Cell Structure and Function

Cell Structure and Function

• Cells are the fundamental units of all living organisms.
• Various cell types exist (e.g., plant, animal, bacterial).
• All cells share common features—cell membrane, cytoplasm, and DNA.

Cell Membrane

• The cell membrane is selectively permeable, regulating material passage.
• Primarily composed of a phospholipid bilayer.
• Embedded proteins perform various functions (transport, signaling).
• Cholesterol is found in animal cell membranes, influencing fluidity.

Cytoplasm

• The cytoplasm is the gel-like substance filling the cell.
• Contains various organelles.
• Cytosol is the fluid component.
• The cytoskeleton maintains cell shape, enabling movement.

Organelles

• Organelles are specialized structures in the cytoplasm, performing specific tasks.
• Examples include:
  • Nucleus: Stores DNA, controls cell functions.
  • Mitochondria: Produce ATP (energy).
  • Endoplasmic Reticulum (ER): Involved in protein and lipid synthesis.
  • Golgi apparatus: Processes and packages proteins.
  • Ribosomes: Synthesize proteins.
  • Vacuoles (plant cells): Storage sacs, maintaining turgor pressure.
  • Lysosomes: Contains enzymes for digestion.
  • Chloroplasts (plant cells): Perform photosynthesis.

Cellular Processes

• Diffusion: Passive movement from high to low concentration.
• Osmosis: Passive movement of water across a selectively permeable membrane.
• Active Transport: Movement against a concentration gradient, requiring energy.
• Endocytosis: Taking substances into the cell using vesicles.
• Exocytosis: Releasing substances from the cell using vesicles.

Cell Types: Plant vs. Animal

• Plant cells: Typically larger, possessing a rigid cell wall for support, chloroplasts, and a large central vacuole.
• Animal cells: Smaller, lacking a cell wall, chloroplasts, and a large central vacuole.

Cell Specialization

• Specialized structures and functions in cells enhance multicellular organism efficiency.

Cell Reproduction

• Mitosis is the process of cell reproduction, used for growth, repair, and asexual reproduction.
• Daughter cells receive identical genetic material.

DNA and Genes

• DNA (deoxyribonucleic acid) carries the genetic code.
• Genes are specific DNA segments coding for proteins.
• DNA is organized into chromosomes.

Basic Chemistry

• Matter is composed of atoms.
• Atoms combine to form molecules.
• Key biological molecules include carbohydrates, proteins, lipids, and nucleic acids.

Biological Macromolecules

• Proteins: Composed of amino acids, with diverse roles (structure, enzymes, transport).
• Carbohydrates: Energy source (sugars, starches), structural components (cellulose).
• Lipids: Diverse group (fats, oils), for energy storage, insulation, cell membranes.
• Nucleic Acids: DNA and RNA, carrying genetic information.

Key Concepts

• Homeostasis maintains a stable internal environment.
• Evolution explains life's diversity through natural selection.
• Adaptation helps organisms survive and reproduce.
• Systems in organisms work interdependently.

Test your knowledge about the basic units of life with this quiz on cell structure and function. Explore various cell types, the composition of cell membranes, and the roles of organelles. Perfect for students studying biology.