9/18/2026

What is the Glycocalyx, and what are its two structural variations?

The superficial "sugary coat" on the outside of the plasma membrane. It consists of Glycoproteins (carbohydrates bound to proteins) and Glycolipids (carbohydrates bound to lipids).

What are the three primary functions of the Glycocalyx?

• Cell Recognition: Identification tag for the immune system.

• Binding: Anchors cells to extracellular matrix structures.

• Lubrication: Reduces physical friction on cell surfaces

List the four core functions of the Plasma Membrane.

• Physical Isolation: Separates cytosol from Extracellular Fluid (ECF).

• Regulation of Exchange: Controls what enters or exits the cell.

• Environmental Sensitivity: Detects extracellular chemical signals.

• Structural Support: Anchors shapes and stabilizes tissues

Name the three elements of the Cytoskeleton from smallest to largest.

• Microfilaments: Form outer extensions/ruffles like microvilli.

• Intermediate Filaments: Durable structural scaffolding inside the cell.

• Microtubules: Dynamic pathways composed of motor proteins

What is the unique purpose of Microvilli, and where are they highly concentrated?

Built by microfilaments to maximize surface area for absorption. They are concentrated heavily inside the digestive tract

What are the two core locations where Microtubules dictate movement, and what do they move?

• Centrioles: Move DNA/chromosomes apart during cell division (mitosis).

• Cilia: Coordinate synchronized, one-way power strokes to sweep fluids/mucus across the outer cell surface

Centrioles

Move DNA/chromosomes apart during cell division (mitosis).

Cilia

Coordinate synchronized, one-way power strokes to sweep fluids/mucus across the outer cell surface

Free ribosomes

drift loosely in the cytoplasm to make internal proteins.

Fixed ribosomes

physically anchored to the Rough ER. [1, 2]

Rough ER (RER)

Studded with fixed ribosomes; synthesizes and adds final chemical modifications to proteins(the "cake icing" phase)

Smooth ER (SER)

Lacks ribosomes; synthesizes lipids (membrane phospholipids, cholesterol, steroid hormones) and carbohydrates(glycogen).

What is the nickname for the Golgi Apparatus

The Cellular Post Office. It sorts and ships proteins via vesicles to Membrane Renewal,Secretion (Exocytosis),Cytosolic Enzymes

Membrane Renewal

Replaces worn-out plasma membrane proteins.

Secretion (Exocytosis)

Dumps contents out of the cell.

Cytosolic Enzymes

Keeps specialized enzymes inside, like packaging Lysosomes.

What are Lysosomes

Vesicles packed with destructive, toxic digestive enzymes created by the Golgi

What is the Lysosomes 3 primary responsibilities

Organelle Recycling,Pathogen Destruction,Autolysis

Organelle Recycling:

Eating worn-out cell parts (e.g., old mitochondria).

Pathogen Destruction

Fusing with and destroying engulfed bacteria.

Autolysis

Bursting open to intentionally self-destruct a heavily damaged/cancerous cell

Define the principle of Membrane Flow.

The dynamic one-way movement of membranes traveling between the ER, Golgi, and plasma membrane. It is not a round-trip taxi; once a vesicle fuses with its destination, its lipids permanently stay at that new site

Describe the internal structural anatomy of the Mitochondria.

Enclosed in a double membrane. The smooth outer membrane surrounds an inner membrane folded into deep shelves called cristae, which contain an internal fluid matrix packed with metabolic enzymes. [1]

Glycolysis

Happens in the cytosol; breaks 1 bulky glucose into 2 pyruvates, making a tiny, inefficient amount of ATP without needing oxygen.

Mitochondrial Respiration

Happens in the mitochondrial matrix; requires oxygen to absorb pyruvate and processes it to make massive amounts of ATP efficiently.

What three vital components do Red Blood Cells (RBCs) completely lack, and what are the physiological consequences?

No centrioles, mitochondria, nucleus

No Centrioles

Cannot divide or replicate.

No Mitochondria

Relies purely on glycolysis for energy; ensures it does not consume the oxygen it is assigned to carry.

No Nucleus

Cannot produce new proteins or adjust its structural operations long-term.

Chromatin

DNA wrapped around histone spools (nucleosomes), loose and uncoiled, found in non-dividing cells.

Chromosomes.

DNA wrapped around histone spools,tightly coiled, visible structures held together by a centromere, found strictly during cell division

Transcription

Occurs in the Nucleus; converts DNA instructions into a portable single-stranded mRNA molecule.

Translation

Occurs in the Cytoplasm (on a ribosome); reads the mRNA codons to string together amino acids into a Protein

Define Selective Permeability and why it applies to human cells.

A state where a membrane allows some substances to freely cross while completely blocking others based on size, electrical charge, and lipid solubility. Human cells are strictly selectively permeable to preserve homeostatic balances

Simple Diffusion

passive(0 ATP spent) moving substances from high to low concentration,Small, nonpolar, lipid-soluble items (steroids, lipids) slip directly through the phospholipid bilayer.

Channel-Mediated (Facilitated) Diffusion

passive (0 ATP spent) moving substances from high to low concentration,Charged ions (\(Na^{+}\), \(K^{+}\)) or polar water molecules must use a transmembrane protein door because they cannot mix with membrane lipids

five factors dictate the speed or rate of diffusion?

Distance, Molecule Size, Temperature, Concentration Gradient, Electrical forces

Distance

Inversely related (shorter distance = faster speed).

Molecule Size

Inversely related (smaller molecules travel faster).

Temperature

Directly related (hotter environments accelerate speed).

Concentration Gradient:

Directly related (steeper high-to-low differences drive faster speed).

Electrical Forces

Attraction between opposite charges accelerates speed. [1]

What is the baseline value for Isotonic Normal Saline, and what happens to a cell placed inside it?

0.9% NaCl. Because solute concentration matches the inside of the cell, water moves in and out at perfectly equal rates, causing no change in cell volume. [1, 2]

What happens to a Red Blood Cell placed in a Hypotonic solution (e.g., pure water)?

Water tracking the higher internal solute concentration violently rushes INTO the cell, causing it to swell and burst (Hemolysis).

What happens to a Red Blood Cell placed in a Hypertonic solution (e.g., concentrated saltwater)

Water rushes OUT of the cell into the saltier environment, dehydrating the cell and causing it to shrivel up like a raisin (Crenation). [1, 2]

Primary Active Transport, and state its most notable cellular example.

An energetic pump mechanism that directly consumes ATP to force molecules against their concentration gradient from low to high concentration. The premier example is the Sodium-Potassium (\(Na^{+}/K^{+}\)) Exchange Pump.

Explain how Secondary Active Transport operates without consuming ATP directly.

• Step 1: A primary pump spends ATP to push Sodium (\(Na^{+}\)) outside, building a massive external stockpile.

• Step 2: A secondary carrier allows that Sodium to naturally diffuse back inside (high to low). As Sodium rushes in, it acts like a current, dragging a second passenger molecule (like glucose) inside with it.

What is Vesicular Transport

Bulk shipment using membrane spheres; strictly requires ATP.

Pinocytosis:

"Cell drinking" — pulling in pockets of extracellular fluid.

Phagocytosis

"Cell eating" — engulfing large solid foreign invaders or bacteria. [1, 2, 3, 4]