Chapter 4 Vocabulary Flashcards
light microscope
an optical instrument with lenses that refract (bend) visible light to magnify images and project them into a viewer’s eye or onto photographic film
magnification
an increase in the apparent size of an object
resolution
a measure of the clarity of an image; the ability of an optical instrument to show 2 objects as separate
cell theory
the theory that all living things are composed of cells and that all cells come from other cells
electron microscope
an instrument that focuses an electron beam through, or onto the surface of a specimen. an electron microscope achieves a thousandfold greater resolution than a light microscope; the most powerful EM can distinguish objects as small as 0.2 nm
scanning electron microscope
a microscope that uses an electron beam to study the surface architecture of a cell or other specimen
transmission electron microscope
a microscope that uses an electron beam to study the internal structure of thinly sectioned specimens
prokaryotic cells
a type of cell lacking a membrane enclosed nucleus and other membrane-enclosed organelles; found only in the domains Bacteria and Archaea
eukaryotic cells
a type of cell that has a membrane enclosed nucleus and other membrane enclosed organelles. all organisms except bacteria and archaea are composed of eukaryotic cells
plasma membrane
the thin layer of lipids and proteins that sets a cell off from its surroundings and acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer in which are embedded molecules of protein and cholesterol
ribosome
a cell organelle consisting of RNA and protein organized into 2 subunits and functions as the site of protein synthesis in the cytoplasm. The ribosomal subunits are constructed in nucleolus
nucleoid
the region in a prokaryotic cell consisting of a concentrated mass of DNA
cell wall
a protective layer external to plasma membrane in plant cells, bacteria, fungi, and sme protists, protects the cell and helps maintain its shape
capsule
a sticky layer that surrounds the bacterial cell wall, protects the cell surface, and sometimes helps give the cell to surfaces
pilus
A short projection on the surface of a prokaryotic cell that helps the prokaryote attach to other surfaces. specialized sex pili are used in conjugation to hold the mating cells together
prokaryotic flagellum
a long surface projection that propels a prokaryotic cell through its liquid environment, totally different from the flagellum of a eukaryotic cell
cytoplasm
everything inside a cell between the plasma membrane and the nucleus; consists of semifluid medium and organelles
organelle
a structure with a specialized function within a cell
cellular metabolism
the chemical activity of cells
nucleus
genetic control center of eukaryotic cell
chromatin
combination of DNA and proteins that constitutes chromosomes; often used to refer to the diffuse, very extended form taken by chromosomes when eukaryotic cell is no dividing
chromosome
A thread-like, gene carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also the main gene-carrying structure of prokaryotic cell. Consists of chromatin.
nuclear envelope
a double membrane, perforated with pores, that encloses he nucleus and separates it from the rest of the eukaryotic cell
nucleolus
a structure within the nucleus of a eukaryotic cell where ribosomal RNA is made and assembled with proteins to make ribosomal subunits; consists of parts of the chromatin DNA, RNA transcribed from the DNA, and proteins imported from the cytoplasm
granum
a stack of hollow disks formed of thylakoid membrane in a chloroplast. Grana ar the sites where light energy is trapped by chlorophyll and converted to chemical energy
vesicles
sacs made of membrane
endomembrane system
a network of membranous organelles that partition the cytoplasm of eukaryotic cells into functional compartments. some of the organelles are structurally connected to each other, whereas others are structurally separate but functionally connected by the traffic of membranous vesicles between them
secretory protein
a protein (such as an antibody) that is secreted by a cell
endoplasmic reticulum
an extensive membranous network in a eukaryotic cell, continuous with the outer nuclear membrane and composed of ribosome studded (rough) and ribosome free (smooth) regions
smooth ER
a network of interconnected membranous tubules in a eukaryotic cell’s cytoplasm. smooth ER lacks ribosomes. enzymes embedded in smooth ER membrane function in the synthesis of certain kinds of molecules such as lipids
rough ER
a network of interconnected membranous sacs in a eukaryotic cell’s cytoplasm. Rough ER membranes are studded with tibosomes that make membrane and secratory proteins. the rough ER constructs membrane from phospholipids and proteins
central vacuole
a membrane-enclosed sac occupying most of interior of mature plant cells having diverse roles in reproduction, growth and development.
chloroplast
an organelle found in plants and photosynthetic protists. enclosed by 2 concentric membranes, a chloroplast absorbs sunlight and uses it to power the synthesis of organic food molecules (sugars)
cristae
folds of the inner membrane of mitochondrion. enzyme molecules embedded in cristae make ATP
glycoprotein
a macromolecule consisting of one or more polypeptides linked to a short chain of sugars
golgi apparatus
an organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the enoplasmic reticulum
intermembrane space
one of the two fluid filled internal compartments of the mitochondrion. the intermembrane space is the narrow region between inner and outer membranes
lysosome
a digestive organelle in eukaryotic cells; contains hydrolytic enzymes that digest the cell’s food and wastes
stroma
a thick fluid enclosed by inner membrane of a chloroplast. sugars are made in the stroma by enzymes of calvin cycle
transport vesicle
a tiny membranous sac in cell’s cytoplasm carrying molecules produced by cell. the vesicle buds from endoplasmic reticulum or golgi and eventually fuses with another membranous organelle or the plasma membranes, releasing its contents
vacuole
a membrane-enclosed sac, part of the endomembrane system of eukaryotic cell, having diverse functions
anchoring junctions
a junction that connects tissue cells to each other (or to an extracellular matrix) and allows materials to pass from cell to cell
basal body
a eukaryotic cell organelle consisting of a 9+0 arrangement of microtubule triplets, may organize the microtubule assembly of a cilium or flagellum, structurally identical to centriole
cilium
a short appendage that propels some protists through water and moves fluid across the surface of many tissue cells in animals. in common with eukaryotic flagella, cilia have a (+2 arrangement of microtubules coverred by cell’s plasma membrane
cytoskeleton
a meshwork of fine fibers in the cytoplasm of a eukaryotic cell, includes microfilaments, intermediate filaments, and microtubules
extracellular matrix
a substance in which the cells of an animal tissue are embedded, consisting of protein and polysaccharides
flagellu,
longer, less numerous appendages on protists
gap junctions
channels between adjacent tissue cells through which water and other small molecules pass freely
intermediate filaments
an intermediate sized protein fiber that is one of the three main kinds of fibers making up cytoskeleton of eukaryotic cells. ropelike; made of fibrous proteins
microfilament
the thinnest of the 3 main inds of protein fibers making up cytoskeleton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin
microtubules
the thickest of the 3 main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a straight, hollow tube made of globular proteins called tubuluns. help form the basis of the structure and movement of cilia and flagella
mitochondrial matrix
fluid contained within inner membrane of a mitochondrion
mitochondrion
an organelle in eukaryotic cells where cellular respiration occurs. enclosed by 2 concentric membranes, it is where most of the cell’s ATP is made
plasmodesmota
open channels in a plant cell wall, through which strands of cytoplasm connect from adjacent walls
tight junctions
a junction the binds tissue cells together in a leakproof sheet
centriole
a structure in an animal cell composed of microtubule triplets arranged in a 9+0 pattern. an animal cell usually has a pair of centrioles within each of its centrosones
