Biology Rev01

What are biomolecules?

The chemical compounds that make up living organisms

What are the four groups of biomolecules?

Carbohydrates, lipids, proteins, nucleic acid

What are carbohydrates?

Organic molecules composed of carbon, hydrogen and oxygen that serve as a primary energy source for cells

What is the general ratio of hydrogen to oxygen in carbohydrates?

Approximately 2:1 (similar to water)

What is a monosaccharide?

A single sugar molecule that is the basic unit of carbohydrates

Give examples of monosaccharides

Glucose and fructose

What is a disaccharide?

Two monosaccharides joined by a glycosidic bond

Give examples of disaccharides

Sucrose, lactose and maltose

What is a polysaccharide?

A polymer made of many monosaccharides e.g. starch and cellulose

What is the function of starch?

Energy storage in plants

What is the function of cellulose?

Structural support in plant cell walls

What is the function of glycogen?

Energy storage in animals

What is the function of glucose?

Primary fuel source for animals and plants

What are lipids?

Hydrophobic biological molecules used for energy storage, insulation and membrane structure

What are the main components of triglyceride?

One glycerol molecule and three fatty acids

What is the primary function of triglycerides?

Long-term energy storage

What is an unsaturated fatty acid?

A fatty acid containing one or more carbon-carbon double bonds

Why are phospholipids important?

They form the main structure of the cell membrane

What are the two parts of a phospholipid?

A hydrophilic phosphate head and a hydrophobic fatty acid tail

What is cholesterol?

A steroid lipid that helps regulate membrane fluidity

What are proteins?

Polymers of amino acids that perform structural and functional roles in cells

What is the monomer of a protein?

An animo acid

How many common amino acids are used to build proteins?

20

What bond joins amino acids together

A peptide bond

What is a polypeptide?

A chain of amino acids linked by peptide bonds

What determines a protein’s function?

It’s three dimensional shape

What is the primary structure of a protein?

The amino acid sequence

What is the secondary structure of a protein?

Local folding such as alpha helices and beta sheets

What is the tertiary structure of a protein?

The overall three dimensional shape of a single polypeptide

What is the quaternary structure of a protein?

The arrangement of multiple polypeptide units (if applicable)

What is denaturation?

Loss of protein structure and function due to changes in temperature, pH or chemicals

What are enzymes?

Proteins that speed up chemical reactions by lowering activation energy

What are nucleic acids?

Biomolecules that store and transmit genetic information

What are the two types of nucleic acid?

DNA and RNA

What is a monomer of nucleic acid?

A nucleotide

What are three components of a nucleotide?

A phosphate group, a sugar and a nitrogeneous base

What sugar is found in DNA?

Deoxyribose

What sugar is found in RNA?

Ribose

Which bases are found in DNA?

Adenine, thymine, cytosine and guanine

Which base replaces thymine in RNA?

Uracil

What is the primary function of DNA?

Long-term storage of genetic information

What is the primary function of RNA?

Assisting with protein synthesis

Which biomolecule provides quick energy?

Carbohydrates

Which biomolecule provides long-term energy storage?

Lipids

Which biomolecules act as enzymes?

Proteins

Which biomolecule stores genetic information?

Nucleic acid

What is the cell membrane?

A selectively permeable barrier that regulates movement of substances into and out of the cell

What does selectively permeable mean?

Allowing some substances to pass while restricting others

What is the main structure of the cell membrane?

A phospholipid bilayer with embedded proteins

Why do phospholipids form a bilayer?

Their hydrophilic heads face water while their hydrophobic heads avoid water

What is a concentration gradient?

A difference in concentration between two areas

What does moving down a concentration gradient mean?

Moving from high concentration to low concentration

What does moving against a concentration gradient mean?

Moving from low concentration to high concentration

What is passive transport?

Movement of substances across a membrane without energy (ATP)

Does passive transport require ATP?

No

In which direction does passive transport occur?

Down a concentration gradient

What is diffusion?

The net movement of particles from an area of high concentration to low concentration

What causes diffusion?

Random movement of molecules

Is diffusion passive or active?

Passive

What type of molecules cross membranes by simple diffusion?

Small nonpolar molecules such as oxygen and carbon dioxide

What happens to diffusion at equilibrium?

Molecules continue moving but there is no net movement

What is osmosis?

The diffusion of water across a selectively permeable membrane

In which direction does water move during osmosis?

From lower solute concentration to higher solute concentration

Why does water move during osmosis?

To balance solute concentrations on both sides of the membrane

Is osmosis passive or active?

Passive

What is a hypotonic solution?

A solution with a lower solute concentration than the cell

What happens to the cell in a hypotonic solution?

Water enters the cell

What is a hypertonic solution?

A solution with a higher solute concentration than the cell

What happens to the cell in a hypertonic solution?

Water leaves the cell

What is an isotonic solution?

A solution with the same solute concentration as the cell

What happens to a cell in an isotonic solution?

No net movement of water

What is facilitated diffusion?

Passive movement of substances through membrane proteins

Does facilitated diffusion require ATP?

No

Why is facilitated diffusion needed?

Some molecules are too large or charged to cross the membrane directly

What types of proteins assist with facilitated diffusion?

Channel and carrier proteins

Give an example of a molecule transported by facilitated diffusion?

Glucose

What is active transport?

Movement of substances across a membrane using energy

Does active transport require ATP?

Yes

In which direction does active transport move substances?

Against a concentration gradient

Why do cells use active transport?

To maintain concentration differences

What type of proteins are used in active transport?

Transport proteins or protein pumps

What is a common example of active transport?

Sodium potassium pump

What is the function of the sodium-potassium pump?

Maintains ion gradients across the cell membrane

How many sodium ions are pumped out per cycle

3

How many potassium ions are pumped out per cycle

2

Does the sodium-potassium pump require ATP?

Yes

What is bulk transport?

Movement of large materials using membrane vesicles

What are the two main types of bulk transport?

Endocytosis and exocytosis

What is endocytosis?

The process of bringing materials into the cell using vesicles

Does endocytosis require energy?

Yes

What is phagocytosis?

A type of endocytosis where a cell engulfs large particles

What is pinocytosis?

A type of endocytosis where a cell takes in extracellular fluid

What is exocytosis?

The process of releasing materials from a cell using vesicles

Does exocytosis require energy?

Yes

Give an example of exocytosis

Release of hormones, neurotransmitters, or digestive enzymes

Which transport mechanisms are passive?

Diffusion, osmosis, and facilitated diffusion

Which transport mechanisms require ATP?

Active transport, endocytosis, and exocytosis

Which transport mechanism moves water?

Osmosis

Which transport mechanism uses channel proteins but no ATP?

Facilitated diffusion

Which transport mechanism moves substances against a concentration gradient?

Active transport