Biochem Exam 1

What makes up a biological macromolecule?

Monomers

What are the 4 most abundant elements in the human body?

Carbon, oxygen, hydrogen, nitrogen

Define a reaction pathway

A distinct set of metabolic reactions

What are the polymers of amino acids?

proteins

Define covalent bonds

Bonds formed by atoms that share electrons

How many covalent bonds can carbon form?

4

How many covalent bonds can nitrogen form?

3

How many covalent bonds can oxygen form?

2

How many covalent bonds can hydrogen form?

1

What is the pH of an amino acid?

7

Circle the functional groups in this compound? What is the name of the compound?

Amino acid

Draw the hydrogen bonding network in a solution of methanol in water. Mark the H-bond donor and the H-bond acceptor

Circle the H-Bond donors in this molecule

Circle the H-bond acceptors in this structure

What ΔEN value range shows that a polar bond is present?

0.5-1.9

Why is water always polar?

It has a permanent dipole

How many hydrogen bonds can 1 water molecule form with another water molecule?

4

Define dispersion forces

due to temporary polarity in the molecules because of unequal electron distribution

Define dipole-dipole attractions

due to permanent polarity in the molecules due to their structure

Define hydrogen bonding

very strong dipole–dipole attraction; H is attached to an electronegative atom (N, O, F)

Define ion-dipole interactions

between ions and water molecules in aqueous solution

What allows electrolytes to dissolve in water?

ion-dipole interactions

What is the bond energy of a charge-charge interaction?

13-17kJ/mol

What is the bond energy of a hydrogen bond interaction?

2-21kJ/mol

What is the bond energy of a van der waals interaction?

0.4-0.8kJ/mol

The strength of noncovalent interactions _____ with ______ in distance

drops ; increase

What are induced dipoles

temporary polarity created due to pi-pi stacking interactions

What impact does extreme pH have on protein structure?

Disrupts hydrogen bonds leading to loss of structure

Explain why ionic compounds are able to be dissolved in water

They have a high dielectric constant of water screens which decreases the electrostatic force between the oppositely charged ions

What is a hydrogen bond acceptor? (HBA)

O or N with a lone pair

What is a hydrogen bond donor? (HBD)

O or N covalently bonded to H

Which distance value between an HBD and HBA signifies a strong hydrogen bond?

2.8

What are the 4 types of macromolecules?

Proteins, lipids, polysaccharides, nucleic acids

How much of the human body is composed of water?

70%

What are the 4 most abundant elements in all living systems

Oxygen, carbon, hydrogen, nitrogen

Which element is involved in both the transfer of energy and the structure of nucleic acids?

Phosphorus

What are the 2 main components that make up the phospholipid bilayer?

Glycoproteins and cholesterol

Define organelles

specialized structures inside a cell that perform specific jobs to keep the cell alive and healthy

Define the central dogma

genetic information flows in one direction from DNA to RNA to a protein

What are the 5 main concepts of biochemistry?

1. Biochemistry is an observational and experimental science

2. The molecules and pathways in life are common amongst organisms

3. Biochemistry is an interdisciplinary science

4. Life obeys the laws of physics

5. Life obeys the laws of chemistry

What happens to energy in an exergonic reaction?

It is released

What happens to energy in an endergonic reaction

It is absorbed

Define the zeroth law of thermodynamics

when two objects are separately in thermodynamic equilibrium with a third object, they are in equilibrium with each other

Define the 1st law of thermodynamics

energy can be converted from one form to another but cannot be created or destroyed

Define the 2nd law of thermodynamics

the entropy of an isolated system will tend to increase to a maximum value

Define the 3rd law of thermodynamics

the entropy of a perfect crystal at absolute zero, 0 K, is zero

Define homeostasis

self-regulating process where an organism maintains a stable, balanced, internal environment while adjusting to external conditions

What are the 2 ways biomolecules interact?

Shape and charge complementarity

Define oxidation-reduction reactions

basis of many biochemical reactions and pathways involving the transfer of electrons

What is the monomer and bond name involved in a protein?

Monomer - amino acid

Bond - peptide bond

What is the monomer and bond name involved in a polysaccharide?

Monomer - monosaccharide

Bond - glycosidic bond

What is the monomer and bond name involved in a nucleic acid?

Monomer - nucleotide

Bond - phosphodiester bond

What type of reaction occurs to join monomers into biopolymers and what compound is released?

Condensation reaction, water is released

Define amphipathic molecules

the foundation for biological membranes with both hydrophobic and hydrophilic groups

What are 2 examples of amphipathic molecules?

Phospholipids and cholesterol

Draw the following functional groups:

Methyl

Ethyl

Aldehyde

Ketone

Carboxyl

Alcohol

Phenyl

Ether

Ester

Amine

Amide

Imidazole

Phosphate

.

What is the function of the nucleus?

membrane-bound structure in a eukaryotic cell that contains DNA wrapped around proteins

What is the function of the nuclear envelope?

surrounds the nucleus

What is the function of the nucleolus?

in the nucleus. Transcribes ribosomal RNAs and assembles processed ribosomes

What is the function of the cytoplasm?

holds organelles in place, gives the cell its shape, and acts as the site for vital chemical reactions

What is the function of the cytoskeleton?

structural framework of the cells and tracks internal movement

What is the function of ribosomes?

consists of RNA and proteins and use mRNA to make proteins

What is the function of the smooth endoplasmic reticulum?

makes lipids and stores calcium ions

What is the function of the rough endoplasmic reticulum?

covered in ribosomes; synthesizes, folds, modifies, and transports proteins

What is the function of the mitochondria?

makes and supplies the cell with ATP via oxidative phosphorylation

What is the function of lysosomes?

contain digestive enzymes and remove damaged organelles and pathogens

What is the function of the golgi apparatus?

Modifies, sorts, and packages secretory proteins and lipids for storage or transport

What is the function of peroxisomes?

carries out cellular reactions involving the transfer of hydrogen from a substrate to O2

Name 4 common examples of a lipid

1. Cholesterol

2. Palmitic acid

3. Phosphatidyl serine

4. Triacylglycerol

Name 5 common examples of a carbohydrate

1. Cellulose

2. Glucose

3. Sucrose

4. Fructose

5. Starch

Name 6 common examples of a protein

1. Insulin

2. Thrombin

3. Trypsin

4. Myoglobin

5. Urease

6. Antibodies

Name 4 common examples of nucleic acids

1. DNA

2. RNA

3. Genes

4. Polynucleotides

Is urea a macromolecule?

No

How many HBA’s are in this molecule? Mark the HBA’s

3, the 3 O’s

Write a reaction showing a bronsted-lowry acid

HCl + NH3 → Cl- + NH4+

Write a reaction showing a bronsted-lowry base

NH3 + H2O → NH4+ + OH-

Define aliphatic group

Carbon atoms in chains rather than a ring

Draw a chiral molecule and mark the chiral center

A weak acid HA is 2% ionized in a 0.25 M solution.

1. Calculate the Ka of this acid;

2. Calculate the pH of this solution.

1. 1.02 × 10^-4

2. 2.30

The pH of acetic acid varies with its concentration. Ka of acetic acid is Ka = 1.74 x 10-5

Calculate the pH of a acetic acid solution with 0.035 M acetic acid

3.11

Calculate the pH of a solution prepared by dissolving 0.560 g of KOH in 250 mL of water.

12.60

What is the pH of a 0.15M HCl solution

0.82

Calculate the pH of a buffer that contains 0.15 M acetic acid (CH3COOH) and 0.25 M sodium acetate (CH3COONa). Ka = 1.74 x 10–5 for acetic acid

4.98

What is the pH of the buffer made by mixing 150mL 1.50 M acetic acid with 100mL 0.35 M sodium acetate? Ka = 1.74 x 10-5

3.95

A 100 mL sample of a 0.10 M acetate buffer, pH 4.40, is treated with 1.0 mL of a 1.00 M NaOH solution. What is the pH of the final solution? Ka = 1.74 × 10^-5

4.59

What volume of 1.0 M NaOH should be added to 150 mL of 0.25 M lactic acid solution to make a buffer with pH 4.20? Lactic acid, Ka = 1.38 x 10–4

25.7mL

What does a buffering capacity of a buffer depend on

Concentration

High buffering capacity = _____ concentration

high

Write the step-wise ionization for H3PO4 .

H₃PO₄ ⇌ H⁺ + H₂PO₄⁻

H₂PO₄⁻ ⇌ H⁺ + HPO₄²⁻

HPO₄²⁻ ⇌ H⁺ + PO₄³⁻

What is the pH equation?

pH = -log[H+]

What is the pOH equation?

pOH = -log[OH-]

What is the relationship between pH and pOH?

pH + pOH = 14

What are Bronsted-Lowry acids?

H+ donors

What are Bronsted-Lowry bases?

H+ acceptors

What happens when strong acids and bases are added to water?

They dissociate completely

What does LogY = X translate to?

10^X = Y

What determines the strength of an acid?

The percentage of acid molecules that ionize when dissolved in water

What does a higher percent ionization mean?

A stronger acid

What does Ka measure?

acid strength

What does a larger Ka mean?

stronger acid