Chemistry Basics for Biology (Chapter 2 Part 2) Notes

Biochemistry and the Role of Chemistry in Biology

There is a strong emphasis on chemistry because biology at the cellular level is driven by chemical processes. Biochemistry is the study of chemistry in living systems.
Living organisms operate because cells work together to form tissues, organs, and organ systems with various purposes; the collective activity of cells is what keeps you alive.
The inside of a cell is a flurry of chemical activity, with thousands of molecules being formed, broken down, or altered to support biology.
To understand how humans work and biology overall, you start with fundamental chemistry concepts and terms.
The first important idea is how atoms and molecules interact and form different things; this is the setting for chemistry in biology.

Matter is a physics term that is important for chemistry and biology: it is anything that occupies space and has mass.
Matter exists; energy is something that does not have mass and therefore is not matter.
There are four states of matter on Earth, identified by two main factors: density of the molecules and the amount of energy in the substance.
Matter is an accumulation of atoms or molecules.

States are organized by how densely packed the molecules are and how much energy they contain; this ordering is described from left to right as density decreases and energy increases.
From left to right (highest density, lowest energy to higher energy, lower density): solid → liquid → gas.
Solid: high density, very little energy; molecules/atoms are tightly packed with bonds that are strong; little movement, mostly vibrational motion.
Liquid: more energy than a solid; density is lower than a solid; molecules are still relatively close but can flow past each other.
Gas: even more energy; molecules are far apart and move rapidly and independently; lots of energy in the system.
Plasma is an additional state of matter, but it is not commonly found on Earth under normal conditions.

Plasma occurs when a gas is subjected to extremely high energy, enough to strip electrons from atoms so the gas becomes a soup of charged particles.
Plasma is not commonly found on Earth in everyday environments because the required energy is enormous; it is found in places with very high energy, such as the Sun.
Plasma can be generated artificially in devices like plasma TV tubes and neon signs, where electric energy creates a plasma state that emits light with distinctive colors.
The description highlights that plasma is an energized state where atoms are highly energetic and electrons are free from their nuclei.

Adding energy to a solid causes it to melt into a liquid; the density decreases somewhat, but the substance remains relatively compact.
Adding more energy to a liquid causes it to transition into a gas; molecules move much more freely and occupy more space.
These transitions illustrate how energy input drives phase changes and alter the physical state of matter.

Common everyday references include solid, liquid, and gas states that people are familiar with from early science education.
Neon signs and plasma televisions are practical examples of plasma in everyday life.
While plasma is not common on Earth in everyday conditions, it is a significant state of matter in high-energy environments like stars and certain industrial applications.

The states of matter and phase transitions underpin the behavior of biomolecules in cells (solids, liquids, and solutions, as well as gaseous environments like respiration).
Understanding matter provides a basis for predicting how molecules interact, react, and move within cells and tissues.
The emphasis on chemistry as the foundation for biology reinforces why biology and chemistry are interconnected disciplines in understanding life.