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Unit 5 – Gene Mutations & Chromosomes
Chapter 12 – Gene Mutations - Pages 224-230, 232-236
Types of Mutations – Table 12.6 - page 225
1.
_________________________ – change in a single DNA base
- may not cause a problem
a.
__________ – purine replaces purine, or pyrimidine replaces pyrimidine
b.
____________________ – purine replaces pyrimidine or vice-versa
c.
Missense – different _____________________ formed
- _______ are harmful
- _________________ = GUG Normal = GAG
d.
_________ – amino acid codon changed to a stop codon or stop turned
into amino acid
GAA  UAA = ________________ deficiency
2.
_____________________ Mutations – can alter site where introns are
normally removed causing incorrect splice and missense mutation.
3.
_______________ mutation – adding or deleting a base that shifts the exon’s
reading frame (____________)
a.
Deletion – ________________________
b.
Insertion – ________________________
4.
___________________________ – insertion with gene repeat
Charcot-Marie Tooth Disease
5.
_________________________ – repeats increase with each generation
- disease becomes _________________________________with each
generation
a)
Friedreich’s ataxia – _____ repeat
b)
Fragile X syndrome – _____ or ____ repeat
6.
______________________ – sequences that vary in number from person to
person
- these may or may not cause problems, but can cause __________________
DNA Repair – nuclear DNA can _____________, but not _______________ DNA
1. Excision repair – incorrect nucleotides ____________ and replaced (page 233)
a. ________________ excision – carcinogens, UV light
b. _____________ excision – oxidative damage
2. ______________ repair – enzymes fix newly replicated DNA (page 234)
DNA Repair Disorders
Trichothiodystrophy
Xeroderma Pigmentosum
Chapter 13 – Pages 240 - 261
Chromosomes – ____ types, (____ total in nucleus)
- invisible in nondividing cells (_____________)
- chromatin = ____ + __________
- protein made of: histones = ___________________
nonhistones = _______________________
- numbers are ________________ specific
- homologs = ________________ of matching chromosomes
- _____ from each parent
- 44 __________________, 2 _________ chromosomes
Chromosome Parts – Figure 13-1 (page 241)
1. ____________________ – tips
2. ____________________ – arms
3. ____________________ – matching arms
4. ________________________ – dark colored bands
5. ________________________ – light bands – has more protein encoding genes
6. ___________________ – largest constriction and place where spindles attach
- ___ arm is short, ___ arm is long
- centromere positions ________ (Figure 13.5, pg. 244)
- humans do not have _________________ chromosomes
Karyotypes
- photo of a cell in ___________________
- arranged in pairs by _____, _____________ location, _________ patterns –
Denver Classification System
- one pair may not be homologous (________________________)
- ____________ major groups (page 245) - Denver Classification System
- largest chromosomes have _____________ except X (__ group) and Y (___
group)
Chromosome staining – helps to _______ chromosomes or _________ regions
1. ____________ – black stripes on white chromosomes
2. ____________ (pg. 248) – fluorescent probe joins to one side of DNA if
complimentary.
3. WCP – Whole Chromosome Painting
- gives ________________________ a specific color
-
___________________ – a chromosome map (page 249)
Kidney Cancer = 3p14.2
Chromosome 3, short arm, region 1, band 4.2
Prenatal Diagnosis
1. ____________________ – a syringe is inserted through the abdomen and 1030 ml. of ________________________ are removed.
- 1/1600 result in _______________________
- done at 15-16 weeks (not enough __________ before)
- test takes ___________ days to get results
- can detect about _____________ defects
Who should have an amniocentesis?
A. Women around ______
B. ________________________ of defects
C. Questionable __________________ test
2. Chorionic Villus Sampling (CVS)
- can be done at the _____ week, but it is __________ than amniocentesis (11x)
- syringe is inserted into the uterus through the vagina
- can cause _____________________ defects (1/2,900)
- can be less accurate due to ________________ if fetal cells do not match
placental cells
3. Fetal Cell Sorting
- fetal cells are separated from _____________________________
- can be found in _____ of all pregnancies
- still experimental
Polyploidy – abnormal multiples of the _______________ number
- ___________ in humans (17% of all miscarriages)
A) ____________________ – 3 sets of chromosomes (69)
- early ___________________ (14 weeks)
- usually caused by ____________________________
- ____ of all conceptions
B) ____________________ – 4 sets of chromosomes (92)
- only the ___________________ forms
- ____ of miscarriages (4-5 weeks)
Aneuploidy – not an exact multiple of the __________________________
- ____________________ chromosomal problem (____ of miscarriages)
- 45 or 47 chromosomes most common
- _________________ should result in equal numbers of monosomies and
trisomies, but monosomy is rarely seen due to lost genetic
information.
A) Monosomy – loss of a __________________
- always ____________ than having too many
- Cases _________________: 15,16, 18, 20, 22, X, Y
B) ___________________ – gain of a chromosome
- found in ____________ chromosomes
- _______________ (________ Syndrome) is the only autosomal
aneuploidy that survives to adulthood.
Autosomal Aneuploidy – linked to _________________________
1. Trisomy 13 – Patau Syndrome (__________)
- 1/15,000 – lethal (avg. life span is ___ months)
- cleft lip and palate, severe internal malformations, polydactaly, cyclopia
2. Trisomy 18 – Edward Syndrome (___________)
- 1/6,000 – lethal (avg. life span ___ months)
- severe organ abnormalities, oddly clenched fists (pg. 253), rocker-bottom feet,
flat skull
3. Trisomy 21 – Down Syndrome (________)
- ____________________ chromosomal problem
- symptoms are a _________________
____ - flat facial profile
85% - poor _______________________
____ - weak muscle control
80% - ________________________
80% - Epicanthic folds (________________)
- frequency of D.S. is __________ births
Under 30 = 1/______
48 = 1/______
- 94.3% caused by _____________________
- occurs in everyone (__________________________)
- 3.3% are caused by ___________________________
- people with this can be normal if a third #21 is not present, but are
________________
- 2.4% are ________________
Why do older women have more D.S. children?
- a mechanism in younger females recognizes a problem and miscarries the
fetus.
- this mechanism may not work well in older women
Down males are __________________________________
Adult complications – obesity, leukemia, heart failure (44%), avg. life span ____,
100% develop _______________________ if they live long enough.
Actually D.S. is _______________ – Discovered in 1971.
Aneuploidy of Sex Chromosomes
- ________________________ than autosomal aneuploidy
- 1/400 males, 1/650 females
1. ______________________ (45, X_)
- 99% of embryos die before birth
- 1/2,500 female births
- webbed neck, short, poor sexual development, normal IQ
- missing X affects __________________________
- hormone therapy used
2. XXX (triplo-X) Syndrome (47, XXX)
- 1/1,000 females
- usually normal, tall, menstrual irregularities, increased risk of sterility, less
_____________________________ (usually still normal IQ)
3. _____________________ Syndrome (47, XXY)
- 1/500 males (60% ___________________________)
- symptoms are expressed at puberty: poor sexual development, low fertility,
breast development (50%), tall, lower IQ.
- testosterone injections help
- _______________________________? 6’ 2.5”
4. ___________________________ (47, XYY)
- 1/1,000 males (96% normal)
- ______________________________________________________
Abnormal Chromosome Structure
Caused by errors in replication/recombination, U.V. light, radiation, viruses,
chemicals.
1. __________________________ – part of a chromosome is missing
Ex.- Cri-du-chat (5), Prader-Willi, Angelman
2. ____________________ – segment moved from one chromosome to another
a. ____________ – two short arms break off of different chromosomes, and long
arms stick together (14/21)
b. __________________ – two different chromosomes exchange parts
Ex.- Down Syndrome, Leukemia
3. __________________ – extra copies of a chromosomal segment
4. _________________ – reversal in order of a chromosome segment
- health consequences __________
5. Isochromosomes – tetrad splits ___________________________________
- Can cause Turner Syndrome
6. ________________________ – telomeres are lost, and ends stick together.
- 1/25,000 conceptions
Ex.- Cat-eye syndrome (22)
_______________________ – a double dose of some genes from one parent and none
from the other.
- not rare, but most embryos are ________________
- ______________________________________ disabilities for survivors
- ____________________________ can give a recessive disease to a child
- may cause errors in genetic testing, and clarify genetic “impossibilities”
- caused by errors in meiosis segregation (____________________)
- Diseases CF (1/500), Hemophilia A
Uniparental Disomy & Genomic Imprinting
1 gene from each parent (1 active + 1 inactive gene)
- 1 of each gene in offspring = balance = normal
- Defect determined by ____________________ giving the disomy
- If disomy from dad (Chrom. 15) = ______________ Syndrome
- If disomy from mom (Chrom. 15) = _________________ Syndrome