Biology S2

Cell Theory

All living organisms are composed of one or more cells; cells are the basic units of structure and function; all cells come from pre-existing cells.

Organelles

Specialized structures within a cell that perform specific functions.

Cell Membrane

The structure that separates the cell contents from the external environment and allows selective transport of materials.

Nucleus

Contains genetic material and controls the activities of the cell; site of DNA replication and transcription.

Nucleolus

Site of ribosome production and storage for RNA.

Centrioles

Structures that help in cell division by forming spindle fibers.

Ribosomes

The site of protein synthesis, translating genetic codes into amino acid chains.

Endoplasmic Reticulum (ER)

Network of membranes connected to the nuclear envelope, involved in transport of materials.

Rough ER

Endoplasmic reticulum with ribosomes, involved in protein synthesis.

Smooth ER

Endoplasmic reticulum without ribosomes, involved in lipid synthesis.

Golgi Bodies

Structures that modify, sort, and package proteins and other substances for transport.

Mitochondria

Known as the powerhouse of the cell, where ATP is produced.

Cytoplasm

Clear gel-like fluid that contains organelles and is the transport medium within the cell.

Flagella

Hair-like structures that enable movement of the entire cell.

Cilia

Short hair-like structures that help in cell movement.

Vacuole

Storage organelle for food, waste, and other materials.

Lysosomes

Organelles that digest food particles and can destroy bacteria.

Cell Wall

Rigid structure that provides support and allows communication in plant cells.

Chloroplasts

Organelles in plant cells that carry out photosynthesis, trapping sunlight to produce glucose.

Interphase

Phase of the cell cycle where the cell grows and prepares for division.

Mitosis

Process of division of the nucleus into two nuclei with the same number of chromosomes.

Apoptosis

Controlled death of cells that are no longer needed.

Necrosis

Death of cells due to factors such as toxins or trauma.

Benign Tumor

Non-cancerous tumor that grows slowly and does not spread.

Malignant Tumor

Cancerous tumor that grows rapidly and can invade surrounding tissues.

Metastasis

Process by which cancer cells spread to other parts of the body.

Stem Cells

Undifferentiated cells that can develop into any cell type.

Differentiation

Process by which cells change in form and function.

Somatic Cells

Body cells that contain the complete set of chromosomes.

Chromatin

Long thread-like form of DNA in non-dividing cells.

Chromosomes

Coiled form of DNA present during cell division.

Asexual Reproduction

Reproduction involving only one parent, resulting in genetically identical offspring.

Sexual Reproduction

Reproduction involving genetic material from two parents, resulting in genetically diverse offspring.

G1 Phase

Phase of cell cycle where the cell grows and copies organelles.

S Phase

Phase where DNA is replicated in preparation for cell division.

G2 Phase

Phase where the cell prepares for mitosis and synthesizes necessary proteins.

Prophase

First stage of mitosis where chromosomes coil up and the nuclear envelope disappears.

Metaphase

Second stage of mitosis where chromosomes line up at the cell's equator.

Anaphase

Third stage of mitosis where sister chromatids are pulled apart to opposite poles.

Telophase

Final stage of mitosis where the nuclear envelopes form around the new nuclei.

Cytokinesis

Process following mitosis where the cytoplasm divides to form two separate cells.

Hierarchy of Structures

Levels of organization in biology, from cells to organisms.

Respiration

The process of gas exchange involving intake of oxygen and expulsion of carbon dioxide.

External Respiration

Gas exchange occurring in the lungs.

Internal Respiration

Gas exchange between blood and body tissues.

Cellular Respiration

Process in which cells use oxygen to make ATP.

Cystic Fibrosis

Genetic disorder affecting respiration due to faulty CFTR protein.

Spirometry

Measurement of lung function and respiratory volumes.

Pulmonary Circulation

Circulation of blood between the heart and lungs.

Capillaries

Small blood vessels where gas exchange takes place.

Nutrients

Substances that provide nourishment for growth and maintenance.

Digestion

The process of breaking down food into usable nutrients.

Absorption

The process by which nutrients enter the bloodstream after digestion.

Elimination

The removal of waste products from the body.

Mechanical Digestion

Physical breakdown of food.

Chemical Digestion

Breakdown of food by enzymes.

Peristalsis

Wave-like muscle contractions that move food through the digestive tract.

Villus

Small intestine structure that absorbs nutrients.