Exam Study Guide for Advanced Patho NRSG 605: Genetics, Immune and Allergic Diseases, Cancer, and Nutrition

Lesson 4:

1. Define the phrase "the dogma of DNA replication"
 In order to maintain accurate DNA, its replication must occur in the proper order
o DNA is replicated by RNA, then proteins made from RNA
 Why?
o DNA can stay pristine
o Information can be coded quickly
o Translation can be controlled and checked

2. Review the role of DNA replication, focusing on how the accuracy of the DNA is
maintained
 DNA unwinds using DNA helicase
 DNA polymerase is responsible for creating the new strand and checking for
errors.
 There are 250-300 million base pairs
o Yet, only one error in every 10-100 billion bases
 Process of replication takes hours

3. Review the role of RNA in the synthesis of proteins in the endoplasmic reticulum.
 DNA is replicated by messenger RNA in the nucleus
 mRNA leaves the nucleus and the message is translated into proteins
o On the ribosome or rough endoplasmic reticulum

4. Define the common mechanisms of mutation of the DNA sequence: base pair
substitution, duplication, translocation.
 Gene Deletion
o Missing portions of genes
o Velocardiofacial syndrome due to a deletion in chromosome 22
 Cleft palate
 Craniofacial anomalies
 Ventricular septal defect
 Retardation
o Cystic fibrosis
 Deletion of a gene that makes a protein that transports chloride
across the cell membrane
 Gene Duplication
o The production of one or more copies of a gene or region of a
chromosome.
o Chromosome 21 codes for beta amyloid protein
o Alzheimer’s and Down’s syndrome both show duplication of a small
region of gene 21

 Gene Insertion
o Addition of one or more genes into a DNA sequence
o Huntington’s and Fragile X syndrome
 Gene Translocation
o The process of exchange of genetic material between chromosomes

, Deletion Duplication Insertion Translocation




5. Explain common genetic diseases due to abnormal numbers of chromosomes.
 Chromosomal Number Changes
o Change in the number, size or arrangement of genes
o Inherited from parents
o Occur during meiosis
o At conception
 Types of disorders
o Diseases of failure of chromosomes to separate into 23
o Some problems lead to disease, others do not
o Down’s Syndrome
 Extra copy of chromosome 21 (therefore 47 total) and located on
21
 Mosaic
 Chromosome 21 can also be placed on Chromosome 14
 Translocation
 Overexpression of genes for
 Premature aging
 Mental retardation
 Heart defects
 Skeletal abnormalities
 DNA synthesis
 Cataracts
 Immune function
 Expression varies

o Klinefelter Syndrome in Males
 47 chromosomes in each cell
 X-X-Y
 Presentation at puberty
 Failure to develop secondary sexual characteristics
 Tall stature
 Learning disabilities
 Personality impairments
 Single palm crease

, o Turner Syndrome
 Females only have 1 X chromosome
 Presentation
 Short stature
 Lack of ovarian development
 Webbed neck, arms that turn out slightly at the elbow
 Low hairline in the back of the head
 Prone to
o Cardiovascular problems, kidney and thyroid
problems, skeletal disorders such as scoliosis or
dislocated hips hearing and ear disturbances

6. Use the Punnett square to determine the risk of transmission of dominant and recessive
traits from parents to children

 Autosomal dominant disease
o A person need have only one abnormal gene to have the disease
o Each generation is affected
o Disease occurs in both genders




 Autosomal recessive disease
o A person must have two copies of the abnormal gene to express the
disease
o Persons with one abnormal gene are called “carriers”