Cell Structure and Function

Cell Structure and Function

• Cells are the basic units of life, exhibiting a wide range of shapes and sizes, adapted to specific functions.
• Prokaryotic cells, like bacteria, lack membrane-bound organelles and have a nucleoid region containing DNA.
• Eukaryotic cells, including animal and plant cells, possess membrane-bound organelles, a true nucleus, and a more complex structure.
• Cell membranes act as a selective barrier, regulating the passage of materials into and out of the cell.
• The nucleus contains the cell's genetic material (DNA) and controls cellular activities.
• Mitochondria are often referred to as the "powerhouses" of the cell, generating ATP (energy) through cellular respiration.
• Ribosomes are involved in protein synthesis, following genetic instructions from the nucleus.
• Endoplasmic reticulum (ER) is a network of membranes involved in protein and lipid synthesis and transport. Rough ER has ribosomes attached, smooth ER lacks ribosomes.
• Golgi apparatus processes, packages, and distributes proteins and lipids.
• Lysosomes contain enzymes that break down waste materials and cellular debris.
• Vacuoles are membrane-bound sacs involved in storage, transport, and maintaining turgor pressure in plant cells.
• Cytoskeleton provides structural support and facilitates cell movement.
• Plant cells possess a cell wall for structural support, a large central vacuole, and chloroplasts for photosynthesis.

Biological Molecules

• Four major classes of biological macromolecules: carbohydrates, lipids, proteins, and nucleic acids.
• Carbohydrates are primarily used for energy storage and structural support; examples include sugars and starches.
• Lipids are diverse molecules, including fats, oils, and phospholipids; they store energy, form cell membranes, and serve as hormones.
• Proteins are crucial for numerous cellular functions; they form structural components, catalyze reactions as enzymes, and transport molecules. Protein structure (primary, secondary, tertiary, and quaternary) determines function.
• Nucleic acids, DNA and RNA, carry genetic information, controlling cellular activities. DNA stores genetic information, while RNA is involved in protein synthesis.

Cellular Processes

• Cellular respiration is the process by which cells break down glucose to release energy in the form of ATP. Aerobic respiration requires oxygen, while anaerobic respiration does not.
• Photosynthesis is the process by which plants and some other organisms convert light energy into chemical energy in the form of glucose.
• Cell division is essential for growth, repair, and reproduction; mitosis produces identical daughter cells, while meiosis produces genetically diverse gametes (sex cells).
• Cellular communication occurs through various signaling pathways. Cell-to-cell communication is critical in coordinating activities within multicellular organisms.
• Active transport requires energy to move molecules against their concentration gradient. Passive transport moves molecules along their concentration gradient, requiring no energy input.

Genetics

• Genes are segments of DNA that contain instructions for building proteins.
• DNA replication ensures that genetic information is accurately copied during cell division.
• Transcription is the process of converting DNA information into RNA.
• Translation is the process of converting RNA information into protein.
• Mutations are changes in DNA sequence that can lead to altered proteins and phenotypic changes.

Evolution

• Evolution is the change in heritable characteristics of biological populations over successive generations.
• Natural selection is a key mechanism of evolution, favoring traits that enhance survival and reproduction.
• Genetic variation is essential for evolution to occur.
• Common ancestry suggests that all life forms share a common ancestor.