Bioprinc - Exam 1

What are the defining characteristics of life?

Organized structure, heritable information (DNA/RNA), energy use, growth, reproduction, and response to the environment.

What is the smallest unit of life?

The cell.

Why is a virus not considered alive?

It is not made of cells and cannot carry out life processes on its own.

What carries heritable information?

DNA or RNA.

Where do animals get their energy?

From food.

What does 'structure and function' mean in biology?

A structure's shape is related to what it does.

What is the correct hierarchy of biological organization (smallest → largest)?

Atoms → Molecules → Organelles → Cells → Tissues → Organs → Organ Systems.

Give an example of a biological molecule.

DNA.

What are prokaryotic cells?

Small cells without a nucleus (e.g., bacteria).

What are eukaryotic cells?

Cells with a nucleus and membrane-bound organelles.

What bases differ between DNA and RNA?

DNA uses thymine (T); RNA uses uracil (U).

What are the steps of the scientific method?

Observation → Question → Hypothesis → Prediction → Test (experiment/observation).

What makes a hypothesis scientific?

It must be testable and falsifiable.

What is a scientific theory?

A well-supported explanation based on repeated testing and evidence.

Name two major biological theories.

Cell Theory and Evolution Theory.

What is matter?

Anything that takes up space and has mass.

What is mass?

The amount of matter in an object.

What is weight?

The force of gravity acting on mass.

What is an element?

A substance that cannot be broken down into other substances.

How many naturally occurring elements exist?

92.

Which four elements make up ~96% of living matter?

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

What elements are common in living organisms besides CHON?

Phosphorus (P) and Sulfur (S).

Why is calcium important?

Bone structure.

What happens with iodine deficiency?

Thyroid enlargement (goiter).

What happens with nitrogen deficiency in plants?

Poor growth.

What is the smallest unit of matter that retains element properties?

An atom.

What particles are found in the nucleus?

Protons and neutrons.

Where are electrons located?

Outside the nucleus in an electron cloud.

What is the charge, mass, and location of a proton?

+1 charge, 1 amu, nucleus.

What is the charge, mass, and location of a neutron?

0 charge, 1 amu, nucleus.

What is the charge, mass, and location of an electron?

−1 charge, negligible mass, outside nucleus.

What does 1 amu equal?

1.7 × 10⁻²⁴ grams.

What is the atomic mass formula?

Protons + neutrons.

How do you calculate neutrons?

Atomic mass − number of protons.

How many neutrons does hydrogen have?

0.

What is an isotope?

An atom with the same protons but different numbers of neutrons.

What is radioactivity used for in biology/medicine?

Dating fossils and medical imaging (PET scans).

What is the Bohr model?

A model showing electrons in energy shells around the nucleus.

What happens to electrons as they move farther from the nucleus?

They have higher energy.

What happens if electrons absorb enough energy?

They can leave the atom.

How many electrons fit in each shell?

1st: 2, 2nd: 8, 3rd: 8.

What is an orbital?

A 3D region where an electron is found 90% of the time.

How do electrons prefer to exist in orbitals?

In pairs.

What is the valence shell?

The outermost electron shell.

Why are valence electrons important?

They determine bonding behavior.

What determines chemical bonding?

Valence electrons.

Acid

a substance that INCREASES the hydrogen ion concentration in a solution; GIVE protons; PRODUCE H+ ions

Base

a substance that DECREASES the hydrogen ion concentration in a solution; pH above 7; ACCEPTS protons; PRODUCES OH- ions

Covalent Bond

A bond formed by atoms sharing electrons

Strongest of all the bonds

Covalent Bond

Polarity

The separation of electrical charge in a molecule; positive and negative

Polar covalent bond

uneven electronegativities; uneven share of electrons; causes separation of charges

Nonpolar covalent bond

even electronegativity; even share of electrons; causes equal charges

How many electrons are involved in a covalent bond?

Two

Octect rule

Determines how many covalent bonds an atom can form

Hydrogen Bond

Bond between molecules where one is hydrogen and other is electronegative

Ionic bond

Bond formed by transfer of electrons; between positive ion and negative ion; non-metal and metal

Electronegativity

The ability of an atom to attract shared electrons; higher electronegativity=higher attraction

Cation

Positive ion

Anion

Negative ion

How many electrons are involved in a double covalent bond?

4

Oxidation

losing electrons

Reduction

gaining electrons

Molecules

2 or more atoms held together; Ex: H2, O2, H2O

Compound

A new substance formed when 2 or more elements combine; Ex: H2O, Na+ Cl-, C6H12O6

NaCl

Sodium chloride; table salt; ionic compound composed of sodium and chloride ions

Buffer

Used to correct pH

What is the human body’s natural buffer?

blood

Isomer

molecules with the same chemical formula but different arrangements

Enatiomers

Molecules that are mirror images of each other

pH

Measures how acidic or basic a solution is

pH has a log of?

10

Functional Groups

Attachments that replace hydrogens bonded to compound

What are function groups responsible for?

Molecules chemical reactivity

Hydroxyl Group

Alcohol (-OH)

Carbonyl Group

Aldehydes / Ketones; carbon double bonded to oxygen

Carboxyl Group

Carboxylic Acid; hydroxyl and carbonyl bonded to SAME carbon atom

Amines Group

Amino; Nitrogen bonded to two hydrogen

Phosphate Group

Phosphate; Phosphate surrounded by oxygen

What is the importance of Phosphates?

Energy production (ATP); Genetic material (DNA)

ATP

Adenosine-Tri-Phosphate

ATP’s purpose

Energy source for cells

DNA

Deoxyribo-Nucleic-Acid

DNA’s purpose

Stores genetic information / instructions

RNA

Ribo-Nucleic-Acid

RNA’s purpose

Converts genetic information from DNA into proteins

Hydrocarbons

Chain of carbon and hydrogen molecules

Nomenclature (1-6)

Number of carbon atoms in a molecule are designated by prefixes

1 Carbon

Meth-

2 Carbons

Eth-

3 Carbons

Prop-

4 Carbons

But-

5 Carbons

Pent-

6 Carbons

Hex-

Single bonds

-ane

Double bonds

-ene

Macromolecules (1-4)

Large organic molecules; grouped by chemical properties

Carbohydrates

PROVIDE energy; formed by glucose

Lipids

STORE energy; insulation; hormones; makes up cell membrane

Protiens

3D polymers of amino acids; includes enzymes