Chromosomal Abberrations Flashcards
are released by specific cells and stimulate other cells
to grow and divide.
Growth Factors
In ________-____________ ___________, crowded cells will stop dividing.
Density-dependent inhibition
However, most cells also exhibit __________ ___________ cells must be
attached to a surface for division.
Anchorage Dependence
is a process where a normal cell is converted to a
cancerous cell.
Transformation
Transformation occurs when the genes that regulate cell growth and
differentiation are altered through
Mutation
Such genes are called _________ __________ ____, meaning all genes whose mutation contributes to the causality
of cancer.
Cancer-critical genes
are genes of the first class that normally promote
growth and division of normal cells.
Proto-oncogenes
overactive forms are called
Oncogenes
are genes of the second class that
normally inhibit division and survival of abnormal cells.
Tumor-Suppressor Genes
abnormal mass of cells within
otherwise normal tissue.
Tumors
If an abnormal mass of essentially normal cells
remains only at the original site in the body, the lump is
called a
Benign Tumor
In contrast to a benign tumor, a ______ ___, is cancerous.
malignant tumor
Malignant tumors invade
surrounding tissues and can ____________, spreading cancer
cells beyond their original site, where they may form
additional tumors.
Metasize
The common chromosomal alterations in humans often lead to spontaneous miscarriages or
create a variety of disorders. These genetic disorders are caused by
Nondisjunction
An individual with an altered
chromosome number is a condition
known as
Anueploidy
A __________ ____ has only one copy of a particular
chromosome (2n – 1)
Monosomic zygote
has three copies of a particular
chromosome (2n + 1).
Trisomic zygote
two types of Abnormal Chromosome Number
Aneuploidy of Autosomes
Aneuploidy of Sex Chromosomes
types of Anueploidy of Autosomes:
Down Syndrome
Edwards Syndrome
Patau Syndrome
is the most common single
cause of congenital disorder in humans affecting 1/740 live births. The physical
and mental impacts of Down syndrome range from mild to severe.
Down Syndrome (Trisomy 21; 47,XX/XY,+21)
is the second most
common autosomal trisomy after trisomy 21. Edwards syndrome occurs in
1/5,000 live births that severely affects all organ systems. Approximately 95%
of conceptions with trisomy 18 die in embryonic or fetal life while 5-10% of
affected children survive beyond the first year of life.
Edwards Syndrome (Trisomy 18; 47,XX/XY,+18)
is a rare abnormality that
affects 1/10,000 live births. Many of the multiple symptoms of Patau syndrome
are not compatible with more than a few months of life. Almost half of the
affected infants do not survive beyond the first month, and about three quarters
die within 6 months.
Patau Syndrome (Trisomy 13; 47,XX/XY,+13)
Types of Aneuploidy of Sex Chromosomes
Turner Syndrome
Klinefelter Syndrome
Jacobs Syndrome
Metafemale Syndrome
is the only known viable
monosomy in humans affecting 1/2000 live female births (and 15% of
spontaneous abortions). Individuals with Turner syndrome are phenotypically
female.
Turner Syndrome (Monosomy X; 45,XO)
approximately affects 1 in 500-1,000 males
born with an extra X chromosome. About 40% of conceptions with Klinefelter
syndrome survive the fetal period.
Klinefter Syndrome (47,XXY)
occurs in 1/1000 live births. Individuals with
Jacob syndrome are usually very tall and thin. Many males experience severe
acne during adolescence. Additional symptoms may include antisocial or
behavioral problems and learning disabilities. Intelligence is usually normal,
although IQ, on average, is 10 to 15 points lower than siblings.
Jacobs Syndrome (47,XYY)
affects 7.4-15.6/10,000 female births or
3.6-7.5/10,000 live births. The fetal death rate of triple X syndrome is not
notably higher than that for conceptions with normal chromosomes. The
clinical features are subtle and can be variable and often not identified in
infancy.
Metafemale (Trisomy X; 47,XXX)
two types of Abnormal Chromosome Structure
Deletion
Translocation
(French for “cry of the cat”) is due to a deletion in the
short arm (p arm) of chromosome 5. Between 1 in 20,000 and 1 in 50,000
babies are affected. Infants with cri-du-chat syndrome commonly have a
distinctive cat-like or high-pitched cry caused by a malformation of the larynx.
Cri-Du-Chat Syndrome
happens between chromosome 9 and a large
portion of the long arm (q arm) of chromosome 22. The translocation is
designated t(9;22). This results in one chromosome 9 longer than normal and
one chromosome 22 shorter than normal.
The Philadelphia Chromosome
occurs when a portion of, or an entire, chromosome
21 fuses with one chromosome 14. An individual is phenotypically normal, but
could have children with Down syndrome.
Down Syndrome Carrier
