Human Genetics

Breaking Down the Definitions Honors1. Sex chromosome2. Autosome3. Sex-linked trait4. Linked gene5. Chromosome map6. Map unit7. Germ-cell mutation8. Somatic-cell mutation9. Lethal mutation10. Deletion

11. Inversion12. Translocation13. Nondisjunction14. Point mutation15. Substitution16. Frameshift mutation17. Insertion mutation18. Pedigree19. Carrier20. Genetic disorder

21. Polygenic22. Complex character23. Multiple allele24. Sex-influenced trait25. Huntington’s Disease26. Amniocentesis27. Chorionic villi sampling28. Genetic counseling29. Gene therapy

Breaking Down the Definitions Reg. Bio1. Karyotype2. Sex chromosome3. Autosome4. Pedigree5. Sex linked gene6. Nondisjunction7. DNA fingerprinting8. Gene Therapy

Sex Chromosomes and Autosomes•The sex chromosomes contain genes that determine the gender of the individual.•Autosomes are the remaining chromosomes that do not affect the gender of the individual.•Males= XY•Females = XX

Gender Determination—What are the chances of having a girl or a boy??

Gene Location• Genes located on the X-Chromosome are called X-Linked

Genes.• Genes located on the Y-Chromosome are called Y-Linked

Genes.• The X Chromosome is much bigger than the Y Chromosome

and therefore there are more genes on it.• A male with a recessive allele on the X chromosome will

exhibit the recessive trait since there is not a counter-part on the smaller Y Chromosome.

Punnett Squares with Sex Chromosomes

Linked Genes•Pairs of genes that tend to be inherited together are called LINKED GENES.•The genes are linked together because they are found on the same chromosome•During crossing-over the genes can be swapped.•Video Clip—Crossing Over

Chromosome Mapping•The farther apart 2 genes are located on a chromosome, the more likely a cross over will occur.•Chromosome Map—a diagram that shows the linear placement of genes on a chromosome.•One MAP UNIT = 1% chance of crossing-over

Mutations•A MUTATION is a change in the nucleotide base sequence of DNA (the letters)

Germ-Cell

• In the Gametes

• Do not affect the organism but can be passed on to offspring

Somatic-Cell

• In the body cells

• Can affect the organism, but are not passed on

Lethal

• Causes death; usually before birth

Chromosome Mutations• CHROMOSOME

MUTATIONS are changes in the structure of a chromosome or the loss/gain of an entire chromosome

• Loss of a piece of a chromosomeDeletion

• A chromosomal segment breaks off, flips backwards, and reattachesInversion

• A piece of one chromosome breaks off and reattaches to another chromosome

Translocation

• A chromosome fails to separate during meiosis, therefore one gamete receives an extra copy and one gamete receives no copy

Nondisjunction

Flapbook—4 types of Chromosome Mutations!

Gene MutationsPoint Mutation• Substitution, addition, or removal of a single nucleotide (letter)• Change occurs within a single gene

Substitution• One nucleotide replaces another• If this occurs in a codon, the amino acid can be changed

Frameshift Mutation• Loss of a nucleotide resulting in the incorrect grouping of codons, making all the amino acids

change

Insertion Mutation• One or more nucleotides are added to a gene• Can also cause a Frameshift mutation

Mutation Video Clip• Give an example of an addition• Give an example of a deletion

Flapbook Gene Mutations!

Inheritance of Traits•A PEDIGREE is a diagram that shows how a trait is inherited over several generations•Squares = males, Circles = females•Filled symbol = has the trait, empty symbol= no trait•Horizontal line =mating, vertical line = offspring

Family Pedigree Practice!• Create a pedigree for eye color for the following family!• Children:• Suzy has brown eyes, Jose has brown eyes, Hiram has

blue eyes, Damien has brown eyes.•Mom has blue eyes, Dad has blue eyes• On mom’s side: Grandma has brown eyes, grandpa has

blue eyes• On dad’s side: grandma has blue eyes, grandpa has blue

eyes

Weekly Homework!--Honors•Create a pedigree for your own family!• Choose 1 trait • attached ear lobes, color blindness, dimples, eye color, tongue

rolling, second toe longer than big toe, gluten allergy, near sightedness, right/left handed, curly/straight hair

• Go back at least to your grandparents, farther if you can.• Talk to people, look at pictures• If unknown, shade in gray• If trait is present-color red• If trait is absent, leave empty

Genetics Classroom Survey• After completing the survey answer the following:1. Which 2-3 traits are the most common?2. Which 2-3 traits are the least common?3. Which gene of yours did you find to be common?4. Which gene of yours did you find to be uncommon?

Pedigree Practice

Genetic Disorders•GENETIC DISORDERS are diseases or disabling conditions that are passed down from parent to offspring•POLYGENIC are traits that are influenced by multiple genes rather than a single allele•COMPLEX CHARACTERS- human conditions that are influenced by a combination of genes and environmental factors.•Skin color, height, heart disease

Multiple Alleles•Genes with 3 or more alleles. Example: Blood types, ABO•Multiple alleles often lead to codominance (both traits expressed) or incomplete dominance (an in-between trait is expressed, ie wavy hair).

Blood Types •4 types•Type A, Type B, Type O, Type AB

•A and B are dominant •O is recessive•AO= A blood type•BO=B blood type•AB=genes are CODOMINANT, blood type is AB•Brain Pop –Blood Types

Blood Typing

•Complete the squares below to determine the different possible genotype combinations for offspring:

A B

A

B

Father’s Genotype

Mot

her’s

Ge

noty

pe

Make Punnett Squares for these as well:1. Mom—OO Dad—AB2. Mom—AA Dad—BB3. Mom—AA Dad—AO4. Mom—BB Dad AO5. Mom—AB Dad OO6. Mom—AO Dad BO

Codominance, ABO practice

X-Linked Traits•X-Linked traits are traits found on the X-chromosome and often only males will exhibit the recessive trait (since they don’t have a counterpart on the Y to dominate it).•Colorblindness is an X-linked trait and therefore more common in males•X-Linked Practice!

Single Allele Traits•More than 200 human traits are controlled by a single allele.•Huntington’s Disease is a single allele, dominant, disease.

Genetic Screening and Genetic Disorders•Many people seek GENETIC SCREENING before having

children.• GENETIC SCREENING is an examination of a person’s genetic

makeup to see what traits may be passed on to an offspring.• GENETIC COUNSELING is when a person seeks professional,

medical guidance about the risks of passing on traits to children• AMNIOCENTESIS is a procedure to test the amniotic fluid

during pregnancy to analyze fetal DNA and check for genetic disease.

Gene Therapy• In your own words, what is gene therapy?• Gene therapy cures blindness?

Genetic Disorder Powerpoints and PresentationsChoose a disorder and complete the presentation. You may choose one from below or find your own.• Huntington’s Disease• Alexander Disease• Alzheimer’s• Autism

• Barth Syndrome• Cerebral Palsy• Cleft Palate• Cystic Fibrosis• Down Syndrome• Hemophilia• Marfan Syndrome• Long Q-T Syndrome

• Progeria• Sickle Cell Anemia• Spina Bifida• Williams Syndrome

A Royal Case Study