Unit 5 Gene Mutations & Chromosomes

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