Transcript Heredity

An introduction
YOUR Traits…
Freckles
No freckles
YOUR Traits…
Freckles
No freckles
Widow’s peak
No widow’s peak
YOUR Traits…
Freckles
No freckles
Widow’s peak
No widow’s peak
Free ear lobe
Attached ear lobe
YOUR Traits…
Freckles
No freckles
Widow’s peak
No widow’s peak
Free ear lobe
Attached ear lobe
Hair on second digit of finger
No hair on digit
YOUR Traits…
Freckles
No freckles
Widow’s peak
No widow’s peak
Free ear lobe
Attached ear lobe
Hair on second digit of finger
No hair on digit
Dimples
No dimples
YOUR Traits…
Freckles
No freckles
Widow’s peak
No widow’s peak
Free ear lobe
Attached ear lobe
Hair on second digit of finger
No hair on digit
Dimples
No dimples
Straight thumb
Hitchhiker’s thumb
YOUR Traits…
Freckles
No freckles
Widow’s peak
No widow’s peak
Free ear lobe
Attached ear lobe
Hair on second digit of finger
No hair on digit
Dimples
No dimples
Straight thumb
Hitchhiker’s thumb
Cleft chin
Smooth chin
YOUR Traits…
Freckles
No freckles
Widow’s peak
No widow’s peak
Free ear lobe
Attached ear lobe
Hair on second digit of finger
No hair on digit
Dimples
No dimples
Straight thumb
Hitchhiker’s thumb
Cleft chin
Smooth chin
Tongue rolls
Tongue cannot roll
YOUR Traits…
Freckles
No freckles
Widow’s peak
No widow’s peak
Free ear lobe
Attached ear lobe
Hair on second digit of finger
No hair on digit
Dimples
No dimples
Straight thumb
Hitchhiker’s thumb
Cleft chin
Smooth chin
Tongue rolls
Tongue cannot roll
Curled up nose
Roman nose
YOUR Traits…
Freckles
No freckles
Widow’s peak
No widow’s peak
Free ear lobe
Attached ear lobe
Hair on second digit of finger
No hair on digit
Dimples
No dimples
Straight thumb
Hitchhiker’s thumb
Cleft chin
Smooth chin
Tongue rolls
Tongue cannot roll
Curled up nose
Roman nose
Dominant traits
Recessive traits
Less desirable traits…
 Polydactyly (6+ fingers/toes; autosomal dominant),
 Marfan syndrome (connective tissue disorder; an
autosomal dominant disorder that has been linked to
the FBN1 gene on chromosome 15)
 Tay-Sachs disease (TSD, fatal in its most common
variant known as Infantile Tay-Sachs disease; fatty acid
deposits in brain nerve cells; autosomal recessive.)
 Huntington's disease (autosomal dominant
neurological disorder, cell death in brain 8/100,000)
Polydactyly
Marfan Syndrome
Less desirable traits
 Neurofibromatosis (autosomal dominant; causes
tumors to grow along types of nerves, can affect the
dev. of non-nervous tissues such as bones and skin.
Type I, chrom. 17, (1/3000);
Type II, chrom. 22, (1/40,000)
 Hypertrophic cardiomyopathy (HCM, disease of
the myocardium (the muscle of the heart) a portion of
the myocardium is hypertrophied (thickened) without
any obvious cause; most famous as a leading cause of
sudden cardiac death in young athletes; a cause of
sudden unexpected cardiac death in any age group and
as a cause of disabling cardiac symptoms.)
Neurofibromatosis
Neurofibromatosis
Neurofibromatosis
 Joseph Merrick
“The Elephant Man”
History
 Hippocrates
 Ancient Greece (400 B.C.)
 Pangenesis


particles from throughout body are passed to sperm or egg;
also, changes in the body are passed on
Problem with it:
 1) Particles from somatic cells don’t make up gametes
 2) Changes in somatic cells (body) don’t affect gametes
History
 Blending Hypothesis
 Early 19th century
 Hereditary materials from m/f blend, or mix.
 Problem with it:

“Mixing” isn’t true, original traits can show up again later.
History
 Gregor Mendel (1866)
 Monk, lived & worked in an abbey in Brunn, Austria.
Had attended U. of Vienna; knew physics,
mathematics, chemistry. Worked in garden.
 Studied peas. Curious as to why certain traits kept
appearing on peas.
History
 Concluded these things:
 1. Inheritance controlled by “factors” passed
from parents to offspring.
 2. Principle of Dominance/Recessiveness
 3. Law of Segregation

Pair of factors is separated during gamete formation
(anaphase)
 4. Law of Independent Assortment

Factors separate independently during gamete formation
(metaphase)
Terms:
 P generation: parents
 F1 generation: offsp. of P’s
 F2 generation: offsp. of
F1 gen.
Terms:
 Hybrid (Cross): offsp. of two diff.varieties
 Monohybrid Cross: Crossing one trait
 Dihybrid: two traits
Tri…
 Allele: alt. forms of same gene
 Homozygous: identical alleles for same char.
 Heterozygous: 2+ diff. alleles for same char.
An example:
Terms:
Phenotype: the expressed traits of an org:
(what it looks like)
Terms
 Genotype (the genetic makeup of an org.)
 This is how Mendel
controlled his crosses
to produce a new
generation…
The F1
generations
were all
heterozygous
for the trait
being
observed. The
original P
generations
were pure
homozygous
for the traits.
Ex: The P gen.
for flower color
was PP x pp.
The F1 was
Pp x Pp.
Terms:
Consider the genotypes
TT
Tt
tt
 Dominant allele (in Heterotroph., allele that
determines phenotype [T])
 Recessive allele (in Het., allele that has no noticeable
affect on phen. [t])
Terms:
 Punnett Square
 Tool used to predict offspring ratios
Try this: Show why there are about ½ males and ½
females born to humans…
An example