Bio Chapter 1 Season 4

Cells

Humans have about 100 trillion (10^14) cells.

DNA

Deoxyribonucleic acid acts as a set of instructions for building an organism.

Nucleotides

The genome has four nucleotides: Adenine (A), Thymine (T), Guanine (G), Cytosine (C).

Cell Theory

One of the unifying principles of biology asserting that all cells come from pre-existing cells.

Virus

A small infectious agent that can replicate only inside a living cell, usually with a DNA or RNA genome in a protein coat.

Characteristics of Living Organisms

Composed of one or more cells, reproduce using DNA, obtain energy, sense and respond to the environment, maintain internal balance, can evolve.

Plasma Membrane

A phospholipid bilayer that separates a cell from its external environment.

Liposome

Formed when a phospholipid bilayer creates a sphere, acting as a semipermeable barrier.

Selective Permeability

Allows only some substances to cross the plasma membrane on their own.

Passive Transport

Movement across a membrane without energy, including diffusion and facilitated diffusion.

Active Transport

Movement that requires energy to transport substances against their concentration gradient.

Osmosis

Specific form of diffusion through a plasma membrane, involving the movement of water.

Isotonic

When cells are surrounded by a fluid with the same solute concentration as the cell's interior.

Hypertonic

When cells are surrounded by a fluid with a higher solute concentration than the cell's interior.

Hypotonic

When cells are surrounded by a fluid with a lower solute concentration than the cell's interior.

Vesicle

Packages formed by sections of the cell’s plasma membrane to transport substances.

Exocytosis

Process used to expel substances from the cell.

Endocytosis

Process used to bring external substances into the cell.

Receptor-mediated endocytosis

Process where receptor proteins recognize and bind to specific molecules to take them into the cell.

Phagocytosis

Endocytosis of a large substance, also known as cellular eating.

Pinocytosis

Endocytosis of a liquid, also known as cellular drinking.