Chapter 1_2 flashcards
(22 cards)
Sodium-Potassium Pump (Na+/K+ Pump): Role in Electrochemical Gradient
Maintains an electrochemical gradient across the plasma membrane by actively pumping Na+ ions out of the cell and K+ ions into the cell[cite: 1, 3]. This creates a higher concentration of K+ inside and Na+ outside[cite: 1].
Na+/K+ Pump: Ions Pumped and Exchange Ratio
Pumps three sodium (Na+) ions out of the cell for every two potassium (K+) ions pumped into the cell[cite: 1, 2].
Na+/K+ Pump: Role in Resting Membrane Potential
Helps maintain resting membrane potential by keeping an unequal distribution of positive charges across the membrane (more positive outside due to 3 Na+ out vs 2 K+ in, and K+ leakiness)[cite: 1, 3]. This is crucial for excitable cells like neurons and muscle cells[cite: 1, 3].
Pharmacological Alteration of Na+/K+ Pump (Example)
Cardiac glycosides (drugs) can slow the Na+/K+ pump in heart muscle cells[cite: 1]. This keeps more calcium inside the heart muscle cell, strengthening its force of contraction[cite: 1].
Lysosomes: Link to Tay-Sachs Disease
Tay-Sachs disease is a lipid storage disease resulting from a deficiency in a specific lysosomal enzyme[cite: 1, 9]. This deficiency causes harmful accumulation of ganglioside (a lipid) in cells[cite: 1, 9].
Tay-Sachs Disease: Effect of Lipid Accumulation on Nervous System
The accumulation of ganglioside (a lipid) due to lysosomal enzyme deficiency primarily affects the central nervous system[cite: 1, 9]. This leads to organ dysfunction and widespread systemic illness, including deterioration of the nervous system[cite: 1].
Differentiate: Lysosomes, Proteasomes, and Peroxisomes
Lysosomes: Contain digestive enzymes (lysozyme, proteases, lipases) to degrade ingested foreign substances, cellular debris, and perform autolysis/heterolysis[cite: 1, 10].
Proteasomes: Enzymatically degrade polypeptide chains and proteins[cite: 1, 10].
Peroxisomes: Break down long-chain fatty acids and free radicals[cite: 1, 10].
Adrenoleukodystrophy: Cause
A disorder of dysfunctional peroxisomes in which long-chain fatty acids accumulate in the nervous system, leading to its deterioration[cite: 1].
Mitochondria: Response to Energy Demands
Mitochondria can reproduce within the cell whenever there is an increased need for ATP formation[cite: 1, 11]. For example, exercise stimulates increased numbers of mitochondria in muscle cells[cite: 1].
Mitochondria: Inheritance of Mitochondrial DNA (mtDNA)
Mitochondrial DNA is derived almost exclusively maternally, as sperm provide minimal mitochondria during fertilization[cite: 1, 11].
Mitochondria: Vulnerability to Free Radicals & Role in Aging/Disease
Mitochondrial DNA is subject to mutation by oxygen-derived free radicals (reactive oxygen species)[cite: 1, 12]. Mitochondrial damage from these mutations is theorized to contribute to cellular impairment in aging and disorders like diabetes, cancer, and heart failure[cite: 1, 12].
Mitochondrial DNA vs. Nuclear DNA: Key Differences
Mitochondrial DNA (mtDNA) is distinct from nuclear DNA: it is located within mitochondria, inherited maternally, and is particularly susceptible to mutations by free radicals[cite: 1, 12]. Nuclear DNA is in the nucleus and inherited from both parents[cite: 1].
DNA Components: Purines
Larger, double-ring nitrogenous bases[cite: 13]. In DNA, these are Adenine (A) and Guanine (G)[cite: 1].
DNA Components: Pyrimidines
Smaller, single-ring nitrogenous bases[cite: 13]. In DNA, these are Thymine (T) and Cytosine (C)[cite: 1].
Base Pairing in DNA
Adenine (A) always pairs with Thymine (T)[cite: 1, 15]. Guanine (G) always pairs with Cytosine (C)[cite: 1, 15].
Bases Unique to RNA (vs. DNA)
In RNA, Uracil (U) replaces Thymine (T)[cite: 1, 14, 15]. Uracil pairs with Adenine (A) in RNA processes[cite: 1].
Protein Synthesis: Role of mRNA (Messenger RNA)
Acts as a blueprint, carrying genetic information copied from DNA in the nucleus to the ribosomes for protein construction[cite: 1].
Protein Synthesis: Role of tRNA (Transfer RNA)
Gathers and joins the specific amino acids that will form the protein, as designated by the mRNA sequence at the ribosome[cite: 1].
Protein Synthesis: Role of rRNA (Ribosomal RNA)
Mainly involved in the formation and structure of the ribosome itself[cite: 1].
Codon: Definition in Protein Synthesis
A sequence of three nitrogenous bases on an mRNA molecule that is interpreted by the ribosome[cite: 1]. Each codon has a specific link to an exact amino acid or signals start/stop of protein synthesis[cite: 1].
ER Stress: Definition & Implication
Occurs when proteins cannot travel to their proper intracellular locations and are rapidly degraded[cite: 1]. Implicated in pathogenesis of neurodegenerative diseases, cancer, obesity, diabetes, and atherosclerosis[cite: 1].
Effect of Severe Hypoxia on Ribosomal Protein Synthesis
Ribosomal protein synthesis ceases during severe hypoxic states[cite: 1].
