Cell Physiology Quiz

Cell Functions

• Cells provide structure for the body's tissues and organs, ingest nutrients and convert them to energy, perform specialized functions, and contain the body's hereditary code.

Cell Components

• The two main parts of a typical cell are the nucleus and the cytoplasm.
• The nuclear membrane separates the nucleus from the cytoplasm, and the cell membrane (or plasma membrane) separates the cytoplasm from the surrounding fluids.

Protoplasm Composition

• Protoplasm is composed of water, electrolytes, proteins, lipids, and carbohydrates.
• Water makes up 70-85% of most cells.

Proteins

• There are two types of proteins in cells: structural proteins and functional proteins.
• Structural proteins form filaments that provide structure, while functional proteins act as enzymes that catalyze chemical reactions.

Lipids

• The primary types of lipids found in cells are phospholipids, cholesterol, and triglycerides.
• Phospholipids and cholesterol form the cell membrane and intracellular membrane barriers, determining the permeability of the membrane to water-soluble substances and contributing to the fluidity of the membrane.
• Triglycerides serve as the body's main storehouse of energy-giving nutrients in fat cells.

Carbohydrates

• Carbohydrates play a major role in cell nutrition and have structural functions as parts of glycoprotein molecules.
• Cells store carbohydrates in the form of glycogen, an insoluble polymer of glucose.

Cell Membrane Structure

• The basic structure of the cell membrane is a lipid bilayer composed of phospholipids, sphingolipids, and cholesterol, with embedded proteins.
• Integral proteins protrude all the way through the membrane, while peripheral proteins are attached only to one surface of the membrane.
• The glycocalyx is a loose carbohydrate coat on the cell's outer surface that provides a negative charge, attaches cells to each other, acts as receptors for hormones, and participates in immune reactions.

Organelles

• Key organelles found in the cytoplasm include the endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, and peroxisomes.
• The endoplasmic reticulum processes molecules made by the cell and transports them to their specific destinations.
• The Golgi apparatus processes and packages substances from the ER into lysosomes, secretory vesicles, and other cytoplasmic components.

Ions and Water

• Ions are necessary for cellular reactions and control mechanisms, such as transmitting electrochemical impulses in nerve and muscle fibers.
• Water acts as a solvent for chemical reactions and suspends particles where reactions take place.

Proteins and Lipids

• Structural proteins form filaments that provide support and organization to cellular components.
• Functional proteins act as enzymes to catalyze specific intracellular chemical reactions.
• Lipids are suitable for forming cellular membranes due to their solubility in fat solvents and insolubility in water, allowing them to form barriers that control substance movement in and out of cells.
• Cholesterol helps determine the membrane's permeability to water-soluble substances and controls its fluidity.

Carbohydrates and Energy Storage

• Glycogen is a readily available energy source that can be quickly mobilized to meet the cell's energy needs.
• Muscle cells can store up to 3% of their mass as carbohydrates, and liver cells can store up to 6%, whereas most other cells store about 1%.

Membrane Proteins

• Integral proteins in the cell membrane form channels for water-soluble substances, act as carriers for transport, and serve as receptors for signaling molecules.
• Peripheral proteins function as enzymes or controllers of substance transport through membrane pores.

Cytoplasm and Organelles

• The cytosol is the jelly-like fluid portion of the cytoplasm containing dissolved proteins, electrolytes, and glucose.
• Ribosomes and rough ER work together to synthesize proteins.