bio exam prep

What is the structure of a phospholipid?

A phospholipid has a hydrophilic head consisting of phosphate and glycerol and hydrophobic fatty acid tails.

Why are membranes considered semi-permeable?

Membranes only allow certain substances to enter the cell.

What are the hydrophilic components of a membrane?

Phosphate heads of phospholipids, hydrophilic parts of integral membrane proteins, peripheral membrane proteins, and carbohydrate chains of glycolipids and glycoproteins.

What are the hydrophobic components of a membrane?

Fatty acid tails of phospholipids, hydrophobic regions of integral membrane proteins, and the steroid rings of cholesterol.

What is the role of integral proteins in the cell membrane?

Integral proteins go through the membrane and transport substances in and out of the cell.

What are peripheral proteins used for in the cell membrane?

Peripheral proteins exist on the outside of the cell membrane and act as enzymes or maintain cell shape.

Which type of molecules can easily pass through the cell membrane?

Only small non-polar molecules can pass through the membrane easily.

How does alcohol affect membrane structure?

Alcohol increases membrane fluidity, alters permeability, impairs membrane protein function, and affects lipid composition, disrupting normal cell function.

What is the fluid mosaic model of the cell membrane?

The membrane is fluid due to the movement of its components, with unsaturated fatty acids creating space for movement and saturated fatty acids packing the phospholipids tightly.

What role does cholesterol play in the membrane?

Cholesterol regulates membrane fluidity; it restricts movement of phospholipids at high temperatures and prevents tight packing at low temperatures.

What are the components of the plasma membrane?

Carrier proteins, glycoproteins/glycolipids, and cholesterol.

What is active transport?

Active transport moves molecules using special transport proteins and energy (ATP) against their concentration gradient, from low to high concentration

What is passive transport or diffusion?

Passive transport is the natural movement of substances from areas of higher concentration to areas of lower concentration without energy.

What is simple diffusion?

Simple diffusion is the movement of small or nonpolar molecules directly through the lipid bilayer without help from proteins.

What is facilitated diffusion?

Facilitated diffusion is the transport of larger molecules through transport proteins embedded in the cell membrane.

What is primary active transport?

Primary active transport directly uses ATP to pump molecules against their concentration gradient through a transport protein.

What is secondary active transport?

Secondary active transport uses ion gradients created by primary active transport to drive the movement of other molecules.either in the same direction, symport, or opposite direction, antiport, to the ion 

What does the sodium-potassium pump do?

The sodium-potassium pump moves 3 sodium ions out of the cell and 2 potassium ions into the cell for each cycle.

What is the importance of the sodium-potassium pump?

It maintains higher sodium concentration outside and higher potassium concentration inside the cell, crucial for cellular function.

What type of proteins are carrier proteins?

Carrier proteins undergo a conformational change when a molecule binds, transporting it across the membrane.

What are channel proteins?

Channel proteins form pores in the membrane allowing specific molecules like ions or water to pass through.

What is osmosis?

Osmosis is the passive transport of water molecules across a semipermeable membrane to reach equilibrium.

What characterizes an isotonic solution?

In an isotonic solution, the solute concentration outside the cell equals that inside the cell, resulting in no net water movement.

What happens to cells in a hypertonic solution?

In a hypertonic solution, water moves out of the cell, causing it to shrink or become crenated.

What happens to cells in a hypotonic solution?

In a hypotonic solution, water moves into the cell, potentially causing it to swell or burst, while plant cells become turgid.

What is cotransport?

Cotransport is when one solute's inward movement powers the transport of another solute in the same direction.

What is antiport?

Antiport is when a channel transports two substances simultaneously in opposite directions.

What is the significance of the kinks in unsaturated fatty acids?

The kinks in unsaturated fatty acids create space, allowing movement and flexibility in the membrane.

What is the difference between primary and secondary active transport?

Primary active transport uses ATP directly to move molecules, while secondary active transport uses ion gradients from primary transport.