MUTATIONSMUTATIONS

Chapter 11.3, Chapter 12Chapter 11.3, Chapter 12

MutationsMutations

MutationMutation = change in DNA sequence = change in DNA sequence Mutations can be caused by Mutations can be caused by errorserrors in in

replicationreplication, , transcriptiontranscription, , translationtranslation, , cell cell divisiondivision, or , or external agentsexternal agents

Mutations in Mutations in reproductive cellsreproductive cells can affect can affect potential offspring potential offspring (ex: inheritable genetic (ex: inheritable genetic disorders)disorders)

Mutations in Mutations in body cellsbody cells do not get passed onto do not get passed onto offspring offspring (ex: if an individual develops skin (ex: if an individual develops skin cancer)cancer)

Types of MutationsTypes of Mutations

Point MutationsPoint Mutations (base substitutions)= a (base substitutions)= a change in a single DNA base pairchange in a single DNA base pair

Frameshift MutationsFrameshift Mutations (addition or (addition or deletion)= a single base is deletion)= a single base is addedadded or or deleteddeleted from DNA from DNA

If a mutation causes a change in the a.a. If a mutation causes a change in the a.a. it’s called a it’s called a missensemissense mutation mutation

If a mutation does not change the a.a. it’s If a mutation does not change the a.a. it’s called a called a silentsilent mutation mutation

If a mutation changes the a.a. to a ‘stop’ If a mutation changes the a.a. to a ‘stop’ codon it’s called a codon it’s called a nonsensenonsense mutation. mutation.

Point Mutations (Base Point Mutations (Base Substitutions)Substitutions)

THE BOY CUT HIS LIP AND ATE THE HOT DOGTHE BOY CUT HIS LIP AND ATE THE HOT DOG Point mutationPoint mutation THE BOY THE BOY BBUT HIS LIP AND ATE THE HOT DOGUT HIS LIP AND ATE THE HOT DOG GAC GAC TAC TAC GAC GAC GAG GAG

Silent mutation is when mutation makes no amino acid Silent mutation is when mutation makes no amino acid changechange CTT CTT CTG CTG Leucine Leucine Leucine (No change!) Leucine (No change!)Animation Quiz 14 - Mutation by Base SubstitutionAnimation Quiz 14 - Mutation by Base Substitutionhttp://www.sinauer.com/cooper5e/animation0404.htmlhttp://www.sinauer.com/cooper5e/animation0404.html

Frameshift MutationsFrameshift Mutations

THE BOY CUT HIS LIP AND ATE THE HOT DOGTHE BOY CUT HIS LIP AND ATE THE HOT DOG Insertion:Insertion: THE BOY CUT HIS THE BOY CUT HIS SSLI PAN DAT ETH EHO TDO GLI PAN DAT ETH EHO TDO G Deletion:Deletion: THE BOY CUT HIS LIP ANA TET HEH OTD OGTHE BOY CUT HIS LIP ANA TET HEH OTD OG http://highered.mcgraw-hill.com/sites/0072552980/http://highered.mcgraw-hill.com/sites/0072552980/

student_view0/chapter9/animation_quiz_5.htmlstudent_view0/chapter9/animation_quiz_5.html

Chromosomal MutationsChromosomal Mutations = missing or = missing or extra pieces of chromosomes, switched extra pieces of chromosomes, switched pieces, extra chromosomespieces, extra chromosomes occurs frequently in plants, “super sized occurs frequently in plants, “super sized

strawberries”strawberries” Few C.M.’s get passed onto offpring Few C.M.’s get passed onto offpring

because the zygote dies and doesn’t because the zygote dies and doesn’t develop or the mature offspring cannot develop or the mature offspring cannot reproducereproduce

Mutation of genetic Mutation of genetic material will affect material will affect the proteins the proteins producedproduced

Cause & RepairCause & Repair

Some mutations are spontaneousSome mutations are spontaneous MutagenMutagen = any agent that causes DNA = any agent that causes DNA

change change (ex: chemicals, radiation)(ex: chemicals, radiation) Cells have Cells have repair mechanismsrepair mechanisms and and

special enzymesspecial enzymes that can fix incorrect that can fix incorrect DNADNA

HUMAN TRAITSHUMAN TRAITS

Chapter 12, Section 1Chapter 12, Section 1

PedigreePedigree PedigreePedigree = map of inheritance of genetic traits = map of inheritance of genetic traits

from generation to generationfrom generation to generation

www.zerobio.com/drag_gr11/pedigree/pedigree_overview.htm

KaryotypeKaryotype

Chromosomes come in pairs, inherited Chromosomes come in pairs, inherited from parentsfrom parents

KaryotypeKaryotype = a chart of chromosome = a chart of chromosome pairs, can be used to visualize pairs, can be used to visualize chromosomal abnormalitieschromosomal abnormalities

Humans have Humans have 23 pairs23 pairs of chromosomes, of chromosomes, 46 total46 total chromosomes chromosomes

AutosomesAutosomes = any chromosome that isn’t a = any chromosome that isn’t a sex chromosomesex chromosome Human has 22 pairs (44 chromosomes)Human has 22 pairs (44 chromosomes)

Sex ChromosomeSex Chromosome = genes that determine an = genes that determine an individuals gender individuals gender (X and Y)(X and Y) Male= XYMale= XY Female= XXFemale= XX Sex chromosomes are the last pair on the Sex chromosomes are the last pair on the

karyotypekaryotype Human has 1 pair (2 chromosomes)Human has 1 pair (2 chromosomes)

Common Chromosomal Common Chromosomal DisordersDisorders

Disorder Chromosome Abnormality

Patau Syndrome Trisomy 13Edwards Syndrome Trisomy 18Down Syndrome Trisomy 21Jacobs Syndrome XYYTurner Syndrome XOKleinfelter Syndrome XXYTriple X XXX   

Recessive HeredityRecessive Heredity

Caused by Caused by recessive allelesrecessive alleles Attached earlobes, Cystic fibrosis Attached earlobes, Cystic fibrosis

(defective protein leads to excessive (defective protein leads to excessive mucus production in lungs), Albinismmucus production in lungs), Albinism

Individual will only display the Individual will only display the recessive recessive phenotypephenotype if its genotype is if its genotype is homozygous homozygous recessiverecessive

Dominant HeredityDominant Heredity

Caused by Caused by dominant alleledominant allele Freckles, Widow’s peak, Hitchhickers Freckles, Widow’s peak, Hitchhickers

thumb, Huntington’s disease (brain thumb, Huntington’s disease (brain degeneration, doesn’t appear until later in degeneration, doesn’t appear until later in age), immunity to poison ivyage), immunity to poison ivy

Individual will display the Individual will display the dominant dominant phenotypephenotype if its genotype is if its genotype is heterozygousheterozygous oror homozygous dominanthomozygous dominant

When Heredity When Heredity Follows Different Follows Different

RulesRules

Chapter 12, Section 2Chapter 12, Section 2

Incomplete DominanceIncomplete Dominance

Complete DominanceComplete Dominance = one allele = one allele completely completely dominates over anotherdominates over another

Incomplete DominanceIncomplete Dominance = phenotype of = phenotype of a a heterozygoteheterozygote is in between the is in between the homozygous phenotypes, homozygous phenotypes, appearance of appearance of a third phenotypea third phenotype

Do not use lower case letters, use prime Do not use lower case letters, use prime instead (‘) apostropheinstead (‘) apostrophe

Codominance & Multiple AllelesCodominance & Multiple Alleles

BothBoth alleles for a gene are expressed in alleles for a gene are expressed in a a heterozygous individualheterozygous individual

Neither allele is dominant or recessiveNeither allele is dominant or recessive Ex: Blood typeEx: Blood type BLOOD TYPE.pptBLOOD TYPE.ppt Blood type also shows Blood type also shows multiple allelesmultiple alleles, ,

more than 2 alleles: A, B, Omore than 2 alleles: A, B, O Eye color also shows multiple allelesEye color also shows multiple alleles

Sex Determination & Sex-Sex Determination & Sex-linked Inheritancelinked Inheritance

Combination of Combination of sex chromosomes (X and sex chromosomes (X and Y)Y) determine an individual’s gender determine an individual’s gender

Males XY, X chromosome comes from Males XY, X chromosome comes from mom & Y chromosome comes from dadmom & Y chromosome comes from dad

Females XX, both mom & dad give an X Females XX, both mom & dad give an X chromosomechromosome

Sex-linked TraitsSex-linked Traits = traits controlled by = traits controlled by genes on sex chromosomesgenes on sex chromosomes

Red-Green colorblindness Red-Green colorblindness Hemophilia (blood doesn’t clot properly)Hemophilia (blood doesn’t clot properly) Male Pattern BaldnessMale Pattern Baldness Duchenne Muscular Distrophy (muscular Duchenne Muscular Distrophy (muscular

degeneration leading to eventual degeneration leading to eventual paralysis)paralysis)

Most sex-linked traits are found on genes Most sex-linked traits are found on genes on the on the X chromosomeX chromosome (X-linked trait)(X-linked trait) because it is larger than the because it is larger than the Y chromosomeY chromosome

X-linked traits display more in males X-linked traits display more in males because they only have 1 X chromosome, because they only have 1 X chromosome, whereas females get 2 X chromosomes so whereas females get 2 X chromosomes so they can be carriers of the trait but not they can be carriers of the trait but not display the phenotypedisplay the phenotype

Polygenic InheritancePolygenic Inheritance Characteristics that are influenced by Characteristics that are influenced by

several genesseveral genes