Chemistry & Macromolecules
What element is found in almost all biological macromolecules?
Carbon
What does it mean that the cell membrane is selectively permeable?
It allows some substances to pass through while restricting others.
What is the net movement of particles from an area of higher concentration to an area of lower concentration called?
Diffusion
What is the net movement of water across a selectively permeable membrane called?
Osmosis.
What are the two main parts of a phospholipid?
A phosphate head and fatty acid tails.
What are the four biological macromolecules?
Carbohydrates, lipids, proteins, and nucleic acids.
Why is the cell membrane referred to as the fluid mosaic model?
It has a flexible membrane made of different components, including phospholipids, proteins, cholesterol, and carbohydrates.
What is the difference between passive diffusion and facilitated diffusion?
Both move substances from high to low concentration without energy. Facilitated diffusion requires a transport protein; simple diffusion does not.
What happens to a cell placed in an isotonic solution?
There is no net movement of water, so the cell generally stays the same size.
Is the phospholipid head hydrophilic or hydrophobic?
Hydrophilic, meaning it likes water.
What are the monomers of proteins and carbohydrates?
Amino acids and simple sugars (monosaccharides).
Which component of the cell membrane helps cells recognize one another and identify chemical signals?
Carbohydrates.
What is ATP, and which organelle uses the most ATP?
ATP is energy and most of it is produced by the mitochondria.
Water moves into a cell, causing it to expand. Is the surrounding solution hypotonic or hypertonic?
Hypotonic.
Are the fatty acid tails hydrophilic or hydrophobic?
Hydrophobic, meaning they repel water.
What is the difference between ionic and covalent bonds?
Ionic bonds involve the transfer of electrons (nm+m), while covalent bonds involve sharing electrons (nm+nm).
Which component of the cell membrane helps maintain membrane stability and regulate fluidity specifically with the fatty acid tails?
Cholesterol.
What is the difference between endocytosis and exocytosis?
Endocytosis brings material into the cell using vesicles, while exocytosis releases material out of the cell using vesicles.
What happens to a cell placed in a hypertonic solution?
Water moves out of the cell, causing it to shrink.
How do phospholipids arrange themselves in the cell membrane, and why?
They form a bilayer, with hydrophilic heads facing the watery environments and hydrophobic tails facing inward.
Which macromolecule builds structures, speeds up chemical reactions, and helps control cell growth?
Proteins
Which component of the cell membrane allows certain substances to cross that cannot easily pass through the phospholipid bilayer?
Transport protein.
A cell uses energy to move a substance from low to high concentration. What type of transport is this?
Active transport
A cell has a higher solute concentration than the surrounding solution. Which way will water move, and what happens to the cell?
Water moves into the cell because the surrounding solution is hypotonic relative to the cell. The cell expands.
Why can oxygen pass directly through the membrane, but a large polar molecule cannot easily do the same?
Oxygen is small and nonpolar, so it can pass through the hydrophobic interior. Large polar molecules interact poorly with that interior.