Cell Structure and Organelles (Lecture Notes: Chapters 4.5-4.6)

A comprehensive set of vocabulary flashcards covering cell discovery, cell types, organelles, the endomembrane system, protein synthesis, and related diseases.

Hooke

English scientist (1665) who coined the term 'cell' after examining cork.

Antonie van Leeuwenhoek

Dutch microscopist (1670s-1680s) who built strong lenses and observed bacteria, protists, blood cells, and sperm cells.

Hand-ground lenses

Microscope lenses ground by hand, enabling about 200x magnification in early microscopy.

Prokaryotic cell

Small, simple cells with no membrane-bound organelles; DNA in a nucleoid; has a plasma membrane and often a cell wall; may have flagella or fimbriae.

Nucleoid

Region in prokaryotes where genetic material is located; not a true nucleus.

Plasma membrane

Phospholipid bilayer surrounding the cell; controls movement of substances in and out.

Cell wall

Rigid layer outside the plasma membrane in many organisms that provides shape and protection.

Flagellum

Long, whip-like structure used for locomotion in some cells.

Fimbriae

Short, hair-like projections that help bacteria adhere to surfaces.

Ribosome

Ribosomal RNA-protein complexes that form peptide bonds and assemble amino acids into polypeptides; can be bound to ER or free in the cytosol.

Endoplasmic Reticulum (ER)

Network of internal membranes connected to the nuclear envelope; consists of rough and smooth ER; ER lumen is the space inside the membranes.

ER lumen

Internal space enclosed by ER membranes where proteins are synthesized and processed.

Rough ER

ER with bound ribosomes; site of protein synthesis and folding; proteins are packaged into transport vesicles.

Smooth ER

ER without ribosomes; synthesizes lipids and carbohydrates, processes steroids, stores Ca2+, detoxifies chemicals, and is abundant in liver cells.

Cholesterol processing

Smooth ER involvement in cholesterol synthesis and processing within cells.

Calcium storage (Ca2+)

Smooth ER stores calcium ions essential for various cellular processes.

Detoxification (Smooth ER)

Smooth ER neutralizes and metabolizes toxic chemicals; excessive production can lead to liver damage (cirrhosis).

Molecular chaperones

Proteins that assist in proper folding of other proteins within the ER.

Golgi apparatus

Stacked flattened membrane sacs (cisternae) that modify, sort, and package proteins; receives vesicles from the ER at the cis face and ships them out at the trans face.

Cis face

Entry side of the Golgi where vesicles from the ER fuse.

Trans face

Exit side of the Golgi where modified proteins are packaged into vesicles for transport.

Vesicles

Small membrane-bound sacs that transport proteins and other molecules between organelles and to the plasma membrane.

Lysosome

Small sacs containing digestive enzymes; acidic (pH ~5); digest debris, bacteria, and damaged organelles; primary lysosomes bud from the Golgi and secondary lysosomes form by fusion.

Primary lysosome

Lysosome that has not yet fused with material to digest.

Secondary lysosome

Lysosome formed by fusion with a vesicle or organelle to digest contents.

Tay-Sachs disease

Lysosomal storage disease caused by lipid accumulation in brain cells, leading to mental retardation, blindness, and death by age 4.

Nucleus

Stores most of a cell's DNA and acts as the control center of the cell; consists of a nuclear envelope, nucleoplasm, and nucleolus.

Nuclear envelope

Double lipid bilayer surrounding the nucleus; contains nuclear pores for transport.

Nuclear pores

Protein complexes that regulate movement between the nucleus and cytoplasm.

Nucleoplasm

Fluid inside the nucleus surrounding the chromatin and nucleolus.

Nucleolus

Nuclear region where ribosomal subunits assemble.

Endomembrane system

Network of membranes including the nuclear envelope, ER, Golgi, lysosomes, vesicles, and vacuoles that coordinate protein synthesis, processing, and transport.

Glycoproteins

Proteins with carbohydrate chains added in the ER and Golgi, important for folding, stability, and targeting.

Intracellular Protein Transport

Process by which polypeptides synthesized on ribosomes enter the ER lumen, are modified (e.g., glycosylated), and are delivered by transport vesicles to their destinations within the cell.