Biochemistry: Peptide Bonds and Metabolism

Substances produced during fat metabolism when the body uses fat for energy instead of glucose. These substances are acidic and can lead to ketoacidosis if produced in excess.

Released during the breakdown of proteins and nucleotides. It contributes to the overall acid load in the body.

Generated from the metabolism of sulfur-containing amino acids. Sulfur is oxidized to sulfate, contributing to the body's acid balance.

Produced during protein metabolism. It's basic and combines with H+ to form ammonium, which is less toxic and excreted by the kidneys.

Produced in metabolic processes or ingested. It's a crucial buffer in the blood, neutralizing acids to maintain a stable pH.

A reduction in arterial pH below 7.35, indicating a higher acidity in the blood.

An increase in arterial pH above 7.45, indicating a higher alkalinity in the blood.

The primary buffer system in blood plasma. It involves an equilibrium between carbonic acid and bicarbonate.

The tendency of a drug to exist in its uncharged form, which allows it to cross cell membranes more easily.

The pH at which a weak acid or base is 50% ionized and 50% un-ionized. It reflects the drug's tendency to donate or accept protons.

The process of a drug moving from the site of administration into the bloodstream.

The environment in the stomach is acidic with a pH of approximately 2.0, which favors the uncharged form of aspirin.

Aspirin is absorbed more effectively in the intestines due to the higher pH.

The stomach acts as a storage depot for drugs, but it's not the primary site of absorption.

The rate at which food leaves the stomach and enters the intestines.

The intestines have a much larger surface area due to villi and microvilli, which significantly enhances drug absorption.

Most amino acids have a central carbon atom (alpha carbon) attached to four different groups, making them chiral.

The L-form of amino acids is found in naturally occurring proteins and is used in protein synthesis.

The D-form of amino acids is rare in nature and is found in bacterial cell walls and some antibiotics.

Glycine, the simplest amino acid, is achiral because its R group is a hydrogen atom, making two of the groups on the alpha carbon identical.

Essential amino acids cannot be synthesized by the human body and must be obtained through diet.

Histidine, arginine, and lysine are considered conditionally essential amino acids, particularly important during childhood and periods of rapid growth.

Amino acids can be classified based on their chemical properties, including nonpolar, polar, acidic, and basic.

The 20 standard amino acids are directly encoded by the genetic code and used in protein synthesis.

The formation of a peptide bond between two amino acids, involving the removal of a water molecule.

A molecule consisting of two amino acids linked by a peptide bond.

The sharing of electrons between the carbonyl group (C=O) and the amide nitrogen (N-H) in a peptide bond, resulting in partial double bond character.

The restricted rotation around the peptide bond due to its partial double-bond character, leading to cis or trans configurations.

The favoured configuration of most peptide bonds, reducing steric hindrance between R groups of nearby amino acids.

The rare configuration of the peptide bond, except in proline, where steric hindrance is similar in both configurations.

The six atoms involved in the peptide bond (C, O, N, H, and the two adjacent alpha carbons) reside within the same plane due to the resonance.

Aging is associated with the accumulation of mitochondrial mutations and dysregulation of the proteome.

Variations in the DNA sequence of a gene that are common within a population. They usually involve differences in one or a few DNA bases.

Changes in the DNA sequence of a gene that are rare within a population. They can be harmful and lead to diseases.

Proteins involved in the immune system that distinguish self from non-self cells. They have many variations across populations, affecting immune responses.

A genetic trait where a single nucleotide mutation in the HBB gene causes the production of an abnormal hemoglobin protein. It protects against malaria and is common in populations with malaria exposure.

Genetic variations in the OCA2 and HERC2 genes that determine eye color. They involve multiple alleles and result in a diverse range of eye colors.

They are changes in the amino acid sequence of a protein that often impact its function. These alterations can be harmful, beneficial, or have no effect.

A mutation in the HBB gene which causes the production of an abnormal hemoglobin protein called HbS. Individuals with this mutation have Sickle Cell Trait or Sickle Cell Disease.

A change that is not necessarily harmful and is common in a population.

At physiological pH (around 7.4), these amino acids have a net positive charge due to their basic side chains.

At physiological pH (around 7.4), these amino acids have a net negative charge due to their acidic side chains.

Histidine's imidazole group has a pKa near physiological pH, allowing it to exist in both protonated (positively charged) and deprotonated (neutral) states depending on the pH.

Due to its pKa being close to physiological pH, histidine can act as a proton donor (acid) or a proton acceptor (base), playing a critical role in various biological processes.

The imidazole ring in histidine contains delocalized electrons, making its double bond arrangement flexible. This flexibility makes its pKa and charge sensitive to the environment it's in within a protein.

A molecule is chiral if it cannot be superimposed onto its mirror image. Think of your left and right hands - mirror images but not identical.

All amino acids, except glycine, have a chiral carbon atom. This central carbon atom is bonded to four different groups: an amino group, carboxyl group, hydrogen, and a variable side chain (R group).

Glycine is the only amino acid that is not chiral because its R group is just a hydrogen atom. Thus, it does not have four distinct groups attached to its central carbon.