chapter 4- cells part 1

Vocabulary flashcards covering microscope types, historical cell discoveries, unified cell theory, and the structural components and organelles of prokaryotic and eukaryotic cells.

Cell

The smallest unit of a living thing and the basic building block of all organisms.

Microscope

An instrument that magnifies an object so it can be studied, derived from micro- ('small') and -scope ('to look at').

Micrograph

A photograph or image of an object or cell taken using a microscope.

Magnification

The process of enlarging an object in appearance.

Resolving power

A microscope's ability to distinguish two adjacent structures as separate, which determines the clarity and detail of an image.

Light microscope

A microscope that passes and bends visible light through a lens system to enable viewing of specimens, commonly magnifying up to 400 times (or 1,000 times using oil immersion).

Electron microscope

A microscope that uses a beam of electrons in a vacuum instead of light, providing higher magnification and resolving power but killing the specimen during preparation.

Scanning electron microscope (SEM)

An electron microscope that moves a beam of electrons back and forth across a cell's surface to produce detailed images of surface characteristics.

Transmission electron microscope (TEM)

An electron microscope where the electron beam penetrates the cell to provide detailed images of its internal structures.

Animalcules

The collective term used in the 1600s by Antony van Leeuwenhoek to describe the movements of single-celled organisms he observed through crafted lenses.

Unified cell theory

The theory proposed by Matthias Schleiden and Theodor Schwann stating that one or more cells comprise all living things, the cell is the basic unit of life, and new cells arise from existing cells.

Cytotechnologist

A professional who studies cells via microscopic examinations and laboratory tests to detect normal and abnormal cellular changes.

Prokaryote

A simple, predominantly single-celled organism that lacks a nucleus or any other membrane-bound organelle, categorized into Bacteria and Archaea.

Nucleoid

The central region of a prokaryotic cell where its chromosomal DNA is localized.

Capsule

A polysaccharide outer structure present in many bacteria that enables the cell to attach to environmental surfaces.

Conjugation

The process by which one bacterium transfers genetic material to another through direct contact using specialized structures called pili.

Fimbriae

Cellular appendages used by bacteria to attach to a host cell.

Flagella

Cellular structures used by some prokaryotes and single-celled organisms for locomotion.

Eukaryote

An organism whose cells possess a membrane-bound nucleus, multiple rod-shaped chromosomes, and membrane-bound organelles.

Plasma membrane

A phospholipid bilayer with embedded proteins and cholesterol that separates the cell's interior contents from its surrounding environment.

Microvilli

Fingerlike foldings of the plasma membrane on absorptive cells, such as those lining the small intestine, that increase surface area for absorption.

Cytoplasm

The entire region of a cell between the plasma membrane and the nuclear envelope, comprising organelles suspended in gel-like cytosol, the cytoskeleton, and dissolved chemicals.

Nuclear envelope

A double-membrane structure punctuated with pores that constitutes the outermost portion of the nucleus, with both inner and outer layers formed by phospholipid bilayers.

Nucleoplasm

The semi-solid fluid inside the nucleus where chromatin and the nucleolus are situated.

Chromatin

The unwound protein-chromosome complexes resembling jumbled threads found during the growth and maintenance phases of a cell's life cycle.

Nucleolus

A darkly staining area within the nucleus that aggregates ribosomal RNA with associated proteins to assemble ribosomal subunits.

Ribosome

A large cellular complex of protein and RNA consisting of large and small subunits responsible for synthesizing proteins.

Mitochondria

Oval-shaped, double-membrane organelles termed the 'powerhouses' or 'energy factories' of the cell that produce ATP via cellular respiration.

Cristae

The folds of the inner mitochondrial membrane that increase surface area for cellular respiration and ATP synthesis.

Mitochondrial matrix

The space enclosed by the inner membrane and cristae of a mitochondrion.

Peroxisome

A small, round, single-membrane organelle that carries out oxidation reactions to break down fatty acids and amino acids and safely converts $H_2O_2$ into oxygen and water.

Glyoxysome

A specialized peroxisome in plant cells responsible for converting stored fats into sugars.

Centrosome

A microtubule-organizing center found near the nuclei of animal cells that contains a pair of perpendicular centrioles.

Centriole

A structure inside an animal cell's centrosome consisting of a cylinder made of nine triplets of microtubules held together by nontubulin proteins.

Lysosome

An organelle in animal cells containing digestive enzymes active at an acidic pH that breaks down macromolecules and worn-out organelles, functioning as the cell's 'garbage disposal.'

Cell wall

A rigid external covering that protects the cell, provides structural support, and gives shape to plant, fungal, and some protistan cells.

Cellulose

A polysaccharide composed of glucose units connected by 1-4 linkages that forms the primary organic structural component of plant cell walls.

Chloroplast

A double-membrane plant and algal cell organelle that contains its own DNA and ribosomes and carries out photosynthesis.

Thylakoid

An interconnected and stacked fluid-filled membrane sac within the chloroplast where light-harvesting photosynthetic reactions take place.

Granum

A stack of thylakoids located inside a chloroplast.

Stroma

The aqueous fluid enclosed by the inner membrane of a chloroplast surrounding the grana where sugar synthesis takes place.

Chlorophyll

A green pigment contained within chloroplasts that captures the light energy driving the reactions of photosynthesis.

Endosymbiosis

A mutually beneficial relationship in which one organism lives inside another; accounts for the evolutionary origin of mitochondria and chloroplasts from ingested bacteria.