Basic Chemistry: Chemical Composition of Cells

Bio 190L

Element

anything that cannot be broken down into a simpler substance and still retain its unique chemical properties

Atom

the smallest unit of matter that makes up an element

Atoms can be broken down into

subatomic particles: neutrons, protons, and elections

Subatomic particles are ___ from one element to the next

not different

Molecules

When atoms react with one another, forming chemical bonds

Chemical formula

shorthand used by scientists to write molecules, which identifies the number of each element in the molecule

Biomolecules

molecules found in living systems that contain 5+ carbon atoms in either ring or chain formation

All cells contain four basic types of biomolecules:

carbohydrates, lipids, proteins, and nucleic acids

Simple molecules

monomers

Complex molecules

polymers (2+ monomers linked together)

Condensation reaction

Two or more monomers linked together to build a polymer

Covalent bond

when two atoms share one or more pairs of electrons to achieve a stable electron configuration

How does a condensation reaction work?

One of the monomers loses an -OH group and the other loses a an -H. The -OH and the -H then join together to produce an H₂O molecule. The two monomers are linked by a new covalent bond and a larger molecule is formed.

Hydrolysis reaction

The reverse process of splitting a larger polymer into two smaller molecules by inserting a molecule of water (e.g. digestion)

Positive color change test

Color change is observed, meaning that the particular molecule is present

Negative color change test

Color change is not observed, meaning that the particular molecule is not present

Control

Used in all chemical tests in this class. We will be using distilled water (dH₂O), which does not contain ant macromolecules. If your control gives you a positive result, your test is invalid.

Substrate

a base material, surface, or specific molecule upon which a process, organism, or chemical reaction acts

Cellular respiration

the metabolic process cells use to convert nutrients (like glucose) into usable energy, known as ATP (adenosine triphosphate), while releasing waste products

Basic building blacks for carbohydrates

sugars (monosaccharides, meaning “one-sugar”)

Examples of monosaccharides

glucose and fructose

Disaccharide (two-sugars)

two monosaccharides joined together by condensation

Sucrose (table sugar)

a disaccharide of glucose and fructose

Polysaccharide (many-sugars)

monosaccharide molecules linked together to form a medium-length chain (e.g. starch, cellulose, and glycogen)

The chemical properties of mono- and polysaccharides are different, so

the two types of molecules can be detected and differentiated by using specific chemical tests

Reagent

a substance or compound added to a system to cause a chemical reaction or to see if one occurs

Benedcit’s test

detects the presence of reducing sugars

Reducing suagrs

usually single sugars or disaccharides, which have a free aldehyde group that can be oxidized

Aldehyde group

-CHO

When heated to boiling in the precedence of Benedict’s reagent, reducing sugars will

turn the reagent green (indicating low concentration), yellow, orange, or red-orange (indicating high concentrations), depending on the concentration of reducing sugar present

If no reducing sugar is present, Benedict's reagent…

stays blue