Cell Structure and Function

Cell Structure and Function

• Cells are the basic units of life, and all living organisms are made up of one or more cells.
• Cells vary greatly in size and shape, reflecting their diverse functions.
• Key components of cells include the cell membrane, cytoplasm, and nucleus (eukaryotic cells).
• Prokaryotic cells lack a nucleus and other membrane-bound organelles.
• Eukaryotic cells contain a nucleus and various organelles, each with specific functions.
• Cell membrane controls the passage of substances into and out of the cell.
• Cytoplasm is the jelly-like substance inside the cell, containing organelles.
• Nucleus contains the cell's genetic material (DNA).
• Mitochondria are responsible for cellular respiration, producing energy.
• Ribosomes synthesize proteins.
• Endoplasmic reticulum (ER) assists in protein and lipid synthesis.
• Golgi apparatus processes and packages proteins.
• Lysosomes contain enzymes for digestion of cellular waste.
• Vacuoles store nutrients and water.
• Chloroplasts (in plant cells) conduct photosynthesis, converting light energy into chemical energy.
• Cytoskeleton provides structural support and facilitates cell movement.

Biological Molecules

• Four major classes of biological molecules: carbohydrates, lipids, proteins, and nucleic acids
• Carbohydrates are composed of carbon, hydrogen, and oxygen, and serve as an energy source.
• Simple sugars (monosaccharides) are the basic building block of carbohydrates.
• Complex carbohydrates (polysaccharides) include starch, glycogen, and cellulose.
• Lipids are composed primarily of carbon and hydrogen and insoluble in water.
• Types of lipids include fats, oils, phospholipids, and steroids.
• Proteins are composed of amino acids and perform diverse functions in the cell, such as catalyzing reactions, transport, and structural support.
• Nucleic acids, DNA and RNA, store and transmit genetic information.

Cellular Respiration

• Cellular respiration is a metabolic pathway that breaks down glucose to produce ATP.
• Aerobic respiration requires oxygen, producing a large amount of ATP.
• Anaerobic respiration occurs without oxygen, producing a smaller amount of ATP.
• Glycolysis is the first stage of cellular respiration, occurring in the cytoplasm.
• Krebs cycle (Citric acid cycle) is the second stage, occurring in the mitochondrial matrix.
• Electron transport chain is the third stage, occurring in the inner mitochondrial membrane.

Photosynthesis

• Photosynthesis is the process by which plants and some other organisms convert light energy into chemical energy.
• Chlorophyll is a pigment that absorbs light energy for photosynthesis.
• Photosynthesis occurs in two main stages: light-dependent reactions and light-independent reactions (Calvin cycle).
• Light-dependent reactions capture light energy and convert it into chemical energy.
• Light-independent reactions use the chemical energy to synthesize glucose.

Genetics

• Genes are segments of DNA that carry genetic instructions
• DNA is a double helix structure that carries genetic information.
• DNA replication is the process of making a copy of DNA.
• Transcription converts DNA into RNA.
• Translation converts RNA into proteins.
• Mutations are changes in DNA sequences, which can alter the traits of an organism.
• Chromosomes are structures that contain DNA and proteins.

Evolution

• Evolution is the change in characteristics of a species over several generations.
• Natural selection is a mechanism of evolution, where organisms with advantageous traits are more likely to survive and reproduce.
• Adaptations are traits that enhance an organism's survival and reproduction in a particular environment.
• Common descent is the concept that all life on Earth shares a common ancestor.
• Speciation is the formation of new species.

Ecology

• Ecology is the study of interactions between organisms and their environment.
• Ecosystems include biotic and abiotic factors.
• Biotic factors refer to living organisms.
• Abiotic factors refer to non-living components.
• Energy flow in an ecosystem follows the food chain or food web.
• Nutrient cycles describe the movement of nutrients through an ecosystem.
• Population dynamics concerns population size and how this changes over time.
• Biodiversity refers to the variety of life forms in an area.

Classification

• Organisms are classified into hierarchical groups (domains, kingdoms, phyla, etc.) based on shared characteristics.
• Modern classification uses evolutionary relationships as the primary basis for grouping species.
• Taxonomists use morphological and molecular data to classify organisms.

Human Biology

• Human biology studies the biology of humans.
• Anatomy and physiology relate to the structure and functions of the human body.
• Systems work together to maintain homeostasis, a stable internal environment.
• Major systems include digestive, respiratory, circulatory, nervous, and endocrine systems.
• Human reproduction involves complex processes, including gamete formation and fertilization.
• Humans show genetic variation, impacting health and predisposition to disease.