1. GOOD?
BAD?
NO EFFECT?
MUTATIONS

2. When you think of mutations…
Does this come to mind? Or this? How about this? Chances are you said…YES! Genetic mutations are not always what we think…

3. What are Genetic Mutations?
Any permanent change to DNA, and sometimes RNA
Beneficial mutations can increase variation and lead to adaptation
Harmful mutations can cause disorders, deformities, or even death
Can occur spontaneously, usually during DNA replication
Can occur due to exposure to external factors
Chemical mutagens: THC, cigarette smoke, toxins
Radiation: UV, X-ray

4. Most Mutations have NO effect!
This because MOST of an organism’s DNA is not active protein encoding DNA, so chances are when and if mutation occurs, it will be in this DNA
Also, if you remember many amino acids have codons with a ‘wobble’ base…so if mutation occurs here it doesn’t change the protein or its function.

5. Body Cell vs Germ Cell Mutation
Body Cell mutations are called somatic mutations
They affect only that cell’s ability to function
They affect any daughter cells resulting from mitosis
They cannot be passed to offspring
Example: cancers caused by behaviors like smoking, exposure to toxins in herbicides and pesticides
Germ Cell mutations are those found in the gametes
They are passed on to offspring
Are present in every cell’s DNA
They affect every cell of the offspring
Examples: Genetic disorders, genetic cancers,
structural /functional protein errors

6. Types of Mutations
Mutation can be as small as a change to a single base, or as large as loss of an entire chromosome!

7. Gene or Point Mutations
Changes to bases-that result in changes to the protein
Examples:
Missense SUBSTITUTIONS: 1 base: codes wrong AA
Nonsense SUBSTITUTIONS: 1 base: codes STOP

8. Gene or Point Mutations
FRAMESHIFT deletions: lose a base
FRAMESHIFT insertions: add a base
Both result in a misreading of codons and wrong protein or no protein
Frameshifts can occur
with the insertion or
deletion of two bases
as well

9. Duplications/Tandem Repeats
DUPLICATIONS: codons are repeated, so amino acids are duplicated
TANDEM REPEATS: repeat
of several of the same codon

10. CHROMOSOMAL MUTATIONS
Include loss/moving of sections, or even the entire chromosome
Like gene mutations, chromosome mutations include substitutions, deletions, and duplications
Unlike genes, these mutations, involve large amounts of DNA and
many genes
Result in greater, mostly negative phenotypes, most are lethal mutations
Other types of chromosome mutations include inversions, translocations and non-disjunctions….let’s take a look at those.

11. Types of Chromosomal Mutations
Deletions: loss of sections of chromosome, may include many genes A B C D E
Duplications: sections are duplicated C D B A E E C D B A

12. Types of Chromosome Mutations
Inversions: sections are ‘flipped’, results in the wrong side of the DNA being transcribed=no protein B A C D E
Translocation: end of one chromosome is attached to the end of a non homologous chromosome
During which event of meiosis are these types of mutations more likely to occur? B A C D E W X Z Y
CROSSING-OVER

13. Non-disjunction Mutations
Disjunction refers to the separation of sister chromatids during anaphase of meiosis I and II
NON-disjunction refers to the failure of chromatids to separate,
as a result…gametes can form
with the incorrect number of chromosomes

14. Non-disjunction Mutations
The severity of non-disjunction mutations depends upon whether they occur during meiosis I or meiosis II
ALL GAMETES ARE AFFECTED
HALF OF THE GAMETES ARE AFFECTED

15. POINT: MISSENSE SUBSTITUTION
AWV
SOMATIC: AFFECT ONLY CELLS OF THE ORGANISM
GERM CELL: AFFECT OFFSPRING
POINT: CHANGES TO BASE OF GENE
CHROMOSOME: LOSS OF MANY GENES
POINT: MISSENSE SUBSTITUTION
SINGLE BASE CHANGES CAN STILL RESULT IN SAME AMINO ACID
EVEN IF AN AMINO ACID IS DIFFERENT, PROTEINS ARE SO LARGE USUALLY LITTLE EFFECT
AWV
6 CODONS: VALINE-SERINE-ALANINE-GLYCINE-PROLINE-LEUCINE-THREONINE-ARGININE
1 CODON: METHIONINE-TRYPTOPHAN
TEF ATC ATA TET HER AT
NO, IT MAKES NO SENSE THIS IS A FRAMESHIFT DELETION MUTATION
105 DIVIDED BY 3 = 35 TOTAL AMINO ACIDS IN PROTEIN
84 DIVIDED BY 3 = 28 CORRECT AMINO ACIDS, 7 INCORRECT

16. SEQUENCE #1 AND #3 ARE THE SAME ILLUSTRATES EVEN WITH DIFFERENT
SER LEU ALA THR ARG SER
SEQUENCE #1 AND #3 ARE THE SAME
ILLUSTRATES EVEN WITH DIFFERENT
CODONS THE SAME PROTEIN CAN RESULT
SER LEU ALA THR SER SER
SER LEU ALA THR ARG SER
NORMAL SICKLE
CCC GAA GAA AAA CCC GUA GAA AAA
PRO GLU-A GLU-A LYS PRO VAL GLU-A LYS
POINT SUBSTITUTION: A SINGLE BASE
IS CHANGED AND 1 AA
CCC GAA GAA UUU
PRO GLU-A GLU-A PHE
PROBABLY; GLU-A IS IN CORRECT
POSITION EVEN THOUGH THERE IS A
DIFFERENT POINT MUTATION FURTHER
DOWN THE BASE SEQUENCE

17. DELETION AT B
DUPLICATION OF B
INVERSION OF B & E
TRANSLOCATION
OF JKL AND DEF
CROSSING-OVER
GENE DELETIONS AFFECT A SINGLE PROTEIN
CHROMOSOME DELETIONS AFFECT MANY GENES THUS MANY PROTEINS

18. EACH GAMETE SHOULD HAVE 2 CHROMOSOMES
FAILURE OF CHROMOSOMES OR CHROMATIDS TO SEPARATE DURING ANAPHASE I OR II
EACH GAMETE SHOULD HAVE 2 CHROMOSOMES
“3 BODIES” = TRISOMY

19. MALE FEMALE 6. MISSING A SEX CHROMOSOME 7. MONOSOMY 8. EXTRA #21
9. TRISOMY 21
DOWN SYNDROME