Cell Biology Basics

Cell Biology

• Study of the structure, function, and behavior of cells

Cell Structure

• Plasma membrane (cell membrane):
  • Semi-permeable membrane that surrounds the cell
  • Regulates what enters and leaves the cell
• Cytoplasm:
  • Jelly-like substance inside the cell membrane
  • Site of many metabolic reactions
• Nucleus:
  • Controls cell growth and reproduction
  • Contains most of the cell's genetic material (DNA)

Function of Cell Membranes

• Cell signaling:
  • Allows cells to communicate with each other
  • Important for development, growth, and response to environment
• Cell adhesion:
  • Cells stick together to form tissues
  • Important for tissue structure and function
• Cell membrane transport:
  • Movement of molecules in and out of the cell
  • Types: passive (diffusion, osmosis) and active transport

Membranous Organelles

• Organelles: specialized structures within the cell
• Membranous organelles: organelles surrounded by a membrane

Types of Membranous Organelles

• Mitochondria:
  • Generate energy for the cell (ATP production)
  • Found in eukaryotic cells
• Endoplasmic Reticulum (ER):
  • Involved in protein synthesis and transport
  • Two types: Rough ER (with ribosomes) and Smooth ER (without ribosomes)
• Golgi Apparatus:
  • Modifies and packages proteins and lipids for transport
  • Receives proteins from ER and sends to other parts of the cell
• Lysosomes:
  • Contain digestive enzymes to break down and recycle cellular waste
  • Important for cellular recycling and defense against pathogens
• Peroxisomes:
  • Involved in fatty acid breakdown and amino acid metabolism
  • Found in eukaryotic cells

Cell Structure

• Plasma membrane is a semi-permeable membrane that surrounds the cell and regulates what enters and leaves the cell.
• Cytoplasm is a jelly-like substance inside the cell membrane where many metabolic reactions take place.
• Nucleus controls cell growth and reproduction, and contains most of the cell's genetic material (DNA).

Function of Cell Membranes

• Cell signaling allows cells to communicate with each other and is important for development, growth, and response to environment.
• Cell adhesion enables cells to stick together to form tissues, which is important for tissue structure and function.
• Cell membrane transport is the movement of molecules in and out of the cell, and includes passive (diffusion, osmosis) and active transport.

Membranous Organelles

• Mitochondria generate energy for the cell through ATP production and are found in eukaryotic cells.
• Endoplasmic Reticulum (ER) is involved in protein synthesis and transport, and has two types: Rough ER (with ribosomes) and Smooth ER (without ribosomes).
• Golgi Apparatus modifies and packages proteins and lipids for transport, receiving proteins from ER and sending them to other parts of the cell.
• Lysosomes contain digestive enzymes to break down and recycle cellular waste, and are important for cellular recycling and defense against pathogens.
• Peroxisomes are involved in fatty acid breakdown and amino acid metabolism, and are found in eukaryotic cells.

Cell Structure

• The cell is the basic unit of life
• Consists of cell membrane, cytoplasm, and genetic material (DNA or RNA)

Cell Membrane (Plasma Membrane)

• Semi-permeable membrane that separates the cell from its environment
• Functions: regulates what enters and leaves the cell, maintains cell shape, and acts as a barrier
• Composed of phospholipid bilayer and proteins (integral and peripheral)

Mitochondria

• Generates energy for the cell through cellular respiration
• Converts glucose into ATP
• Structure: double membrane (outer and inner), inner membrane has folds (cristae) to increase surface area

Endoplasmic Reticulum (ER)

• Synthesizes and transports proteins and lipids
• Modifies and packages proteins for transport
• Types: Rough ER (has ribosomes attached), Smooth ER (no ribosomes)

Golgi Apparatus

• Modifies and packages proteins and lipids for transport
• Forms vesicles for transport
• Structure: stack of flattened sacs (cisternae)

Lysosomes

• Breaks down and recycles cellular waste and foreign substances
• Contains digestive enzymes
• Structure: single membrane-bound sac

Ribosomes

• Performs protein synthesis
• Translates mRNA into a polypeptide chain
• Structure: found in cytoplasm, either freely floating or attached to ER

Peroxisomes

• Breaks down fatty acids and amino acids
• Contains oxidative enzymes
• Structure: single membrane-bound sac