membrane and respiration Flashcards
(39 cards)
What is the major component of the plasma membrane?
A double layer of phospholipids.
Where are the hydrophilic heads and hydrophobic tails of phospholipids located in the membrane?
Hydrophilic heads face the aqueous environment, and hydrophobic tails face inward.
What contributes to the fluidity of the plasma membrane?
The lateral movement of phospholipids.
How do unsaturated hydrocarbon tails affect membrane fluidity?
They cause kinks that prevent tight packing, making the membrane more fluid.
Which molecules pass through the membrane more easily: hydrophilic or hydrophobic molecules?
Hydrophobic molecules pass through the membrane more easily.
What are the two types of membrane proteins?
Peripheral proteins (bound to the surface) and transmembrane (integral) proteins (span the entire membrane).
How does cholesterol affect membrane fluidity?
It increases fluidity and prevents solidification at cold temperatures.
Name the six major functions of membrane proteins.
Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton and ECM.
how do membrane carbohydrates assist in cell recognition?
They bind to molecules on the extracellular side of the membrane, helping cells identify each other.
What is the difference between channel proteins and carrier proteins?
Channel proteins provide a tunnel for molecules to pass, while carrier proteins bind to molecules and change shape to move them across the membrane.
What is the function of the sodium-potassium pump?
It moves sodium ions (Na+) out of the cell and potassium ions (K+) into the cell, maintaining concentration gradients.
What is the purpose of active transport?
It moves substances against their concentration gradient, requiring energy (ATP).
What is a gated ion channel?
An ion channel that opens or closes in response to a stimulus, regulating ion flow.
What are the steps in active transport for the sodium-potassium pump?
1.Na+ binds to the pump.
2.ATP phosphorylation changes the pump’s shape.
3.Na+ is released outside.
4.K+ binds, and phosphate is released.
5. K+ is released, and the pump returns to its original shape.
What is the difference between symport, antiport, and uniporter?
Uniporter transports one molecule in its concentration gradient.
Symport moves multiple molecules in the same direction.
Antiport moves multiple molecules in opposite directions.
What initiates signal transduction?
Signal transduction begins when a ligand binds to a receptor, triggering a cascade of cellular or systemic responses.
What is the first law of thermodynamics?
Energy cannot be created or destroyed; it can only be transformed from one form to another (e.g., electrical energy from falling water).
What is the difference between exocytosis and endocytosis?
Exocytosis: Vesicles fuse with the membrane to release contents outside the cell.
Endocytosis: The cell engulfs materials by forming vesicles from the membrane.
How does HIV infect cells?
HIV binds to CD4 receptors and CCR5 co-receptors on T-helper cells, allowing infection. Individuals lacking CCR5 are resistant to HIV.
Name the three types of endocytosis.
Phagocytosis (“cellular eating”)
Pinocytosis (“cellular drinking”)
Receptor-mediated endocytosis
What does the second law of thermodynamics state?
In every energy transaction, useful energy decreases, and some energy escapes as heat.
What’s the difference between autotrophs and heterotrophs?
Autotrophs make their own food (e.g., plants via photosynthesis), while heterotrophs consume other organisms for energy (e.g., humans).
What does ATP hydrolysis do?
ATP hydrolysis breaks the phosphoanhydride bond, releasing 7 kcal/mol of energy.
What are redox reactions in cellular respiration?
Oxidation is the loss of electrons (glucose to CO2) and reduction is the acceptance of electrons (O2 to H2O).
