Carbohydrates
What are the monomers that make up carbohydrates?
Monosaccharides (simple sugars like glucose, fructose, galactose).
Explain why oil doesn’t dissolve in water.
Oil molecules are nonpolar and cannot form hydrogen bonds with polar water molecules, so they separate.
What is the difference between a saturated and an unsaturated fatty acid?
Saturated: no double bonds, saturated with hydrogen; solid at room temp.
Unsaturated: has one or more double bonds, causing bends in the chain; liquid at room temp.
Name two structures found in both prokaryotes and eukaryotes.
Plasma membrane and ribosomes.
(Also possible: cytoplasm, DNA, cytoskeleton (in some bacteria).)
What is the function of the nucleus?
It stores the cell’s genetic information (DNA) and controls gene expression and cell activities.
What type of bond links two monosaccharides?
Glycosidic linkage (formed by dehydration synthesis).
Define diffusion and osmosis.
Diffusion: movement of molecules from high → low concentration.
Osmosis:the diffusion of water across a semipermeable membrane
What is the fluid-mosaic model of the membrane?
The plasma membrane is a fluid structure of phospholipids with proteins, cholesterol, and carbohydrates embedded or moving laterally within it, like a “mosaic.”
Where is DNA located in prokaryotes? In eukaryotes?
In prokaryotes, DNA is found in the nucleoid region (not membrane-bound).
In eukaryotes, DNA is enclosed within the nucleus.
What is the function of ribosomes?
Ribosomes synthesize proteins by linking amino acids according to mRNA instructions.
(They can be free in the cytoplasm or attached to the rough ER.)
What determines whether glucose is α or β form?
The position of the hydroxyl group (-OH) on the carbon (the first carbon in the ring). α ( down), β ( up).
What is active transport, and how does it differ from passive transport?
Active transport moves substances against their concentration gradient using ATP or another energy source.
Passive transport moves substances down the gradient, requiring no energy.
What happens to a cell placed in a hypertonic solution? In a hypotonic solution?
Hypertonic: water exits the cell → cell shrinks .
Hypotonic: water enters the cell → cell swells and may burst.
What is the cytoplasm, and what does it contain?
The cytoplasm is the gel-like fluid inside the cell membrane that contains cytosol, organelles, and various molecules, such as ions and enzymes.
What does the rough ER do? The smooth ER?
Rough ER: Synthesizes and folds proteins (studded with ribosomes).
Smooth ER: Synthesizes lipids, detoxifies drugs/toxins, and stores calcium.
Glucose + fructose forms what disaccharide?
Sucrose.
What is the difference between simple diffusion and facilitated diffusion?
Simple diffusion: molecules pass directly through the lipid bilayer.
Facilitated diffusion: molecules cross via channel or carrier proteins (still no ATP required.)
What is a concentration gradient, and how does it drive diffusion?
:A difference in solute concentration across a membrane.
Molecules move from high to low concentration until equilibrium is reached.
Which organelle is responsible for recycling and digestion of cellular waste?
The lysosome.
(Peroxisomes also detoxify and break down fatty acids, but don’t digest macromolecules.)
What are the main functions of the Golgi apparatus?
It modifies, sorts, and packages proteins and lipids for transport or secretion.
Often compared to the “shipping center” of the cell.
Hydrolysis vs. dehydration reaction?
Hydrolysis breaks bonds using water; dehydration forms bonds by removing water.
Which of the following would a lipid bilayer be most permeable to?
a) a large charged molecule
b) a small charges molecule
c) a large nonpolar molecule
d) a small nonpolar molecule
a small nonpolar molecule
Why? The hydrophobic nature of the lipid bilayer allows these nonpolar molecules to dissolve and pass through the membrane easily.
Why do lipids form micelles?
so that the polar head faces water while the nonpolar tail is buried inside
How do vesicles help transport cargo within the cell?
Vesicles are small, membrane-bound sacs that transport proteins and lipids between organelles and to the cell surface
Describe the endomembrane system from protein synthesis to secretion.
Ribosome (on RER) → Rough ER (protein made and initially folded) → Vesicle → Golgi apparatus (processing & packaging) → Vesicle → Plasma membrane (fuses to release protein outside the cell through exocytosis).