DAT Comprehensive Biology Review Flashcards

What are the four major biological macromolecules?

Carbohydrates, lipids, proteins, and nucleic acids.

What is the definition of a monomer?

A single subunit used to build larger molecules.

What is a polymer?

A chain of repeating monomers.

What process joins monomers together?

Dehydration synthesis.

What happens during dehydration synthesis?

A water molecule is removed and a bond forms between monomers.

What process breaks polymers apart?

Hydrolysis.

What happens during hydrolysis?

Water is added to break a bond between monomers.

Which specific reaction is used to build glycogen from glucose?

Dehydration synthesis.

Which specific reaction is used to break starch into glucose?

Hydrolysis.

Why is water required for digestion?

Digestion uses hydrolysis to break macromolecules apart.

What are the two major functions of carbohydrates?

Energy storage and structural support.

What is the monomer of carbohydrates?

Monosaccharide.

What is the polymer of carbohydrates?

Polysaccharide.

What specific type of bond joins monosaccharides?

Glycosidic bond.

What are the two types of glycosidic bonds?

Alpha ($\alpha$) and beta ($\beta$).

What is a monosaccharide?

A single sugar molecule.

Name three common monosaccharides.

Glucose, fructose, and galactose.

What is a disaccharide?

Two monosaccharides joined together.

Glucose plus fructose forms what disaccharide?

Sucrose.

Glucose plus galactose forms what disaccharide?

Lactose.

Glucose plus glucose forms what disaccharide?

Maltose.

What is a polysaccharide?

A long chain of monosaccharides.

What polysaccharide is used for energy storage in plants?

Starch.

What polysaccharide stores energy in animals?

Glycogen.

What polysaccharide provides structural support in plants?

Cellulose.

What polysaccharide provides structural support in fungi?

Chitin.

Which polysaccharides contain $\alpha$-glucose?

Starch and glycogen.

Which polysaccharide contains $\beta$-glucose?

Cellulose.

Why can humans digest starch but not cellulose?

Humans can break $\alpha$-glycosidic bonds but not $\beta$-glycosidic bonds.

What is the structural advantage of glycogen being highly branched?

It allows for rapid glucose release.

What happens to excess glucose in animals?

It is stored as glycogen.

What happens to excess glucose in plants?

It is stored as starch.

Which carbohydrate is most directly used by the cell to produce $ATP$?

Glucose.

What are the major functions of lipids?

Energy storage, insulation, signaling, and membrane structure.

Are lipids considered true polymers?

No.

What two components are triglycerides composed of?

Glycerol and three fatty acids.

What is the primary energy-storage lipid?

Triglyceride.

What type of bond joins fatty acids to glycerol?

Ester bond.

What is the definition of a saturated fatty acid?

It contains no carbon-carbon double bonds.

What is the definition of an unsaturated fatty acid?

It contains one or more carbon-carbon double bonds.

Which type of fatty acids increase membrane fluidity?

Unsaturated fatty acids.

Why do unsaturated fats increase fluidity?

Double bonds create bends that prevent tight packing.

Which type of fatty acids decrease membrane fluidity?

Saturated fatty acids.

What is a phospholipid?

A lipid with a phosphate-containing head and two fatty acid tails.

Which part of a phospholipid is hydrophilic?

The phosphate head.

Which part of a phospholipid is hydrophobic?

The fatty acid tails.

What structure do phospholipids form when placed in water?

Lipid bilayer.

What is cholesterol?

A steroid lipid found in animal cell membranes.

What are steroids characterized by structurally?

Four fused hydrocarbon rings.

What vitamin is derived from cholesterol?

Vitamin D.

What class of hormone is derived from cholesterol?

Steroid hormones.

What are porphyrins?

Molecules consisting of four joined pyrrole rings surrounding a metal ion.

What metal ion is found in hemoglobin?

Iron ($Fe$).

What metal ion is found in chlorophyll?

Magnesium ($Mg$).

Why do cells increase the amount of unsaturated fatty acids in cold temperatures?

To prevent membranes from becoming too rigid.

Why do cells increase the amount of saturated fatty acids in hot temperatures?

To prevent membranes from becoming too fluid.

What is the role of cholesterol in membrane fluidity?

It prevents both excessive rigidity and excessive fluidity.

Why are phospholipids considered ideal for biological membranes?

They are amphipathic (both hydrophilic and hydrophobic).

Which macromolecule stores the most energy per gram?

Lipids.

Which macromolecule forms the majority of cell membranes?

Phospholipids.

What lipid serves as the precursor to many hormones?

Cholesterol.

What are the major functions of proteins?

Structure, transport, enzymes, signaling, movement, immunity, storage, channels, pumps, and hormones.

What is the monomer of proteins?

Amino acid.

What is the polymer of proteins?

Polypeptide (protein).

What bond joins amino acids?

Peptide bond.

What are the three parts found in every amino acid?

Amino group, carboxyl group, and R group.

What determines the identity and chemical properties of an amino acid?

Its R group (side chain).

How many standard amino acids exist in nature?

20.

What is the primary structure of a protein?

The linear sequence of amino acids.

What specific bonds stabilize the primary structure of a protein?

Peptide bonds.

What is the secondary structure of a protein?

Local folding into $\alpha$-helices and $\beta$-pleated sheets.

What stabilizes the secondary structure of a protein?

Hydrogen bonds.

What is the tertiary structure of a protein?

The overall $3D$ shape of a single polypeptide.

What interactions stabilize the tertiary structure?

Hydrogen bonds, ionic interactions, hydrophobic interactions, and disulfide bridges.

What is the quaternary structure of a protein?

Multiple polypeptide chains assembled together.

What is a classic example of a protein with quaternary structure?

Hemoglobin.

Which amino acid is capable of forming disulfide bridges?

Cysteine.

What is denaturation?

The loss of protein shape and function.

What external factors can cause protein denaturation?

Heat, $pH$ changes, salts, and chemicals.

Which level of protein structure is destroyed first by heat?

Secondary structure.

Does denaturation usually break peptide bonds?

Usually no.

Why does cooking an egg turn the egg white from clear to white?

Protein denaturation.

Which level of protein structure determines all higher levels of folding?

Primary structure.

What happens to a protein if a single amino acid in the sequence changes?

The protein structure and function may change.

What is an enzyme?

A biological catalyst.

What is the function of an enzyme?

To increase the reaction rate.

Do enzymes change the $\Delta G$ of a reaction?

No.

Do enzymes change the equilibrium of a reaction?

No.

How do enzymes speed up chemical reactions?

By lowering the activation energy.

What is activation energy?

The energy needed to start a reaction.

What is a substrate?

The molecule acted upon by an enzyme.

What is an active site?

The region of the enzyme where the substrate binds.

What is the enzyme-substrate complex?

A temporary complex formed during the process of catalysis.

What is the concept of induced fit?

The active site changes shape slightly upon substrate binding to improve the fit.

What is a cofactor?

A nonprotein helper required for enzyme activity.

Name common examples of metal ion cofactors.

$Zn^{2+}$, $Mg^{2+}$, $Fe^{2+}$.

What is a coenzyme?

An organic cofactor.

Vitamins often function as what in the cell?

Coenzymes.

What is competitive inhibition?

An inhibitor competes with the substrate for the active site.

Can competitive inhibition be overcome by adding more substrate?

Yes.