Cell Structure and Function

Cell Structure

• Cell Membrane (Plasma Membrane): A semi-permeable membrane surrounding the cell; regulates substance movement (e.g., transport proteins).
• Cell Wall: A rigid outer layer in plant cells, fungi, and some bacteria; provides support and protection (e.g., cellulose fibers in plant cells).
• Cytoplasm: The gel-like substance within the cell membrane; contains all cell components and organelles (e.g., ribosomes, mitochondria, cytoskeleton).
• Nucleus: Membrane-bound organelle in eukaryotic cells; contains the cell's DNA (e.g., nuclear membrane).
• Nucleolus: A dense region within the nucleus where ribosomes are made.
• Mitochondria: Organelles that produce energy (ATP) through cellular respiration (e.g., cristae, the inner membrane folds).
• Ribosomes: Small structures that make proteins by translating mRNA.
• Endoplasmic Reticulum (ER): Network of membranes involved in protein and lipid synthesis.
  • Rough ER: Studded with ribosomes; involved in protein synthesis.
  • Smooth ER: Lacks ribosomes; involved in lipid synthesis and detoxification.
• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles (e.g., vesicles).
• Lysosome: Organelles with digestive enzymes; break down waste materials and cellular debris (e.g., acid hydrolases).
• Vacuole: Membrane-bound sac for storage, waste disposal, and maintaining turgor pressure (e.g., water, nutrients, waste).
• Chloroplast: Organelles in plant cells; carry out photosynthesis (e.g., chlorophyll).
• Cytoskeleton: Network of protein fibers maintaining cell shape, securing organelles, and enabling movement (e.g., actin filaments, microtubules, intermediate filaments).

Cell Types

• Prokaryotic Cell: Lacks a nucleus and membrane-bound organelles (e.g., bacteria, cell wall, single circular DNA).
• Eukaryotic Cell: More complex; has a nucleus and membrane-bound organelles (e.g., animal cells, plant cells, fungi, protists).
• Plant Cell: Eukaryotic; has a cell wall, chloroplasts, and a large central vacuole.
• Animal Cell: Eukaryotic; lacks a cell wall and chloroplasts but has lysosomes and centrioles.

Cell Processes

• Cellular Respiration: Cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water (e.g., mitochondria).
• Photosynthesis: Plants and some organisms use sunlight, carbon dioxide, and water to produce glucose and oxygen (e.g., chloroplasts, chlorophyll).

Molecular Biology & Other Vocabulary

• ATP (Adenosine Triphosphate): Primary energy carrier in cells (e.g., muscle contraction).
• DNA (Deoxyribonucleic Acid): Carries genetic instructions for growth, development, and function (e.g., genes).
• RNA (Ribonucleic Acid): Involved in protein synthesis and carrying genetic information (e.g., mRNA, tRNA, rRNA).
• Enzyme: Protein catalyst that speeds up chemical reactions in cells (e.g., amylase).
• Chlorophyll: Green pigment in chloroplasts; absorbs light energy for photosynthesis.