Chapter 7 Quiz

Phospholipid Bilayer

Core of the membrane, separates the inside of a cell from its externals; hydrophillic head + hydrophobic tail

Integral Proeins

Proteins that penetrate the hydrophobic core and often span the membrane

Peripheral Proteins

Proteins that are not embedded in the membrane

Hypertonic solutions

Solution where solute concentration is greater than the inside of a cell; cell loses water

Hypotonic Solutions

Solution where solute concentration is less than the inside cell; cell gains water

Isotonic solutions

Solute concentrations are the same in the cell and solution; no net movement across membrane

Permeability

the ability of a membrane to allow certain substances to pass through it

Channel proteins

Proteins that provide corridors that allow specific molecules or ions to cross the membrane

Osmosis

the diffusion of water across a selectively permeable membrane

Osmoregulation

the process by which organisms regulate the concentrations of water and salts in their body fluids to maintain homeostasis

Turgidity

the state of being swollen or firm; happens in hypotonic solutions

Plasmolysis

The process of water leaving plant cells, allowing the cytoplasm and membrane to shrink away from the cell wall

Crenulation

The phenomenon that happens when animal cells are exposed to hypertonic solutions

Exocytosis

process of moving large molecules to exterior of cell

Endocytosis

process of moving large molecules into the cell

Pinocytosis

type of endocytosis where the cell creates a vesicle around fluid

Phagocytosis

Type of endocytosis where cell is engulfed into a vacuole

Cotransport

Occurs when active transport of a solute indirect drives transport of another solute

Active Transport

Movement of large polar molecules that requires ATP and goes against the concetration gradient

Passive transport

Movement of small molecules (ions) without needing energyFaci

Facilitated diffusion

Transport proteins speed the movements of molecules across membrane

Why is Membrane referred to as Fluid Mosaic Model

he Fluid Mosaic Model describes cell membranes as flexible structures with various protein molecules embedded in or attached to a fluid lipid bilayer

What experiment supports the fluid mosaic model?

Frye-Eddin's experiment showed that when two cells are fused, the proteins of both diffuse around the membrane and mingle, rather than being locked to their area.

3 Factors that allow membrane to remain fluid:

1. Phospholipid Bilayer

2. Presence of cholesterol

3. Temperature

What does cholesterol do in the membrane

Cholesterol stabilizes the fluidity of cell membranes by preventing them from becoming too rigid at low temperatures and too fluid at high temperatures, thus maintaining membrane integrity.

What do Integral proteins do for cells?

Integral proteins span the membrane, facilitating the transport of molecules across the lipid bilayer and playing key roles in cell signaling and maintaining structural integrity.

What do Peripheral proteins do for cells?

Peripheral proteins are located on the membrane's surface, providing structural support, assisting in signaling, and helping to anchor the membrane to the cytoskeleton.

Example of Integral proteins

include channels and transporters.

Example of peripheral proteins

include enzymes and receptors that are involved in signaling pathways and membrane stabilization.

Where are cell membranes constructed?

Cell membranes are primarily constructed in the endoplasmic reticulum; modified in golgi

Difference Between Carrier and Transport Protein

• Carrier proteins bind and change shape to move molecules

• Transport proteins facilitate the movement of substances across the membrane without altering their structure.

Diffusion

Tendency for molecules to spread out evenly into available space

What allows Diffusion to happen across a cell membrane

The concentration gradient of molecules, which is the difference in concentration between two regions, drives diffusion across the selectively permeable cell membrane.

Why will non-woody plants wilt if not water for a while?

Cells lose pressure; become flaccid and unable to support the plant’s structure and cell wall

Differences Between Active and Passive transport

• Active Transport

  • Require ATP; moves large polar molecule

• Passive Transport

  • No energy needed; moves small molecules/ions

What are proton pumps?

Proton pumps are membrane proteins that transport protons (H+) across a membrane, creating an electrochemical gradient

Why are proton pumps important to living things?

They help in creating gradients that drive cellular processes, such as ATP synthesis and secondary active transport.

How do cells know what to “eat” during phagocytosis?

Cells recognize and bind to specific molecules on the surfaces of particles, often through receptors, signaling their need to engulf those particles.