Animal and Plant Cells

• Cells are the basic structural and functional units of all known living organisms
• An animal cell is a eukaryotic cell that lacks a cell wall and has membrane-bound organelles
• A plant cell is a eukaryotic cell with a cell wall, chloroplasts, and a large central vacuole

Animal Cell Structure

• Cell Membrane: Outer boundary, controls entry and exit of substances
• Nucleus: Contains genetic material (DNA), controls cell activities
• Cytoplasm: Gel-like substance filling the cell, where organelles are located
• Ribosomes: Sites of protein synthesis
• Mitochondria: Powerhouse of the cell, generates energy (ATP)
• Endoplasmic Reticulum (ER): Network of membranes involved in protein and lipid synthesis
• Rough ER: Contains ribosomes
• Smooth ER: Lacks ribosomes
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids
• Lysosomes: Contains enzymes for breaking down waste and cellular debris
• Centrioles: Involved in cell division (not found in plant cells)

Plant Cell Structure

• Cell Membrane: Same function as in animal cells
• Nucleus: Same function as in animal cells
• Cytoplasm: Same function as in animal cells
• Ribosomes: Same function as in animal cells
• Mitochondria: Same function as in animal cells
• Endoplasmic Reticulum (ER): Same function as in animal cells
• Rough ER: Contains ribosomes
• Smooth ER: Lacks ribosomes
• Golgi Apparatus: Same function as in animal cells
• Vacuole: Large, fluid-filled sac that stores water, nutrients, and waste; helps maintain cell turgor
• Chloroplasts: Site of photosynthesis, contains chlorophyll
• Cell Wall: Rigid outer layer made of cellulose, provides support and protection

Key Differences Between Animal and Plant Cells

• Cell Wall: Present in plant cells, absent in animal cells
• Chloroplasts: Present in plant cells, absent in animal cells
• Vacuoles: Plant cells have a large central vacuole; animal cells have small vacuoles, if any
• Centrioles: Present in animal cells, absent or rare in plant cells
• Shape: Animal cells have irregular shapes; plant cells have more regular shapes due to the cell wall

Cell Membrane (Plasma Membrane)

• Structure: A lipid bilayer composed of phospholipids, cholesterol, and proteins
• Function:
• Controls the movement of substances into and out of the cell (selective permeability)
• Protects the cell from its surroundings
• Cell signaling and adhesion

Nucleus

• Structure:
• Nuclear envelope: Double membrane surrounding the nucleus
• Nucleolus: Site of ribosome synthesis
• Chromatin: DNA and proteins that make up chromosomes
• Function:
• Contains and protects the cell's genetic material (DNA)
• Controls cell growth, metabolism, and reproduction

Cytoplasm

• Structure:
• Cytosol: Fluid portion of the cytoplasm
• Organelles: Various membrane-bound structures with specific functions
• Function:
• Supports and suspends organelles
• Site of many chemical reactions

Ribosomes

• Structure: Made of ribosomal RNA (rRNA) and proteins
• Function: Protein synthesis (translation)

Mitochondria

• Structure: Double membrane-bound organelle
• Inner membrane folded into cristae
• Function:
• Cellular respiration (ATP production)
• Powerhouse of the cell

Endoplasmic Reticulum (ER)

• Structure: Network of interconnected membranes
• Rough ER: Studded with ribosomes
• Smooth ER: Lacks ribosomes
• Function:
• Rough ER: Protein synthesis and modification
• Smooth ER: Lipid synthesis, detoxification, calcium storage

Golgi Apparatus

• Structure: Stack of flattened membrane-bound sacs (cisternae)
• Function:
• Modifies, sorts, and packages proteins and lipids
• Forms lysosomes

Lysosomes

• Structure: Membrane-bound vesicles containing hydrolytic enzymes
• Function:
• Intracellular digestion
• Breaks down waste and cellular debris

Vacuoles (Plant Cells)

• Structure: Large, fluid-filled sac
• Function:
• Stores water, nutrients, and waste
• Maintains cell turgor pressure

Chloroplasts (Plant Cells)

• Structure: Double membrane-bound organelle containing chlorophyll
• Thylakoids: Internal membrane system where photosynthesis occurs
• Function: Photosynthesis (conversion of light energy into chemical energy)

Cell Wall (Plant Cells)

• Structure: Rigid outer layer made of cellulose
• Function:
• Provides support and protection
• Maintains cell shape

Centrioles (Animal Cells)

• Structure: Cylindrical structures made of microtubules
• Function: Involved in cell division (formation of spindle fibers)

Cellular Processes

• Cell Respiration: Process by which cells break down glucose to produce ATP (energy)
• Photosynthesis: Process by which plants convert light energy, water, and carbon dioxide into glucose (sugar) and oxygen
• Protein Synthesis: Process by which cells build proteins from amino acids based on genetic instructions
• Transcription: DNA is transcribed into mRNA
• Translation: mRNA is translated into protein at the ribosome
• Cell Division: Process by which cells divide to produce new cells
• Mitosis: Cell division that results in two identical daughter cells (for growth and repair)
• Meiosis: Cell division that results in four genetically different daughter cells (for sexual reproduction)

Importance of Cell Structure and Function

• Understanding cell structures and their functions is crucial for comprehending how organisms live, grow, and reproduce
• It helps in diagnosing and treating diseases by understanding the underlying cellular mechanisms
• It provides insights into the development of new technologies and treatments in medicine, agriculture, and other fields