Cell Biology Basics

Characteristics of Cells

• Multicellular organisms are made up of many cells that group together to form various body parts
• Each cell has a specific function in the body
• Cells are the basic building units of living organisms
• Cells were first discovered by Robert Hooke in 1665

Cell Structure

• Cells are enclosed by a plasma membrane composed of lipids and proteins
• The plasma membrane is flexible and regulates the movement of materials between the cell and its environment
• In plant cells, a cell wall composed mainly of cellulose is located outside the cell membrane

Cell Transport

• Osmosis is the movement of water from a region of high concentration to a region of low concentration through a partially permeable membrane
• Cells can gain or lose water through osmosis depending on the concentration of the surrounding solution
• Isotonic solution: a solution with the same concentration as the cell
• Hypertonic solution: a solution with a higher concentration than the cell
• Cells can divide to produce cells of their own kind, and all cells come from pre-existing cells

Cell Organelles

• Nucleus: plays a central role in cellular reproduction and determines the way the cell will develop
• Cytoplasm: the fluid content inside the plasma membrane, contains many specialized cell organelles
• Endoplasmic Reticulum (ER): functions as a passageway for intracellular transport and as a manufacturing surface
• Golgi Apparatus: consists of stacks of membrane-bound vesicles that function in the storage, modification, and packaging of substances manufactured in the cell
• Lysosomes: contain digestive enzymes and help break down and recycle cellular waste
• Mitochondria: generate energy for the cell through cellular respiration
• Plastids: found in plant cells, can be chromoplasts (contain chlorophyll and perform photosynthesis) or leucoplasts (used for storage)

Cell Types

• Prokaryotes: lack a nuclear membrane, example: bacteria
• Eukaryotes: have a nuclear membrane, example: animals, plants, fungi