Human Genetics
Vocabulary—Woo Hoo!
1.
2.
3.
4.
5.
6.
7.
8.
Sex-linked trait
Linked gene
Chromosome map
Deletion
Inversion
Translocation
Nondisjunction
Point mutation
9. Substitution
10. Frameshift
mutation
11. Insertion mutation
12. Pedigree
13. Carrier
14. Genetic disorder
15. Polygenic
16. Multiple allele
17. Amniocentesis
18. Genetic counseling
19. 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
Somatic-Cell
• In the
Gametes
• Do not
affect the
organism
but can be
passed on
to
offspring
• 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
Deletion
•Loss of a piece of a
chromosome
Inversion
• A chromosomal segment breaks off,
flips backwards, and reattaches
Translocation
• A piece of one chromosome breaks
off and reattaches to another
chromosome
Nondisjunction
• A chromosome fails to separate during
meiosis, therefore one gamete receives an
extra copy and one gamete receives no copy
Gene Mutations
Point 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
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
Pedigree Handout
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
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
Genetic Disorder Pedigree—Hemophilia Case
STudy
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:
Father’s
Genotype
A
Mother’s
Genotype
A
B
B
Make Punnett Squares for these
as well:
1. Mom—OO Dad—AB
2. Mom—AA Dad—BB
3. Mom—AA Dad—AO
4. Mom—BB Dad AO
5. Mom—AB Dad OO
6. Mom—AO Dad BO
Codominance, ABO practice
X-Linked Traits
• X-Linked traits are traits found on the Xchromosome 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
Presentations
Choose a disorder and • Barth Syndrome
complete the
• Bicuspid Aortic Valve
presentation. You may
choose one from below • Cerebral Palsy
• Cleft Palate
or find your own.
• Huntington’s Disease • Cystic Fibrosis
• Down Syndrome
• Alexander Disease
• Hemophilia
• Alzheimer’s
• Marfan Syndrome
• Autism
• Long Q-T Syndrome
• Progeria
• Sickle Cell Anemia
• Spina Bifida
• Williams Syndrome