Cells, Genetics Flashcards
Metaplasia, Dysplasia, Neoplasia?
Metaplasia: change from one cell type to another, ex. Barrett’s esophagus (grow stomach cells in the esophagus bc heartburn)
Dysplasia: abnormal cell, can be cancerous
Neoplasia: disorganized growth, can be cancerous, ex: warts
Hypertrophy vs. hyperplasia?
Hypertrophy: increase size of cells, ex: skeletal, kidney, and cardiac cells
Hyperplasia: increase number of cells, ex: BPH
What commonly occurs in reversible vs. irreversible cell injury?
Ex: glycolysis, ATP, acidosis/alkalosis, electrolytes
Reversible: decreased oxygen, decreased ATP, increased glycolysis (ADP’s convert to ATP’s), decreased glycogen, cell swelling, increased lactate (to buffer the H+), decreased pH (H+ wins, no more lactate) causes DNA chromatin clumping (still intact) and swelling of lysosomes, increased intracellular Na and Ca, increased extracellular K, ROS (reactive oxygen species)/ free radicals
Irreversible: increased free radicals release enzymes (CPK, LDH), increased Ca causing cellular death, pyknosis/karyolysis/karyorrhexis (chopped up DNA), defects in cell membrane, lysosomal enzymes released and autodigestion
Hypoxia vs. hypoxemia?
Hypoxia: low TISSUE oxygen level
Hypoxemia: low BLOOD oxygen tension/pressure (decreased O2 sats)
What is a free radical?
An uncharged atom with an unpaired electron. This electron wants to leave which is what makes it such a strong reactor/oxidizer. Example: hydrogen peroxide
Free radicals are made by the mitochondria, you make more when you exercise bc you’re making more ATP.
What is reperfusion injury?
After an area has been without oxygen (anoxia), reoxygenation/reperfusion injury is possible because reactive oxygen radicals are formed and calcium leaked in the cell, this can cause cell necrosis
What do these 3 antioxidant mechanisms do? SOD, catalase, and glutathione?
SOD: converts super oxide to hydrogen peroxide
Catalase: converts hydrogen peroxide to water
Glutathione converts the hydrogen peroxide to hydroxide (then it can convert to water)
What is the difference in the way apoptosis occurs vs. necrosis?
In apoptosis, nuclear chromatin condensation and fragmentation, followed by cytoplasmic budding and phagocytosis of apoptotic bodies (fun-size snickers), no leaking, no inflammation
In necrosis, chromatin clump, organelles swell, and membranes are damaged, cytoplasms leaks out signaling inflammatory mediators
Coagulative necrosis
This can happen in the kidney, heart, adrenal glands (most places in the body EXCEPT for the brain) caused by ischemia, the cells DIE IN PLACE and become firm and white
Caseous necrosis
Happens with TB, looks like cottage cheese because dead cells disintegrate but the debris is not digested completely by enzymes
Liquefactive necrosis: What is it and where does it happen?
Happens in the brain, the cells are digested by their own hydrolytic enzymes, the tissue liquifies and causes cysts and abcesses
Fat necrosis
In breast, pancreas, and abdominal structures, lipases break down triglycerides, release free fatty acids which combine with electrolytes creating soaps (saponification). The necrotic tissue appears white
Dry gangrene vs. wet gangrene vs. gas gangrene?
Dry: usually due to coagulative necrosis (diabetes)
Wet: usually liquefactive necrosis occurring in internal organs
Gas: caused by bacterial infections of clostridium
How does length of a telomere relate to cell divisions? What is senescence?
As a telomere gets shorter, it has less cell divisions left until senescence (when the cell can’t divide anymore)
Note: cancer cells can maintain telomere length indefinitely to proliferate with the help of an enzyme called telomerase (normal somatic cells don’t have telomerase but stem cells do)
Review Normal Lab Values!!
Decribe difference among somatic cells, gametes, autosomes, and sex chromosomes
Somatic cells have 46 chromosomes that are diploid (in pairs), so 23 pairs
Gametes are haploid (singles), 23 chromosomes, created by meiosis
We have 22 autosome pairs (homologous in male and females), and 1 pair of sex chromosomes (homologous in female XX, non-homologous in males XY)
What is transcription vs. translation?
Transcription: RNA is synthesized from DNA using mRNA, begins when RNA polymerase binds to a promotor site on the DNA
Translation: RNA synthesizes a polypeptide using tRNA with a specific anticodon to match mRNA’s codon, ribosomes help to process the amino acids
karyotype
ordered display of chromosomes
SNP (single nucleotide polymorphism) vs frameshift mutation?
SNP replaces one nucleotide with something else, most likely won’t cause a huge change, but possible
Frameshift mutation is insertion or deletion of a base pair, this will shift everything by one base pair and is very likely to cause a huge change, (ex: humans have a frameshift mutation from chimps that caused us to have a weak temporalis muscle, making room for our brains)
Euploid vs. Aneuploid
Euploid: cells with the normal number of chromosomes (ex: gametes-haploid and somatic cells-diploid)
Aneuploid: do not contain a multiple of 23 chromosomes (ex: 3 copies of a chromosome is trisomy, 1 copy is monosomy)
*Note: trisomy survives more than monosomy
Nondisjunction
Results in aneuploidy, an error in which homologous chromosomes or sister chromatids fail to separate normally during meiosis or mitosis, resulting in monosomic or trisomic zygote for that chromosome
Occurs more with age in females, doesn’t occur in males
Examples: Turner and Klinefelter syndrome, Down Syndrome
Describe Down Syndrome
Prevalence: 1/800, 97% caused by nondisjunction (trisomy 21)
IQ from 25-70
Facial features: low nasal bridge, epicanthal folds, protruding tongue, flat and low ears
Poor muscle tone, short stature, reduced ability to fight respiratory infection, increased leukemia, Alzheimers by age 40
Turners Syndrome
45,X a sex chromosome is missing (monosomy)
Characteristics: short stature, female genitalia, webbed neck, shield-like chest, underdeveloped breasts, wide nipples, imperfectly developed ovaries, get menopause before menarchy so there’s a problem reproducing
Klinefelter Syndrome
47, XXY presence of two or more X chromosomes with one Y chromosome
Characteristics: male with small testes, some breast development, sparse body hair, long limbs, can’t produce viable sperm so problem reproducing
Chromosomal translocation
Interchanging (cross-over) of genetic material between two non-homologous chromosomes
2 problems: offspring will have issues with deletions/duplication, and the ends of the chromosomes can cause problems with fertility or cancer
Dominant vs. Recessive diseases
What is a carrier?
Dominant: allele whose effects are observable
Recessive: allele whose effects are hidden
Carrier: individual who has a disease-causing allele but is phenotypically (outward appearance) normal
Penetrance vs. Expressivity
Penetrance: the percentage of individuals with a specific genotype who also exhibit the expected phenotype
Expressivity: the extent of variation in phenotype associated with a particular genotype
Autosomal Dominant Inheritance
Occurs in 1/500
Criteria: 2 sexes exhibit the trait equally, there is no skipping of generations, affected heterozygous individuals transmit the trait to half their children
Examples: familial hypercholesterolemia, huntington, achondroplasia, marfan, retinoblastoma, Li-Fraumeni
Autosomal Recessive Inheritance
Occurs 1/2500
Criteria: effects males and females equally, consanguinity (parents are related) can be present, disease is seen in siblings and usually not their parents, 1/4 offspring of carrier parents effected
Examples: sickle cell anemia, cystic fibrosis, lysosomal storage diseases (Tay-Sachs), phenylketouria, glycogen storage diseases
X-linked Inheritance
Criteria: trait seen more often in males (females must inherit 2 recessive alleles to express, males only need to inherit 1 recessive allele), never transmitted from father to son, skips generations because transmitted by carriers
Examples: duchenne muscular dystrophy, hemophilia A&B
Which disease is achondroplasia? How is it characterized?
Autosomal dominant disease, short limbs relative to trunk, prominent forehead, low nasal root, redundant skin folds on arms and legs
With 1 affected parent, 1/2 the kids are affected, normal kids don’t pass it down, but affected kids pass it down to 1/2 their kids
Are these diseases autosomal dominant, autosomal recessive, or X-linked: Familial hypercholesterolemia, phenylkeouria, duchenne muscular dystrophy, cystic fibrosis, huntington disease, lysosomal storage diseases (Tay-Sachs), glycogen storage diseases, marfan, hemophilia A&B, retinoblastoma, Li-Fraumeni, sickle cell anemia, cystic fibrosis, achondroplasia
Dominant: familial hypercholesterolemia, huntington, achondroplasia, marfan, retinoblastoma, Li-Fraumeni
Recessive: sickle cell anemia, cystic fibrosis, lysosomal storage diseases (Tay-Sachs), phenylketouria, glycogen storage diseases
X-linked: duchenne muscular dystrophy, hemophilia A&B
