Pathophysiology Chapter 3

Gene

Gene

Fundamental unit of DNA. Changes in DNA can be linked to diseases

Epigenetic Changes

Alterations in gene expression due to environmental stressors, behaviors, and lifestyle

Pharmacogenomics

Gene function in health, disease, and responses to medications

Genetics

Study of inherited traits

Genomics

Study of interaction of all genetic material

DNA Structure

Double-helical structure of nucleotides

Nucleotides are made up of

pentose sugar, phosphate, and purine or pyrimidine nitrogen base

Nitrogen Bases of DNA

adenine, thymine, guanine, and cytosine. A-T C-G pairings

Nitrogen Bases of RNA

adenine, uracil, guanine, and cytosine. A-U C-G pairings

Exons

portion of genome that encodes proteins

Introns

portion of genome that does NOT encode proteins

Codon

set of three nucleotides that signal a specific amino acid

Genetic Mutations

damage or change to a gene that alters genetic code. may be inherited or occur sporadically

Germ cell mutation

gametes are affected and may be passed onto offspring

Somatic cell mutation

body cells are affected and are not passed onto offspring

How many chromosomes do humans have?

23

Autosomes

1st 22 pairs of chromosomes

Sex

23rd pair of chromosomes. XX = Female XY = Male

Down Syndrome Chromosomal Abnormality

Trisomy 21st pair having 3 copies

Transcription

Turning DNA into mRNA in which RNA polymerase uses DNA as a template to form mRNA strand

Translation

mRNA to protein where ribosomes “read” mRNA transcript and convert it into tRNA to create nucleotide sequence

Regulation of Gene Expression

transcription factor binding sites on DNA affect DNA transcription rates

Allele

gene inherited from one parent

Genotype

genetic code (Ex. PP Pp pp)

Phenotype

physical expression of the genes (Ex. blonde hair, blue eyes)

Heterozygous

Alleles carrying different traits (both dominant and recessive Xx)

Homozygous

Alleles carrying identical traits (both dominant XX or both recessive xx)

Dominant Trait

1 or 2 allele needed for expression

Recessive Trait

2 alleles needed for expression

Carrier

heterozygous for recessive trait

CRISPR

Clustered Regulatory Interspaced Short Palindromic Repeats is gene editing in embryonic development

Pharmacogenomics

Interaction between a person’s genetics and medications (Ex. Slow acetylator phenotype where people lack an enzyme to metabolize certain medications)

Proto-oncogenes

normal genes that control cell proliferation (rapid growth of cells)

Oncogenes

enables uncontrolled cell proliferation (rapid growth of cells)

Oncoproteins

regulate cell cycle, produced from oncogenes

Tumor Suppressor Genes

Inhibits uncontrolled cell proliferation (Ex. stops mitosis of cells)

Knudson’s “Two Hit” Hypothesis

First Hit is the initial hereditary allele mutation. Second Hit is the mutation or damage to another allele

Aneuploidy

different number of chromosomes rather than the normal 46

Translocation

one piece of a chromosome breaking off and joining another

Deletion

piece of chromosome is broken off and lost

Pedigree (Genogram)

multigeneration genetic history

Prenatal Screening

usually done with woman 35 and older to discover abnormal ultrasound findings

Prenatal Diagnosis of Genetic Disorders

can be used to identify defects such as down syndrome and cleft palate

Gene Therapy

use of genes to prevent or treat diseases. normal genes are used to replace abnormal genes

Familial Hypercholesterolemia

lack of LDL receptors which results in elevated levels of LDL in the blood causing cholesterol levels to be very high

Familial Adenomatous Polyposis

early onset of polyps (clusters of cells) that form in the colon leading to increase risk of colon cancer

Marfan’s Syndrome

Connective tissue disorder leading to damage to aorta, heart valves, and lungs

Neurofibromatosis

genetic disorder that causes tumors to grow in the nervous system and skin

Ehlers-Danlos Syndrome

diminished strength and integrity of skin, joints, and connective tissues

Cystic Fibrosis

excess mucus that disrupts lung function and pancreatic secretions leading to malabsorption of nutrients in digestive system

Lysosomal Storage Disease

failure of lysosomes in cells in the body leading to the build up of toxins in cells

Wilson’s Disease

copper excretion is impaired leading to the buildup of copper in organs such as the liver and brain

Klinefelter Syndrome

47 chromosomes XXY karyotype leading to lack of testicles and low testosterone levels

Turner Syndrome

45 chromosomes X0 karyotype leading to infertility, lack of ovaries, and low estrogen levels

Angelman’s Syndrome

delayed development, problems with speech and balance, mental disability, and, sometimes, seizures. Many people with Angelman syndrome smile and laugh often

Huntington’s Disease

causes nerve cells in the brain to decay overtime with no cure and usually occurs in adults between 35 and 44 years old