Transcript Mutation - TeacherWeb

DNA
3 billion base pairs long!
Genes
Small sections of your DNA
20,000 to more than 150,000 genes
Chromatin
DNA wrapped around histone protein;
loose, tangled group
Chromosomes
•DNA
wrapped around histone protein
which are tightly packed and organized
•Chromatin makes up chromosomes
46 chromosomes (23 pairs) in humans
DNA is not always perfect…
Mutations can occur
What do you think about when you hear
genetic mutation?
Well, that’s FAKE! Here is what’s real.
MUTATION
Overview:
Gene mutation
Point mutation
Frame shift mutation
Chromosomal mutation
MUTATIONS
 NOT
all mutations have a negative
influence!
 Some
mutations can be beneficial
(positive)!
 Other mutations may be neutral;
neither negative or positive
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
Gene Mutation example
 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
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:
Origanl DNA:
TACGCATGGAAA
DNA with substitution mutation:
TACGTATGGAAA
o What is the RNA sequence?
o What is the Amino Acid sequence?
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 RNA sequence?
o What is the Amino Acid sequence?
o How is this AA sequence different from the one
above?
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: TACCATGGAAT
o What is the RNA sequence?
o What is the Amino Acid sequence?
o How is this AA sequence different from the one
above?
FRAME SHIFT MUTATION

Insertions and deletions are also
called frame shift mutations  the
mutation shifts the “reading frame” of
the genetic code.

This shift can change every amino
acid that follows the mutation
FRAMESHIFT MUTATION
CHROMOSOMAL MUTATION
Chromosomes come in pairs.
 Each cell of in organism have the same number of
chromosomes, except the sex cells.

 How

many chromosomes do we have in one cell?
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


Chromosomal mutations take place when the number
of chromosomes changes or when structural changes
occur in the chromosomes
Below depicts a normal female and male karyotype.
CHROMOSOMAL MUTATIONS

Human disorders due to the amount of
chromosomes present

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
Pg. 308 in textbook
GENETIC MUTATIONS IN THE WORLD