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