Cell Structure and Function

Cell Structure

• A cell is the basic structural and functional unit of living organisms
• Consists of:
  • Cell membrane (plasma membrane)
  • Cytoplasm
  • Genetic material (DNA or RNA)
  • Organelles (e.g. mitochondria, ribosomes, lysosomes)

Cell Membrane

• Semi-permeable membrane that surrounds the cell
• Functions:
  • Regulates what enters and leaves the cell
  • Maintains cell shape
  • Provides mechanical support
• Composed of:
  • Phospholipid bilayer
  • Proteins (integral and peripheral)
  • Cholesterol

Cell Division

• Process by which a cell divides into two daughter cells
• Types:
  • Mitosis (somatic cells)
  • Meiosis (gamete cells)
• Stages of Mitosis:
  1. Interphase
  2. Prophase
  3. Metaphase
  4. Anaphase
  5. Telophase
  6. Cytokinesis

Cellular Respiration

• Process by which cells generate energy from glucose
• Stages:
  1. Glycolysis (cytoplasm)
  2. Pyruvate oxidation (mitochondria)
  3. Krebs cycle (mitochondria)
  4. Electron transport chain (mitochondria)
• Produces:
  • ATP (energy)
  • NADH and FADH2 (electron carriers)

Gene Expression

• Process by which genetic information is converted into a functional product
• Steps:
  1. Transcription (DNA → RNA)
  2. Translation (RNA → protein)
• Regulation:
  • Transcription factors
  • Gene promoters and enhancers
  • Epigenetic modifications

Animal Cells

• Characteristics:
  • Lack cell wall
  • Have centrioles
  • Have lysosomes
  • Have mitochondria
• Functions:
  • Movement (muscle cells)
  • Sensation (nerve cells)
  • Protection (immune cells)

Plant Cells

• Characteristics:
  • Have cell wall (cellulose)
  • Have chloroplasts (photosynthesis)
  • Have vacuoles (storage)
  • Have plasmodesmata (cell-cell communication)
• Functions:
  • Photosynthesis (chloroplasts)
  • Support (cell wall)
  • Storage (vacuoles)

Cell Structure

• A cell is the basic structural and functional unit of living organisms
• Consists of cell membrane, cytoplasm, genetic material, and organelles

Cell Membrane

• Semi-permeable membrane surrounding the cell
• Regulates what enters and leaves the cell, maintains cell shape, and provides mechanical support
• Composed of phospholipid bilayer, proteins, and cholesterol

Organelles

• Mitochondria: site of cellular respiration, generates energy for the cell
• Ribosomes: site of protein synthesis
• Lysosomes: contain digestive enzymes, break down and recycle cellular waste and foreign substances
• Other organelles include endoplasmic reticulum, Golgi apparatus, and centrioles

Cell Division

• Process by which a cell divides into two daughter cells
• Types: mitosis (somatic cells) and meiosis (gamete cells)
• Stages of Mitosis: interphase, prophase, metaphase, anaphase, telophase, and cytokinesis

Cellular Respiration

• Process by which cells generate energy from glucose
• Stages: glycolysis, pyruvate oxidation, Krebs cycle, and electron transport chain
• Produces ATP, NADH, and FADH2

Gene Expression

• Process by which genetic information is converted into a functional product
• Steps: transcription (DNA → RNA) and translation (RNA → protein)
• Regulation: transcription factors, gene promoters and enhancers, and epigenetic modifications

Animal Cells

• Characteristics: lack cell wall, have centrioles, lysosomes, and mitochondria
• Functions: movement, sensation, protection, and other specialized functions

Plant Cells

• Characteristics: have cell wall (cellulose), chloroplasts, vacuoles, and plasmodesmata
• Functions: photosynthesis, support, storage, and cell-cell communication