How can we help?

You can also find more resources in our Help Center.

AP Biology Chapter 4

A Tour of the Cell
STUDY
PLAY
light microscope (LM)
an optical instrument with lenses that refract visible light to magnify images and project them into a viewer's eye or onto photographic film
micrograph
a photograph taken through a microscope
cell theory
the theory that all living things are composed of cells and that all cells come from other cells
electron microscope (EM)
a microscope that uses magnets to focus an electron beam through or onto the surface of a specimen
scanning electron microscope (SEM)
a microscope that uses an electron beam to study the fine details of cell surfaces or other specimens
transmission electron microscope (TEM)
a microscope that uses an electron beam to study the internal structure of thinly sectioned specimens
plasma membrane
the membrane at the boundary of every cell that acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer with embedded proteins
prokaryotic cells
a type of cell lacking a membrane-enclosed nucleus and other membrane-enclosed organelles; only found in the domains Bacteria and Archaea
eukaryotic cells
a type of cell that has a membrane-enclosed nucleus and other membrane-enclosed organelles
chromosomes
a threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; the main gene carrying structure of a prokaryotic cell
ribsomes
polypeptide (protein) synthesis
cytoplasm
the contents of a eukaryotic cell between the plasma membrane and the nucleus
nucleoid
a dense region of DNA in a prokaryotic cell
flagella
a long cellular appendage specialized for locomotion, like cilia it has a 9+2 arrangement of microtubules covered by the cell's plasma membrane
organelles
a membrane-enclosed structure with a specialized function within a cell
cellular metabolism
all the chemical activities of a cell
nucleus
DNA replication, RNA synthesis; assembly of ribosomal subunits
chromatin
the combination of DNA and proteins that constitutes eukaryotic chromosomes; often used to refer to the diffuse, very extended form taken by chromosomes when a cell is not dividing
nuclear envelope
a double membrane that encloses the nucleus, perforated with pores that regulate traffic with the cytoplasm
nucleolus
a structure within the nucleus where ribosomal RNA is made and assembles with proteins imported from the cytoplasm to make ribosomal subunits
endomembrane system
a network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles
vesicles
a sac made of membrane in the cytoplasm of a eukaryotic cell
endoplasmic reticulum (ER)
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 endoplasmic reticulum
lipid synthesis; detoxification in liver cells; calcium ion storage
rough endoplasmic reticulum
synthesis of membrane lipids and proteins, secretory proteins and hydrolytic enzymes
glycoprotein
a protein with one or more short chains of sugars attached to it
transport vesicle
a small membranous sac in a eukaryotic cell's cytoplasm carrying molecules produced by the cell
golgi apparatus
modification and sorting of macromolecules; formation of lysosomes and transport vesicle
lysosome
digestion of ingested food, bacteria and a cell's damaged organelles and macromolecules for recycling
vacuoles
digestion (food); storage of chemicals and cell enlargement (central); water balance (contractile)
central vacuole
in a plant cell, a large membranous sac with diverse roles in growth and the storage of chemicals and wastes
peroxisomes
diverse metabolic processes, with breakdown of toxic hydrogen peroxide by-product
mitochondria
conversion of chemical energy in food to chemical energy of ATP
mitochondrial matrix
the compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle
cristae
an infolding of the inner mitochondrial membrane
chloroplasts
conversion of light energy to chemical energy of sugars
stroma
the dense fluid within the chloroplast that surrounds the thylakoid membrane and is involved in the synthesis of organic molecule from CO2 and water
thylakoids
a flattened membranous sac inside a chloroplast; it contains chlorophyll and the molecular complexes of the light reactions of photosynthesis
granum
a stack of membrane-bounded thylakoids in a chloroplast; the site where light energy is trapped by chlorophyll and converted to chemical energy during light reactions of photosynthesis
endosymbiont theory
a theory that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic cell; the engulfed cell and its host cell then evolved into a single organism
cytoskeleton
maintenance of cell shape; anchorage for organelles; movement of organelles within cells; cell movement
microfilaments
the thinnest of the three main kinds of protein fibers making up the cytoskeleton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin
intermediate filaments
an intermediate-size protein fiber that is one of the three main kinds of fibers making up the cytoskeleton of eukaryotic cells
microtubules
the thickest of the three main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a hollow tube made of globular proteins called tublins
cilia
a short cellular appendage specialized for locomotion, formed from a core of nine outer doublet microtubules and two single microtubules covered by the cell's plasma membrane
extracellular matrix (ECM)
support; regulation of cellular activities; the mesh-work surrounding animal cells
integrins
a transmembrane protein that interconnects the extracellular matrix and the cytoskeleton
cell wall
support and protection; binding of cells in tissues
plasmodesmata
an open channel in a plant cell wall through which strands of cytoplasm connect from adjacent cells
cell junctions
communication between cells; binding of cells in tissues