2 Biological Molecules Free Online FlashCards

What makes a water molecule polar?

Water is polar because oxygen attracts shared electrons more strongly than hydrogen, giving oxygen a partial negative charge and the hydrogen ends partial positive charges.

How do carbohydrates differ by the number of sugar units?

One sugar unit is a monosaccharide, two joined units form a disaccharide, and many joined units form a polysaccharide.

How does glucose provide energy for cells?

Cells break down glucose during cellular respiration to transfer energy into ATP.

What are two important facts about cellulose?

Cellulose is a major component of plant cell walls. Humans cannot digest it, but it provides dietary fiber.

What distinguishes lipids from many other biological molecules?

Lipids are largely nonpolar and do not mix well with water. Unlike proteins and nucleic acids, most are not polymers made from repeating monomers.

What are fats and oils commonly made of, and why are they useful energy stores?

Fats and oils commonly consist of glycerol joined to three fatty acids. Their many energy-rich carbon–hydrogen bonds make them effective long-term energy stores.

How do phospholipids arrange to form a cell membrane boundary?

Their water-attracting heads face watery environments while their water-repelling tails point inward, forming a bilayer that creates the basic boundary of cell membranes.

How does a protein’s amino-acid sequence relate to its function?

Proteins are amino-acid chains linked by peptide bonds. Their amino-acid order affects folding, and their resulting shapes enable specific jobs such as catalysis, transport, and support.

What is protein denaturation?

Denaturation is a change in a protein’s shape that can impair its function. Changes in temperature or pH can cause it.

What are nucleotides made of, and how do DNA bases pair?

A nucleotide contains a sugar, a phosphate group, and a nitrogen-containing base. In DNA, adenine pairs with thymine, while cytosine pairs with guanine.

How do the three major types of RNA help make proteins?

RNA usually has one strand and uses uracil instead of thymine. Messenger RNA carries information, transfer RNA delivers amino acids, and ribosomal RNA is part of protein-making machinery.

How do hydrogen bonds help water moderate temperature?

Hydrogen bonds absorb or release heat as they form or break, so water changes temperature relatively slowly.