Chapter 6 Study Guide
Vocabulary:
Word Roots:
centro- = the center
-soma = a body
chloro- = green
cili- = hair
cyto- = cell
-ell = small
endo- = inner
eu- = true
extra- = outside
flagell- = whip
glyco- = sweet
lamin- = sheet/layer h
lyso- = loosen
micro- = small
-tubul = a little pipe
nucle- = nucleus
-oid = like
phago- = to eat
-desma = a band or bond
pro- = before
karyo- = nucleus
pseudo- = false
-pod = foot
thylaco- = sac or pouch
trans- = across
Key Terms:
actin: A globular protein that links into chains, two of which twist helically about
each other, forming microfilaments in muscle and other contractile elements in
cells.
cell wall: A protective layer external to the plasma membrane in plant cells,
bacteria, fungi, and some protists. In plant cells, the wall is formed of cellulose fibers
embedded in a polysaccharide-protein matrix.
central vacuole: A membranous sac in a mature plant cell with diverse roles in
reproduction, growth, and development.
chloroplast: An organelle found only in plants and photosynthetic protists that
absorbs sunlight and uses it to drive the synthesis of organic compounds from
carbon dioxide and water.
chromosome: A threadlike, gene-carrying structure found in the nucleus. Each
chromosome consists of one very long DNA molecule and associated proteins.
collagen: A glycoprotein in the extracellular matrix of animal cells that forms strong
fibers, found extensively in connective tissue and bone
contractile vacuole: A membranous sac that helps move excess water out of the cell.
crista: (plural, cristae) An infolding of the inner membrane of a mitochondrion that
houses the electron transport chain and the enzyme catalyzing the synthesis of ATP.
cytoplasm: The entire contents of the cell, exclusive of the nucleus, and bounded by
the plasma membrane.
cytoplasmic streaming: A circular flow of cytoplasm, involving myosin and actin
filaments, that speeds the distribution of materials within cells.
cytoskeleton: A network of microtubules, microfilaments, and intermediate
filaments that branch throughout the cytoplasm and serve a variety of mechanical
and transport functions.
cytosol: The semifluid portion of the cytoplasm.
desmosome: A type of intercellular junction made of intermediate filaments in
animal cells that functions as an anchor.
endomembrane system: The collection of membranes inside and around a
eukaryotic cell, related either through direct physical contact or by the transfer of
membranous vesicles.
eukaryotic cell: A type of cell with a membrane-enclosed nucleus and membraneenclosed organelles, present in protists, plants, fungi, and animals; also called
eukaryote.
extracellular matric (ECM): The substance in which animal tissue cells are
embedded, consisting of protein and polysaccharides.
flagellum: (plural, flagella) A long cellular appendage made of microtubules
specialized for locomotion.
food vacuole: A membranous sac formed by phagocytosis.
gap junction: A type of intercellular junction in animal cells that allows the passage
of material or current between cells.
glycoprotein: A protein covalently attached to a carbohydrate.
Golgi apparatus: An organelle in eukaryotic cells consisting of stacks of flat
membranous sacs that modify, store, and route products of the endoplasmic
reticulum.
granum: (plural, grana) A stacked portion of the thylakoid membrane in the
chloroplast. Grana function in the light reactions of photosynthesis.
intermediate filament: A component of the cytoskeleton made of subunits of keratin
that includes all filaments intermediate in size between microtubules and
microfilaments.
lysosome: A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm
of eukaryotic cells.
microfilament: A solid rod of actin protein in the cytoplasm of almost all eukaryotic
cells, making up part of the cytoskeleton and acting alone or with myosin to cause
cell contraction.
microtubule: A hollow rod of tubulin protein in the cytoplasm of all eukaryotic cells
and in cilia, flagella, and the cytoskeleton.
mitochondrial matrix: The compartment of the mitochondrion enclosed by the
inner membrane and containing enzymes and substrates for the citric acid cycle.
mitochondrion: (plural, mitochondria) An organelle in eukaryotic cells that serves
as the site of cellular respiration.
nuclear envelope: The membrane in eukaryotes that encloses the nucleus,
separating it from the cytoplasm.
nuclear lamina: A netlike array of protein filaments that maintains the shape of the
nucleus.
nucleoid: A dense region of DNA in a prokaryotic cell.
nucleolus: (plural, nucleoli) A specialized structure in the nucleus, formed from
various chromosomes and active in the synthesis of ribosomes.
nucleus: The chromosome-containing organelle of a eukaryotic cell.
organelle: One of several formed bodies with specialized functions, suspended in
the cytoplasm of eukaryotic cells.
phagocytosis: A type of endocytosis involving large, particulate substances,
accomplished mainly by macrophages, neutrophils, and dendritic cells.
plasma membrane: The membrane at the boundary of every cell that acts as a
selective barrier, thereby regulating the cell’s chemical composition.
plasmodesma: (plural, plasmodesmata) An open channel in the cell wall of plant
through which strands of cytosol connect from an adjacent cell.
plastid: One of a family of closely related plant organelles that includes chloroplasts,
chromoplasts, and amyloplasts.
prokaryotic cell: A type of cell lacking a membrane-enclosed nucleus and
membrane-enclosed organelles; found only in the domains Bacteria and Archaea.
pseudopodium: (plural, pseudopodia) A cellular extension of amoeboid cells used in
moving and feeding.
ribosome: A cell organelle constructed in the nucleolus and functioning as the site
of protein synthesis in the cytoplasm; consists of rRNA and protein molecules, which
make up two subunits.
rough ER: That portion of the endoplasmic reticulum studded with ribosomes.
smooth ER: That portion of the endoplasmic reticulum that is free of ribosomes.
stroma: The fluid of the chloroplast surrounding the thylakoid membrane; involved
in the synthesis of organic molecules from carbon dioxide and water.
thylakoid: A flattened membrane sac inside the chloroplast, used to convert light
energy to chemical energy.
tight junction: A type of intercellular junction in animal cells that prevents the
leakage of material between cells.
tonoplast: A membrane that encloses the central vacuole in a plant cell, separating
the cytosol from the vacuolar contents
transport vesicle: A tiny membranous sac in a cell’s cytoplasm carrying molecules
produced by the cell.
vacuole: A membrane bound vesicle whose specialized function varies in different
kinds of cells
vesicle: A sac made of membrane inside of cells.
Chapter 6 Important Points:
2 major types of cells:
 Prokaryotic: Bacteria, Archaea Domains
o Smaller, simpler than eukaryotic
o Lack membrane bound organelles including nucleus (have DNA in
concentrated nucleoid region instead)
 Eukaryotic
o Animal, Plant, Fungi, Protist Kingdoms
o Larger and more complex than prokaryotic
o Have many specialized membrane bound organelles including
membrane bound nucleus
All cell types have:
 Plasma membrane
 DNA
 Ribosomes
 Cytoplasm
Structures unique to animal cells vs. plant:
 Lysosomes
 Centrosomes with centrioles
 Flagella (except some plant sperm)
 Gap junctions, tight junctions, desmosomes
Structures unique to plant cells vs. animal:
 Cell wall
 Plasmodesmata in cell wall
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Central vacuole
Chloroplasts
Amyloplasts
Chromoplasts
1.) Plasma membrane
 Function: Selective barrier that controls what can enter and leave cell,
contains cytoplasm, defines cell as separate from environment
 Structure: Double layer of phospholipids w/ proteins embedded in them;
carbohydrate side chains on outside
2.) Nucleus
 Function: Contains genes (DNA)
 Structure: Enclosed by double layer nuclear membrane
 Membrane has pores: protein structure called pore complex lines pore,
controls what can enter or leave nucleus
 Nuclear lamina: lines inside of nuclear membrane, has protein filaments
intermediate filaments), maintains shape of nucleus
3.) Nucleolus
 Function: area w/in nucleus where ribosomal components synthesized
 Structure: dense area w/in nucleus near chromatin
4.) Ribosomes
 Function: Site of protein synthesis
 Structure: Made of ribosomal RNA (rRNA) & protein; 2 subunits
 2 types:
A. Free ribosomes: in cytosol, proteins they make are used in cytoplasm
B. Bound ribosomes: attached to endoplasmic reticulum; makes
proteins exported out of cell or used w/in other cell organelles
Endomembrane System
 Various membrane structures that are responsible for protein and lipid
synthesis and detoxification of poisons; May be directly connected or use
vesicles to move cellular products between members
 Members: nuclear envelope, ER, Golgi apparatus, lysosomes,
vacuoles/vesicles, plasma membrane
5.) Endoplasmic reticulum (ER)
 Overall structure: Network of membranes arranged in sacs (cisternae); Has
internal compartments (ER lumen) that is separate from cytosol
 2 distinct regions:
1. Smooth ER:
 Function: Synthesis of lipids, metabolism of carbohydrates,
detoxification of drugs; makes sex hormones
 Structure: No ribosomes give “smooth” appearance
2. Rough ER:
 Function: Secretion of specialized proteins Rough ER packages
proteins into transitional ER then into bubbles called transport
vesicles which move to Golgi
 Structure: Contains ribosomes giving “rough” appearance
6.) Golgi Apparatus
 Function: Accepts transport vesicles containing cellular products from ER;
Clearing house---modifies, sorts, ships proteins ready to be secreted or for
use somewhere else in cell; places ID tags on outside of vesicles leaving Golgi
to arrive at correct location
 Structure: flat membranous sacs (cisternae)
o 2 opposite sides: Cis face (receiving); Trans face (shipping)
7.) Lysosome
 Function: Contains enzymes which digest macromolecules
o Enzymes work in pH of about 5 so it’s separated from rest of cell
o Autophagy: recycling of cell’s own organic materials
o Phagocytosis: digestion of large food particles; food vacuoles merge
w/ lysosomes for digestion
 Structure: Membrane bound sacs of digestive enzymes
8.) Vacuoles (larger), vesicles
 Structure: large membrane bound sacs
 3 Types:
1. Food vacuoles:
Function: formed by phagocytosis; allow digestion of large food particles
2. Contractile:
Function: Freshwater protists use to pump out excess internal water
3. Central:
Function: in plant cells, enclosed by tonoplast membrane; Storage, disposal
of wastes; pigments; poisons; growth; holds water
9.) Mitochondria
 Function: site of cell respiration (process of extracting energy from food)
 Structure: enclosed by 2 membranes
o Outer membrane smooth; inner convoluted (Cristae: increases
surface area)
o Intermembrane space: b/t inner and outer membranes
o Mitochondrial matrix: w/in inner membrane
o Mitochondria have own DNA, ribosomes; can reproduce itself
10.) Chloroplasts
 Function: site of photosynthesis (conversion of sun energy into chemical
energy/glucose) in plants and algae
 Structure: Has 2 membranes
o Contains chlorophyll, a green pigment in thylakoids (sacs of
membranes)
o Grana: stacks of thylakoids
o Stroma: fluid outside thylakoids
o Contains own DNA and ribosomes
11.) Other plastids
 Function: storage of various cellular materials
o Amyloplasts: colorless; stores starch
o Chromoplasts: stores plant pigments that give flowers and fruits
colors
 Structure: Double membrane organelle
12.) Cytoskeleton
 Function: Overall: network of fibers in cytoplasm; organizes and anchors
organelles, gives structural support
3 types of cytoskeleton
1.) Microtubules
 Function: Compression resistant for maintaining shape of cell
o Provides organelle “tracks”
o Moves chromosomes during cell division
o Cell motility: Cilia and Flagella: locomotive appendages
 Structure: thickest of 3 types; hollow, made of tubulin
o Can be disassembled and re-built from pieces
2.) Microfilaments
 Function: Bears tension (pulling forces), supports cell shape
 Muscle contraction: microfilaments of actin interact w/ another protein
(myosin)
 Cleavage furrow: tightening band of microfilaments divides cell
 Gel-sol state:
o Cytoplasm on periphery of cell thicker (gel); inner area is more fluid
(sol)
o Pseudopodia: cellular extensions of amoebas caused by localized
breakdown of microfilaments from gel to sol state
o Cytoplasmic streaming: flow of cytoplasm: sol to gel state; distributes
substances w/in cell
 Structure: Solid, made of actin, twisted, double chain
 Can be assembled and re-built from pieces
3.) Intermediate Filaments
 Function: Provide shape and support of cell
 Organelle location (nucleus anchor)
 Makes up nuclear lamina (inside lining of nucleus)
 Forms desmosomes, rivets that hold cells together
 Structure: Larger than microfilaments, smaller than microtubules
o Made of keratin
o Permanent
13.) Cell Surfaces and Junctions:
 Plant cell walls:
o Function: Gives shape, support, protection to plant cells
o Structure: Fibrils of cellulose (polysaccharide) embedded in
polysaccharide matrix, proteins
 Extracellular matrix (ECM) of an animal cell
o Function: Gives support, adhesion, regulation to animal cells
o Structure: Outside of plasma membrane
 Made mostly of glycoproteins (collagen is primary one)
 Bonded to integrins, proteins built into plasma membrane; allows
communication b/t ECM and inside of cell
 Series of proteoglycan complex of polysaccharide molecules joined to protein
cores
Intercellular Junctions
 Plants: Plasmodesmata: channels in cell walls; connects cells; allows
exchange of cytoplasm and cellular material b/t adjacent cells
 Animals:
o Tight Junctions: fused continuous connection bonding cells together,
sealed; prevents leakage between cells
o Desmosomes: rivets that anchor cells together; made of intermediate
filaments
o Gap Junctions (communicating): communication; channels that
connect cells; allows exchange of cytoplasm and cellular material b/t
adjacent cells