Cell biology I Flashcards
What are the three constituents of the cell?
1) Organelles2) Inclusions3) Cytoplasmic matrix (cytosol)
What is the definition of cytoplasm?
The part of the cell external to the nucleus. It suspends organelles and inclusions
What is the region of the cell external to the nucleus, which suspends organelles and inclusions?
Cytoplasm
What is the definition of cytoplasmic matrix (cytosol)?
Portion of cytoplasm devoid of organelles and inclusions
What is the region of the cell that is devoid or organelles and inclusions?
Cytoplasmic matrix (cytosol)
What are inclusions?
Nonliving entities found in the cytoplasm and nucleus (e.g. food, pigments, crystalline)
Are inclusions membrane-bound?
No
Are proteins stored in the cytoplasm as inclusions?
No
Is glycogen an inclusion?
Yes
What stain would you use to detect glycogen?
PAS Reaction
What is McArdle Disease?
A disorder of glycogen storage caused by a genetic defect in muscle phosphorylase. It is specific to skeletal muscle.
McArdle Disease is specific to what type of muscle?
Skeletal muscle
Is fat an inclusion?
Yes
Is carotene an inclusion?
Yes
Is carotene fat soluble or water soluble?
Fat soluble
What is anthracosis?
Accumulation of carbon particles in lungs and regional lymph nodes. Harmless condition
Is hemoglobin an endogenous or exogenous pigment?
Endogenous
Where is hemosiderin usually found?
Macrophages of spleen and liver
What is hemosiderosis?
Increased deposition of hemosiderin in tissues
When is hemosiderosis usually observed?
1) Increased absorption of iron in diet2) Impaired use of iron by the body3) Hemolytic anemias4) Transfusions
What condition could be caused by increased absorption of iron in the diet?
Hemosiderosis
What condition could be caused by impaired use of iron by the body?
Hemosiderosis
What condition could be caused by hemolytic anemias?
Hemosiderosis
What condition could be caused by transfusions?
Hemosiderosis
What is hemochromatosis?
A more severe accumulation of iron due to a genetic defect, resulting in excessive iron absorption or transfusion
If hemosiderin is found in macrophages, what condition could be considered?
Congestive heart failure
What are ‘heart failure cells’?
Macrophages filled with hemosiderin
Macrophages filled with hemosiderin are referred to as ___________.
Heart failure cells
Where is melanin found?
Membrane-limited granules in the epidermis and pigment layer of retina
What pigment is found in membrane-limited granules in the epidermis and pigment layer of the retina?
Melanin
What are two endogenous forms of melanin?
1) Eumelanin2) Neuromelanin
Where is neuromelanin normally found?
Substantia nigra of brainstem (also locus coeruleus)
What is phaeomelanin?
Red pigment responsible for red hair color
Does melanin increase or decrease in Addison’s disease?
Increase
Why does melanin increase in Addison’s disease?
Melanin stimulating hormone (MSH) and adrenocorticotropic hormone (ACTH) share the same precursor molecule. Increased ACTH from adrenal insuffiency causes increased MSH levels as well (hyperpigmentation of areas exposed to UV light
A lack of tyrosinase in albinos leads to a lack of what pigment?
Melanin
Is neuromelanin membrane-limited?
Yes
What is lipofuscin (lipochrome pigment)?
Brownish-yellow pigment that is an amalgam of lipids, metals, and organic molecules (the wear-and-tear pigment)
What is the “wear-and-tear” pigment?
Lipofuscin
What pigment accumulates in long-lived cells?
Lipofuscin
Accumulation of lipofuscin is indicative of what cellular conditions?
Cellular stress - malnutrition, cachexia (wasting syndrome)
Where are crystalline inclusions usually found?
1) Cells of Leydig (crystal of Reinke)2) Sertoli cells (inclusion of Charcot-Bottcher)
What is the plasmalemma?
The dynamic organelle that separates the cell’s internal environment from its external environment
How much of the cell is made up of the plasmalemma?
2-5%
How thick is the plasmalemma?
7.5-10 nm
What three types of lipids make up the plasmalemma?
1) Phospholipids2) Glycolipids3) Cholesterol
What is the most abundant lipid in the plasmalemma?
Phospholipids
What does cholesterol do to the plasmalemma?
Strengthens / makes it less deformable (but makes it less permeable to small, water soluble molecules)
What are lipid rafts?
Areas in the plasma membrane where sphingolipids and cholesterol are concentrated
What is the primary function of lipid rafts?
Cell signaling
What is the function of simvastatin?
Decreases the amount of cholesterol and thus raft formation, leading to apoptosis (reduced rafts decreases Akt, which is a cell survival protein kinase molecule)
What is Akt?
A cell survival protein kinase molecule
What does a reduction in cholesterol do to lipid raft formation?
Decreases
What does a decrease in lipid raft formation do to Akt?
Decreases
