Fundamental Concepts of Cell Biology

Study Notes

Fundamental Concepts of Cell Biology

Cells are the basic units of life, exhibiting a wide range of shapes and sizes.
Cells are enclosed by a plasma membrane, a selectively permeable barrier that controls the movement of substances into and out of the cell.
Cells contain various organelles that perform specific functions, like the nucleus, mitochondria, and ribosomes. Different cell types have different sets of organelles based on their specialized roles.
Genetic material (DNA) within the nucleus directs the cell’s activities and dictates protein synthesis.
The cytoplasm, the region outside the nucleus, houses various cellular structures and processes.
Cells exhibit a continuous dynamic activity encompassing metabolic reactions, movement of molecules and the cell itself, and cell division.

Cell Membrane Structure and Function

The cell membrane is a phospholipid bilayer, which is a double layer of phospholipid molecules.
Embedded within the phospholipid bilayer are proteins, which act as transporters, receptors, and enzymes.
Cholesterol molecules are also present in the membrane to maintain fluidity and stability at varying temperatures.
The membrane is selectively permeable, meaning it regulates the movement of substances in and out of the cell.
Transport across the membrane occurs through passive transport (diffusion and osmosis) or active transport.
Diffusion is the movement of molecules from a high concentration to a low concentration.
Osmosis is the movement of water across a semipermeable membrane from a high water concentration to a low water concentration.
Active transport requires energy to move molecules against their concentration gradient.
Membrane proteins facilitate both passive and active transport.

Cellular Organelles

Nucleus: Contains the cell’s genetic material (DNA) organized into chromosomes. Controls cellular activities through gene expression.
Mitochondria: Known as the powerhouse of the cell, they generate ATP (adenosine triphosphate) – the cell’s primary energy currency – through cellular respiration.
Endoplasmic Reticulum (ER): A network of membranes involved in protein synthesis and lipid metabolism. Rough ER has ribosomes attached for protein synthesis, smooth ER lacks ribosomes and is involved in lipid synthesis.
Golgi apparatus: Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
Ribosomes: Sites of protein synthesis. They can be free in the cytoplasm or bound to the rough ER.
Lysosomes: Contain enzymes that break down waste materials and cellular debris.
Vacuoles: Storage sacs for water, nutrients, or waste products. Particularly prominent in plant cells.
Cytoskeleton: A network of protein fibers that provides structural support, facilitates cell movement, and allows for intracellular transport.
Peroxisomes: Contain enzymes that carry out specific metabolic reactions, such as breaking down fatty acids.

Cell Division

Cell division is essential for growth, repair, and reproduction in organisms.
Mitosis is the process of nuclear division that results in two identical daughter cells, crucial for growth and repair.
Meiosis is the process of nuclear division that results in four genetically different daughter cells, essential for sexual reproduction.

Types of Cells

Prokaryotic cells lack a nucleus and membrane-bound organelles, whereas eukaryotic cells possess a nucleus and various membrane-bound organelles.
Prokaryotes include bacteria and archaea.
Eukaryotes include plant, animal, fungi, and protist cells, characterized by more complex structures and functions.
Plant cells have unique features including cell walls and chloroplasts for photosynthesis.
Animals cells vary in shape and function, possessing specialized structures for respective roles.

Basic Cellular Processes

Cellular respiration converts food molecules into a usable energy form (ATP).
Photosynthesis converts light energy into chemical energy (sugars) in plants and some other organisms.
Protein synthesis involves the production of proteins using genetic information from DNA.
Intracellular transport involves the movement of molecules and organelles within the cell.
Metabolism encompasses all chemical reactions occurring within a cell, involving breaking down molecules (catabolism) and building up molecules (anabolism).

Description

Explore the essential principles of cell biology, including the structure and function of cells and their organelles. This quiz covers cell membranes, genetic material, and the dynamic activities cells engage in. Test your knowledge of how cells operate as the fundamental units of life.