Cell Structure and Function

Cell Structure and Function

• Cells are the basic units of life, exhibiting a complex internal structure and functions.
• Prokaryotic cells (bacteria and archaea) lack a nucleus and membrane-bound organelles; eukaryotic cells (plants, animals, fungi, protists) possess a nucleus and organelles.
• Major cellular components include the cell membrane, cytoplasm, nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and chloroplasts (in plant cells).

Cellular Processes

• Cellular respiration breaks down glucose to release energy as ATP.
• Photosynthesis uses light energy to convert carbon dioxide and water into glucose and oxygen.
• DNA replication creates an exact copy of a DNA molecule.
• Protein synthesis involves transcription (DNA to RNA) and translation (RNA to protein).
• Cell division (mitosis and meiosis) is vital for growth, repair, and reproduction.

Biological Molecules

• Carbohydrates (carbon, hydrogen, oxygen) are a primary energy source.
• Lipids (fats and oils) are cell membrane components and energy storage molecules.
• Proteins are complex molecules crucial for cellular functions (structure, catalysis, transport).
• Nucleic acids (DNA and RNA) store and transmit genetic information.

Plant vs. Animal Cells

• Plant cells have a cell wall, chloroplasts, and a large central vacuole; animal cells lack these.
• Plant cells store energy as starch; animal cells store energy as glycogen.
• Plant cell shape is fixed due to the cell wall; animal cells are flexible.

Genetics

• Genes are DNA segments that code for specific proteins.
• DNA carries the genetic code, determining organism traits.
• Heredity transmits genetic information between generations.
• Chromosomes are DNA and protein structures carrying genes.
• Mutations are DNA sequence changes, potentially altering traits.

Ecology

• Ecology studies organism-environment interactions.
• Ecosystems include biotic (living) and abiotic (non-living) factors.
• Biodiversity is the variety of life, encompassing genetic, species, and ecosystem diversity.
• Food chains and webs describe energy transfer.
• Population dynamics analyze population growth and size.
• Competition and predation influence community interactions.

Evolution

• Evolution is the change in heritable characteristics over generations.
• Natural selection favors traits suited to an environment.
• Adaptation improves survival and reproduction.
• Common ancestry suggests all organisms share a common ancestor.

Classification

• Organisms are grouped hierarchically by shared characteristics and evolutionary relationships.
• Taxonomy classifies and names organisms.
• The Linnaean system uses a hierarchy (Kingdom, Phylum, Class, Order, Family, Genus, Species).

Homeostasis

• Homeostasis maintains a stable internal environment.
• Temperature, water balance, pH, and other factors are crucial for cellular function and survival.
• Feedback mechanisms (positive and negative) regulate internal conditions.

Cellular Respiration & Photosynthesis Details

• Cellular Respiration occurs in stages (glycolysis, Krebs cycle, electron transport chain) producing ATP.
• Photosynthesis involves light-dependent and light-independent stages, capturing light energy to produce glucose from carbon dioxide and water.

DNA Replication

• DNA replication involves unwinding the double helix, separating strands, and synthesizing complementary strands using DNA polymerase.

Protein Synthesis

• Transcription converts DNA's genetic code to mRNA.
• Translation uses the mRNA code to synthesize proteins using ribosomes and tRNA.
• Different RNA types have specific roles in this process.