Flashcards in Cellular and Molecular Biology and Genetics Deck (55)
The sites for cellular protein sythesis in either rough ER or cytoplasm
Activities occurring in cytosol include:
Ribosomal protein synthesis
Why do O2 and CO2 diffuse easily through the cell membrane?
They're small size allows them to move through cell membrane
Why are glucose and H+ unable to diffuse through the cell membrane passively?
Glucose molecules are too large to diffuse through the membrane. H+ cannot moving against an opposing charge. Both need a transporter across the cell membrane.
The plasma membrane is composed primarily of:
Amphipathic molecules hydrophobic (inner, tails) and hydrophillic (outer, heads)
Define passive transport
Movement with a gradient; from high concentration to low concentration. Examples: Diffusion, Filtration, and Osmosis
Define active transport
Transport requiring and energy source, often ATP. Examples: Na-K pump and Ca channel pump
Which mode of cellular transport can move substances against the concentration gradient?
Describe facilitated diffusion
Diffusion that requires carrier proteins which provide a tunnel for hydrophillic molecules to move through. No energy is requires for this mode of transport.
Hypertonic solutions affect the cell how?
Hypertonic describes a situation where there is a high concentration of solute outside of the cell which causes water to move out the cell.
Hypotonic solutions affect the cell how?
Hypotonic describes a situation where this is a low concentration of solute outside of the cell so the water moves into the cell.
For a cell to engage in active transport processes it requires:
An expenditure of energy
Give an example of bulk transport:
Endocytosis and exocytosis
Give three examples of active transport:
Hypercholesterolemia occurs due to defects in which type of cellular transport?
Bulk transport. Problem with endocytosis; the cell is unable to take in the cholesterol from the blood causing high levels of cholesterol in the circulating blood volume.
What does the Nernst Equation calculate?
It quantifies the membrane potential by calculating the equilibrium potential for an ion based on the charge of the ion and its concentration gradient across the membrane.
What happens when a cell reaches it's membrane potential?
Voltage gated channels open and the Na+ ions move into the cell, making it more positive (depolarization)
What happens during repolarization of a cell?
Na+ gates close and K+ voltage gates open causing K+ to move out of the cell making it more negative
What happens during hyperpolarization of a cell?
The cell becomes too negative because the K+ channels releasing positive ions into the extracellular fluid are slow to close. Once K+ channels close the cell settles at its resting membrane potential.
Name the three types of cellular communication.
1. Gap Junction (protein channels)
2. Direct Contact (plasma mem bound molecules)
3. Signaling by secreted molecules (over longer distances)
Give some examples of ligands that bind with membrane receptors:
Name the three major types of cell surface receptor proteins.
1. Ion channel linked receptors (ligand-gated channels.
2. Enzyme linked receptors
3. G-protein linked receptors
What are the 2 major second messenger pathways activated following the binding of a G-protein?
cAMP and Ca
What is normal fluid homeostasis?
Equilibrium between hydrostatic and osmotic pressure (Starling forces)
Name the three main etiologies of edema.
1. Decreased capillary oncotic pressure (caused by decreased production of plasma protiens ie-malnutrition or cirrhosis)
2. Increased tissue oncotic pressure (leading to decreased transport of capillary filter protein causing lymph obstruction and decreased absorption of interstitial fluid)
3. Increased capillary hydrostatic pressure (seen in venous obstruction, Na+ retention, and heart failure)
Define hydrostatic pressure.
Mechanical force of water pushing against the cellular membrane. (**outward push)
Define oncotic pressure.
A form of osmotic pressure exerted by proteins in the blood that pulls water into the circulatory system (**inward pull)
Describe hyponatremia, its etiology, and clinical manifestation.
Too little Na+ in the circulating blood (too much water/dilute). Examples of are SIADH; too much ADH causes the secretion of Na+ and the retention of water. s/s: CNS dysfunction
Describe hypernatremia, its etiology, and clinical manifestations.
Too much Na+ in the blood volume (too little water/concentrated). Occurs with a gain of more salt than water or loss of more water than salt (severe dehydration). s/s: CNS dysfunction.