Download Tumor-suppressor genes - School District of New Berlin

Human Genetics
Biology: Exploring Life
Campbell, Williamson, Heyden
Prentice Hall
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12.1
The nucleus contains an
information richgenome.
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DNA Packing in a Single Cell

1 chromosome = 1 DNA strand

Genome


Order of bases in DNA
Histones

DNA wraps around tiny proteins
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Human Genome Project



Determine the sequence
and functions of all human
chromosomes
“rough-draft” done in 2000
Introns vs exons

Coding vs non-coding
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12.2
Accidents affecting
chromosomes can
cause disorders.
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Down Syndrome

Abnormal chromosomes


Trisomy 21



Miscarriage
Down Syndrome
Three chromosomes 21
Characteristics





Facial features
Below-average height
Heart defects
Immune dysfunction
Mental disability
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Nonseparation of Chromosomes

Nondisjunction


Failure of
chromosomes to
separate
Causes?


Not known
Older women
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Damaged Chromosomes

Duplication


Deletion


Fragment is lost
Inversion


Part of chromosome
is duplicated
Reversing a fragment
Translocation

Fragment attaches to
non-homologous
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Jumping Genes

Barbara McClintock


1940’s
Single genes can move
around

Transposons

Genetic element that
moves from one location
to another in a genome
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12.3
Mendel’s principles
apply to humans.
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Human Pedigrees


Analyze patterns of inheritance
Pedigree


Family tree that records occurrences of traits
Use the pedigree


Attached earlobe is
recessive
Not enough info
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Disorders Inherited as Recessive Traits

Carrier

Has copy of allele
but does not show
symptoms

Range of severity

Albinism

Tay-Sachs


Major nerve damage
Cystic Fibrosis


1/25 from European decent
Defective protein secretes
excessive mucus
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Disorders Inherited as Dominant Traits

Examples



Extra fingers and toes
Achondroplasia



Heterozygous
Two copies – fatal
99.99% population has
homozygous recessive
Recessive alleles
sometimes common


Death
Huntington's
Disease


Middle-age nervous
system
degeneration
Chromosome #4
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Sex-linked Disorders



Most located on X
chromosome
♂ only needs one “bad”
allele
♀ needs both “bad”
alleles
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Predicting and Treating Genetic Disorders

Genetic counselor


Tests before birth


Collects, analyzes and explains
patterns of inheritance
Trisomy 21
Tests after birth

Phenylketonuria (PKU)

Causes metal disability
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12.4
Genetic Changes
contribute to cancer.
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Cancer Genes

Pics




Growth factor


Initiate cell division
Tumor-suppressor genes


Breast cancer
Brain cancer
Immune system attacks
cancer
Proteins to stop cell division
Oncogene

Cancer causing gene
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“Inherited” Cancer



Always is from damaged
or changed DNA
Not passed from parent
to child if non-sex cell
Mutated tumorsuppressor-gene BRCA1

More likely to form breast
cancer
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Permission Statement
Restricted to the use of New Berlin Eisenhower High School
(New Berlin, WI) Students, Faculty and Staff.
Contact the Science Department for usage permissions.
©2006
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