BIOL 125 – BIOLOGY I Study Guide – Ch. 5 – Biological Membranes

These flashcards cover essential terms and concepts related to biological membranes, providing a comprehensive review for students preparing for their exam.

What is the role of the plasma membrane in cells?

The plasma membrane regulates the movement of substances in and out of the cell.

What properties of phospholipids cause them to form lipid bilayers?

Phospholipids are amphipathic molecules with hydrophilic heads and hydrophobic tails.

What is the fluid mosaic model?

The fluid mosaic model describes the membrane structure as a flexible layer of lipid molecules with mosaic of proteins.

How does a cell regulate the fluidity of its plasma membrane?

A cell may adjust lipid composition, such as fatty acid saturation, temperature, and cholesterol content to regulate fluidity.

What are integral membrane proteins?

Integral membrane proteins are embedded in the lipid bilayer and can span across the membrane.

How do carrier proteins and channel proteins differ?

Carrier proteins bind specific molecules to transport them, while channel proteins provide passages for molecules to pass through.

Where are proteins destined for the inside of the membrane made?

Proteins destined for the inside of the membrane are made in the ribosomes of the rough endoplasmic reticulum.

What happens to an animal cell in an isotonic solution?

An animal cell remains stable, with no net movement of water.

How do plant cells respond in hypertonic and hypotonic solutions?

In hypertonic solutions, plant cells undergo plasmolysis; in hypotonic solutions, they maintain turgor pressure.

What is the difference between simple diffusion and facilitated diffusion?

Simple diffusion does not require assistance, while facilitated diffusion requires specific channel or carrier proteins.

How might a cell maintain a concentration gradient?

A cell maintains a concentration gradient using active transport mechanisms, such as the GLUT 1 transporter.

What distinguishes active transport from passive transport?

Active transport requires energy to move substances against a concentration gradient, while passive transport does not.

How does the sodium-potassium pump function?

The sodium-potassium pump moves 3 sodium ions out and 2 potassium ions into the cell using ATP energy.

What is indirect active transport?

Indirect active transport uses energy from other gradients, typically created by active transport, instead of direct ATP.

Can you give an example of a uniporter?

An example of a uniporter is the glucose transporter (GLUT).

What are the differences between phagocytosis, pinocytosis, and receptor-mediated endocytosis?

Phagocytosis engulfs large particles, pinocytosis takes in fluid, and receptor-mediated endocytosis targets specific molecules.

What are the functions of tight junctions?

Tight junctions prevent leakage of materials between epithelial cells.

What is the role of desmosomes?

Desmosomes provide strength and stability by anchoring cells to one another.

What is a gap junction?

Gap junctions allow for communication between adjacent cells by offering cytoplasmic channels.