Cells, Genetics

Question 0

Metaplasia, Dysplasia, Neoplasia?

Answer 0

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

Question 1

Hypertrophy vs. hyperplasia?

Answer 1

Hypertrophy: increase size of cells, ex: skeletal, kidney, and cardiac cells
Hyperplasia: increase number of cells, ex: BPH

Question 2

What commonly occurs in reversible vs. irreversible cell injury?
Ex: glycolysis, ATP, acidosis/alkalosis, electrolytes

Answer 2

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

Question 3

Hypoxia vs. hypoxemia?

Answer 3

Hypoxia: low TISSUE oxygen level
Hypoxemia: low BLOOD oxygen tension/pressure (decreased O2 sats)

Question 4

What is a free radical?

Answer 4

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.

Question 5

What is reperfusion injury?

Answer 5

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

Question 6

What do these 3 antioxidant mechanisms do? SOD, catalase, and glutathione?

Answer 6

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)

Question 7

What is the difference in the way apoptosis occurs vs. necrosis?

Answer 7

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

Question 8

Coagulative necrosis

Answer 8

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

Question 9

Caseous necrosis

Answer 9

Happens with TB, looks like cottage cheese because dead cells disintegrate but the debris is not digested completely by enzymes

Question 10

Liquefactive necrosis: What is it and where does it happen?

Answer 10

Happens in the brain, the cells are digested by their own hydrolytic enzymes, the tissue liquifies and causes cysts and abcesses

Question 11

Fat necrosis

Answer 11

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

Question 12

Dry gangrene vs. wet gangrene vs. gas gangrene?

Answer 12

Dry: usually due to coagulative necrosis (diabetes)
Wet: usually liquefactive necrosis occurring in internal organs
Gas: caused by bacterial infections of clostridium

Question 13

How does length of a telomere relate to cell divisions? What is senescence?

Answer 13

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)

Question 14

Review Normal Lab Values!!

Question 15

Decribe difference among somatic cells, gametes, autosomes, and sex chromosomes

Answer 15

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)

Question 16

What is transcription vs. translation?

Answer 16

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

Question 17

karyotype

Answer 17

ordered display of chromosomes

Question 18

SNP (single nucleotide polymorphism) vs frameshift mutation?

Answer 18

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)

Question 19

Euploid vs. Aneuploid

Answer 19

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

Question 20

Nondisjunction

Answer 20

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

Question 21

Describe Down Syndrome

Answer 21

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

Question 22

Turners Syndrome

Answer 22

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

Question 23

Klinefelter Syndrome

Answer 23

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

Question 24

Chromosomal translocation

Answer 24

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

Question 25

Dominant vs. Recessive diseases

What is a carrier?

Answer 25

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

Question 26

Penetrance vs. Expressivity

Answer 26

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

Question 27

Autosomal Dominant Inheritance

Answer 27

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

Question 28

Autosomal Recessive Inheritance

Answer 28

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

Question 29

X-linked Inheritance

Answer 29

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

Question 29

Which disease is achondroplasia? How is it characterized?

Answer 29

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

Question 31

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

Answer 31

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