cognitive and emotional self
It leads to severe incapacitation and eventual death
It usually affects adults (30–45 yr)
Symptoms: uncontrollable movements, abnormal balance when
walking, slurred speech, thinking difficulties, and personality changes
There is no cure and no effective treatment
Dominant effect: The allele that causes the disease is dominant
50% of the kids will also have the disease (if only the father has the
gene); if both the father and the mother have the gene 75% of the kids
will have the disease; if one of the parents has both dominant
hutington alleles, 100% of the kids will have the disease.
PKU (Phenylketonuria):
PKU is a metabolic disorder caused by a deficiency of the liver enzyme
phenylalanine hydroxylase (PAH)
It prevents normal metabolization of phenylalanine (Phe) which is
present in protein rich foods
Damage occurs to the nervous system leading to mental retardation
Prevention is fairly simple! Diet
Recessive effect: The allele that causes PKU is Recessive only 25% of the kids will have the
disease (if the parents both have heterozygous alleles)
Hemophilia:
Can’t stop bleeding
On the X chromosome
Exceptions to Mendel’s second law (The law of independent assortment
(inheritance of one gene is not affected by the inheritance of another gene))
The law holds:
For genes on different chromosomes
For genes that are far apart on the same chromosome (e.g. color and
shape)
The law DOES NOT hold for:
, Genes in close proximity on the same chromosome (mostly passed on together)
X-linked inheritance: sex-dependent transmission cannot split from the sex chromosome
- e.g. color blindness color-blind-father = 0% of sons; color-blind-mother= 100% of sons
because it is a recessive allele only on the X chromosome
- for daughters to get color blindness both of the parents need to have color blindness
(then also the sons will have it), in general more males can only get color blindness if the
mom is a carrier because men
Quantitative Traits (Complex traits) even here the mendelian laws of genetics keep
important
Lecture 2
Most people are almost identical due to the same atoms in our DNA: oxygen, carbon, hydrogen,
nitrogen, calcium; and molecules in our body : Water (almost 99%), lipids, protein, RNA, DNA
Building blocks From a physics/chemistry angle:
We consist of atoms → molecules
A particular combination and arrangement of molecules → life
Differences in organisms due to different molecular composition
Complexity:
Describing behavior by physics/chemistry laws is very difficult
Ancient world: Parents pass on characteristics to offspring
Pythagoras suggested that the father supplies the essential characteristics (“form”) and the
mother supplies the material building blocks
Aristotle thought children were made from “purified blood from the testes” (semen) and
menstrual blood
Antonie van Leeuwenhoek (1632 – 1723) and Nicolaas Hartsoeker (1656 –1725)
Invented the microscope and started the field of microbiology
They developed/refined the Theory of Preformationism: we all come from miniature
versions of ourselves. Sperm contain complete preformed individuals called “homunculus"
What are the flaws with that theory? (And a benefit?)
- No influence of new environments
- If only men provided the offspring and the mother only functioned to provide nutrition, how
could females then be born?
- It should already have a little homunculus in it already, and one in him etc
- Benefit: at the time is provided evidence that the nature of humans were in line with the
bible (Adam and Eva)
Francis Galton (1822-1911): founded psychometrics, differential psychology, and behavior genetics
He studied twins and family trees (pedigree) to understand hereditary (genetic influences)
E.g. Eminent status was more likely to appear in close relatives, with the likelihood of
eminence decreasing as the degree of relationship became more remote
“Nature prevails enormously over nurture.” that parents also pass on the environment
and not only genes
Darwin: Voyage of the Beagle most important trip for science
The idea of “blending inheritance” Though Darwin was on the
right track about many things, he was terribly off track about the
mechanism behind inheritance. As were everyone else before
Mendel!!
Charles Darwin’s Theory of Pangenesis: contributions to egg or
sperm from every part of the body. Also implied blending
inheritance
What is the problem with these “blending” theories of
inheritance? How does it affect the Theory of Natural Selection?
- No variety if everything is blended! consequence: there
is nothing to be selected every variation will be
averaged out
- If you blend elements, you can never get it’s origin back
Gregor Mendel (1822-1884) Mendel concluded that there are:
two “elements” of heredity for each trait in each individual (dominant and recessive)
these two elements separate, or segregate, during reproduction.
Offspring receive one of the two elements from each parent.
These conclusions are the essence of Mendel’s first law The
Law of Segregation
The Punnett square: a diagram used to predict the
genotypes of a cross or breeding experiment. Useful to
determine the probability of an offspring having a
particular genotype
, - Dominant Allele (Upper case “S”) An allele that expresses its phenotypic effect even when
heterozygous with a recessive allele. So, if S is dominant over s, then SS and Ss have the same
phenotype
- Recessive Allele (Lower case “s” or any other letter) An allele whose phenotypic effect is not
expressed in a heterozygote. It is only expressed when
homozygous, like if s is recessive over S, only ss would
show the recessive phenotype.
saved the theory of selection and vanished away the theory of
blending
What happened when Mendel looked at two or more traits at
the same time?
Mendel’s 2nd law The Law of Independent Assortment:
The inheritance pattern of one trait will not affect the
inheritance pattern of another (inheritance of one traits is
independent of the inheritance of other traits) so
independent of each other, but dependent on the
segregation of the trait itself
Humans have two genomes: one from the father and one from the mother
Mendelian Disorders: Controlled by one gene and therefor easy to predict
Huntington’s Disease:
Brain disorder causing progressive deterioration of the physical, cognitive and emotional self
It leads to severe incapacitation and eventual death
It usually affects adults (30–45 yr)
Symptoms: uncontrollable movements, abnormal balance when
walking, slurred speech, thinking difficulties, and personality changes
There is no cure and no effective treatment
Dominant effect: The allele that causes the disease is dominant
50% of the kids will also have the disease (if only the father has the
gene); if both the father and the mother have the gene 75% of the kids
will have the disease; if one of the parents has both dominant
hutington alleles, 100% of the kids will have the disease.
PKU (Phenylketonuria):
PKU is a metabolic disorder caused by a deficiency of the liver enzyme
phenylalanine hydroxylase (PAH)
It prevents normal metabolization of phenylalanine (Phe) which is
present in protein rich foods
Damage occurs to the nervous system leading to mental retardation
Prevention is fairly simple! Diet
Recessive effect: The allele that causes PKU is Recessive only 25% of the kids will have the
disease (if the parents both have heterozygous alleles)
Hemophilia:
Can’t stop bleeding
On the X chromosome
Exceptions to Mendel’s second law (The law of independent assortment
(inheritance of one gene is not affected by the inheritance of another gene))
The law holds:
For genes on different chromosomes
For genes that are far apart on the same chromosome (e.g. color and
shape)
The law DOES NOT hold for:
, Genes in close proximity on the same chromosome (mostly passed on together)
X-linked inheritance: sex-dependent transmission cannot split from the sex chromosome
- e.g. color blindness color-blind-father = 0% of sons; color-blind-mother= 100% of sons
because it is a recessive allele only on the X chromosome
- for daughters to get color blindness both of the parents need to have color blindness
(then also the sons will have it), in general more males can only get color blindness if the
mom is a carrier because men
Quantitative Traits (Complex traits) even here the mendelian laws of genetics keep
important
Lecture 2
Most people are almost identical due to the same atoms in our DNA: oxygen, carbon, hydrogen,
nitrogen, calcium; and molecules in our body : Water (almost 99%), lipids, protein, RNA, DNA
Building blocks From a physics/chemistry angle:
We consist of atoms → molecules
A particular combination and arrangement of molecules → life
Differences in organisms due to different molecular composition
Complexity:
Describing behavior by physics/chemistry laws is very difficult
