Bimm 110 Section 3 Slides

47 DAYS UNTIL FINAL

BIMM 110 Section 3 George Chen [email protected] OH: Tu 12:30-1:30p Sierra Summit

G. Chen 2009. Slide 1

Questions from last section ●

How does a male's X chromosome know not to inactivate?

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In Kleinfelter's and Triple-X syndrome, are the extra X chromosomes inactivated?

G. Chen 2009. Slide 2

Nondisjunction related genetic diseases ●

Autosomal ●

Monosomy ● ●

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None viable Several partial deletions

Trisomy ● ● ●

21 Down's Syndrome 13 Patau Syndrome 18 Edwards Syndrome

G. Chen 2009. Slide 3

Nondisjunction and maternal age ●

Possible theory explaining increased risk of nondisjunction related to maternal age is that constant hormone exposure somehow negatively affects premature eggs.

G. Chen 2009. Slide 4

Down Syndrome and AD ●

Alzheimer's Disease is caused by amyloid precursor protein (APP) accumulated in amyloid-beta deposits and tau proteins accumulated in neurofibrillary tangles

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Downs patients have excessive amounts of APP, leading to early onset AD

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APP gene is on chromosome 21

G. Chen 2009. Slide 5

Patau Syndrome ●

Severe mental retardation

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Small eyes, split in iris

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Cleft palate

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Weak muscle tone

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Increased risk of heart defects

G. Chen 2009. Slide 6

Edwards Syndrome ●

Heart defects

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Kidney problem

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Developmental delays

G. Chen 2009. Slide 7

Sex Related ●

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Monosomy ●

XO Turner's

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YO ??

Disomy ●

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XY Female, XX Male

Trisomy ●

XXY Kleinfelter's

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XYY

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XXX Triple X G. Chen 2009. Slide 8

Turners ●

No mental retardation

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Congenital heart disease

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Kidney problems

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Infertile

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Treated with growth hormone

G. Chen 2009. Slide 9

PARs ●

Pseudoautosomal regions found at tips of X and Y chromosomes

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Mutant SHOX have shorter stature

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2 copies of SHOX required for proper height development

G. Chen 2009. Slide 10

XX Male, XY Female ●

Treated with hormone replacement

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Caused by deletions, crossing over

G. Chen 2009. Slide 11

Kleinfelter's (XXY) ●

IQ from well below to well above average

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Behavioral problems

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Hypogonadism, hypogenitalism

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Treated with testosterone replacement

G. Chen 2009. Slide 12

XYY ●

Fertile, will give birth to normal offspring

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Normal IQ

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Behavioral problems – once thought linked to delinquency

G. Chen 2009. Slide 13

XXX ●

Fertile, will give birth to normal offspring

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Quiet

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Delayed development

G. Chen 2009. Slide 14

Sex differentiation ●

Mesonephric duct = Wolffian duct

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Paramesonephric duct = Mullerian duct

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Requires Y chromosome for differentiation

G. Chen 2009. Slide 15

Sex Differentiation ●

SRY (Sex determining region Y) encodes for a protein TDF (Testes determining factor)

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Production of testosterone leads to development of male genitalia

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Production of Mullerian Inhibiting Substance from Sertoli cells inhibits Mullerian ducts from developing into female genitalia

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Default pathway is female G. Chen 2009. Slide 16

Gamete formation ●

Spermatogenesis

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Oogenesis

G. Chen 2009. Slide 17

Fertilization ●

Sperm acrosome releases Hyleuronidase, an enzyme to break down the 'glue' holding the corona radiata together

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Sperm wedges into zona pellucida, binds to ZP3 receptor

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Acrosome contents exocytosed, zona pellucida locally broken down

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Fusion of acrosome and egg causes fusion of cortical granules to membrane preventing polyspermy G. Chen 2009. Slide 18

Infertility In MALES ● Low sperm count ●

Poor sperm health

In FEMALES ●

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Structural problems ●

Scarring/blockage

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Absence of structures

Functional problems ●

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Non functional ovaries

Endometriosis

Shared problem ●

Woman has antibodies against partner’s sperm

G. Chen 2009. Slide 19

Artificial Reproductive Techniques ●

In Vitro Fertilization

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Zygote Intrafallopian Transfer

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Gamete Intrafallopian Transfer

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Intracytoplasmic Sperm Injection

G. Chen 2009. Slide 20