Micro. Chapter #2

What is an element?

A substance that cannot be broken down into simpler substances by ordinary chemical means.

What four elements are most common in organisms?

Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N).

What is an atom?

The smallest unit of an element that retains the properties of that element.

What are the three subatomic particles?

Protons, neutrons, and electrons.

Where are protons found?

In the nucleus of an atom.

Where are neutrons found?

In the nucleus of an atom.

Where are electrons found?

In the electron cloud/orbitals surrounding the nucleus.

What is an atom's atomic number?

The number of protons in the nucleus.

What is atomic mass (atomic weight)?

The total mass of the atom, approximately equal to the number of protons + neutrons.

What is an isotope?

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Why do isotopes of the same element have the same atomic number?

Because they have the same number of protons.

How can isotopes be used in medicine?

Radioactive isotopes can be used for medical imaging, diagnosis, and treatment of certain diseases.

What determines which element an atom is?

The number of protons.

What is a molecule?

Two or more atoms chemically bonded together.

How do you read a molecular formula?

The subscript tells you how many atoms of that element are present.

What is a chemical bond?

An attractive force that holds atoms together.

What is a covalent bond?

A bond in which atoms share electrons.

What is an ionic bond?

A bond formed by the attraction between oppositely charged ions after electrons are transferred.

What is a hydrogen bond?

A weak attraction between a partially positive hydrogen and another electronegative atom.

Which chemical bonds are strong?

Covalent bonds are strong bonds.

Which chemical bonds are weak?

Hydrogen bonds are weak bonds.

Which bond is most common in biological molecules?

Covalent bonds.

What is the main difference between covalent and ionic bonds?

Covalent = share electrons.
Ionic = transfer electrons and attract opposite charges.

What is an ion?

An atom or molecule that has an electrical charge because it has gained or lost electrons.

How does an atom become a cation?

It loses electrons.

How does an atom become an anion?

It gains electrons.

What does pH measure?

The concentration of hydrogen ions (H⁺) in a solution.

What pH range is acidic?

Below 7

What pH is neutral?

7

What pH range is basic (alkaline)?

Above 7

What does a low pH mean?

There is a higher concentration of H⁺ ions, making the solution more acidic.

What does a high pH mean?

There is a lower concentration of H⁺ ions, making the solution more basic.

What is a buffer?

A substance that helps resist changes in pH.

What is a macromolecule?

A large molecule containing many atoms, often made of repeating smaller subunits.

What does "organic" mean in biology?

A molecule that contains carbon and hydrogen

What are the four major types of macromolecules?

Carbohydrates, lipids, proteins, and nucleic acids

What are carbohydrates primarily used for?

Providing cellular energy.

What is a monosaccharide?

A simple sugar made of one sugar unit.

What are monosaccharides primarily used for?

Making cellular energy (ATP).

What is a polysaccharide?

A complex carbohydrate made of many sugar units

What carbohydrate do animals use to store energy?

Glycogen.

What carbohydrate do plants use to store energy?

Starch

What carbohydrate makes up plant cell walls?

Cellulose.

What carbohydrate is found in fungal and arthropod cell walls/exoskeletons?

chitin

What carbohydrate is found in bacterial cell walls?

Peptidoglycan.

What is a major characteristic of lipids?

They are hydrophobic, meaning they do not mix well with water.

What are triglycerides?

Fat and oil molecules that cells use primarily to store energy.

What is a saturated fat?

A fat whose fatty acid chains contain no carbon-carbon double bonds.

What is an unsaturated fat?

A fat whose fatty acid chains contain one or more carbon-carbon double bonds.

What are phospholipids used for?

They are major components of cell membranes and other membrane-bound structures.

What are steroids?

Lipids containing four connected carbon rings.

Give examples of steroids.

Cholesterol and some hormones.

What are proteins made of?

Amino acids.

How many different amino acids do cells use to build proteins?

20

What is the primary job of proteins in cells?

They perform most of the cell's work.

Where can structural proteins be found?

In structures such as cell walls, cell membranes, flagella, cilia, and organelles.

What are HDL and LDL?

Transport proteins involved in carrying lipids through the body.

Give an example of a protein hormone.

Insulin.

What are enzymes?

Proteins that help speed up metabolic reactions.

Why are proteins important to metabolism?

Many proteins function as enzymes that catalyze metabolic reactions.

What are nucleic acids made of?

Smaller subunits called nucleotides.

What are the three types of nucleic acids listed in your notes?

DNA, RNA, and ATP.

What is the subunit of nucleic acids?

A nucleotide.