NU 578
Unit 7 Study Guide
Key Concepts & Exam Review
University of South Alabama.
This Exam Features:
It summarizes key concepts, lecture highlights, and
exam-relevant material to support efficient last-
minute review. The guide is structured to help
students reinforce understanding, identify weak areas, and
prepare confidently for the assessment.
, Unit 7 Study Guide
1) Specific chromosomal abnormality responsible for Down Syndrome (Ch. 4, Pg. 146)
● Aneuploid cells are defined as those that do not contain a multiple of 23 chromosomes.
● An aneuploid cell containing three copies of one chromosome is said to be trisomic (termed trisomy).
● Trisomy of the twenty-first chromosome is the autosome aneuploidy which causes Down Syndrome
2) Causes of mental retardation (page numbers below)
Chromosome abnormalities are the leading know cause of mental retardation. (pg. 143)
● About 75% of individuals with spina bifida have secondary hydrocephalus, which sometimes in turn produces
mental retardation. (pg. 168)
● Cri du chat Syndrome – disease caused by chromosomal deletion. (pg. 148)
● Fragile X Syndrome – A fragile site (a number of areas on chromosomes develop microscopically observable
breaks and gaps when the cells are cultured in a folate-deficient medium) located on the long arm of the X
chromosome. Fragile X syndrome is the second most common genetic cause of mental retardation (after Down
Syndrome) effecting 1 in 4,000 males and 1 in 8,000 females. (pg. 151)
● Phenylketonuria (PKU) genotype – Affects infants. If left untreated, abnormal metabolites of phenylalanine will
begin to accumulate in the infant’s brain and irreversible mental retardation will occur. By imposing dietary
restrictions to limit the intake of food containing phenylalanine, however, retardation can be prevented.
Although the child still has the PKU genotype, a modification of the environment (in this case the child’s diet)
produces an outwardly normal phenotype. (pg. 151)
● Prader-Willi Syndrome – disease of imprinting. Inherited from the father. Associated with the deletion of about 4
million base pairs (Mb) of the long arm of chromosome 15. (pg. 187)
● Angelman Syndrome – Same 4-Mb deletion but inherited from the mother. (pg. 187)
● Down Syndrome
● Wilms tumor (pg. 444)
3) What gene abnormality causes cystic fibrosis? (Ch. 36, pg. 1311)
The cystic fibrosis transmembrane conductance regulator (CFTCR) gene mutation results in the abnormal expression
of cystic fibrosis transmembrane conductance regulator (CFTCR) protein, which is a cyclic adenosine mono-
phosphate (cAMP)–activated chloride channel present on the surface of many types of epithelial cells, including
those lining airways, bile ducts, the pancreas, sweat ducts, and the vas deferens.
4) How is a recessive disease inherited? Explanation in long drawn-out detail from pages
151-162 in chapter 4.
This summary I located on www.knowyourgenes.org
Genes 101
How are genetic diseases inherited?
● Most genetic diseases affecting children are recessive, meaning the normally functioning gene in a pair will
override the abnormal one, if a normal gene is present.
What does it mean to be a carrier?
● A carrier is a healthy person who has one altered copy of a gene and one normally functioning copy. Because
carriers do not become ill, many families pass recessive gene mutations down from generation to generation
without ever knowing it.
*Recessive gene mutations are known as "autosomal recessive" if they occur on one of the 22 pairs of non-sex
chromosomes and "X-linked" if they occur on an X chromosome.
Autosomal recessive inheritance
, ● Autosomal recessive diseases occur when both parents are carriers of the same disease and their child inherits
an altered gene from each of them. Children of carrier parents have:
- A 25% chance of inheriting two altered genes and developing the disease.
- A 25% chance of inheriting two normally functioning genes.
- A 50% chance of inheriting only one altered gene and becoming a carrier.
X-linked recessive inheritance
● X-linked conditions like Fragile X syndrome occur when there is a gene mutation on the X chromosome. An X-
linked condition is usually inherited from a woman who is a carrier of the condition. Carrier females have a
working copy of a gene on one X chromosome and an altered copy on the other.
● Women pass on one of their X chromosomes in each egg. When the X chromosome with the mutation is passed
on in an egg and a Y chromosome is passed on in a sperm, the resulting male fetus will have the X-linked
condition.
● Males with X-linked inheritance are generally affected and females are unaffected carriers. However, X-linked
inheritance is complex. Depending on the specific disease and mutation, an affected boy may be symptom-free
or a carrier girl may have mild symptoms
5) Inheritance of Hemophilia A – Pages 1071 & 157-158
● Hemophilia A (classic hemophilia) is caused by factor VIII deficiency
● occur in 1 in 5000 male births.
● It is the most common of the hemophilia's, 80 to 85%. Hemophilia A is inherited as an X-linked recessive
disorder that affects men and is transmitted by women.
● In X-linked recessive disorders, the recessive gene located on the one X chromosome of the male is not balanced
by the dominant allele on the Y chromosome and is thus expressed.
● Only mating between an affected male and a carrier (affected) female should result in an affected female.
● Males affected with an X-linked recessive disorder cannot transmit the gene to sons, but they transmit it to all
daughters.
● An unaffected female who is heterozygous for the recessive gene transmits it to 50% of her sons and daughters.
● Characteristics of X-linked recessive inheritance are that (1) males are predominantly affected; (2) affected males
cannot transmit the genes to sons, but they can transmit the gene to all daughters; (3) sons of female carriers
have a 50% risk of being affected; and (4) daughters of female carriers have a 50% risk of being carriers.
6) Risk factors for DM II; why is obesity an important risk factor in DM II? – Pages 174-178
● Incidence of type 2 diabetes is rising dramatically among adolescents and young adults in developed countries,
however, is strongly associated with an increased incidence of obesity.
● The empirical recurrence risks for first degree relatives of type 2 diabetes ceases are higher than type1, ranging
from 15-40%.
● The two most important risk factors for type 2 diabetes are positive family history and obesity; the latter
increases insulin resistance.
● The disease tends to rise in prevalence when populations adopt a diet and exercise pattern typical of U.S. and
European populations. Ex. Japanese immigrants to the US, South Pacific natives to the US, Australia and the
Americas.
● Studies have shown that regular exercise can substantially lower one’s risk of developing type 2 diabetes, even
among individuals with a family history of the disease. This is partly because exercise reduces obesity. However,
even in the absence of weight loss, exercise increases insulin sensitivity and improves glucose tolerance.
● Prevalence of type 2 is rising rapidly and the average age of onset is decreasing. A small portion of type 2
diabetes cases occurs early in life, typically before 25 years of age, and typically exhibits autosomal dominant
inheritance (unlike most types of diabetes).
- This subset is termed maturity-onset diabetes of the young (MODY)
- Half of MODY cases are caused by mutations in the glucokinase gene.
- Glucokinase converts glucose to glucose-6-phosphate in the pancreas.
, - A sedentary lifestyle and over consumption of calories often leads to overweight and obesity, and since
exercise increases insulin sensitivity; lack of physical activity will result in the opposite effects; thus
increase the individual’s risk to diabetes type 2.
7) Definition of carcinoma – Page 364
● Cancers are named according to the cell type from which they originate.
● Cancers arising in the epithelial tissues of the skin or lining of internal organs are called carcinomas, and they
arise from or form ductal or glandular structures are named adenocarcinomas.
8) How do cancer cells gain access to the circulation? – Pages 389-390
● In order for cells to move away from their normal niche, they must be able to detach from the stroma and
migrate.
● Cells are normally attached to extracellular matrix (ECM).
● To facilitate cancer spread, many tumors and their associated inflammatory cells secrete proteases and protease
activators, such as the matrix metalloproteinases (MMPs) and plasminogen activators.
- Active proteases digest the extracellular matrix and basement membranes, creating pathways through
which cells can move, while releasing bioactive peptides as digestion products that further stimulate
tumor growth and mobility.
● After release from the extracellular matrix (ECM) and digestion from basement membranes, cancer cells gain
access to the circulation through new tumor-associated blood vessel growth and angiogenesis
(neovascularization).
● Mobile tumor cells are able to enter the circulation, likely facilitated by the leaky newly made vessels and
attraction of the cells because of chemo attractants coming from these new vessels.
● Once in circulation, metastatic cells must be able to withstand the physiologic stresses of travel in the blood and
lymphatic circulation, including high shear rates and exposure to immune cells.
● One mechanism is for tumor cells to bind to blood platelets, giving them a protective coat of nonmalignant blood
cells that both shields the tumor cells and creates a small tumor embolus, or cancer clot, that can promote
cancer cell survival in distant locations.
● Two distinct mechanisms give rise to patterns of distant spread.
- (1) cancer cells spread through vascular and lymphatic pathways, as well as natural tissue planes.
- The neovascularization of cancer offers malignant cells direct access into the venous blood, and draining
lymphatics can carry malignant cells to regional lymph nodes.
- Single cells, clumps, and even tumor fragments can disseminate by these routes.
- (2) There is also a major yet poorly understood selectivity of different cancers for different sites.
9) What is adjuvant chemotherapy? (P.397-8)
● Adjuvant chemotherapy is given after surgical excision of cancer with the goal of eliminating micrometastases
● Considered for use in advanced stages of squamous cell carcinoma (P. 1643)
10) Most common time childhood cancers are diagnosed (P.443)
● Childhood cancers are most often diagnosed during peak times of physical growth
● In general, they are extremely fast growing, with 80% having metastasis at diagnosis
● More common in white children & boys
11) DES exposure prenatally (P.410, 445)
Unit 7 Study Guide
Key Concepts & Exam Review
University of South Alabama.
This Exam Features:
It summarizes key concepts, lecture highlights, and
exam-relevant material to support efficient last-
minute review. The guide is structured to help
students reinforce understanding, identify weak areas, and
prepare confidently for the assessment.
, Unit 7 Study Guide
1) Specific chromosomal abnormality responsible for Down Syndrome (Ch. 4, Pg. 146)
● Aneuploid cells are defined as those that do not contain a multiple of 23 chromosomes.
● An aneuploid cell containing three copies of one chromosome is said to be trisomic (termed trisomy).
● Trisomy of the twenty-first chromosome is the autosome aneuploidy which causes Down Syndrome
2) Causes of mental retardation (page numbers below)
Chromosome abnormalities are the leading know cause of mental retardation. (pg. 143)
● About 75% of individuals with spina bifida have secondary hydrocephalus, which sometimes in turn produces
mental retardation. (pg. 168)
● Cri du chat Syndrome – disease caused by chromosomal deletion. (pg. 148)
● Fragile X Syndrome – A fragile site (a number of areas on chromosomes develop microscopically observable
breaks and gaps when the cells are cultured in a folate-deficient medium) located on the long arm of the X
chromosome. Fragile X syndrome is the second most common genetic cause of mental retardation (after Down
Syndrome) effecting 1 in 4,000 males and 1 in 8,000 females. (pg. 151)
● Phenylketonuria (PKU) genotype – Affects infants. If left untreated, abnormal metabolites of phenylalanine will
begin to accumulate in the infant’s brain and irreversible mental retardation will occur. By imposing dietary
restrictions to limit the intake of food containing phenylalanine, however, retardation can be prevented.
Although the child still has the PKU genotype, a modification of the environment (in this case the child’s diet)
produces an outwardly normal phenotype. (pg. 151)
● Prader-Willi Syndrome – disease of imprinting. Inherited from the father. Associated with the deletion of about 4
million base pairs (Mb) of the long arm of chromosome 15. (pg. 187)
● Angelman Syndrome – Same 4-Mb deletion but inherited from the mother. (pg. 187)
● Down Syndrome
● Wilms tumor (pg. 444)
3) What gene abnormality causes cystic fibrosis? (Ch. 36, pg. 1311)
The cystic fibrosis transmembrane conductance regulator (CFTCR) gene mutation results in the abnormal expression
of cystic fibrosis transmembrane conductance regulator (CFTCR) protein, which is a cyclic adenosine mono-
phosphate (cAMP)–activated chloride channel present on the surface of many types of epithelial cells, including
those lining airways, bile ducts, the pancreas, sweat ducts, and the vas deferens.
4) How is a recessive disease inherited? Explanation in long drawn-out detail from pages
151-162 in chapter 4.
This summary I located on www.knowyourgenes.org
Genes 101
How are genetic diseases inherited?
● Most genetic diseases affecting children are recessive, meaning the normally functioning gene in a pair will
override the abnormal one, if a normal gene is present.
What does it mean to be a carrier?
● A carrier is a healthy person who has one altered copy of a gene and one normally functioning copy. Because
carriers do not become ill, many families pass recessive gene mutations down from generation to generation
without ever knowing it.
*Recessive gene mutations are known as "autosomal recessive" if they occur on one of the 22 pairs of non-sex
chromosomes and "X-linked" if they occur on an X chromosome.
Autosomal recessive inheritance
, ● Autosomal recessive diseases occur when both parents are carriers of the same disease and their child inherits
an altered gene from each of them. Children of carrier parents have:
- A 25% chance of inheriting two altered genes and developing the disease.
- A 25% chance of inheriting two normally functioning genes.
- A 50% chance of inheriting only one altered gene and becoming a carrier.
X-linked recessive inheritance
● X-linked conditions like Fragile X syndrome occur when there is a gene mutation on the X chromosome. An X-
linked condition is usually inherited from a woman who is a carrier of the condition. Carrier females have a
working copy of a gene on one X chromosome and an altered copy on the other.
● Women pass on one of their X chromosomes in each egg. When the X chromosome with the mutation is passed
on in an egg and a Y chromosome is passed on in a sperm, the resulting male fetus will have the X-linked
condition.
● Males with X-linked inheritance are generally affected and females are unaffected carriers. However, X-linked
inheritance is complex. Depending on the specific disease and mutation, an affected boy may be symptom-free
or a carrier girl may have mild symptoms
5) Inheritance of Hemophilia A – Pages 1071 & 157-158
● Hemophilia A (classic hemophilia) is caused by factor VIII deficiency
● occur in 1 in 5000 male births.
● It is the most common of the hemophilia's, 80 to 85%. Hemophilia A is inherited as an X-linked recessive
disorder that affects men and is transmitted by women.
● In X-linked recessive disorders, the recessive gene located on the one X chromosome of the male is not balanced
by the dominant allele on the Y chromosome and is thus expressed.
● Only mating between an affected male and a carrier (affected) female should result in an affected female.
● Males affected with an X-linked recessive disorder cannot transmit the gene to sons, but they transmit it to all
daughters.
● An unaffected female who is heterozygous for the recessive gene transmits it to 50% of her sons and daughters.
● Characteristics of X-linked recessive inheritance are that (1) males are predominantly affected; (2) affected males
cannot transmit the genes to sons, but they can transmit the gene to all daughters; (3) sons of female carriers
have a 50% risk of being affected; and (4) daughters of female carriers have a 50% risk of being carriers.
6) Risk factors for DM II; why is obesity an important risk factor in DM II? – Pages 174-178
● Incidence of type 2 diabetes is rising dramatically among adolescents and young adults in developed countries,
however, is strongly associated with an increased incidence of obesity.
● The empirical recurrence risks for first degree relatives of type 2 diabetes ceases are higher than type1, ranging
from 15-40%.
● The two most important risk factors for type 2 diabetes are positive family history and obesity; the latter
increases insulin resistance.
● The disease tends to rise in prevalence when populations adopt a diet and exercise pattern typical of U.S. and
European populations. Ex. Japanese immigrants to the US, South Pacific natives to the US, Australia and the
Americas.
● Studies have shown that regular exercise can substantially lower one’s risk of developing type 2 diabetes, even
among individuals with a family history of the disease. This is partly because exercise reduces obesity. However,
even in the absence of weight loss, exercise increases insulin sensitivity and improves glucose tolerance.
● Prevalence of type 2 is rising rapidly and the average age of onset is decreasing. A small portion of type 2
diabetes cases occurs early in life, typically before 25 years of age, and typically exhibits autosomal dominant
inheritance (unlike most types of diabetes).
- This subset is termed maturity-onset diabetes of the young (MODY)
- Half of MODY cases are caused by mutations in the glucokinase gene.
- Glucokinase converts glucose to glucose-6-phosphate in the pancreas.
, - A sedentary lifestyle and over consumption of calories often leads to overweight and obesity, and since
exercise increases insulin sensitivity; lack of physical activity will result in the opposite effects; thus
increase the individual’s risk to diabetes type 2.
7) Definition of carcinoma – Page 364
● Cancers are named according to the cell type from which they originate.
● Cancers arising in the epithelial tissues of the skin or lining of internal organs are called carcinomas, and they
arise from or form ductal or glandular structures are named adenocarcinomas.
8) How do cancer cells gain access to the circulation? – Pages 389-390
● In order for cells to move away from their normal niche, they must be able to detach from the stroma and
migrate.
● Cells are normally attached to extracellular matrix (ECM).
● To facilitate cancer spread, many tumors and their associated inflammatory cells secrete proteases and protease
activators, such as the matrix metalloproteinases (MMPs) and plasminogen activators.
- Active proteases digest the extracellular matrix and basement membranes, creating pathways through
which cells can move, while releasing bioactive peptides as digestion products that further stimulate
tumor growth and mobility.
● After release from the extracellular matrix (ECM) and digestion from basement membranes, cancer cells gain
access to the circulation through new tumor-associated blood vessel growth and angiogenesis
(neovascularization).
● Mobile tumor cells are able to enter the circulation, likely facilitated by the leaky newly made vessels and
attraction of the cells because of chemo attractants coming from these new vessels.
● Once in circulation, metastatic cells must be able to withstand the physiologic stresses of travel in the blood and
lymphatic circulation, including high shear rates and exposure to immune cells.
● One mechanism is for tumor cells to bind to blood platelets, giving them a protective coat of nonmalignant blood
cells that both shields the tumor cells and creates a small tumor embolus, or cancer clot, that can promote
cancer cell survival in distant locations.
● Two distinct mechanisms give rise to patterns of distant spread.
- (1) cancer cells spread through vascular and lymphatic pathways, as well as natural tissue planes.
- The neovascularization of cancer offers malignant cells direct access into the venous blood, and draining
lymphatics can carry malignant cells to regional lymph nodes.
- Single cells, clumps, and even tumor fragments can disseminate by these routes.
- (2) There is also a major yet poorly understood selectivity of different cancers for different sites.
9) What is adjuvant chemotherapy? (P.397-8)
● Adjuvant chemotherapy is given after surgical excision of cancer with the goal of eliminating micrometastases
● Considered for use in advanced stages of squamous cell carcinoma (P. 1643)
10) Most common time childhood cancers are diagnosed (P.443)
● Childhood cancers are most often diagnosed during peak times of physical growth
● In general, they are extremely fast growing, with 80% having metastasis at diagnosis
● More common in white children & boys
11) DES exposure prenatally (P.410, 445)
