Cell Biology Basics Quiz

The Cell - Basic Unit of the Body

• The cell is the basic living unit of the body.
• Each organ is comprised of many cells held together by intercellular structures.
• Each cell type is specialized for specific functions.
• While cells vary, they share fundamental characteristics, including the ability to reproduce.

Body Fluid Composition

• Approximately 60% of the adult human body is fluid, primarily water-based.
• This fluid is categorized into intracellular (inside cells) and extracellular (outside cells).
• Extracellular fluid comprises ions and nutrients vital for cellular function.

Fluid Distribution in the Body

• Intracellular fluid makes up 67% of total body fluid.
• Interstitial fluid constitutes 26% of total body fluid.
• Intravascular fluid (blood plasma) accounts for 7% of total body fluid.
• Cerebrospinal fluid makes up less than 1% of total body fluid.

Intracellular Fluid

• Intracellular fluid is the liquid inside cells.
• It provides the environment for cells to live, grow, and function; this depends on the concentration of oxygen, glucose, various minerals, amino acids, fatty substances and others.

Cell Structure

• Cells consist of a nucleus and cytoplasm.
• The nucleus and cytoplasm are separated by a nuclear membrane and a plasma membrane.
• The different substances in a cell are collectively called protoplasm.
• Protoplasm consists of water, electrolytes, proteins, lipids, and carbohydrates.

Water in Cells

• Water is the principal fluid medium in cells (excluding fat cells)
• Many cellular chemicals are dissolved in the water.
• Others are suspended in the water in the form of small particles.

Ions in Cells

• Key ions in cells include potassium, magnesium, phosphate, sulfate, bicarbonate, sodium, chloride, and calcium.
• Ions are crucial for cellular reactions.
• At the cell membrane ions are vital for nerve and muscle impulse transmission

Proteins in Cells

• Proteins, after water, are the most abundant substances in cells.
• They can be classified into structural and functional proteins.
• Structural proteins form filaments, microtubules, and organelles.
• Functional proteins, mainly enzymes, catalyze cellular chemical reactions.

Lipids in Cells

• Lipids are various substances grouped based on their solubility in fat solvents.
• Important lipids include phospholipids and cholesterol, which form cell membranes.
• In some cells, triglycerides (neutral fats) account for a large portion of the cell's mass.
• Triglycerides serve as the body's primary energy storage.

Carbohydrates in Cells

• Carbohydrates play a significant role in cell nutrition, although they primarily function as parts of glycoprotein molecules.
• Glucose is always dissolved in extracellular fluid, making it readily accessible to cells.
• Glycogen, a form of stored glucose, supplies quick energy to cells.

Cell Membrane Structure

• The cell membrane, also called the plasma membrane, is a thin, elastic structure.
• Mostly composed of proteins and lipids.
• Approximately 7.5 to 10 nanometers thick.

Cell Membrane Lipids

• The cell membrane's basic structure is a lipid bilayer.
• This bilayer is composed of phospholipid molecules.
• One end of each phospholipid is water-soluble (hydrophilic).
• The other end is fat soluble (hydrophobic)
• Cholesterol, a lipid, is also present in the membrane.

Cell Membrane Proteins

• Membrane proteins are globular masses floating in the lipid bilayer.
• Integral proteins span across the entire membrane.
• Peripheral proteins are attached to only one side of the membrane.
• Some membrane proteins are glycoproteins
• Many integral proteins form channels, facilitating the passage of molecules across the membrane
• Others act as carrier proteins or enzymes.

Cell Membrane Carbohydrates

• Membrane carbohydrates are typically linked to proteins or lipids.
• These carbohydrates, often protruding to the cell's exterior, are involved in cell recognition and communication.

Membrane Functions

• The cell membrane functions include signaling and transport.
• Integral proteins provide a mechanism for conveying environmental information to the cell interior.
• Peripheral proteins often act as enzymes or regulate transport through membrane channels.
• Some carbohydrates act as receptors for hormones.