1. Mutations and Karyotyping

2. 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

3. 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 mutations are repaired by enzymes.

4. Are Mutations Helpful or Harmful?
Some harmful - Skin cancers and some leukemias result from somatic mutations
Most mutations have no affect, some have detrimental affects and a few mutations may improve an organism’s survival (beneficial)

5. 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.

6. Gene mutation- 2 types 1. Point Mutation
A change in a single base pair in DNA.
Changes the amino acid in the protein
Does not always cause a problem.
THE DOG BIT THE CAT
THE DOG BIT THE CAR

7. 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

8. Chromosome Mutations Five types exist: Deletion Inversion
Translocation
Nondisjunction
Duplication

9. Deletion Part of a chromosome is lost/deleted.
A B C D E F G H
A B C E F G H

10. Duplication/Insertion A part of the chromosome repeats
A B C D E F G H
A B C B C D E F G H

11. Inversion Part of a chromosome breaks off; reattaches backward
A B C D E F G H
H A D C B E F G

12. Translocation Part of a chromosome breaks off; attaches to a different chromosome that is not homologous A B C D E F G H W X A B C D E F G H W X Y Z Y Z W X Y Z Y Z
Translocation
Translocation

13. Nondisjunction
Failure of pair of chromosomes to separate during meiosis
Example Down Syndrome

14. Chromosome Mutation Animation

17. Karyotyping
Ch. 6 pg

18. 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

19. 2 types of abnormalities in chromosomes
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

20. How Scientists Read Chromosomes?
To "read" a set of human chromosomes, scientists first use three key features to identify their similarities and differences:
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).
Image taken from:
Using these key features, scientists match up the 23 pairs –
one set from the mother and one set from the father.

21. Typical Karyotype

22. Typical Karyotype

24. Trisomy 21- Down’s Syndrome - Karyotype
47 Total Chromosomes
Three Chromosomes at the 21st Pair
Image taken from:

25. Monosomy X - Turner Syndrome - Karyotype
45 Total Chromosomes
One “X” Chromosome
Image taken from:

26. XYY Karyotype 47 Total Chromosomes One “X” and Two “Y” Chromosomes
Image taken from:

27. 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

28. 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