Mutations and karyotyping
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Mutations and Karyotyping. Mutations Ch. 10. pg. 219-220. Changes in nucleotide sequence of DNA May occur in somatic cells (body cells) not passed to offspring May occur in gametes (eggs & sperm) passed to offspring. Causes. Mutations happen regularly

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Mutations and Karyotyping

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Mutations and karyotyping

Mutations and Karyotyping


Mutations ch 10 pg 219 220

Mutations Ch. 10. pg. 219-220

  • Changes in nucleotide sequence of DNA

  • May occur in somatic cells (body cells)

    • not passed to offspring

  • May occur in gametes (eggs & sperm)

    • passed to offspring


Causes

Causes

  • Mutations happen regularly

  • Any agent that causes a change in DNA is called a mutagen.

  • Mutagens include radiation, chemicals, and even high temperatures.

    • Ex. of radiation: X rays, cosmic rays, ultraviolet light, and nuclear radiation.

    • Chemicals: Benzene

  • Many mutationsare repaired by enzymes.


Are mutations helpful or harmful

Are Mutations Helpful or Harmful?

  • Some harmful - Skin cancers and some leukemias result from somaticmutations

  • Most mutations have no affect, some have detrimental affects and a few mutations may improve an organism’s survival (beneficial)


Types of mutations

Types of Mutations

  • 2-Types

    • 1. Gene mutations - change in one DNA sequence of a gene.

    • 2.Chromosomal mutations – change in structure or loss or gain of part of a chromosome.


Gene mutation 2 types 1 point mutation

Gene mutation- 2 types1. Point Mutation

  • A change in a single base pair in DNA.

  • Changes the amino acidin the protein

  • Does not always cause a problem.

  • THE DOG BIT THE CAT

  • THE DOG BIT THE CAR


2 frameshift mutation

2. Frameshift Mutation

  • A single base is added or deleted from the DNA causing all the other bases to be out of position.

  • More harmful than a regular point mutation.

  • THE DOG BIT THE CAT

  • THE DOB ITT HEC AT


Chromosome mutations

Chromosome Mutations

  • Five types exist:

    • Deletion

    • Inversion

    • Translocation

    • Nondisjunction

    • Duplication


Deletion part of a chromosome is lost deleted

DeletionPartof a chromosome is lost/deleted.

ABCDEFGH

A B C E F G H


Duplication insertion a part of the chromosome repeats

Duplication/InsertionA part of the chromosome repeats

A B C D E F G H

A B C B C D E F G H


Inversion part of a chromosome breaks off reattaches backward

InversionPart of a chromosome breaks off;reattaches backward

A B C D E F G H

H A D C B E F G


Mutations and karyotyping

TranslocationPart of a chromosome breaks off; attaches to a different chromosome that is not homologous

A

F

G

H

E

B

C

D

F

G

W

X

B

C

D

E

H

A

X

Y

Z

Y

Z

W

X

Y

Z

Y

Z

W

Translocation

Translocation


Nondisjunction

Nondisjunction

  • Failureof pair of chromosomes to separate during meiosis

    • Example Down Syndrome


Chromosome mutation animation

Chromosome Mutation Animation


Karyotyping

Karyotyping

Ch. 6 pg. 122-123


Mutations and karyotyping

  • Some mutations that cause chromosomal abnormalities can be detected by analyzing a karyotype.

  • Karyotype – photo of the chromosomes in a dividing cell that shows the chromosomes arranged by size, number, and shape.

    • Identifies gender and genetic disorders


Mutations and karyotyping

  • Amniocentesis – medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections

    • small amount of amniotic fluid, which has fetal tissues, is extracted from the amniotic sac surrounding a developing fetus

  • 2 types of abnormalities in chromosomes

    • Autosomal abnormalities– abnormalities of chromosomes not directly involved in determining gender

    • Sex Chromosomal abnormalities– abnormalities that affect the gender of an individual

      • XX – female

      • XY - male


How scientists read chromosomes

How Scientists Read Chromosomes?

  • Size. This is the easiest way to tell two different chromosomes apart.

  • Banding pattern. The size and location of Giemsa bands on chromosomes make each chromosome pair unique.

  • Centromere position. Centromeres are regions in chromosomes that appear as a constriction. They have a special role in the separation of chromosomes into daughter cells during mitosis cell division (mitosis and meiosis).

To "read" a set of human chromosomes, scientists first use three key features to identify their similarities and differences:

Image taken from:

http://learn.genetics.utah.edu/content/begin/traits/scientists/

Using these key features, scientists match up the 23 pairs –

one set from the mother and one set from the father.


Typical karyotype

Typical Karyotype


Mutations and karyotyping

Typical Karyotype


Trisomy 21 down s syndrome karyotype

Trisomy 21- Down’s Syndrome - Karyotype

47 Total Chromosomes

Three Chromosomes at the 21st Pair

Image taken from: http://worms.zoology.wisc.edu/zooweb/Phelps/karyotype.html


Monosomy x turner syndrome karyotype

Monosomy X - Turner Syndrome - Karyotype

45 Total Chromosomes

One “X” Chromosome

Image taken from: http://worms.zoology.wisc.edu/zooweb/Phelps/karyotype.html


Xyy karyotype

XYY Karyotype

47 Total Chromosomes

One “X” and Two “Y” Chromosomes

Image taken from: http://worms.zoology.wisc.edu/zooweb/Phelps/karyotype.html


Examples

Examples

Cri du chat – deletion of #5

Wilson’s Disease – can’t get rid of excess copper

Down's syndrome – extra copy of #21

Patau Syndrome – extra copy of #13

Klinefelter's syndrome (XXY)

Turner syndrome (X instead of XX or XY)

XYY syndrome. XYY

Triple-X syndrome (XXX)

XXXX Syndrome


Mutations and karyotyping

Colored Blindness

Hemophilia – bleeding disorder

Huntington’s Disease – faulty protein (mental/nervous disorder)

Jackson-Weiss Syndrome – fusion of face/foot bones

Sickle Cell Disease – red blood cells sickle shaped

Tay-Sachs Disease – brain/nerve disorder

Polydactyly – extra digit


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