Biology - Human Genetics
Info within the Nucleus

______________________________________: complete set of genetic info in an
organism (or group of organisms).

DNA wraps around proteins called _____________________________; this allows
the coiling (or condensing) of DNA within the nucleus.

Humans have ___________________ chromosomes in every cell (except RBCs &
gametes).

Human genome contains ~3 billion bases.
The Human Genome Project:

This is the _______________________________________ of all of the DNA of
humans (as well as other organisms)

This begun in 1988 and ended in 2000.

They originally thought there were 90,000 genes but there are only about
__________________________________-30,000 genes.

The goal was to sequence all genes for both normal and abnormal functions
(normal and diseased genes).
Project’s Goal:

To use this information for in the fields of genetic
________________________________________________ (the use of
biotechnology, using biochemical techniques to identify, study and modify
genes).

(The hope is to gain understanding in) genetic ___________________________
(medical treatments that attempt to change a genome with the use of genetic
engineering).

Other organisms’ genomes have also been sequenced: mice, cats, dogs, fruit fly
(Drosophila), yeast, Escherichia coli (bacteria), Helicobacter pylori (ulcer causing
bacteria), and some viruses (not living).
The Human Gene Map

A __________________________________ is a chart of chromosomes that
scientists use to study the differences in chromosome shape, structure & size.

In humans, doctors use karyotypes to determine the baby’s genetic
_____________________ & to see if there is an abnormal
___________________________________________________ or
_______________________________________________________________.
Chromosomal Abnormalities:

Chromosomal Abnormalities show on karyotypes.
o They can be too ______________________________ or too few chromosomes.
o This is the result of chromosome ________________________________ not
separating in meiosis: during ______________________________ in meiosis I
or during _______________________________________ in meiosis II.

This is called ______________________________________________, meaning not
separating.
Nondisjunction:

1 daughter cell receives an extra copy of a ________________________________
while another daughter cell does not receive a copy of the chromosome
o Result = gametes have an abnormal amount of chromosomes (or genetic
material).
o If this gamete joins with another, the resulting offspring will be abnormal if it
survives.

A ______________________________________________ is when a zygote has 1 less
chromosome (2n-1, or 45 chromosomes).

A ______________________________________________ is when a zygote has 1
extra chromosome (2n + 1, or 47 chromosomes)
Very few monosomies or trisomies in humans survive. Some that survive are:

Down Syndrome is trisomy ___________________ (3 chromosome #21).

The sex chromosomes tolerate far more manipulations.
o Trisomy _________ (XXX) or XXY survives as well as monosomy X (Xo)
survives.

A _____________________________________ is the result of a complete set of
chromosomes not separating.

In animals, the organism generally does not survive but in plants, a
_____________________________ plant is produced.
o In general, the best characteristics of both parents are taken and the plants are
healthier and stronger.

________________________________ of ALL plants are polyploids.

This includes wheat used to make bread, potatoes, oats,
_______________________________, peanuts, barley, plums,
_______________________________, sugar-cane, ____________________________,
& cotton.
Gene Mutations:

These may involve single _______________________________________ or small
sections of ___________________.

These include Frameshift mutations, Point mutations, and Jumping genes
1. Frameshift Mutations:
The addition or deletion of nucleotides that alters the sequence of bases (or
________________________________________________________).
2. Point Mutations:

Result in substitution of only ________________ nucleotide that only affects 1
codon.
o may affect affect _______________________________________________.
o About 30% of point mutations produce no changes in proteins. These are
called ___________________________ mutations.
3. Jumping Genes:

Insertions of larges ________________________ of DNA into the gene.
o Barbara _______________________________ (1947), an American geneticist
studying corn, discovered these.
o Jumping genes are called ___________________________________________
Damaged Chromosomes:

Deletions: when __________________________ of chromosomes are removed

Duplications: when fragment of the deleted chromosome attaches to the
_________________________________ chromosome, resulting in extra copies of genes

________________________________________ when fragment of deleted
chromosome attaches to original chromosome but
_____________________________________________ down

Translocation: when fragment of deleted chromosome attaches to
________________________________________________ chromosome.
Predictions & People:
Pedigree Studies:

Human studies are not as easy to study like pea plants. WHY?
o Generations are slow, humans reproduce too
___________________________________, humans have
_________________________ offspring and genetic studies on humans can be
____________________________________________.
o A _________________________________________ is a chart that shows how
a trait and the gene that controls it are inherited within a family.
Key:
A circle =female; a square = male
Shaded =has the trait; ½ shaded =carrier of the trait; horizontal line between male &
female =marriage line; Roman numerals =indicate generations; Arabic numerals
=individuals within generations
Genetic Counseling:

A genetic _______________________________________ is a person who provides
information about probabilities of offspring and genetic disorders.

They use ____________________________________, Punnett squares &
_________________________________________________________.

They explain probabilities and possibilities.

If the people they are counseling are pregnant, they also give options and possibly more
tests that may determine, for example, if the child has Down Syndrome (an extra
chromosome).

_________________________________________, or phenylketonuria, is a genetic
disease that is tested for on newborn babies in the US.
o A person with this disease lacks the ___________________________________
to break down phenylalanine (an amino acid found in many food products, like
milk and gum).
o If a person eats this, phenylalanine builds up & causes developmental
disabilities and eventually __________________________________________.
o The treatment is to avoid ____________________________________________.
Diseases:
It takes 2 __________________________________________ alleles to reveal a recessive
disease or trait (otherwise the trait or disease will “hide” behind the dominant allele and the
person is a carrier).
1. Tay-Sachs Disease is a disease in which a person cannot break down
_____________________________________________.

They accumulate in the brain and this results in blindness & brain damage.

Eventually, death occurs.
2. Cystic Fibrosis (found on chromosome #7) is a disease that results in excessive
secretions of _____________________________________ which accumulates in the
digestive tract & lungs.
3. Albinism has various forms that is the result of _________________________ of
pigment.

A true albino lacks skin __________________________________.

Other forms have _____________________________ skin and white-blond
hair.

Albinism affects all races and _________________________________.
Dominant Traits:

Some dominant traits are: freckles, widow’s peak, far-sightedness, and
_______________________________________________(extra fingers & toes).
Dominant Diseases:

Achondroplasia (________________________________________________)
o Individuals are _____________________________________ (b/c
homozygous = fatal)
Dominant Diseases:

Huntington disease. (results in the _______________________________ of the
nervous system which develops in the late 30’s or early 40’s)
o There is a genetic test that can be performed to determine if one will develop
this disease.
o Found on chromosome #____________________________
Genetic Cancers

_____________________________ factors: proteins that initiate cell division

_____________________________________-suppressor genes: make proteins that
stop cell division (prevent cancer)
o When _________________________________ accumulate to genes that
regulate control of the cell cycle, tumors (possibly cancer) may develop.

_______________________________________: cancer-causing genes

Technically, cancer is “genetic” b/c it results from a mutation in the DNA.

However, The REALITY is: inherited mutations that cause cancer (inherited
cancer genes) ONLY result in a ___________________________________
_________________________________ of cancer. If inherited it does not mean the
person WILL get cancer.

Ex: _______________________________ (mutated tumor-suppressor gene for
breast cancer)