Chemistry of Living Organisms

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What type of hybridization occurs in the methane molecule, $CH_4$?

$sp^2$

$sp$

$s^2p^2$

$sp^3$ (correct)

Which of the following best describes the electron cloud around the C-H bonds in methane?

Spherically symmetrical

Cylindrically symmetrical (correct)

Planar and symmetrical

Asymmetrical

What is the bond energy of each C-H bond in methane?

83 kcal/mole

104 kcal/mole

110 kcal/mole

99 kcal/mole (correct)

Which orbital hybridization occurs in ethylene, $CH_2=CH_2$?

$sp^2$ Signup and view all the answers

What type of molecular orbital is formed by the overlap of the two unused $2p$ orbitals in ethylene?

$ au$-type orbital Signup and view all the answers

How many sigma bonds are formed in the ethane molecule, $CH_3-CH_3$?

6 Signup and view all the answers

What type of molecular orbitals are formed in the bonding of C-H in both methane and ethane?

$ au$-type orbitals Signup and view all the answers

What distinguishes a $ ext{π}$-type molecular orbital in ethylene from a $ ext{σ}$-type orbital?

It has electron density above and below the plane Signup and view all the answers

What represents the most prevalent substance in the weight of a typical mammal?

Water Signup and view all the answers

Which ions are commonly found dissolved in water within living organisms?

$K^+$ and $Na^+$ Signup and view all the answers

How are proteins characterized in biological systems?

Long-chain polymers of amino acids Signup and view all the answers

What serves as the 'specifications' for biological processes in living organisms?

Nucleic acids Signup and view all the answers

What role do lipids play within living organisms?

Part of the structural components of cells Signup and view all the answers

Which statement about polymers is accurate?

Branched-chain polymers have varying physical properties Signup and view all the answers

What is the predominant function of ions in living organisms?

Facilitating chemical reactions Signup and view all the answers

What distinguishes living matter from nonliving matter in terms of chemistry?

Complexity and organization of reactions Signup and view all the answers

At physiological pH 7, which amino acids will predominantly exist in their charged forms?

Lys and Arg Signup and view all the answers

Which of the following best describes the ionization state of the Tyr hydroxyl group at pH 7?

Weakly acidic with 0.1 percent ionization Signup and view all the answers

What role do nonpolar residues primarily play in proteins?

Create a nonpolar environment away from water Signup and view all the answers

Which classification of amino acids is characterized by being negatively charged and often located on the surface of proteins?

Acidic residues Signup and view all the answers

Which statement about His at pH 7 is accurate?

It exists largely in an uncharged state Signup and view all the answers

What is the bond energy difference between a carbon-carbon double bond and a single bond?

64 kcal/mole Signup and view all the answers

What occurs when one end of the ethylene molecule is twisted by $90^ ext{o}$?

The double bond becomes a single bond. Signup and view all the answers

How are the carbon-oxygen bonds in an ionized carboxyl group characterized?

Two equivalent bonds with intermediate length. Signup and view all the answers

What is a common misconception regarding resonance in bond structures?

Resonance involves a static flipping between two structures. Signup and view all the answers

What leads to resonance stabilization energy in a bond structure?

The presence of multiple resonance structures. Signup and view all the answers

In the context of proteins, what is the primary role of side chains?

They are responsible for the specific functions of the protein. Signup and view all the answers

What is the role of nonpolar groups in the stabilization of a protein molecule in aqueous solution?

They contribute to forming the 'oil drop' model. Signup and view all the answers

Which statement best describes the behavior of electrons in delocalized bonds?

They have lower energy since they can move freely. Signup and view all the answers

What is suggested to be misleading about the term 'resonance' in chemistry?

It implies that bond structures are dynamic. Signup and view all the answers

Which of the following amino acids is not typically categorized as a larger nonpolar group?

Glycine (Gly) Signup and view all the answers

What is the typical location of charged side chains in a protein molecule?

On the surface of the molecule. Signup and view all the answers

Which amino acids can exist in either uncharged or charged form based on pH conditions?

Asp and Glu Signup and view all the answers

What happens to the ratio of charged to uncharged forms of amino acids when the pH is shifted one or two units away from the pK?

It might change to 10:1 or 100:1. Signup and view all the answers

How do Gly and Ala differ from larger nonpolar amino acids regarding their placement in proteins?

They can be situated either inside or outside with equal ease. Signup and view all the answers

What is the characteristic of Tyr and Trp regarding their location in proteins?

They can be found both inside and outside the protein structure. Signup and view all the answers

What is the function of neutral polar residues in a protein when they are inside the structure?

To form hydrogen bonds with similar residues or carbonyl groups. Signup and view all the answers

Study Notes

The Makeup of Living Organisms

The chemistry of living things is complex, organized and sophisticated, but still follows the same principles as nonliving matter.
Living organisms are primarily composed of water, containing dissolved ions, inorganic and organic molecules. These molecules are essential to the functioning of the organism.
The structural components of living organisms are made up of substances like bones, teeth, chitin, and lipids.
Nucleic acids, DNA and RNA, provide the instructions for the construction and functionality of the organism.
Proteins are amongst the most important chemical substances in living organisms.

Proteins as Polymers of Amino Acids

Proteins are made up of long chains of amino acids, called polypeptides.
Amino acids are linked together by peptide bonds.
The structure of a protein is critical to its function.
The properties of proteins are influenced by the side chains of the amino acids they are made of.

The Influence of Side Chains

Nonpolar side chains are typically found in the interior of the molecule, where they help to stabilize the protein by reducing interaction with water.
Polar side chains are typically found on the surface of the molecule, where they can interact with the aqueous environment.
Charged side chains (acidic and basic) can be found both inside and outside the molecule, and their charge can vary with pH.
The pK value of an amino acid determines the pH at which it is equally likely to be charged or uncharged.
The different types of side chains contribute to the diverse functions of proteins.
Neutral polar side chains often hydrogen bond to other residues, contributing to the stability of the protein three-dimensional structure.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the intricate chemistry that makes up living organisms, focusing on the crucial components like water, nucleic acids, and proteins. Understand how proteins function as polymers of amino acids and the importance of their structure in biological processes. Test your knowledge of these foundational concepts in biology.