Unit 5 – Gene Mutations & Chromosomes
Chapter 12 – Gene Mutations - Pages 224-230, 232-236
Types of Mutations – Table 12.6 - page 225
- ______– 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 astop codon or stop turned
into amino acid
GAA UAA = ______deficiency
- ______Mutations – can alter site where introns are normally removed causing incorrect splice and missense mutation.
- ______mutation – adding or deleting a base that shifts the exon’s reading frame (______)
- Deletion – ______
- Insertion –______
- ______– insertion with gene repeat
Charcot-Marie Tooth Disease
- ______– repeats increase with each generation
- disease becomes ______with each
generation
a)Friedreich’s ataxia – _____ repeat
b)Fragile X syndrome – _____ or ____repeat
- ______– 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
- Excision repair –incorrect nucleotides ______and replaced (page 233)
a. ______excision – carcinogens, UV light
b. ______excision – oxidative damage
- ______repair – enzymes fix newly replicated DNA (page 234)
DNA Repair Disorders
Trichothiodystrophy
XerodermaPigmentosum
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)
- ______– tips
- ______– arms
- ______– matching arms
- ______– dark colored bands
- ______– light bands – has more protein encoding genes
- ______– 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
- ______– black stripes on white chromosomes
- ______(pg. 248) – fluorescent probe joins to one sideof DNA if complimentary.
- 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
- ______– a syringe is inserted through theabdomen and 10-30 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 (____ ofmiscarriages)
- 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.
AutosomalAneuploidy – 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 clenchedfists (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 autosomalaneuploidy
-1/400 males, 1/650 females
- ______(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
- ______– segment moved from one chromosome to another
a.______– two short arms break off of different chromosomes, and long
arms sticktogether (14/21)
b. ______– two different chromosomes exchange parts
Ex.- Down Syndrome, Leukemia
- ______– extra copies of a chromosomal segment
- ______– reversal in order of a chromosome segment
- health consequences ______
- Isochromosomes – tetrad splits ______
-Can cause Turner Syndrome
- ______– 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
UniparentalDisomy & 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