BIOL 102 - WEEK 2 LECTURE 1

Vocabulary practice flashcards covering microscopy principles, organelle structures, endomembrane system functions, cytoskeletal elements, cell junctions, and specialized eukaryotic cell types from BIOL 102 lecture material.

Light microscopy

A microscopy technique based on passing a beam of light through a specimen.

Electron microscopy

A microscopy technique based on passing a beam of electrons over or through a specimen.

Resolution

The minimum distance two points can be separated and still be distinguishable.

Nucleus

Contains cells chromosomes made up of chromatin

Magnification

The ratio of an object's image size to its real size.

Contrast

The difference in brightness between light and dark areas of a specimen image.

Cytoplasm

The interior of a cell (excluding the nucleus) containing organelles suspended in cytosol.

Cytosol

The jelly-like fluid substance within the cytoplasm in which organelles are suspended.

Epidermal pavement cells

Specialized jigsaw-puzzle-shaped plant epidermal cells that differ in morphology from standard textbook plant cell diagrams.

Ribosomes

Complexes of protein and ribosomal RNA (rRNA) responsible for protein synthesis in cells.

Free ribosomes

Ribosomes suspended in the cytosol that synthesize proteins functioning within the cytosol.

Bound ribosomes

Ribosomes associated with the endoplasmic reticulum or nuclear envelope.

Endomembrane system

A cell system consisting of the nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and plasma membrane, connected directly or via vesicles.

Chromatin

The cellular material that makes up chromosomes, consisting of DNA complexed with proteins.

Nuclear envelope

A double membrane enclosing the nucleus, composed of two lipid bilayers lined by the nuclear lamina.

Nuclear lamina

A network of protein filaments lining the inner surface of the nuclear envelope that provides structural support.

Nucleolus

A specialized sub-nuclear region where ribosomal RNA (rRNA) transcription and ribosome assembly take place.

Smooth ER

A region of the endoplasmic reticulum involved in metabolic processes including lipid synthesis, drug detoxification, and calcium storage.

Rough ER

A region of the endoplasmic reticulum studded with ribosomes involved in synthesizing exported proteins, protein glycosylation, and membrane synthesis.

Golgi apparatus

An organelle that sorts molecules, releases vesicles for transport, alters the structure of macromolecules, and synthesizes secreted polysaccharides.

Lysosomes

Membranous sacs with an acidic interior containing hydrolytic enzymes for hydrolyzing macromolecules.

Vacuoles

Large vesicles containing an internal solution that differs in composition from the cytoplasm.

Mitochondria

Organelles that serve as the sites of cellular respiration, generating ATP from organic fuels and oxygen.

Chloroplasts

Photosynthetic organelles found in plant cells that synthesize sugars from carbon dioxide, water, and light energy.

Endosymbiont theory

The theory describing the evolutionary origins of mitochondria and chloroplasts from engulfed prokaryotes, such as an alphaproteobacterium and a cyanobacterium.

Cytoskeleton

A dynamic network of fibers extending throughout the cytoplasm that provides mechanical support, anchorage, and cell motility.

Microtubules

Hollow tubes made of $\alpha$-tubulin and $\beta$-tubulin dimers with a $25\,\text{nm}$ diameter and $15\,\text{nm}$ lumen, functioning as compression-resisting girders, tracks for organelle movement, and structures for cilia and flagella.

Microfilaments

Cytoskeletal elements consisting of two intertwined strands of actin ($7\,\text{nm}$ diameter) that function as tension-bearing elements, support cell shape changes, and drive muscle contraction.

Intermediate filaments

Fibrous protein cables ($8\,\text{nm}$ to $12\,\text{nm}$ diameter) made of proteins like keratins, providing tension-bearing support, anchoring the nucleus and organelles, and forming the nuclear lamina.

Plasmodesmata

Channels connecting plant cell walls that allow the physical transfer of compounds between adjacent cells.

Gap junctions

Communicating junctions between adjacent animal cells that function as the equivalent of plant plasmodesmata.

Tight junctions

Intercellular junctions that form tight seals between animal cells, preventing the movement of extracellular fluid across a cell layer.

Desmosomes

Anchoring cell junctions in animal cells that fasten cells together into strong sheets, anchored by intermediate filaments.

Hepatocytes

Liver cells possessing extensive smooth ER, rough ER, Golgi apparatus, and $1000$ to $2000$ mitochondria per cell to facilitate drug detoxification, lipid synthesis, and protein secretion.

Erythrocytes

Mammalian red blood cells that lack a nucleus, mitochondria, DNA, RNA, Golgi apparatus, and ER, producing ATP solely through fermentation and carrying cell-surface glycoproteins that determine blood type.

Keratinocytes

Epidermal skin cells that permanently withdraw from the cell cycle, lose organelles, and rely on an extensive network of keratin intermediate filaments for rigidity and desmosomes for adhesion.

Sarcomere

The basic contractile unit of a skeletal muscle cell composed of organized actin microfilaments and myosin filaments.