Levels of Structural Organization and Cell Biology

Practice flashcards covering the levels of biological organization, organ systems, homeostasis, and cellular structure and transport based on lecture notes.

Chemical Level

The simplest level of structural organization involving atoms that combine to form molecules like water, sugar, and proteins.

Cellular Level

The level of structural organization representing the smallest unit of living things.

Tissue Level

Groups of similar cells that have a common function.

Connective Tissue

Tissue types such as bone, cartilage, tendons, and blood that support, bind, and protect the body while storing and transporting substances.

Organ Level

A structure composed of two or more tissue types that perform a specific function.

Organism

The highest level of structural organization, representing the sum total of all organ systems.

Integumentary System

The external body covering that protects deeper tissue, synthesizes vitamin D, and houses cutaneous receptors and glands.

Skeletal System

System that protects and supports organs, provides a framework for movement, forms blood cells, and stores minerals.

Nervous System

A fast-acting control system that responds to internal and external changes by activating muscles and glands.

Endocrine System

Glands that secrete hormones to regulate processes such as growth, reproduction, and nutrient use.

Metabolism

All chemical reactions occurring within body cells, including breaking down substances and using nutrients to produce $ATP$ energy.

Homeostasis

The body's ability to maintain relatively stable internal conditions even though the outside environment changes.

Receptor

The component in a homeostatic control system that detects changes or stimuli in the environment.

Negative Feedback Mechanism

A system where the effectors stop their response once the variable has returned to normal, decreasing any deviation from the homeostatic set point.

Positive Feedback Mechanism

A mechanism where the deviation from normal is increased, seen in processes like blood clotting through thrombin or childbirth via uterine contractions.

Fluid Mosaic Model

A description of the plasma membrane as two lipid layers where protein molecules float and change patterns.

Hydrophilic

The 'water-loving' property of phospholipid heads that lie on the inner and outer surfaces of the membrane.

Hydrophobic

The 'water-fearing' property of phospholipid tails that lie in the center of the plasma membrane.

Tight Junctions

Impermeable junctions fused together like a zipper to prevent substances from passing through the space between cells.

Gap Junctions

Communication junctions composed of hollow protein cylinders called connexons that allow the passage of nutrients and ions.

Mitochondria

The double-membrane 'powerhouse of the cell' where oxygen is used to break down food and release energy captured as $ATP$.

Ribosomes

The actual sites of protein synthesis within the cell.

Rough Endoplasmic Reticulum

A network of channels studded with ribosomes that folds proteins and dispatches them in transport vesicles.

Lysosomes

Membranous sacs containing digestive enzymes that break down bacteria, worn-out cell structures, and foreign substances.

Peroxisomes

Self-replicative sacs containing oxidase and catalase enzymes that detoxify free radicals and hydrogen peroxide.

Cytoskeleton

The internal framework of the cell consisting of microfilaments ($actin$ and $myosin$), intermediate filaments, and microtubules.

Passive Transport

Substance movement across the membrane that requires no $ATP$, including diffusion and filtration.

Osmosis

The specific movement of water from an area of higher concentration to an area of lower concentration.

Isotonic Solution

A solution with an equal concentration of solutes compared to the cell.

Sodium-Potassium Pump

An active transport mechanism that uses $ATP$ to move $3\,Na^+$ out of the cell and $2\,K^+$ into the cell.

Phagocytosis

A 'cell eating' endocytosis mechanism used for the ingestion of solid and large particles like bacteria.

Pinocytosis

A 'cell drinking' endocytosis mechanism used for the ingestion of liquid and small particles.