Free Energy

Photo Source: OpenStax Biology 2e Chemical reactions release energy when energy-storing bonds break, an important next question is how do we quantify and express the chemical reactions with the associated energy? How can we compare the energy that releases from one reaction to that of another reaction? We use a measurement of free energy to quantitate … Continue reading Free Energy

Anabolic and Catabolic Pathways

Anabolic pathways are those that require energy to synthesize larger molecules. Catabolic pathways are those that generate energy by breaking down larger molecules. Both types of pathways are required for maintaining the cell’s energy balance.Source: OpenStax Biology 2e OpenStax Biology 2e Anabolic pathways require an input of energy to synthesize complex molecules from simpler ones. Synthesizing … Continue reading Anabolic and Catabolic Pathways

Intermediate Filaments

Intermediate filaments consist of several intertwined strands of fibrous proteins.Source: OpenStax Biology 2e OpenStax Biology 2e Several strands of fibrous proteins that are wound together comprise intermediate filaments. Cytoskeleton elements get their name from the fact that their diameter, 8 to 10 nm, is between those of microfilaments and microtubules. Intermediate filaments have no role in … Continue reading Intermediate Filaments

Carbohydrate Metabolism

Plants, like this oak tree and acorn, use energy from sunlight to make sugar and other organic molecules. Both plants and animals (like this squirrel) use cellular respiration to derive energy from the organic molecules that plants originally produced. (credit “acorn”: modification of work by Noel Reynolds; credit “squirrel”: modification of work by Dawn Huczek) … Continue reading Carbohydrate Metabolism

Receptor-mediated Endocytosis

In receptor-mediated endocytosis, the cell's uptake of substances targets a single type of substance that binds to the receptor on the cell membrane's external surface. (credit: modification of work by Mariana Ruiz Villareal) OpenStax Biology 2e A targeted variation of endocytosis employs receptor proteins in the plasma membrane that have a specific binding affinity for … Continue reading Receptor-mediated Endocytosis


In pinocytosis, the cell membrane invaginates, surrounds a small volume of fluid, and pinches off. (credit: modification of work by Mariana Ruiz Villareal) OpenStax Biology 2e A variation of endocytosis is pinocytosis. This literally means “cell drinking”. Discovered by Warren Lewis in 1929, this American embryologist and cell biologist described a process whereby he assumed that … Continue reading Pinocytosis

Membrane Fluidity

A hydrophilic head and two hydrophobic tails comprise this phospholipid molecule. The hydrophilic head group consists of a phosphate-containing group attached to a glycerol molecule. The hydrophobic tails, each containing either a saturated or an unsaturated fatty acid, are long hydrocarbon chains.Source: OpenStax Biology 2e OpenStax Biology 2e The membrane's mosaic characteristic helps to illustrate … Continue reading Membrane Fluidity

Highlights: A Chemical Compound Kills Antibiotic Resistant Bacteria

Photo Credit: Lightspring/ A compound called SCH-79797 can damage and destroy cell walls and folate in bacteria.The team consists of researchers from Princeton University.The compound can kill both Gram-positive and Gram-negative bacteria without detectable resistance.The compound targets folate metabolism and membrane integrity which are two different mechanisms within one molecule. Scientists are hoping that this … Continue reading Highlights: A Chemical Compound Kills Antibiotic Resistant Bacteria