CELL STRUCTURES AND THEIR FUNCTIONS

Vocabulary flashcards covering the major cell structures, membranes, transport mechanisms, protein synthesis, and the cell cycle described in the lecture notes.

Cell

The basic living unit of all organisms.

Organelles

Specialized structures inside cells with specific functions.

Metabolism

All chemical reactions inside cells that release energy.

Synthesis of molecules

Cells create important molecules like proteins, fats, and DNA; different cells make different molecules.

Communication

Cells send and receive signals to talk to each other.

Reproduction and inheritance

Genetic information (DNA) passes to offspring via sperm and egg.

Nucleus

Membrane-bound organelle containing DNA and nucleolus; site of RNA synthesis and ribosome assembly.

DNA

Genetic material; carries the instructions for making proteins.

Chromosomes

DNA-protein structures in the nucleus that carry genetic information.

Nucleolus

Nuclear region that makes ribosomes; lacks a membrane.

Ribosomes

Tiny structures that synthesize proteins; free in cytoplasm or attached to rough ER.

Rough Endoplasmic Reticulum (RER)

ER with ribosomes; site of protein synthesis.

Smooth Endoplasmic Reticulum (SER)

ER without ribosomes; site of lipid synthesis and detoxification.

Golgi Apparatus

Packages and ships proteins and fats made by the ER to their destinations.

Secretory Vesicles

Vesicles that store and transport substances; release contents by exocytosis.

Lysosomes

Enzyme-containing sacs that digest material and waste; used by white blood cells to destroy bacteria.

Peroxisomes

Small sacs with enzymes that degrade harmful substances.

Mitochondria

Powerhouses of the cell; produce ATP via aerobic respiration; have two membranes.

ATP

Adenosine triphosphate; the cell’s main energy source.

Centrioles

Two centrioles near the nucleus that organize microtubules during cell division.

Centrosome

Region near the nucleus containing the two centrioles; organizes microtubules.

Cilia

Hair-like projections that move mucus and particles; found on some cells (e.g., respiratory tract).

Flagella

Long, whip-like structures that propel some cells (typically one per cell, e.g., sperm).

Microvilli

Tiny extensions increasing surface area for absorption; do not move.

Microtubules

Cytoskeletal filaments that support the cell and form structures for division and cilia/flagella.

Cytoplasm

Jelly-like interior of the cell outside the nucleus; contains cytosol and organelles.

Plasma Membrane (Cell Membrane)

Outer boundary of the cell; protects the cytoplasm; regulates entry/exit and communication.

Phospholipid Bilayer

Double layer of phospholipids forming the core of the cell membrane.

Hydrophilic Head

Water-loving phospholipid region facing the watery exterior and interior.

Hydrophobic Tails

Water-fearing phospholipid region facing inward away from water.

Cholesterol

Sterol in the membrane that adds strength and stability by restricting movement of phospholipids.

Carbohydrates

Sugar chains on membrane proteins/lipids that modify function.

Fluid-Mosaic Model

Dynamic view of the membrane with a fluid phospholipid bilayer and embedded proteins.

Membrane Proteins

Proteins that function as channels, carriers, receptors, enzymes, or structural supporters in the membrane.

Passive Transport

Movement across the membrane without energy input (diffusion, osmosis, facilitated diffusion).

Diffusion

Movement of solutes from high to low concentration; no energy required.

Concentration Gradient

Difference in solute concentration between two points driving diffusion/osmosis.

Osmosis

Movement of water across a semipermeable membrane from low to high solute concentration.

Hypotonic

Solution with lower solute concentration outside the cell; water enters; cell swells.

Isotonic

Solution with equal solute concentrations inside and outside; no net water movement.

Hypertonic

Solution with higher solute concentration outside; water leaves; cell shrinks.

Carrier-Mediated Transport

Transport across the membrane via a carrier molecule for large/charged molecules.

Facilitated Diffusion

Diffusion that uses a carrier or channel; does not require energy.

Active Transport

Energy-requiring transport (ATP) that moves substances against a gradient.

Secondary Active Transport

Energy-driven transport powered by gradients created by primary active transport.

Endocytosis

Cell takes in large particles by wrapping membrane into a vesicle.

Phagocytosis

Cell eating; ingestion of large particles, used by white blood cells.

Pinocytosis

Cell drinking; uptake of fluid and small molecules.

Receptor-Mediated Endocytosis

Endocytosis initiated by receptor binding specific molecules; involves coated vesicles.

Exocytosis

Release of large molecules or wastes from the cell via vesicle fusion with the membrane.

Transcription

Process where DNA is read to produce mRNA; occurs in the nucleus.

Translation

Process where mRNA is used by ribosomes to assemble amino acids into a protein.

mRNA

Messenger RNA; carries genetic message from DNA to ribosomes.

tRNA

Transfer RNA; carries amino acids to the ribosome; anticodons pair with codons.

rRNA

Ribosomal RNA; component of ribosome; helps catalyze protein synthesis.

Codon

Three-nucleotide sequence in mRNA that codes for an amino acid.

Anticodon

Three-nucleotide sequence in tRNA that pairs with an mRNA codon.

Gene Expression

Process by which information in DNA directs protein synthesis.

Interphase

Non-dividing phase where the cell grows and copies DNA (G1, S, G2).

G1 Phase

Cell grows and carries out normal functions.

S Phase

DNA replication occurs.

G2 Phase

Cell grows and prepares to divide.

Prophase

Chromosomes condense; nuclear envelope dissolves; spindle forms.

Metaphase

Chromosomes align at the cell center; spindle attaches to chromatids.

Anaphase

Sister chromatids separate and move to opposite poles.

Telophase

Nuclei form around separated chromosomes; division completes.

Mitosis

Nuclear division producing two identical nuclei; followed by cytokinesis.

Differentiation

Process by which cells develop specialized structures and functions.

Apoptosis

Programmed cell death; normal regulation of cell numbers.

Nucleolus

Nuclear region that synthesizes ribosomes; does not have a membrane.