Cell Structure and Function

Cell Structure and Function

• Cells are the fundamental units of life, exhibiting diverse shapes and sizes, specialized for specific functions.
• Prokaryotic cells lack a nucleus and membrane-bound organelles; examples include bacteria and archaea.
• Eukaryotic cells possess a nucleus and membrane-bound organelles, including plants, animals, fungi, and protists.
• Plant cells feature cell walls, chloroplasts, and large central vacuoles.
• Animal cells have diverse organelles like mitochondria and lysosomes.
• The cell membrane regulates substance passage into and out of the cell.
• The nucleus, the cell's control center, contains the cell's genetic material (DNA).
• Mitochondria generate cellular energy via respiration.
• Ribosomes synthesize proteins.
• Endoplasmic reticulum (ER) modifies and synthesizes proteins and lipids.
• Golgi apparatus processes, sorts, and packages proteins and lipids.
• Lysosomes digest cellular waste and participate in intracellular digestion.
• Vacuoles are involved in storage and transport.
• The cytoskeleton provides support and structure for the cell.

Cellular Respiration

• Cellular respiration is a series of metabolic reactions breaking down glucose and other molecules to produce ATP, the cell's energy currency.
• Cellular respiration involves glycolysis, the Krebs cycle, and oxidative phosphorylation.
• Glycolysis converts glucose to pyruvate, yielding a small ATP amount.
• The Krebs cycle (citric acid cycle) further oxidizes pyruvate, producing more ATP, NADH, and FADH2.
• Oxidative phosphorylation, occurring in the inner mitochondrial membrane, utilizes electron carriers (NADH and FADH2) to create a large amount of ATP through the electron transport chain and chemiosmosis.
• Aerobic respiration requires oxygen for optimal ATP production.
• Anaerobic respiration, in the absence of oxygen, uses alternative pathways for ATP generation, often producing less energy.

Photosynthesis

• Photosynthesis converts light energy into chemical energy (glucose) in plants and other organisms.
• Photosynthesis occurs within chloroplasts, specifically in thylakoid membranes and stroma.
• Light-dependent reactions capture light, split water (releasing oxygen), and produce ATP and NADPH.
• Light-independent reactions utilize ATP and NADPH to fix carbon dioxide and create glucose and other organic molecules.
• Photosynthesis maintains atmospheric oxygen levels and forms the base of many food chains.

Genetics

• DNA, the molecule of heredity, forms a double helix structure storing genetic information.
• Genes are DNA segments coding for specific proteins.
• Chromosomes are DNA and protein structures organizing genetic material.
• DNA replication copies genetic material before cell division.
• Meiosis produces gametes (sperm and egg) for sexual reproduction.
• Mitosis creates two genetically identical daughter cells from one parent cell, critical for growth and repair.
• Mutations are DNA sequence changes potentially altering protein production and phenotypes.
• Mendelian genetics describes inheritance patterns based on allele segregation and independent assortment.

Evolution

• Evolution is the heritable change in a biological population over successive generations.
• Natural selection is the process where better-adapted organisms survive and reproduce more.
• Adaptations enhance survival and reproduction in a specific environment.
• Speciation forms new and distinct species through evolutionary processes.
• Common ancestry connects all living organisms to a common ancestor.
• Biodiversity is the variety of life from genes to ecosystems.

Ecology

• Ecology studies the relationships between organisms and their environment.
• Ecosystems encompass all living (biotic) and non-living (abiotic) components in an area.
• Food chains and food webs illustrate energy and nutrient flow.
• Populations are groups of the same species interacting within a particular area.
• Communities include different species interacting in a given area.
• Biomes are large areas marked by similar climates and vegetation.
• Ecological interactions, such as competition, predation, and symbiosis, are vital aspects of ecological relationships.

Homeostasis

• Homeostasis is an organism's ability to maintain internal stability through environmental changes.
• Mechanisms like feedback loops regulate body temperature, water balance, and pH levels, essential for cellular function.