Untitled Quiz

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Questions and Answers

What is the role of membrane proteins in providing structural support?

They are embedded in the phospholipid bilayer.

They interact with the cytoskeleton. (correct)

They can bind to lipids only.

They act solely as receptors.

Which statement about protein receptors is accurate?

They can bind only to a single type of molecule.

They bind to a variety of molecules due to having low specificity. (correct)

They have high specificity for particular molecules.

They are always found within the nucleus.

What is true about the interior portion of the plasma membrane?

It is hydrophobic.

It is hydrophilic. (correct)

It is a solid structure.

It is composed of carbohydrates.

How do proteins behave once embedded in the plasma membrane?

They cannot change shape. Signup and view all the answers

What effect do acids or bases have on enzyme activity?

They can change enzyme activity. Signup and view all the answers

What can be inferred if a potato placed in distilled water grows in size?

The solution is hypotonic. Signup and view all the answers

Where would hydrolytic enzymes be found in a cell?

In the lysosomes. Signup and view all the answers

How many sodium ions are pumped out of the cell for every potassium ion that is pumped in?

3 sodium ions Signup and view all the answers

What energy molecule is required for the sodium/potassium pump to function?

ATP Signup and view all the answers

In terms of cell structures, what is the function of cholesterol in the cell membrane?

To provide rigidity. Signup and view all the answers

What does 'no net movement' indicate in terms of molecular behavior?

There is constant movement in both directions. Signup and view all the answers

What is the main function of dehydrogenase enzymes based on their nomenclature?

To promote oxidation-reduction reactions Signup and view all the answers

Which of the following statements best describes the test result from dipping a sucrose strip into a glucose solution?

It would yield a negative result. Signup and view all the answers

What is the primary role of a semi-permeable membrane?

To selectively control the passage of certain molecules Signup and view all the answers

Which statement about glycocalyx is true?

It is composed of carbohydrate chains linked to proteins. Signup and view all the answers

What is the main purpose of active transport in cells?

To require energy input for molecule movement Signup and view all the answers

Which process involves the movement of water molecules?

Osmosis Signup and view all the answers

What is RME primarily associated with?

Oxygen transport from the lungs to the blood Signup and view all the answers

What is the function of the Na+/K+ pump?

To create an electrochemical gradient across membranes Signup and view all the answers

Which statement accurately describes endocytosis?

It encompasses various mechanisms including the removal of toxins. Signup and view all the answers

What effect does an extremely hypertonic solution have on a cell?

It results in dehydration and possible plasmolysis. Signup and view all the answers

Which statement best describes facilitated diffusion?

It utilizes carrier proteins to assist in molecule transport. Signup and view all the answers

What is the characteristic of a hypotonic solution?

It causes cells to gain water and possibly swell. Signup and view all the answers

Study Notes

Cell Membrane Components

Cell membrane is made up of a phospholipid bilayer, with the hydrophilic heads facing outwards and hydrophobic tails facing inwards.
Cholesterol is a component of the cell membrane, providing structural support and fluidity.
Membrane proteins are embedded within the phospholipid bilayer, providing structural support, acting as receptors, and facilitating transport.
Glycocalyx is a layer of carbohydrates attached to membrane proteins – this layer helps with cell recognition and signaling.

Cell Structures

The nucleus houses the cell's genetic material (DNA) in the form of chromatin.
Lysosomes are organelles containing hydrolytic enzymes responsible for breaking down cellular waste and debris.
Microfilaments are part of the cytoskeleton, providing structural support and enabling cell movement.
Cellulose, a structural polysaccharide, is found in the cell wall of plant cells, providing rigidity and support.

Transport Across the Cell Membrane

Passive transport does not require cellular energy.
- Diffusion: movement of molecules from an area of high concentration to an area of low concentration.
- Facilitated diffusion: requires the help of membrane proteins but still relies on a concentration gradient.
Active transport requires the cell to expend energy (ATP) to move molecules against their concentration gradient.
Sodium-Potassium pump is an example of active transport—it pumps 3 sodium ions out of the cell for every 2 potassium ions pumped in.
Endocytosis is the process of taking in large molecules by engulfing them in a vesicle.
Exocytosis is the process of releasing large molecules from the cell by fusing vesicles with the cell membrane.

Osmosis

Water travels from areas of high water concentration to areas of low water concentration.
Hypertonic solution: high solute concentration, causing water to move out of the cell and shrink.
Hypotonic solution: low solute concentration, causing water to move into the cell and swell.
Isotonic solution: equal solute concentration, meaning no net movement of water across the membrane.
No net movement refers to a state where there is an equal balance of movement of molecules in and out of a system.

Enzymes

Enzymes are catalysts that accelerate biochemical reactions by lowering activation energy.
Dehydrogenase enzymes are involved in redox reactions, often using coenzymes to facilitate electron transfer.
Sucrase enzymes break down sucrose into glucose and fructose.
Endergonic reaction: energy is absorbed, so the change in free energy is positive.
Exothermic reaction: energy is given off, so the change in free energy is negative.
Enzymes can lower the activation energy required for both endergonic and exothermic reactions.

Cell Functions

The cell membrane is considered semi-permeable: it controls the movement of substances in and out of the cell.
RME: Receptor-mediated endocytosis - a form of endocytosis that uses receptors on the cell membrane to specifically bind and internalize particular molecules.
The sodium-potassium pump is crucial for maintaining the electrochemical gradient across the cell membrane, which is essential for many cell functions, including muscle contraction and nerve impulse transmission.
Endocytosis is used for the removal of cellular toxins.
Lysis is the bursting of a cell, which can be caused by an extremely hypotonic solution.