Anatomy and Physiology: Biochemistry Lesson, Structure & Functions

Lesson Overview

• What Is Biochemistry in Anatomy and Physiology?
• How Do Electrolytes Maintain Body Function?
• What Types of Carbohydrates Exist and How Do They Function?
• How Do Lipids Contribute to Structure and Energy?
• What Are Proteins Made Of and How Do They Function?
• How Is Protein Structure Related to Stability and Function?
• What Are Enzymes and How Do They Influence Metabolic Reactions?
• How Are Proteins Assembled from Amino Acids?
• What Are the Key Features of Nucleic Acids?
• What Is ATP and Why Is It Called the Energy Currency of the Cell?
• How Are Nucleic Acids Organized from Their Smallest Units?
• How Does Biochemistry Link Molecular Structure to Physiology?

When Maya blanked on ATP structure during her physiology quiz, she realized memorization wasn't enough. Understanding anatomy & physiology: biochemistry takes more than flashcards. This lesson guides students through macromolecules, enzymes, and energy systems with clarity, so they can confidently answer quiz questions and truly grasp how the body works.

What Is Biochemistry in Anatomy and Physiology?

This section introduces biochemistry as the foundation of life processes and molecular interactions within the human body.

Biochemistry in anatomy and physiology refers to the chemical processes and substances that support the structure, function, and regulation of biological systems. Biochemistry focuses on understanding how macromolecules such as carbohydrates, proteins, lipids, and nucleic acids participate in metabolic pathways. Biochemical principles are essential for explaining how cells derive energy, communicate through signaling molecules, synthesize proteins, and replicate genetic material.

How Do Electrolytes Maintain Body Function?

This section explains the role of electrolytes in maintaining electrical activity and fluid balance in physiological systems.

Electrolytes are charged particles, or ions, that result from the dissociation of salts, acids, and bases in aqueous solutions. Sodium ions (Na+), potassium ions (K+), calcium ions (Ca2+), magnesium ions (Mg2+), and chloride ions (Cl-) are the most common electrolytes in the human body. These ions are critical for conducting electrical impulses in neurons and muscle cells. The movement of sodium and potassium ions across cell membranes enables the generation of action potentials. Calcium ions regulate muscle contractions and enzyme activity. Bicarbonate ions (HCO3-) act as buffers to maintain pH balance. The kidneys regulate electrolyte concentration through filtration and reabsorption processes.

What Types of Carbohydrates Exist and How Do They Function?

This section classifies carbohydrates and outlines their structure, energy function, and biological significance.

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio. Monosaccharides are the simplest carbohydrates and include glucose, fructose, and galactose. Each monosaccharide has a carbon backbone of 3 to 7 atoms and commonly forms ring structures in solution. Disaccharides such as sucrose and lactose are formed by the condensation of two monosaccharides. Polysaccharides like glycogen and cellulose are large molecules composed of repeating monosaccharide units. Glycogen is the primary storage carbohydrate in animals and is highly branched to allow rapid mobilization of glucose. Cellulose provides structural support in plant cell walls and is not digestible by human enzymes.

How Do Lipids Contribute to Structure and Energy?

This section discusses lipid types, molecular features, and functional diversity in physiological systems.

Lipids are nonpolar biomolecules made primarily of carbon and hydrogen atoms. Lipids include triglycerides, phospholipids, steroids, and prostaglandins. Triglycerides are composed of glycerol and three fatty acids and serve as long-term energy storage molecules. Saturated fatty acids contain no double bonds, while unsaturated fatty acids have one or more. Phospholipids have two fatty acids and a phosphate group, forming the basis of biological membranes. Their amphipathic nature results in bilayer structures that are essential for compartmentalization in cells.

Steroids are lipids characterized by four fused carbon rings. Cholesterol stabilizes plasma membranes and serves as a precursor for steroid hormones such as testosterone and estrogen. Prostaglandins are lipid signaling molecules that regulate inflammation, fever, and pain. These molecules are synthesized by the cyclooxygenase (COX) pathway and act locally on nearby cells.

What Are Proteins Made Of and How Do They Function?

This section explores protein structure, function, and the significance of amino acid sequences.

Proteins are polymers composed of amino acids linked by peptide bonds formed through dehydration synthesis. Each amino acid consists of a central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable side chain (R group). There are 20 different amino acids, and the sequence of these determines protein shape and function. Proteins are responsible for diverse roles such as enzymatic activity, structural support, immune defense, and transport.

Protein functions include the following:

• Structural proteins (e.g., collagen) provide strength and support.
• Contractile proteins (e.g., actin and myosin) enable muscle contraction.
• Transport proteins (e.g., hemoglobin) bind and carry molecules.
• Enzymes catalyze biochemical reactions with specificity.
• Antibodies recognize and neutralize foreign substances.
• Buffering proteins regulate pH by accepting or donating H+ ions.

How Is Protein Structure Related to Stability and Function?

This section examines the four levels of protein structure and factors that affect protein conformation.

Protein structure is hierarchical. The primary structure is the sequence of amino acids. Secondary structure includes alpha helices and beta sheets stabilized by hydrogen bonds. Tertiary structure involves the overall 3D folding of a single polypeptide due to interactions between R groups, such as hydrophobic effects and disulfide bridges. Quaternary structure arises when multiple polypeptide chains assemble into a functional complex, such as hemoglobin.

Proteins are sensitive to environmental conditions. High temperatures, extreme pH, ionic imbalances, and chemical denaturants disrupt weak interactions, causing proteins to unfold-a process called denaturation. Denatured proteins lose function.

What Are Enzymes and How Do They Influence Metabolic Reactions?

This section explains how enzymes operate, their structure, and their regulatory properties.

Enzymes are biological catalysts composed mostly of proteins. Enzymes increase reaction rates by lowering activation energy. Each enzyme binds specifically to its substrate at the active site. Enzymes operate under the principles of specificity, saturation, and regulation.

• Specificity ensures enzymes interact only with appropriate substrates.
• Saturation occurs when all enzyme molecules are occupied, limiting further increases in reaction rate.
• Regulation includes activation or inhibition by cofactors, feedback mechanisms, and environmental factors.

Enzymes may contain non-protein components such as cofactors (e.g., Zn2+, Mg2+) or coenzymes (e.g., NAD+, FAD, vitamins) necessary for catalytic function. Enzymes can be reused after reactions.

How Are Proteins Assembled from Amino Acids?

This section addresses the biochemical mechanism of peptide bond formation and the sites of protein synthesis.

Protein synthesis begins with the formation of peptide bonds between amino acids. The carboxyl group of one amino acid reacts with the amino group of another, releasing water and forming a covalent peptide bond. This dehydration synthesis occurs in ribosomes during translation.

Protein synthesis requires messenger RNA (mRNA), which conveys genetic information from DNA. Transfer RNA (tRNA) delivers specific amino acids to the ribosome, where elongation of the polypeptide occurs. Peptide bond formation continues until the entire protein is assembled and folded.

What Are the Key Features of Nucleic Acids?

This section outlines the structure and function of DNA and RNA in genetic information storage and transmission.

Nucleic acids include deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA is composed of nucleotides containing deoxyribose sugar, a phosphate group, and nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T). RNA contains ribose sugar and substitutes uracil (U) for thymine.

DNA is double-stranded, arranged in an antiparallel double helix, and located in the nucleus. DNA stores hereditary information and directs protein synthesis. RNA is single-stranded and found in the nucleus and cytoplasm. RNA types include mRNA, tRNA, and rRNA, all critical to gene expression.

What Is ATP and Why Is It Called the Energy Currency of the Cell?

This section explores ATP's molecular composition and role in biological work.

Adenosine triphosphate (ATP) is composed of adenine, ribose sugar, and three phosphate groups. The high-energy bonds between phosphate groups release energy when hydrolyzed to adenosine diphosphate (ADP) and inorganic phosphate (Pi). This energy powers cellular activities including muscle contraction, active transport, and biosynthesis.

ATP synthesis occurs via cellular respiration. Glycolysis, the citric acid cycle, and oxidative phosphorylation in mitochondria contribute to ATP production. ATP turnover in active cells is rapid and essential for survival.

How Are Nucleic Acids Organized from Their Smallest Units?

This section describes the structural hierarchy from nitrogenous bases to complete nucleic acids.

The structural units of nucleic acids follow this order:

1. Nitrogenous base (e.g., adenine)
2. Nucleotide (nitrogenous base + sugar + phosphate)
3. Nucleic acid (polymer of nucleotides)

This organization underlies the structure of DNA and RNA. The sequence of nucleotides in DNA encodes the information required for synthesizing proteins and directing cellular function.

How Does Biochemistry Link Molecular Structure to Physiology?

This section connects biochemical knowledge to organ function and physiological homeostasis.

Biochemistry underlies every function in the human body. Carbohydrates provide glucose for energy. Lipids store energy, form membranes, and produce hormones. Proteins catalyze reactions, defend against infection, and maintain structure. Nucleic acids store and transmit genetic data. Enzymes coordinate metabolism. ATP provides usable energy.

Students studying biochemistry gain insight into physiological mechanisms such as nerve conduction, muscle contraction, immune defense, and genetic regulation. This knowledge enables a deeper understanding of disease, diagnostics, and treatments.

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