IB Biology HL - Cell Structure (A2.2)

Flashcards on Cell Structure and Function

Cell Theory

All living organisms are composed of one or more cells; The cell is the basic unit of structure and function in all living organisms; All cells arise from pre-existing cells.

Scientific Theory

A well-substantiated explanation of some aspect of the natural world, backed by repeated observations and experiments.

Inductive Reasoning

Drawing general conclusions based on specific observations or patterns.

Deductive Reasoning

Making specific predictions based on a general principle or theory.

Plasma Membrane

Controls the movement of substances in and out of the cell; maintains homeostasis.

Cytoplasm

Site of biochemical reactions and contains organelles or cellular components.

Ribosomes

Synthesize proteins based on genetic instructions.

DNA

Stores genetic information necessary for cell function and reproduction.

Prokaryote

A unicellular organism with a simple structure and no membrane-bound organelles.

Eukaryote

Complex, compartmentalized cells that make up all plants, animals, fungi, and protists.

80S Ribosomes

Site of protein synthesis (translation); Free-floating in the cytoplasm (makes proteins for internal use); Attached to rough ER (makes proteins for secretion or membrane integration).

Nucleus

Stores genetic material (DNA); Controls cell activities through gene expression and protein synthesis.

Cytoskeleton

Provides structural support; Involved in intracellular transport (e.g., vesicle movement); Helps with cell division (spindle fibers) and cell movement (cilia, flagella).

Mitochondria

Site of aerobic respiration, producing ATP; Often called the 'powerhouse' of the cell.

Endoplasmic Reticulum (ER)

Rough ER (RER) synthesizes and modifies proteins for export or membrane insertion; Smooth ER (SER) synthesizes lipids and detoxifies toxins.

Golgi Apparatus

Modifies, sorts, and packages proteins and lipids for secretion or use within the cell; Produces lysosomes.

Lysosomes

Breaks down waste, cellular debris, and pathogens; Plays a role in autophagy (self-digestion of damaged organelles).

Aseptate Fungal Hyphae

Continuous cytoplasm with many nuclei (no septa that divides cells).

Skeletal Muscle

Multinucleated and very long cells.

Red Blood Cells

No nucleus (increases oxygen-carrying capacity).

Phloem Sieve Tube Elements

Lack nuclei and rely on companion cells for metabolic activity.

Metabolism

All chemical reactions that sustain life, including respiration and enzyme activity.

Homeostasis

Maintaining internal stability (e.g., water balance, temperature regulation).

Excretion

Removal of metabolic waste (e.g., CO₂, ammonia).

Nutrition

Obtaining food for energy (autotrophic or heterotrophic).

Paramecium

A single celled eukaryotic organism which uses cilia for movement, engulfs food via phagocytosis, and excretes waste through an anal pore.