Download Mutations Slideshow/Notes Mutations PPTMW_2

Do Now: 3/16/17
1. What if in one of your Snorks, the gene for # of
legs had an extra nucleotide (extra A,G,C,orT)
How do you think that might affect your Snork?
2. What if it had a T where there should be a C?
3. What if it had 3 extra nucleotides?
Think-Pair-Share
Mutations: Notes in notebook
• Mutation – sudden genetic change (changes in base
pair sequence of DNA)
• Can be :
Harmful mutations – organism less able to survive:
genetic disorders, cancer, death
Beneficial mutations – allows organism to better
survive: provides genetic variation
Neutral mutations – neither
harmful nor helpful to organism
• Mutations can occur in 2 ways:
chromosomal mutation or
gene/point mutation
Chromosomal mutation:
• less common than a gene mutation
• more drastic – affects entire chromosome, so affects
many genes rather than just one
• caused by failure of the homologous chromosomes to
separate normally during meiosis
• chromosome pairs no longer look the same or have the
same # – too few or too many genes, different shape
• Example:
Down’s syndrome – (Trisomy 21) 47 chromosomes,
extra chromosome at pair #21
Turner’s syndrome – only 45 chromosomes, missing a
sex chromosome (X)
Girls affected – short, slow growth, heart problems
Klinefelter’s syndrome – 47 chromosomes, extra X
chromosomes (XXY)
Boys affected – low testosterone levels, underdeveloped
muscles, sparse facial hair
• Having an extra set of chromosomes is fatal in animals,
but in plants it makes them larger and hardier.
Hardier
Gene or Point Mutation (one example)
• most common and least drastic
• only one gene is altered
• Examples of point mutations:
Recessive gene mutations:
Cystic fibrosis – mucous builds up
in the lungs
Tay-Sachs Disease – deterioration
of the nervous system – early
death
Mutated genes produce enzymes that are less
effective than normal at breaking down fatty
cell products known as gangliosides. As a
result, gangliosides build up in the lysosomes
and overload cells. Their buildup ultimately
causes damage to nerve cells.
Now You Try it
• Read the introduction on Mutations and track
one mutation through the process of protein
synthesis
• Then try to identify some other types of
mutations and their effects on protein
production- use mRNA to Amino acid chart on
pg. 530 DUE TODAY
• Haven’t finished Snorks?? Complete that
assignment FIRST (Due today!!)
Do Now: 3/20/17- no Do Now/LT sheet today, just
discuss
1.T/F
Mutations are always bad
2.T/F
Mutations can involve
chromosomes, parts of chromosomes, or
individual genes
3.T/F
Mutations can always be seen in the
phenotype of an organism
4.T/F
Mutations can increase an
organism’s ability to survive
Self correct work
1. Which type of mutation stops the translation of the mRNA? NONSENSE
2. Which type of mutation is responsible for new variations of a trait? FRAME SHIFT
AND MISSENSE
3. Which type of mutation results in abnormal amino acid sequence? FRAME SHIFT,
NONSENSE, AND MISSENSE
Analysis/Conclusion: Add to bottom of worksheet
1.
2.
3.
Name one amino acid that has more than one codon. Name an amino
acid that has only ONE codon. How many stop codons are there? Use
pg. 530
Look at the following sequence: THE FAT CAT ATE THE RAT. Delete the
first H and regroup the letters in groups of 3- write them out. Does
the sentence still make sense? What type of mutation is this an
example of?
You have a DNA sequence that codes for a nucleotide that is 105
nucleotides long. A frameshift mutation occurs at the 85th base- how
many amino acids will be correct in this protein?
Conclusion: Summarize this activity by writing a claimevidence-reasoning statement about the effect
(increase or decrease) mutations have on genetic
variation.