Mutations
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Transcript of Mutations
Mutations
A mutation is a mistake in the cell’s DNA.
GTTACG GGTACG
DNA contains the information on how to make proteins.
Codons of the mRNA will code for a specific amino acid.
The order and length of the amino acid chain determine how it is folded and shaped.
If any of the amino acids are changed or the length is changed, the shape is different.
The protein’s function may change or not work at all.
Mutations are only passed on to your offspring if they occur in your gametes (egg or sperm)
Mutations that occur in your body cells may cause cancer.
Types of Mutations: Substitution
(point mutation: change in one nucleotide)
Examples Cystic fibrosis
Sickle Cell Disease GAG = glu GTG = val
One amino acid in the protein hemoglobin changes the shape of the cell
Silent Mutation:
Insertion This causes a frameshift mutation. All the
previous codons are now changed into different codons and therefore, different amino acids.
(also known as missense mutation)
Multiple insertions. A gene may be duplicated.
Deletion: A nitrogen base is deleted and a frameshift
mutation occurs.
A gene may be deleted.
Inversion The order of nitrogen bases can be
switched around. A few amino acids may change.
Genes may switch places. May not be expressed properly.
What causes mutations? Induced mutations: Toxic chemicals and
radiation
Examples of plants that were produced via mutation breeding are given in the table below.
Crop Cultivar Name Method Used to Induce Mutation
rice Calrose 76 gamma rays
wheatAbove sodium azide
Lewis thermal neutrons
oats Alamo-X X-rays
grapefruitRio Red thermal neutrons
Star Ruby thermal neutrons
burmuda grass
Tifeagle gamma rays
Tifgreen II gamma rays
Tift 94 gamma rays
Tifway II gamma rays
lettuceIce Cube ethyl methanesulphonate
Mini-Green ethyl methanesulphonate
common beanSeafarer X-rays
Seaway X-rays
lilac Prairie Petite thermal neutrons
St. Augustine grassTXSA 8202 gamma rays
TXSA 8212 gamma rays
Spontaneous mutations Mistakes in DNA replication.
Your DNA contains 3 billion base pairs. These are copied every time you make a new skin cell, liver cell, stomach cell….
Enzymes check the DNA to make sure there are no mistakes in the copying process.
But…. No process is 100% accurate. About one in every 50 million nucleotides
has a mutation occur. This means every new cell contains about
120 new mutations!
Worried? Don’t be… As much as 97% of your DNA doesn’t
code for proteins. We don’t know what this DNA is for. Also, Silent Mutations occur which don’t
change the protein.
Are all mutations bad? No, some are good.
Antibiotic resistance in bacteria
Sickle cell resistance to Malaria
Resistance to artherosclerosis
Immunity to HIV
Lactose tolerance
Blue Skin… (diaphorase deficiency)
Werewolf syndrome (congenital generalized hypertrichosis)