Biochemistry

Where does the electron transport chain take place in eukaryotes?

Inner mitochondrial membrane

Where does the electron transport chain take place in prokaryotes?

Cell membrane

What type of RNA strand is itself an mRNA and can be transcribed directly into DNA?

Positive sense RNA strand

In which phase of the cell cycle is DNA replicated?

S phase

What term refers to the number of complete sets of chromosomes in a cell?

Ploidy

What are the chromosome pairs for females?

XX

What are the chromosome pairs for males?

XY

What is the identity of the amino acid represented by the structure shown? (Glycine)

Glycine

What is the identity of the amino acid represented by the structure shown? (Alanine)

Alanine

What is the identity of the amino acid represented by the structure shown? (Valine)

Valine

What is the identity of the amino acid represented by the structure shown? (Leucine)

Leucine

What is the identity of the amino acid represented by the structure shown? (Isoleucine)

Isoleucine

What is the identity of the amino acid represented by the structure shown? (Methionine)

Methionine

What is the identity of the amino acid represented by the structure shown? (Proline)

Proline

What is the identity of the amino acid represented by the structure shown? (Phenylalanine)

Phenylalanine

What is the identity of the amino acid represented by the structure shown? (Tryptophan)

Tryptophan

What is the identity of the amino acid represented by the structure shown? (Serine)

Serine

What is the identity of the amino acid represented by the structure shown? (Threonine)

Threonine

What is the identity of the amino acid represented by the structure shown? (Tyrosine)

Tyrosine

What is the identity of the amino acid represented by the structure shown? (Cysteine)

Cysteine

What is the identity of the amino acid represented by the structure shown? (Asparagine)

Asparagine

What is the identity of the amino acid represented by the structure shown? (Glutamine)

Glutamine

What is the identity of the amino acid represented by the structure shown? (Lysine)

Lysine

What is the identity of the amino acid represented by the structure shown? (Arginine)

Arginine

What is the identity of the amino acid represented by the structure shown? (Histidine)

Histidine

What is the identity of the amino acid represented by the structure shown? (Aspartate)

Aspartate

What is the identity of the amino acid represented by the structure shown? (Glutamate)

Glutamate

What is this group? (Indole)

Indole group

What is this group? (Imidazole)

Imidazole group

What is this group? (Guanidinium)

Guanidinium group

What are amino acids composed of?

Carboxyl (—COOH) group and amino (—NH2) group

Which amino acid is not chiral?

Glycine

What is the stereochemistry of the α-carbon in most eukaryotic amino acids?

L configuration

What configuration do all chiral amino acids except cysteine have?

(S) configuration

What do L and D indicate in terms of stereochemistry?

Relative configuration

What do S and R indicate in terms of stereochemistry?

Absolute configuration

What can amphoteric molecules act as?

Base or acid

What is the pH at which half of the species is deprotonated called?

pKa

What does a low pH do to amino acids?

Full protonation

What pH is an amino acid in zwitterion form?

Isoelectric point

What is a zwitterion?

When all charges cancel out, making a molecule neutral

What is the isoelectric point formula when there is no side chain?

pI = (pKa1 + pKa2) / 2

What is the isoelectric point formula when there is a neutral side chain?

pI = (pKa1 + pKa2) / 2

What is the isoelectric point formula when there is a basic side chain?

pI = (pKa1 + pKa2) / 2

What is the isoelectric point formula when there is an acidic side chain?

pI = (pKa1 + pKa2) / 2

What is the pH at the midpoint of a titration?

pKa

What is the pH at the equivalence point of a titration?

pI

What does the 1° structure of proteins refer to?

The linear sequence of amino acids in a peptide

What does the 2° structure of proteins refer to?

The local folding of neighboring amino acids including α-helices and β-pleated sheets

What does the 3° structure of proteins refer to?

The 3-D shape of a single polypeptide chain

What does the 4° structure of proteins refer to?

The interaction between peptides in proteins that contain multiple subunits

What are α-helices?

Clockwise coils around a central axis and a common 2° protein structure

What are β-pleated sheets?

Rippled strands that can be parallel or antiparallel and a common 2° protein structure

What amino acid can interrupt 2° protein structure?

Proline

What is denaturation?

When a protein loses its 4°, 3°, and 2° structures due to broken non-covalent interactions

What effect pushes hydrophobic R groups to the interior of a protein?

Hydrophobic effect

What are disulfide bonds?

Covalent bonds formed when cysteine molecules are oxidized

What are conjugated proteins?

Complex proteins consisting of amino acids combined with other substances

What is the attached molecule in a conjugated protein?

Prosthetic group

What do peptide bonds link between amino acids?

The α-carboxyl group of one amino acid to the α-amino group of the next amino acid

What are enzymes?

Reusable catalysts that are unchanged by the reactions they catalyze

What do exergonic reactions do to energy?

Release energy

What do endergonic reactions do to energy?

Require energy

What is an oxidoreductase?

An enzyme that catalyzes REDOX reactions involving electron transfer

What does a transferase do?

Moves a functional group from one molecule to another

What does a hydrolase do?

Catalyzes cleavage with the addition of H2O

What does a lyase do?

Catalyzes cleavage without the addition of H2O and without transferring electrons

What does an isomerase do?

Catalyzes the interconversion of isomers

What does a ligase do?

Joins two large biomolecules, often of the same type

What does a lipase do?

Catalyzes the hydrolysis of fats

What does a kinase do?

Adds a phosphate group from ATP to a substrate

What does a phosphatase do?

Removes a phosphate group

What does a phosphorylase do?

Adds a phosphate group from inorganic phosphate to a substrate

What is a Michaelis-Menten curve?

Hyperbolic

What is Km?

The substrate concentration that gives a reaction rate halfway to Vmax

What is Vmax?

The maximum rate at which an enzyme can catalyze a reaction

What is the Michaelis–Menten equation?

V0 = Vmax[S] / (Km + [S])

What type of curve do cooperative enzymes display?

Sigmoidal

What is cooperative binding?

When the binding of the first molecule changes the binding affinity of the second molecule

What is the active site?

The site of catalysis on an enzyme

What is the lock and key theory?

The enzyme and substrate fit together like a key into a lock

What is the induced fit theory?

The enzyme and substrate undergo conformational changes to interact fully

What is a cofactor?

A metal cation required by some enzymes

What is a coenzyme?

An organic molecule required by some enzymes

What is feedback inhibition?

When an enzyme is inhibited by high levels of a product from a later step in the pathway

What is a competitive inhibitor?

Binds at the active site and prevents the substrate from binding

What is an uncompetitive inhibitor?

Binds only with the enzyme-substrate complex

What is a noncompetitive inhibitor?

Binds at the allosteric site away from the active site

What happens in competitive inhibition according to Vmax and Km?

Vmax has no change; Km goes up

What happens in uncompetitive inhibition according to Vmax and Km?

Both Vmax and Km go down

What happens in noncompetitive inhibition according to Vmax and Km?

Vmax goes down; Km has no change

What are the Lineweaver-Burk Plot intercepts and slope?

X-intercept = -1/Km; Y-intercept = 1/Vmax; Slope = Km/Vmax

What does the Lineweaver Burk competitive plot describe?

The activity of a competitive inhibitor

What does the Lineweaver Burk uncompetitive plot describe?

The activity of an uncompetitive inhibitor

What does the Lineweaver Burk noncompetitive plot describe?

The activity of a noncompetitive inhibitor

What does it mean that Lineweaver-Burk plots are double reciprocal plots?

X-intercept is -1/Km and Y-intercept is 1/Vmax, both being reciprocals

What is an irreversible inhibitor?

An inhibitor that covalently binds to the active site of an enzyme, eliminating activity

What is suicide inhibition?

An irreversible form of enzyme inhibition when an enzyme binds a substrate analog and forms an irreversibly complex

What is an allosteric effector?

Binds at the allosteric site and changes the conformation of the enzyme

What is a homotropic effector?

An allosteric regulator that is also the substrate