Cell Membrane Structure and Transport Mechanisms

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Questions and Answers

What is the role of activation energy in a chemical reaction?

It determines the speed of a reaction. (correct)

It produces more products than reactants.

It increases the concentration of reactants.

It decreases the temperature of a reaction.

What characterizes the hydrophilic and hydrophobic regions of phospholipid bilayers?

Both regions freely interact with water.

Both regions are hydrophobic.

The hydrophobic tail attracts water molecules.

The hydrophilic head is attracted to water, while the hydrophobic tail repels it. (correct)

What distinguishes active transport from passive transport?

Passive transport requires energy input.

Active transport does not depend on concentration gradients. (correct)

Passive transport involves energy-driven pump systems.

Active transport occurs only in cellular walls.

Which statement about carriers as transmembrane proteins is true?

They move molecules through conformational changes. Signup and view all the answers

Which type of protein acts as a receptor for hormones or neurotransmitters?

Transmembrane proteins Signup and view all the answers

What happens when sodium ions are attracted into a cell?

There is a net excess of negative charges inside the cell. Signup and view all the answers

Which process describes the movement of oxygen across the cell membrane?

Simple diffusion Signup and view all the answers

What is the definition of homeostasis in biological systems?

The process of maintaining a constant internal environment. Signup and view all the answers

What process does homeostasis refer to in the body?

Maintaining a constant internal environment Signup and view all the answers

What is the primary requirement for active transport compared to passive transport?

The addition of energy Signup and view all the answers

What occurs when a neutral calcium atom forms an ion?

It loses two electrons Signup and view all the answers

What would happen to the membrane potential if the Na+/K+ pump was deactivated?

It would equalize to 0 mV Signup and view all the answers

Which statement is false regarding graded potentials?

They are limited by the refractory period Signup and view all the answers

In the context of the knee-jerk reflex, how is the muscle spindle stretch reflex classified?

Spinal, somatic, innate, monosynaptic Signup and view all the answers

What happens to inhibitory postsynaptic potentials (IPSPs)?

They stabilize the membrane at resting potential Signup and view all the answers

What is required for ions to pass the blood-brain barrier?

Active transport across endothelial cells Signup and view all the answers

Study Notes

Phospholipid Bilayer Structure

Phospholipid bilayers form micelles in aqueous solutions.
They contain a hydrophilic head and a hydrophobic tail.
They form bilayers in cell membranes.

Transmembrane Proteins

Carrier proteins, receptors for hormones or neurotransmitters and channel proteins are types of transmembrane proteins.

Activation Energy

Determines the speed of a reaction.
Acquired from kinetic energy of colliding molecules.

Cellular Ions

If sodium ions are attracted to the inside of a cell, there's a net excess of negative charges inside the cell compared to outside.

Simple Diffusion

Simple diffusion describes the movement of oxygen molecules across cell membranes.

Active Transport vs. Passive Transport

Active transport requires energy; passive transport does not.
Active transport involves adding energy for molecules to move across the membrane.
Passive transport does not use extra-energy to help molecules move across membranes.

Transmembrane Protein Function

A carrier protein is a transmembrane protein that uses conformational changes in its shape to move molecules across the membrane.

Homeostasis

Homeostasis is the body's ability to maintain constant internal environment.
Conformational changes in proteins are critical to this process.

Action Potential

The action potential has phases: rapid depolarization, repolarization, and after-hyperpolarization.
Graded potentials are limited in duration, not by the refractory period.

Postsynaptic Potentials

Inhibitory postsynaptic potentials (IPSPs) move the membrane potential of the postsynaptic neuron away from threshold.

Membrane Potential

If the sodium-potassium pump was turned off, the membrane potential would become zero mV (no difference in charge inside vs. outside the cell).

Electrical Gradients

The electrical gradient for chloride ions (Cl-) moves chloride ions outwards.

Neurotransmitters

Excitatory postsynaptic potential (EPSPs) and inhibitory postsynaptic potentials (IPSPs) can cause membrane potentials to change.

Blood Supply to the Brain

The brain requires a constant supply of blood for energy production.

Blood-Brain Barrier

Ions must be transported through endothelial cells in the blood-brain barrier to enter the brain's tissues.

Reflexes

Muscle spindle stretch reflexes (knee-jerk reflex) are classified as spinal, somatic, innate, and monosynaptic.

Temperature Receptors

Receptors for cold have a temperature range of 20-35°C and above 45°C.

Nervous System

The spinal thalamic tract deals with sensory pathways.
Sodium channels are largely closed during the absolute refractory period in the nervous system's response.

Cardiac Function

Stroke volume is influenced by end-diastolic volume and ventricular contraction force.

Blood Vessel Contraction

Several factors can influence the vasoconstriction or widening of blood vessels.

Blood Clotting

Platelet plugs require von Willebrand factor and thromboxane for formation.

Respiration

External respiration does not include the use of oxygen nor the generation of carbon dioxide.

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Description

This quiz covers essential concepts related to cell membrane structure and transport processes. Topics include the phospholipid bilayer, transmembrane proteins, activation energy, and the differences between active and passive transport. Test your knowledge on how substances move across cell membranes in biological systems.