2. MUTATIONS
Mutation is defined as changes in
chromosome or genetic materials that are
heritable and essentially permanent.
Mutations may be caused by mistakes during
cell division, or they may be caused by
exposure to DNA-damaging agents in the
environment.
8. SMALL-SCALE MUTATIONS
Small-scale mutations refer to changes in one or
a few nucleotides.
Affect DNA at the molecular level by changing
the normal sequence of nucleotide base pairs.
Occur during the process of DNA replications
(either meiosis or mitosis).
10. SUBSTITUTION
A substitution is a mutation that exchanges one
base for another.
Substitution occur when a nucleotide is replaced
with a different nucleotide in the DNA sequence.
This type of mutation only affects the codon for
a single amino acid.
12. SUBSTITUTION: SICKLE CELL ANEMIA
Sickle cell anemia is a genetic disorder caused by a
substitution mutation in the gene encoding
hemoglobin, the protein on blood cells responsible for
carrying oxygen.
This mutation causes the hemoglobin protein to fold
incorrectly, preventing the protein from carrying
oxygen to the red blood cells.
15. INSERTION
Insertions are mutations in which extra base
pairs are inserted into a new place in the DNA.
Addition of a nucleotide to the DNA sequence.
Addition of even a single nucleotide to a gene
alters every codon after the mutation.
17. INSERTION: CYSTIC FIBROSIS
Cystic fibrosis is a genetic disorder that primarily
affects the lungs. People who have cystic fibrosis
have a faulty protein that affects the body's cells, its
tissues, and the glands that make mucus and sweat.
Many mutations can cause cystic fibrosis, one of which
is an insertional mutation of A-T nucleotides at site
2566 and another insertional mutation of nucleotide
sequence T-C at site 1154.
20. DELETION
Deletions are mutations in which a section of
DNA is lost, or deleted.
Deletion is the removal of a nucleotide from the
DNA sequence.
Removal of even a single nucleotide from a gene
alters every codon after the mutation.
26. ANEUPLOIDY
Aneuploidy is the gain or loss
of one or more chromosomes.
Categories:
• Addition of chromosomes
• Subtraction of chromosomes
27. ANEUPLOIDY: ADDITION
TRISOMIC TETRASOMIC DOUBLE
TRISOMIC
The chromosome
is represented
thrice
(2n +1)
e.g. AAA
Gain of extra two
chromosomes
(2n + 2)
e.g. AAAA
Gain of extra two
completely different
chromosomes
(2n + 1 + 1)
e.g. AABC
28. ANEUPLOIDY: SUBSTRACTION
MONOSOMIC NULLISOMIC
chromosome is
represented
once (2n -1)
e.g. A
lack of both the
normal chromosomal
pairs 2n – 2
e.g. AABB = AA or
BB
DOUBLE
MONOSOMIC
missing one chromosome
from each of the
two pairs of homologous
chromosome (2n – 1 – 1)
e.g. AABB =AB
30. DELETION
Single chromosome mutation
The loss of one or more gene(s)
from the parent chromosome.
Example:
Cri du chat - deletion of the short
arm of chromosome 5. The most
characteristic finding is a high-
pitched, monotonous cry
31. DUPLICATION
Single chromosome mutation.
The addition of one or more
gene(s) that are already present in
the chromosome.
Example:
Pallister-Killian mosaic syndrome
– a result of extra 12 chromosome
material.
32. INVERSION
Single chromosome mutation
The complete reversal of one or
more gene(s) within a chromosome;
the genes are present, but the order
is backwards from the parent
chromosome.
Example: Hemophilia - an X-linked
disorder caused by mutations in the
factor VIII gene.
33. v INSERTION
Multiple chromosome mutation
One or more gene(s) are removed
from one chromosome and inserted
into another non-homologous
chromosome.
Huntington’s Disease - an insertion
mutation where the same three bases,
CAG, are repeated many more times
than usual at the end of the gene.
35. v NON-DISJUNCTION
Does not involve any errors in DNA
replication or crossing-over.
Mutations occur during the
anaphase and telophase when the
chromosomes are not separated
correctly into the new cells.
Common non-disjunctions are
missing or extra chromosomes.
37. v EFFECTS OF MUTATION: SMALL-SCALE MUTATIONS
1. Silent/Same sense - The nucleotide is replaced, but the
codon still produces the same amino acid.
2. Missense - The codon now results in a different amino acid,
which may or may not significantly alter the protein’s function.
3. Nonsense - The codon now results in a “stop” command,
truncating the protein at the location where the mutated codon is
read; this almost always leads to a loss of protein functionality.
38. v EFFECTS OF MUTATION: LARGE-SCALE MUTATIONS
Effects of large-scale mutations are more obvious than those
of small-scale mutations.
Duplication of multiple genes causes those genes to be
overexpressed while deletions result in missing or
incomplete genes.
Mutations that change the order of the genes on the
chromosome—such as deletions, inversions, insertions and
translocations—result in genes that are close together.
39. v EFFECTS OF MUTATION: LARGE-SCALE MUTATIONS
When certain genes are positioned
closely together, they may encode
for a “fusion protein”.
A fusion protein is a protein that
would not normally exist but is
created by a mutation in which two
genes were combined.
40. v EFFECTS OF MUTATION: LARGE-SCALE MUTATIONS
The new proteins give cells
a growth advantage, leading
to tumors and cancer.
Often, large-scale mutations
lead to cells that are not
viable – the cell dies due to
the mutation.
42. INFLUENCES OF MUTATIONS
EXPOSURE TO
CHEMICALS
RETROVIRUSES
Carcinogenic
chemicals may
cause cancer.
Retroviruses such as
HIV naturally
experience mutations
at a much higher rate
than other organisms
EXPOSURE TO
RADIATION
High-energy radiation, such
as x-rays, gamma rays,
alpha particles, beta
particles, and neutrons, can
damage DNA and cause
cancer.
These include severe intellectual disability, poor muscle tone, "coarse" facial features, and a prominent forehead.
Classical hemophilia, also known as hemophilia A, is a hereditary hemorrhagic disorder resulting from a congenital deficit of factor VIII that manifests as protracted and excessive bleeding either spontaneously or secondary to trauma.
What is Huntington's disease? Huntington's disease (HD) is an inherited disorder that causes nerve cells (neurons) in parts of the brain to gradually break down and die.
What is Huntington's disease? Huntington's disease (HD) is an inherited disorder that causes nerve cells (neurons) in parts of the brain to gradually break down and die.
What is Huntington's disease? Huntington's disease (HD) is an inherited disorder that causes nerve cells (neurons) in parts of the brain to gradually break down and die.
fusion tags can improve protein solubility, achieve native protein folding, and increase total yield by improving expression and decreasing degradation.
All cancers develop because something has gone wrong with one or more of the genes in a cell.
