BIS 2A Lecture Notes - Lecture 4: Cell Nucleus, Acid Dissociation Constant, Olive Oil

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29 Apr 2019

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An attractive interaction between hydrogen and an electronegative atom of another molecule. Not limited to water - only needs hydrogen bond donor (h+) and hydrogen bond acceptor (-) Primarily between hydrogen and nitrogen, not on carbon. Chemical groups that can interact with other molecules. One molecule of a equals one molecule of b. Assumed that reactions are equal so as a molecule of a changes, a molecule of b changes as well, and assumed that reactions take place in an aqueous solution. When written as a b then a or b can be the reactant or the product, left is usually the reactant. Keq = [b]/[a] ph ph=-log[h+] ph 7 = 10-7 protons per mole. A high ph has a low proton concentration, bases = low protons pka ph where functional group is halfway ionized and the other half is not ionized. Ka is concentration of protonated form pka = ph when protonated form concentration = deprotonated concentration.

Related Questions

1. Use the following definitions and phrases to describe to which molecules of life and their subunits it belongs:

a. Energy-storing molecule, typically water soluble - b. Subunits are called monosaccharides â c. Used to speed chemical reactions - d. Subunits are joined to each other with peptide bonds - e. Most prevalent molecule in cell membranes - f. Some of them function as hormones - g. Used for storing, transmitting, and executing genetic information - h. Subunits are nucleotides

2. Weak hydrogen bonds between water molecules are responsible for the many properties of water. Acidity is expressed as pH. Buffers stabilize pH. a. What characteristics of water molecule makes it polar? Provide two examples why this property is important in microbiology. b. What is the role of buffers in living organisms, including microbes? c. What must be added to pure water to decrease OH- and/or H+ concentration, respectively

3. Carbohydrates serve as storage molecules and structural material. Lipids are hydrophobic molecules; phospholipids are main component of cell membranes. Protein has a complex structure based on identity and sequence of amino acids. Nucleic acids (DNA and RNA) are genetic station of storage information and for synthesis of proteins. ATP serve as the main energy source in the living cell. a. Name the subunits (building blocks) of carbs, simple lipids, proteins, and nucleic acids b. What level of protein structure is described as an alpha helix? c. If DNA is placed in boiling water, what and how the molecule would change?

The type of macromolecule found in highest concentration on a weight basis in a HeLa cell is

protein.

lipid.

polysaccharide.

nucleic acid.

water

Co and Zn ions are required by humans in

microgram amounts.

gram or near gram amounts.

kilogram amounts.

d. milligram amounts.

Which description best characterizes the length of a hydrogen bond between water molecules?

About the same length as the calculated van der Waals distance for two water molecules.

About the same length as a covalent O----H bond.

Shorter than a covalent O---H bond.

Longer than a covalent O---H bond, but shorter than the calculated van der Waals distance between water molecules.

Which of the following statements about water is not true?

Water will hydrogen bond into highly ordered structures or "cages" around non-polar molecules.

The electron-rich oxygen atom of one water molecule can interact with an electron-poor hydrogen on another water molecule to form a hydrogen bond.

Water is a key player in the energetics of the hydrophobic effect.

In an ice crystal water molecules pack into open lattices consisting of five-membered oxygen rings.

At 25 degrees celsius liquid water is about 85% as hydrogen bonded as the water in ice, with each molecule in an average of 3.4 hydrogen bonds.

Which of the following is the strongest?

Ionic interactions

Permanent dipole - permanent dipole interactions

London dispersion forces

Co-linear hydrogen bonds

Which of the following is the best explanation for the hydrophobic effect?

It is caused by the attraction of hydrophobic groups for each other.

It is an entropic effect caused by the tendency of hydrophobic groups to increase their entropy by associating with other hydrophobic groups.

It is an entropic effect, caused by the tendency of water molecules to increase their entropy by excluding hydrophobic groups, which they must otherwise surround with highly ordered structures.

It is caused by the attraction of water for hydrophobic groups.

It is an entropic effect, caused by the tendency of water molecules to increase their entropy by forming highly ordered structures around the hydrophobic groups.

Which of the following is NOT defined as a buffer? (pKa PIPES-H⁺ = 6.76; pKa MOPS-H⁺ = 7.15; pKa HEPES-H⁺ = 7.47)

0.15 M MOPS, pH 6.50

0.05 M HEPES-H⁺ / 0.04 M HEPES

0.20 M PIPES, pH 7.97

0.01 M HEPES, pH 7.30

Life Chemistry LabReport

Elements of Living Organisms
Name the five most abundant elements found in the humanbody.

Cells organize into tissues which work together to form

What is the difference between an atom and an element?

Molecules

Is glucose an atom or molecule? What are the atoms inglucose?

How many bonds can oxygen form?

Is C₆H₁₂O₆ a molecular orstructural formula? What is the name of this molecule?

Based on lab, Section II, draw and label a ball and stickrepresentation of a carbon dioxide, water and ethyl alcoholmolecule. Use circles to designate atoms and lines for bonds, thenindicate the chemical symbol for each atom. Sign, date and preparean image of your drawing and include it with this lab report.

Molecular Make Up of Living Organisms

Name the four groups of organic molecules.

_______ are the most abundant organic molecules in livingorganisms.

Name a polysaccharide, monosaccharide, protein and alipid.

Go to the lab, Section 3, Exercises 2, 3, 4 and 5 to completethe following table:

Type of Organic Molecule	Reagent	Sample Tested	Positive Color	Negative Color
Carbohydrate (starch)	Iodine
Sugar	Benedictâs solution
Lipid (fat)	Sudan IV
Protein	Biuret

Go to the lab, Section 3, Exercise 6 to locate starch in potatocells. Describe the microscopic appearance of starch in terms ofcolor and location within the cells.

Measurement of pH

What substance has an equal number of hydrogen ions(H⁺) and hydroxide ions (OH^-)?

What is the pH of the above substance?

How does the addition of hydroxide ions (OH^-) affectthe pH of your stomach?

Go to lab, Section 4, Exercise 7 to test the pH of commonsolutions. Which solution tested had a pH closest to neutral? Whichsolution was most acidic?

Summary Questions

What is the smallest subunit of carbohydrates?

Which reagent could be used to test for diabetes?

A member of your family has a high blood cholesterol count. Yousee âfat freeâ crackers in the grocery store and decide to test theproduct for the presence of lipids. How would this testproceed?

A family member has been cautioned about eating foods high insugar. Explain how a test could be run for the presence ofsugar.

Explain how to test for the presence of protein in milk.

A friend complains of stomach acidity. Which substance testedmight safely help relieve your friendâs symptoms?

Explain how solutions are classified as acids or bases. Then,give an example of a weak acid.

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BIS 2A Lecture Notes - Lecture 4: Cell Nucleus, Acid Dissociation Constant, Olive Oil

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