MUTATIONS Chapter 11.3, Chapter 12

Mutations Mutation = change in DNA sequence Mutations can be caused by errors in replication, transcription, translation, cell division, or external agents Mutations in reproductive cells can affect potential offspring (ex: inheritable genetic disorders) Mutations in body cells do not get passed onto offspring (ex: if an individual develops skin cancer)

Types of Mutations Point Mutations (base substitutions)= a change in a single DNA base pair Frameshift Mutations (addition or deletion)= a single base is added or deleted 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 missense mutation If a mutation does not change the a.a. it’s called a silent mutation If a mutation changes the a.a. to a ‘stop’ codon it’s called a nonsense mutation.

Point Mutations (Base Substitutions) THE BOY CUT HIS LIP AND ATE THE HOT DOG Point mutation THE BOY BUT HIS LIP AND ATE THE HOT DOG GAC  TAC GAC  GAG Silent mutation is when mutation makes no amino acid change CTT  CTG Leucine  Leucine (No change!) Animation Quiz 14 - Mutation by Base Substitution http://www.sinauer.com/cooper5e/animation0404.html

Frameshift Mutations THE BOY CUT HIS LIP AND ATE THE HOT DOG Insertion: THE BOY CUT HIS SLI PAN DAT ETH EHO TDO G Deletion: THE BOY CUT HIS LIP ANA TET HEH OTD OG http://highered.mcgraw-hill.com/sites/0072552980/student_view0/chapter9/animation_quiz_5.html

Chromosomal Mutations = missing or extra pieces of chromosomes, switched pieces, extra chromosomes occurs frequently in plants, “super sized strawberries” Few C.M.’s get passed onto offpring because the zygote dies and doesn’t develop or the mature offspring cannot reproduce

Mutation of genetic material will affect the proteins produced

Cause & Repair Some mutations are spontaneous Mutagen = any agent that causes DNA change (ex: chemicals, radiation) Cells have repair mechanisms and special enzymes that can fix incorrect DNA

HUMAN TRAITS Chapter 12, Section 1

Pedigree Pedigree = map of inheritance of genetic traits from generation to generation

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

Karyotype Chromosomes come in pairs, inherited from parents Karyotype = a chart of chromosome pairs, can be used to visualize chromosomal abnormalities Humans have 23 pairs of chromosomes, 46 total chromosomes

Autosomes = any chromosome that isn’t a sex chromosome Human has 22 pairs (44 chromosomes) Sex Chromosome = genes that determine an individuals gender (X and Y) Male= XY Female= XX Sex chromosomes are the last pair on the karyotype Human has 1 pair (2 chromosomes)

Common Chromosomal Disorders Chromosome Abnormality Patau Syndrome Trisomy 13 Edwards Syndrome Trisomy 18 Down Syndrome Trisomy 21 Jacobs Syndrome XYY Turner Syndrome XO Kleinfelter Syndrome XXY Triple X XXX  

Recessive Heredity Caused by recessive alleles Attached earlobes, Cystic fibrosis (defective protein leads to excessive mucus production in lungs), Albinism Individual will only display the recessive phenotype if its genotype is homozygous recessive

Dominant Heredity Caused by dominant allele Freckles, Widow’s peak, Hitchhickers thumb, Huntington’s disease (brain degeneration, doesn’t appear until later in age), immunity to poison ivy Individual will display the dominant phenotype if its genotype is heterozygous or homozygous dominant

When Heredity Follows Different Rules Chapter 12, Section 2

Incomplete Dominance Complete Dominance = one allele completely dominates over another Incomplete Dominance = phenotype of a heterozygote is in between the homozygous phenotypes, appearance of a third phenotype Do not use lower case letters, use prime instead (‘) apostrophe

Codominance & Multiple Alleles Both alleles for a gene are expressed in a heterozygous individual Neither allele is dominant or recessive Ex: Blood type BLOOD TYPE.ppt Blood type also shows multiple alleles, more than 2 alleles: A, B, O Eye color also shows multiple alleles

Sex Determination & Sex-linked Inheritance Combination of sex chromosomes (X and Y) determine an individual’s gender Males XY, X chromosome comes from mom & Y chromosome comes from dad Females XX, both mom & dad give an X chromosome Sex-linked Traits = traits controlled by genes on sex chromosomes

Red-Green colorblindness Hemophilia (blood doesn’t clot properly) Male Pattern Baldness Duchenne Muscular Distrophy (muscular degeneration leading to eventual paralysis)

Most sex-linked traits are found on genes on the X chromosome (X-linked trait) because it is larger than the Y chromosome X-linked traits display more in males because they only have 1 X chromosome, whereas females get 2 X chromosomes so they can be carriers of the trait but not display the phenotype

Polygenic Inheritance Characteristics that are influenced by several genes