40 terms

Capter 3: Molecules of Life

A sugar (monosaccharide) or one of its dimers (disaccharides) or polymers (polysaccharides).
A long molecule consisting of many similar or identical monomers linked together.
The simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides. Also known as simple sugars, the molecular formulas of monosaccharides are generally some multiple of CH2O.
A double sugar, consisting of two monosaccharides joined by dehydration synthesis.
A polymer of up to over a thousand monosaccharides, formed by dehydration reactions.
A structural polysaccharide of cell walls, consisting of glucose monomers joined by β-1, 4-glycosidic linkages
An extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch.
Carbohydrates... name and explain each
Carbohydrates include sugars and polymers of sugars. These molecules are used as building materials and sources of energy. Single sugar molecules (called monosaccharides) and linked pairs of sugars (called disaccharides) are important as building blocks and cellular fuels. Polysaccharides are long chains of sugars. A polysaccharide called cellulose is a major component of plant cell walls. Plant cells store sugars in the form of a polysaccharide called starch. (Animals store a polysaccharide called glycogen.) Polysaccharides on cell membranes act as cell identification tags.
examples of disaccharides
Here are several examples:

-- Plants make sucrose by joining glucose and fructose. Sucrose circulates in plant sap, and we obtain it from sugar cane and sugar beets and use it as table sugar.

-- Lactose is formed by joining galactose and glucose. Lactose is the disaccharide that gives milk its sweet taste.

-- Maltose consists of two linked glucose molecules. Digestion of starch-- in a sprouting seed or in the intestine of an animal-- produces this disaccharide.
cell wall
A protective layer external to the plasma membrane in plant cells, prokaryotes, fungi, and some protists. In plant cells, the wall is formed of cellulose fibers embedded in a polysaccharide-protein matrix. The primary cell wall is thin and flexible, whereas the secondary cell wall is stronger and more rigid and is the primary constituent of wood.
_____ is the most abundant organic compound on Earth
Which of these is a source of lactose?
glucose + glucose —> _____ by _____.
maltose + water ... dehydration synthesis

Maltose is the disaccharide formed when two glucose molecules are linked by dehydration synthesis.
Glycogen is _____
a polysaccharide found in animals

Animals store energy in the form of glycogen.
Ahe building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group.
double helix
The form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape.
DNA is composed of building blocks called _____.
In eukaryotic cells DNA has the appearance of a _____.
double helix
The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases.
hydrogen bonds

Nitrogenous base pairs are joined by hydrogen bonds.
A nucleotide is composed of a(n) _____.
phosphate group, a nitrogen-containing base, and a five-carbon sugar

These are the components of a nucleotide.
A three-dimensional biological polymer constructed from a set of 20 different monomers called amino acids.
Defensive proteins are manufactured by the _____ system.
Which of these does NOT contain a structural protein?

its actually a structure protein
Your body contains thousands of different types of proteins, each with a specific function. A protein's function is largely determined by its _____
The primary structure of a protein is like the arrangement of beads on a string. In this analogy, the beads are _____, of which there are _____ different kinds.
amino acids ... 20
A protein's alpha helices and beta sheets fold together to create an overall shape at the _____ level of protein structure.
What happens to the shape and function of a protein if one of the amino acids is replaced with a different type of amino acid?
It depends on the role of the amino acid that is altered. One amino acid might be replaced with no measurable effect on the protein's function; replacing another might cause a total loss of function.
Large proteins, like DNA polymerase and hemoglobin, are often composed of several polypeptides that are linked together. The _____ level of protein structure describes how the polypeptides are joined to create a larger complex.
One of a family of compounds, including fats, phospholipids, and steroids, that are insoluble in water.
A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.
A type of lipid characterized by a carbon skeleton consisting of four rings with various functional groups attached.
A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids.
Which of these is NOT a lipid?

RNA is a nucleic acid
A function of cholesterol that does not harm health is its role _____.
as a component of animal cell membranes

Cholesterol is an important component of animal cell membranes.
Which of the following pairs of molecules share the same chemical composition but differ in molecular structure?
glucose and fructose

Glucose and fructose are isomers, molecules that share the same chemical composition but differ in their final structures.
Which best describes how charges are distributed on a water molecule?
The oxygen end is negative relative to the end with the two hydrogen atoms
Relative to other substances, water tends to resist changes in temperature. Why?
Water is highly cohesive. Its molecules tend to resist increases in their motion. When water is heated, some of the energy is used to disturb the hydrogen bonds between neighboring molecules.
The innermost electron shell of an atom can hold up to _____ electrons.
What determines the types of chemical reactions that an atom participates in?
the number of electrons in the outermost electron shell
Which of these relationships is true of an uncharged atom?
The number of protons is equal to the number of electrons.