Biology Chapter 10
Base sub: Sickle Cell Anemia
One base substitution in a certain location in the gene for hemoglobin causes red blood cells to become abnormally-shaped and clog blood vessels. If someone has two copies of this mutation then they will have the disease
Point mutations
They can cause health disorders because they end up changing the way important proteins work
How can the wrong amino acid be added during translation?
a base substitution mutation in mRNA
Frameshift Mutation
a mutation caused by an insertion or deletion, which causes a shift in the translational reading frame
Insertions
a point mutation in which one or more base pairs is added to a DNA sequence
Deletion
a point mutation in which one or more base pairs is deleted.
Silent mutation
a point mutation that has no overall effect on a protein's function
Nonsense mutation
a point mutation that turns one codon into a stop codon
pyrimidine
a single-ring base, like thymine and cytosine.
What might a nonsense mutation in the mRNA result in?
a truncated copy of the protein Klq is produced
Reading frame
a way of dividing the mRNA into codons and focusing on one codon at a time
DNA polymerase
always double-checks its work to make sure all the nucleotides have been replicated correctly. When it finds an error in the DNA sequence, it quickly stops and fixes it before replication.
Duchenne muscular dystrophy (DMD)
disorder that's caused by a nonsense mutation. Patients suffer from severe muscular weakness that gets worse over time.
Mutagen
environmental agent, chemical or physical, that causes a mutation in an organisms' DNA
UV radiation, chemical, x rays, extreme heat
examples of mutagen
What is an efficient way of causing multiple mutations in a bacterial cell?
exposing the bacteria to UV light
The enzyme affected in Tay-Sachs disease is
hexosaminidase A
when will a frameshift not occur even if there is insertion or deletion?
if an insertion or deletion consists of nucleotides numbering a factor of 3, then a frameshift will not occur.
In Tay-Sachs disease, a frameshift mutation of the hexosaminidase gene causes _____ of the enzyme.
incorrect synthesis
Purine
is a double-ring nitrogenous base, like adenine and guanine.
Tay-Sachs Disease
is a human disorder caused by a frameshift mutation. People may suffer from muscle weakness, seizures, deafness, blindness, or dementia.. Its job is to keep harmful chemicals from building up in our nerve cells.
Missense mutation
is a point mutation that changes a codon to indicate a different amino acid
Hemoglobin
is a protein that helps us carry the oxygen in our bloodstream
Dystrophin
is a structural protein that helps make up our muscle tissue.
Sickle-cell anemia
is one disease that is caused by a missense mutation. The mutation occurs in the hemoglobin gene.It also affects the shape of our red blood cells, which need to be round in order to move smoothly through our blood vessels. trouble circulating oxygen
A mutation in DNA can affect the amino acid sequence because it affects the code found in
mRNA
What causes point mutations?
random mistakes that occur while a DNA sequence is being built. don't usually happen to more than one nucleotide. They generally involve a single nucleotide being added, subtracted, or replaced with a different kind.
Nucleotides
repeating units of a DNA sequence
DNA
the unit of heredity of all organisms
Base substitutions' two types
transitions and transversions.
Transversion
when a purine is switched with a pyrimidine, or vice-versa,
Insertion: Tay Sachs disease
when a short nucleotide sequence is inserted into the hexosaminidase gene. This gene makes a protein important in removing specific toxins from the nervous system. If a mutation occurs in this gene, then nerve cells will start to die
When can a genetic mutation get passed down through successive generations?
when it does not affect the organism's ability to survive and reproduce
Which is an example of a transversion?
5' CCAC 3' is mutated to 5' CCTC 3'
Deletion: Duchenne Muscular dystrophy
A deletion of a certain nitrogenous base in the dystrophin gene causes the disease. This disease is sex-linked and tends to be much more common in males than females. It causes weakened muscles and early death, just by one little base being removed.
Mutation
any change in the nucleotide sequence of an organism's DNA
Transitions
are base substitutions that swap a purine for another purine or a pyrimidine for another pyrimidine.
Point Mutations (smaller mutations)
are changes in the genetic sequence that occur at a specific point along the DNA strand.
Base substitutions
are just what they sound like; they're point mutations in which one nitrogenous base is substituted by a different base.
point mutations' s two basic types
base substitutions and insertions and deletions.
mutations can cause a variety of disorders:
cystic fibrosis, color blindness, Tay-Sachs disease, sickle-cell anemia, and cancer.
Tay-Sachs disease results from a buildup of harmful chemicals in the
nerve cells
mutagen
origin of mutations
gen
origin or creation of something
Genes
sequences of DNA that code for proteins