Transcript Mutation - TeacherWeb

DNA
3 billion base pairs long!
Genes
Small sections of your DNA
Chromatin
DNA wrapped around histone protein;
 loose, tangled
Chromosomes
•DNA
wrapped around histone protein,
tightly packed and organized
•Chromatin makes up chromosomes
46 chromosomes (23 pairs) in humans
IN HUMANS…


Full set of DNA is
 46 chromosomes!
 (23 pairs)
 Full set in somatic cells NOT sex cells
DNA codes for protein.
Influences appearance
 Involved in bodily processes
 Involved in bodily repair


DNA is found in the nucleus of eukaryotes
DNA is not always perfect…
Mutations can occur
What do you think about when you hear
genetic mutation?
MUTATIONS
 NOT
all mutations have a negative
influence!
 can
be beneficial (positive)!
 may be neutral; neither negative or
positive
MUTATION
Overview:
Gene mutation
Point mutation
Frame shift mutation
Chromosomal mutation
GENE MUTATION

A gene mutation is a permanent change in the DNA
sequence that makes up a gene.

Gene mutations range in size: from a single DNA
base to a larger segment
POINT MUTATIONS

A single base pair in DNA has been changed.

three types of point mutations:
 Substitution
 Insertion
 Deletion
SUBSTITUTION

Normal DNA sequence and resulting Amino Acid
sequence:
DNA: TACGCATGGAAA
RNA: AUGCGUACCUUU
AA: Met-Arg-Thr-Phe
Substitution Mutation:
Original DNA: TACGCATGGAAA
DNA with substitution mutation:
TACGTATGGAAA
o What is the Amino Acid sequence?
o Met- His- Thr-Phe
INSERTION
 Normal
DNA sequence and resulting
Amino Acid sequence:
DNA: TACGCATGGAAA
RNA: AUGCGUACCUUU
AA: Met-Arg-Thr-Phe
Insertion Mutation:
Original DNA: TACGCATGGAAA
DNA with Insertion mutation: TACAGCATGGAAA
o What is the Amino Acid sequence?
o Met- Ser- Tyr- Leu
DELETION
 Normal
DNA sequence and resulting
Amino Acid sequence:
DNA: TACGCATGGAAA
RNA: AUGCGUACCUUU
AA: Met-Arg-Thr-Phe
Deletion Mutation:
Original DNA: TACGCATGGAAA
DNA with deletion mutation: TACCATGGAAA
o What is the Amino Acid sequence?
o Met-Val- Pro
FRAME SHIFT MUTATION

Insertions and deletions are also
called frame shift mutations  the
mutation shifts the “reading frame”

1codon, 1 reading frame

shift can change every amino acid
that follows the mutation
FRAMESHIFT MUTATION
CHROMOSOMAL MUTATION

Chromosomes come in pairs



Where do the pairs come from?
Each cell of in organism have the same number of
chromosomes, except the sex cells
Size and number of chromosomes vary among species.
Ex. Camel- 70 chromosomes, squirrel-40 chromosomes,
bat- 44 chromosomes, house fly- 12 chromosomes, rice24 chromosomes
http://morgan.rutgers.edu/MorganWebFrames/Level1/Page2/ChromNum.html
CHROMOSOMAL MUTATIONS

Autosomes 1-22, Sex chromosomes pair 23

Chromosomes ordered in Karyotype by size,
 paired using size, centromere position, banding pattern
Below depicts a normal female and male karyotype.

CHROMOSOMAL MUTATIONS

Occurs due to: nondisjunction
Down syndrome (trisomy 21)
 Patau syndrome (trisomy 13)
 Edward's syndrome (trisomy 18)


Nondisjunction of the sex chromosomes (X or Y
chromosome)

Klinefelter syndrome: XXY males, XYY males, Trisomy X:
XXX females, Monosomy X (Turner's syndrome)

the only viable monosomy in humans - women with Turner's have only
45 chromosomes!!!
CHROMOSOMAL MUTATION: STRUCTURAL
CHANGES
CHROMOSOMAL MUTATION: PIECES

Karyotype 46,XX,del(6)(q24 to qatar) showing deletion
 Gene
Mutation That Causes Rare
Form of Deafness Identified


ScienceDaily (July 13, 2010)
mutation in the DIAPH3 gene that causes
over-production of a compound known as a
diaphanous protein
GENETIC MUTATIONS IN THE WORLD
Syndactyl/Ectodactyl, polydactyl
Myostatin gene, vitiligo
MUTATION AND CELL CYCLE…
Cell cycle is a regulated process
 Cell cycle involves cell division
 Most of the cells in our body go through cell
division
 Mutations to certain genes that regulate the cell
cycle can cause problems
