Bio-H Chapter 3: The Molecules of Life

condensation

Chemical reaction in which a large molecule is assembled from smaller subunits; water also forms.

enzyme

Organic molecule that speeds up a reaction without being changed by it.

functional group

An atom (other than hydrogen) or a small molecular group bonded to a carbon of an organic compound; imparts a specific chemical property.

hydrocarbon

Compound that consists only of carbon and hydrogen atoms.

hydrolysis

Water-requiring chemical reaction that breaks a molecule into smaller subunits.

metabolism

All of the enzyme-mediated reactions in a cell.

monomer

Molecule that is a subunit of a polymer.

organic

Describes a molecule that consists mainly of carbon and hydrogen atoms.

polymer

Molecule that consists of repeated monomers.

reaction

Process of molecular change.

True or False: There are two different types of elements, one for nonliving and the other for living organisms

false

What is a key difference in the composition of a human body compared to sand or seawater?

A human body has a much larger proportion of carbon atoms.

What types of molecules are abundant in living bodies?

Complex carbohydrates, lipids, proteins, and nucleic acids.

A carbon atom is unusual among elements because it can bond ___ with many other ___.

stably; elements

How many vacancies does a carbon atom have?

4

How many covalent bonds can a carbon atom form?

4

What is the structural shape of a bond with carbon?

rings

The versatility of carbon atoms means that they can be assembled into a wide variety of…

organic compounds

Is a hydrocarbon polar or nonpolar?

nonpolar

Each functional group imparts a particular ___ to an organic compound.

chemical property

What chemical property do carboxyl groups have?

they make amino acids and fatty acids acidic

What chemical property do hydroxyl groups have?

They have a polar character, thus increasing solubility in water, they can also turn hydrocarbons into alcohols.

What chemical property do methyl groups have?

They add a nonpolar character to the group and acts as an "off" switch for DNA

How are carbon rings in glucose and other sugars typically depicted?

As polygons.

What does it imply if no atom is shown at a corner or the end of a bond in a structural formula?

A carbon atom is implied at that location.

What model is used to depict an organic molecule's three-dimensional arrangement of atoms?

Ball-and-stick models.

What type of model is used to show the overall shape of an organic molecule?

Space-filling models.

The ___ and ___ of different molecules formd ifferent versons of the molecules of life.

numbers; arrangements

sugars, fatty acids, amino acids, and nucleotides are all examples of…

monomers

What happens during condensation?

An enzyme joins one monomer to another, and water is formed, also known as dehydration.

Cells ___ monomers to form polymers, and ___ polymers to release monomers.

link; break apart

carbohydrate

Molecule that consists primarily of carbon, hydrogen, and oxygen atoms in a 1:2:1 ratio.

cellulose

Crosslinked polysaccharide of glucose monomers; the major structural material in plants.

chitin

Nitrogen-containing polysaccharide that composes fungal cell walls and arthropod exoskeletons.

disaccharide

Carbohydrate that consists of two monosaccharide monomers.

glycogen

Highly branched polysaccharide of glucose monomers. Principal form of stored sugars in animals.

monosaccharide

Simple sugar; consists of one sugar unit so it cannot be broken apart into monomers.

polysaccharide

Carbohydrate that consists of hundreds or thousands of monosaccharide monomers.

starch

Coiled polysaccharide of glucose monomers. Principal form of stored sugars in plants.

saccharides

carbohydrate units (sugar)

How many carbon atoms does a monosaccharide have?

5-6

How many hydroxyl atoms does a monosaccharide have?

2+

How do the functional groups of monosaccharides affect their properties?

They impart solubility, allowing monosaccharides to move easily through water-based environments.

What is the primary function of glucose in cells?

Cells break the bonds of glucose to release energy for other reactions.

What are ribose and deoxyribose?

Five-carbon monosaccharides that are components of RNA and DNA nucleotides, respectively.

How are monosaccharides used in the body?

As structural materials to build larger molecules and as precursors for other molecules.

Can human cells convert glucose into vitamin C?

No, human cells cannot make this conversion and must obtain vitamin C from food.

What is an example of a molecule that can be made from glucose in plants and animals?

Vitamin C.

What are examples of disaccharides?

lactose and sucrose

Lactose is made out of…

glucose and galactose

Sucrose is made out of…

glucose and fructose

What is the most plentiful sugar in nature?

sucrose

oligosaccharides

short chains of 3 or more monosaccharides (at least 10)

What are the most common examples of polysaccharides?

cellulose, starch, and glycogen

What is one similarity that cellulose, starch, and glycogen all share?

They are ONLY made of glucode monomers

What is one difference that cellulose, starch, and glycogen all share?

their monomers are in different patterns + covalent bonding

What is the most abundant organic molecule on earth?

cellulose

Where is cellulose found?

the rods inside stems and other plant parts

Why is cellulose important for plants?

It forms tough fibers that help resist wind and mechanical stress.

True or False: Cellulose is not soluable in water

true

True or False: mammals can digest cellulose

false

Dietary fiber

the indigestible cellulose in vegetable foods.

How do some animals digest cellulose?

Bacteria in the guts of termites and grazers like cattle and sheep help them digest cellulose.

What role do enzymes play in cellulose breakdown?

Some bacteria and fungi produce enzymes that can break cellulose apart into its component sugars.

True or False: Starch can readily dissolve in water

false

Which can be broken down more easily: cellulose or starch?

starch

What is the bonding pattern of glucose monomers in starch?

A different covalent bonding pattern that makes a chain coil up into a spiral.

What happens to sugars in seeds like corn, rice, and beans?

Sugars are converted to starch for storage.

What process occurs when a mature seed sprouts?

Hydrolysis enzymes break the bonds between starch's glucose monomers.

How is glucose used by a young plant after sprouting?

It is used to fuel the growth of the young plant until it can make its own food.

Why is starch an important component of human food?

Humans have enzymes that break down starch, making it digestible.

Where can glycogen be found?

in muscle + liver cells

fat

Substance that consists mainly of triglycerides.

fatty acid

Organic compound that consists of an acidic carboxyl group "head" and a long hydrocarbon "tail."

lipid

Fatty, oily, or waxy organic compound.

lipid bilayer

Double layer of phospholipids arranged tail-to-tail; structural foundation of cell membranes.

phospholipid

A lipid with two (hydrophobic) fatty acid tails and a (hydrophilic) phosphate group in its head.

saturated fatty acid

Fatty acid with only single bonds linking the carbons in its tail.

steroid

Lipid with four carbon rings, no fatty acid tails.

triglyceride

A molecule with three fatty acids bonded to a glycerol; main component of fats.

unsaturated fatty acid

Fatty acid with one or more carbon-carbon double bonds in its tail.

wax

Water-repellent substance that is a complex, varying mixture of lipids with long fatty acid tails bonded to long-chain alcohols.

All lipids are either partly or completely...

hydrophobic

Is the tail of a fatty acid hydrophobic or hydrophilic?

hydrophobic

Is the head of a fatty acid hydrophobic or hydrophilic?

hydrophilic

Fatty acids are a main component of what?

soap

True or False: Saturated fats are extremely flexible

true

True or False: Unsaturated fats are not flexible

true

kink

twist

glycerol

type of alchol

What happens when a carboxyl group of a fatty acid reacts with glycerol?

It loses its hydrophilic character.

What is the solubility characteristic of triglycerides?

Triglycerides are entirely hydrophobic and do not dissolve in water.

What is the most abundant and richest energy source for vertebrates?

triglyceride

What does a saturated fat have?

three saturated fatty acids in each triglyceride

What does an unsaturated fat have?

at least 1 unsaturated fatty acid in each triglyceride

What state is a saturated fat at room temperature?

solid

What state is an unsaturated fat at room temperature?

liquid

What is an example of an unsaturated fat?

vegtable oil

What makes the head of a phospholipid hydrophilic?

The polar phosphate group.

How are the heads of phospholipids oriented in the lipid bilayer?

The heads of one layer face the cell's fluid interior, and the heads of the other layer face the cell's watery surroundings.