BIOL 443/543 LECTURE SLIDES 3 (Overview of Eukaryotic Cell Structures)

A complete set of vocabulary flashcards covering eukaryotic cell structures, organelles, endomembrane components, and membrane dimensions from lecture notes.

Nucleus

An organelle with an approximate diameter of $6\,\mu m$ that contains the cell's genetic material (chromosomes, DNA, and proteins) separated from the cytoplasm by a nuclear envelope.

Nuclear envelope

A double membrane structure consisting of two lipid bilayers that separates the nucleoplasm from the cytoplasm.

Chromatin

The nuclear complex composed of eukaryotic DNA (measuring $2\,nm$ wide by up to $< 400\,cm$ long) bound to proteins.

Nucleolus

A specialized region of chromatin within the nucleus dedicated to the assembly of ribosomes.

Nuclear pores

Channels embedded in the nuclear envelope that regulate the transport and passage of molecules between the nucleus and cytoplasm.

Lumen

The internal compartment space enclosed within the membrane sacs or tubes of the endoplasmic reticulum.

Cisterna

The individual structural unit of the endoplasmic reticulum, encompassing both the membrane and its enclosed lumen (plural: cisternae).

Smooth endoplasmic reticulum

A region of the endoplasmic reticulum involved in the breakdown and synthesis of lipids and other non-polar molecules.

Rough endoplasmic reticulum

A region of the endoplasmic reticulum associated with ribosomes that synthesize proteins for the endomembrane system or secretion.

Golgi apparatus

An organelle consisting of flattened membrane sacs formed by vesicles from the endoplasmic reticulum that chemically modifies proteins and lipids before routing them to destinations.

Lysosomes

Membrane-bound vesicles found in animal cells that contain digestive enzymes for cellular breakdown.

Endosomes

Internal membrane vesicles formed by endocytosis at the plasma membrane that transport cargo, such as membrane-bound proteins, to cellular organelles.

Endomembrane system

A system of functionally and origin-linked cytoplasmic membranes—including the endoplasmic reticulum, nuclear envelope, Golgi apparatus, endosomes, and lysosomes—that transport materials via vesicles.

Ribosomes

Molecular complexes of rRNA and protein divided into a large subunit and a small subunit that translate mRNA to synthesize polypeptides.

80S vs. 70S ribosomes

Eukaryotic cytoplasmic ribosomes are classified as $80S$, whereas prokaryotic ribosomes and those inside mitochondria and chloroplasts are classified as $70S$.

Microbodies

Small, single-membrane-bound organelles outside the endomembrane system that perform specific oxidative metabolic reactions.

Peroxisomes

Microbodies that generate $H_2O_2$ as a product of oxidative reactions and subsequently break it down using the enzyme catalase.

Glyoxysomes

Specialized microbodies in plant cells, such as in germinating seeds, that convert stored oils into sucrose.

Mitochondria

Complex organelles of endosymbiotic prokaryotic origin ranging from $0.5 \times 2\,\mu m$ to $3 \times 10\,\mu m$ in size containing their own DNA and $70S$ ribosomes, whose chief function is oxidizing organic molecules to release energy.

Cytoskeleton

A network of protein filaments extending throughout the cytoplasm and into the nucleus that provides structural support, shape, and movement.

Chloroplasts

Plastid organelles in plants and photosynthetic algae ranging from $2 \times 5\,\mu m$ to $4 \times 10\,\mu m$ in size that serve as the site of photosynthesis.

Vacuoles

Organelles accounting for $70\%$ to $90\%$ of plant cell volume that store water, salts, acids, sugars, and pigments while hosting biochemical reactions.

Plasma membrane

A phospholipid bilayer structure approximately $5.5$ to $7.5\,nm$ thick that separates internal and external cell environments to maintain homeostasis.

Phospholipid bilayer

The primary structural unit of cellular membranes, composed of hydrophilic heads exposed to water and hydrophobic tails measuring approximately $3\,nm$ long.

Water (cellular solvent)

The main cellular solvent molecule measuring approximately $0.126\,nm$ long, with a Van der Waals radius of $2.82\,\text{\AA}$, O-H bond lengths of $0.957\,\text{\AA}$ to $1.00\,\text{\AA}$, and H-O-H bond angles of $104.52^\circ$ to $109.5^\circ$.