Cell Structure and Function

Cell Structure and Function

• Cells are the basic units of life, exhibiting a wide variety of shapes and sizes.
• Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have a nucleus and various organelles.
• Common eukaryotic organelles include the nucleus, mitochondria, endoplasmic reticulum (ER), Golgi apparatus, and lysosomes.
• The nucleus houses the cell's genetic material (DNA).
• Mitochondria are the powerhouses of the cell, generating ATP through cellular respiration.
• The endoplasmic reticulum is involved in protein synthesis and lipid metabolism.
• The Golgi apparatus modifies, sorts, and packages proteins.
• Lysosomes contain digestive enzymes for breaking down waste materials.

Cell Membrane

• The cell membrane is a selectively permeable barrier controlling substance passage.
• It's primarily a phospholipid bilayer with embedded proteins.
• The phospholipid bilayer creates a hydrophobic barrier regulating molecule movement.
• Membrane proteins facilitate substance transport (ions, nutrients, waste).
• Passive transport (diffusion, osmosis) doesn't require energy.
• Active transport (sodium-potassium pump) needs energy to move substances against their concentration gradient.

Cellular Respiration

• Cellular respiration breaks down glucose to release energy as ATP.
• It occurs in three stages: glycolysis, the Krebs cycle, and the electron transport chain.
• Glycolysis happens in the cytoplasm, breaking glucose into pyruvate.
• The Krebs cycle (citric acid cycle) occurs in the mitochondria, further oxidizing pyruvate.
• The electron transport chain, also in the mitochondria, creates a large amount of ATP through electron transfer.

Biological Molecules

• The four main biological molecules are carbohydrates, lipids, proteins, and nucleic acids.
• Carbohydrates (composed of C, H, and O) are a primary energy source.
• Lipids are diverse hydrophobic molecules (fats, oils, steroids).
• Proteins (amino acid polymers) have diverse functions (structure, catalysis).
• Nucleic acids (DNA, RNA) store and transmit genetic information.

Genetics

• Genes are DNA segments coding for protein production.
• DNA replication copies DNA to ensure each new cell has a complete set of genetic instructions.
• Gene expression involves DNA transcription into RNA and RNA translation into protein.
• Mutations are DNA sequence changes impacting traits.
• The central dogma describes the flow of genetic information (DNA to RNA to protein).

Ecology

• Ecology studies organism-environment interactions.
• Ecosystems have biotic (living) and abiotic (non-living) components.
• Food webs depict energy flow in ecosystems.
• Populations are groups of the same species in an area.
• Communities are groups of different populations interacting.
• Biomes are large ecosystems with unique climates and vegetation.

Evolution

• Evolution is change in heritable characteristics over generations.
• Natural selection favors advantageous traits for survival and reproduction.
• Genetic drift is a random change in allele frequencies.
• Speciation is the formation of new species.
• Fossil records, comparative anatomy, and molecular biology support evolution.

Photosynthesis

• Photosynthesis converts light energy to chemical energy in plants.
• It converts carbon dioxide and water into glucose and oxygen.
• Photosynthesis occurs in chloroplasts, specifically the thylakoid membranes.
• Light-dependent reactions capture light, producing ATP and NADPH.
• Light-independent reactions use ATP and NADPH to form glucose from carbon dioxide.

Homeostasis

• Homeostasis maintains stable internal conditions.
• It involves temperature, pH, and other physiological regulation.
• Feedback mechanisms are crucial for maintaining homeostasis.
• Negative feedback loops counter changes; positive feedback loops amplify them.

Explore the fundamental components of cell structure and function in this quiz. Learn about the differences between prokaryotic and eukaryotic cells, various organelles, and the role of the cell membrane. Test your understanding of how cells operate and maintain life.