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Mutations. What is a mutation?. Any change in the DNA base sequence. What are the two different classes of mutations?. Gene Mutations Chromosomal Mutations. What is a gene mutation?. A change in the base sequence of one gene. What causes gene mutations?. Errors in DNA replication

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Presentation Transcript
what is a mutation
What is a mutation?

Any change in the DNA base sequence

what are the two different classes of mutations
What are the two different classes of mutations?
  • Gene Mutations
  • Chromosomal Mutations
what is a gene mutation
What is a gene mutation?
  • A change in the base sequence of one gene
what causes gene mutations
What causes gene mutations?
  • Errors in DNA replication
  • Chemicals
  • UV/X-ray Radiation
types of gene mutations
Types of Gene Mutations
  • Substitution
  • Deletion
  • Insertion

Original DNA Strand

two types of gene mutations
Two types of Gene Mutations

Point mutation

A change in ONE nitrogenous base, the overall number of bases stays the same (Substitution)

Frame shift mutation

A change in the number of overall nitrogenous bases in the genetic code (Insertion or Deletion)

substitution mutation
Substitution Mutation
  • Substitution – One nitrogenous base is substituted for another.
deletion and insertion mutations
Deletion and Insertion Mutations
  • Deletion– One or more nitrogenous bases are removed
  • Insertion – Extra nitrogenous bases are added to the genetic code.
how does a mutated protein affect a cell
How does a mutated protein affect a cell?
  • If the shape of the protein is altered, it MIGHTdisruptits normal activity OR (functioning).
what are some characteristics of gene mutations
What are some characteristics of gene mutations?
  • They can be dominant or recessive
  • They can occur on autosomal chromosomes (pairs 1-22) or sex chromosomes (pair 23)
  •  People that are heterozygous for a recessive genetic disorder are called carriers
  •  Carriers have one normal allele and one diseased allele; They do not show symptoms for the disease but may pass the allele to future offspring


genetic diseases caused by gene mutations
Genetic Diseases caused by gene mutations:

Cystic Fibrosis

Faulty gene produces a

defective protein that does not allow for the proper

removal of mucous lining the cells of the lung and GI


gene mutations
Gene Mutations:

Tay-Sachs Disease

Faulty gene produces a defective enzyme

which cannot help remove fat from nerve cells.

sickle cell anemia1
Sickle-Cell Anemia:

One base is substituted for another and this causes

the production of a distorted hemoglobin molecule

(protein) which cannot function properly.

what do these three gene mutations have in common
What do these three gene mutations have in common?

They all affect the shape of proteins!! If we change

the shape of proteins (enzymes) they will not

function properly and this will affect our phenotype.

how do we trace identify gene mutations in a population or family
How do we trace/identify gene mutations in a population or family?
  • Pedigree Charts: - A diagram that shows the presence or absence of a particular trait through each generation.
  • Genetic Testing: Ability to diagnose vulnerabilities to various genetic disorders
h dominant allele h recessive
H – Dominant Allele; h - Recessive















what is a chromosomal mutation
What is a chromosomal mutation?
  • Any change in the number or structure of chromosomes
chromosome damage
Chromosome Damage:

Part of a chromosome is


Part of a chromosome is


Reversing a fragment of the


A fragment of one

chromosome attaches to a

nonhomlogous chromosome.

abnormal numbers of chromosomes
Abnormal Numbers of Chromosomes
  • Polyploidy: Having many sets of chromosomes – 1.5n, 3n, 4n, 5n
abnormal numbers of chromosomes1
Abnormal Numbers of Chromosomes
  • Aneuploidy: The addition or loss of a whole chromosome
how do these mutations occur
How do these mutations occur?
  • NONDISJUNCTION: occurs when homologous

chromosomes or sister chromatids fail to separate during meiosis.