CHAP 6-7 (6.6 Cytoskeleton is a network of fibers that organizes…
6.6 Cytoskeleton is a network of fibers that organizes structures and activities in the cell
intermediate filaments- named for their diameter, which is larger than the diameter of microfilaments but smaller than that of microtubules.
Microfilaments (actin filaments)
cytoplasmic streaming- circular flow of cytoplasm within cells.
Pseudopodia- cellular extensions.
myosin- interaction to cause contraction of muscle cells.
Cortex- the semisolid consistency of a gel, in contrast with the more fluid state of the interior cytoplasm.
Actin- globular protein
Microfilaments- thin solid rods
Cilia and Flagella- microtubule-containing extensions that project from some cells.
dyneins- that are attached along each outer microtubule doublet.
basal body- which structurally very similar to a centriole, with microtubule triplets in a "9+0" pattern (figure 6.24c).
centrosomes and centrioles
centrioles- composed of nine sets of triplet microtubles arranged in a ring.
centrosome- region that is often located near the nucleus
Microtubules- hollow rods constructed from globular proteins called tubulins.
motor proteins- work together with plasma membrane molecules to allow whole cells to move along fibers outside the cell.
cytoskeleton- network of fibers extending throughout the cytoplasm (figure 6.20).
6.4 Endomembrane systemregulates protein traffic and performs metabolic functions
Vacuoles: diverse maintenance compartments
Central vacuole- develops by the coalesence of smaller vacuoles.
Contractile vacuoles- pump excess water out of the cell, thereby maintaining a suitable concentration of ions and molecules inside the cell.
Food vacuoles- formed by phagocytosis, have already been mentioned
Vacuoles- large vesicles derived from the endoplasmic reticulum and golgi apparatus.
Lysosomes: Digestive Compartments
Phagocytosis- amoebas and many other unicellular eukaryotes eat by engulfing smaller organisms or food particles.
Lysosome- membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest macromolecules.
Golgi apparatus- a wharehouse for receiving, sorting, shipping, and even some manufacturing.
Functions of Rough ER
Transport vesicles- vesicles in transit from one part of the cell to another.
Glycoproteins- proteins with carbohydrate covalently bonded to them.
Endoplasmic reticulum: Biosynthetic factory
Rough ER- studded with ribsomes on the outer surface
Smooth ER- because the outer surface lacks ribosomes
Endoplasmic reticulum (ER)- such an extensive network of membrane in many eukaryotic cells.
Vesicles- sacs made of membrane
endomembrane system- includes the nuclear envelope, the endoplasmic reticulum, the golgi apparatus, lysosomes, various kinds of vesicles and vacuoles, and the plasma membrane.
6.5 Mitochondria and chloroplasts change energy from one form to another
Peroxisome- a specialized metabolic compartment bounded by a single membrane (figure 6.19).
Chloroplasts: capture of light energy
plastids- plant organelles.
stroma- fluid outside the thylakoids, which contains the chloroplast DNA and ribosomes as well as many enzymes.
granum- each stack
thylakoids- inside the chloroplast another membranous system in the form of flattened, interconnected sacs, stacked like poker chips.
Mitochondria: chemical energy conversion
mitochondrial matrix- enclosed by the inner membrane, contains many enzymes as well as the mitochondrial DNA and ribosomes.
Cristae- outer membrane is smooth, but the inner membrane is convoluted, with infoldings
Endosymbiont theory- illustrated in (Figure 6.16), states that an early ancestor of eukaryotic cells engulfed oxygen-using nonphotosynthetic prokaryotic cell.
Chloroplasts- found in plants and algae, are the sites of photosynthesis.
mitochondria- are the sites of cellular respiration, the metabolic process that uses oxygen to drive the generation of ATP by extracting energy from sugars, fats, and other fuels.
6.7 Extracellular components and connections between cells help coordinate cellular activities
plasmodesmata in plant cells
plasmodesmata- channels that connect cells.
The extracellular Matrix (ECM) of animal cells
integrins- that are built into the plasma membrane.
fibronectin- bind cell-surface receptor proteins.
proteoglycans- consists of a small core protein with many carbohydrate chains covalently attached.
Collagen- most abundant glycoproteins in the ECM of most animal cells.
Extracellular matrix (ECM)- animal cells that lack akin
Cell walls of plants
Secondary cell wall- between the plasma membrane and the primary wall.
middle lamella- thin layer rich in sticky polysaccharides called pectins.
Primary cell wall- relatively thin and flexible cell wall that a young plant excretes.
Cell wall- is an extracellular structure of plant cells.
CHAP 7 Life at the edge
7.1 Cellular members are fluid mosaics of lipids and proteins
The role of membrane carbohydrates in cell-cell recognition
glycproteins- however most bond to proteins.
glycolipids- membrane carbohydrates covalentyl bonded to lipids.
membrane proteins and their functions
Peripheral proteins- not embedded in lipid bilayer at all, loosely bound to the surface of the membrane, often to exposed parts of integral proteins.
integral proteins- penetrate the hydrophobic interior of the lipid bilayer.
fluid mosaic model- the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.
Selective permeability- allows some substances to cross it more easily than others
6.1 Biologists use microscopes and biochemistry to study cells
Cell fractionation- Which takes cells apart and seperates major organelles and other subcellular structures from one another.
Transmission electron microscope (TEM)- used to study the internal structure of cells. ( Figure 6.3 )
Scanning electron microscope (SEM)- especially useful for detailed study of the topography of a specimen (Figure 6.3)
Electron microscope (EM)- focuses beam of electron through the specimen or onto its surface.
Organelles- membrane-enclosed structures within eukaryaotic cells.
Light microscopy (LM)- visible light is passed through the specimen and then through glass lenses.
7.4 Active transport uses energy to move solutes against their gradients
Cotransport- transport protein can couple the "downhill" diffusion of the solute to the "uphill" transport of a second substance against its own concentration gradient.
How ion pumps maintain membrane potential
Proton pump- main electrogenic pump of plants, fungi, and bacteria
Electrogenic pump- transport protein that generates voltage across a membrane.
electrochemical gradient- combination of forces acting on an ion.
membrane potential- voltage across a membrane.
The need for active transport
Sodium-potassium pump- which exchanges Na+ for K+ across the plasma membrane of animal cells.
Active transport- type of membrane traffic.
7.2 Transport Proteins
aquaporins- channel proteins.
Transport proteins- span the membrane
7.3 Passive transport is diffusion of a substance across a membrane with no energy investment
Facilitated diffusion: passive transport aided by proteins
gated channels- which open or close in response to a stimulus.
Ion channels- channel proteins that transport ions.
Facilitated diffusion- the help of transport proteins that span the membrane.
water balance of cells with cell walls
plasmolysis- causes the plant to wilt and can lead to plant death.
Flaccid- the plant wilts.
turgid-(very firm) healthy state of most plant cells.
Water balance of cells without cell walls
osmoregulation- control of solute concetraations wand water balance.
hypotonic- cell will gain water
Hypertonic- lose water.
isotonic- no water movement across the plasma membrane.
Tonicity- the ability of a surrounding solution to cause a cell to gain or lose water.
osmosis- diffusion of free water across a selectively permeable membrane, whether artificial or cellular.
passive transport- the diffusion of a substance across a biological membrane.
concentration gradient- region along which the density of a chemical substance increases or decreases.
diffusion- movement of particles of any substance so that they spread out into the available space.
Eukaryotic cells's genetic instructions are housed in the nucleus and carried out by the ribosomes
The Nucleus: information center
Ribosomes: protein factories
ribosomes- which are complex made of ribosomal RNAs and proteins, are the cellular components that carry out protein synthesis (figure 6.10)
Nucleolus- which appears through the electron microscope as a mass of density stained granules and fibers adjoining part of the Chromatin.
Chromatin- complex of DNA and proteins making up chromosomes.
Chromosomes- structures that carry the genetic information.
Nuclear lamina- netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope.
nuclear envelope- encloses the nucleus (figure 6.9), separating its contents from the cytoplasm.
Nucleus- contains most of the genes in eukaryotic cell.
6.2 Eukaryotic cells have internal membranes that compartmentalize their functions
Comparing Prokaryotic and eukaryotic cells
Plasma membrane- functionsas a selective barrier that allows passage of enough oxygen, nutrients, and wastes tom service the entire cell (Figure 6.6)
Cytoplasm- in eukaryotic, the region between the nucleus and the plasma membrane.
prokaryotic cell- DNA is concentrated in a region that is not membrane-enclosed, called the nucleoid
eukaryotic cell- most of the DNA is in an organelle called the nucleus, which is bounded by a double membrane (firgure 6.8)
Cytosol- inside the cells is semifluid, jelly like substance, in which subcellular components are suspended.
Bulk transport across the plasma membrane occurs by exocytosis and endocytosis
endocytosis- cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane.
Exocytosis- cell secrets certain molecules by the fussion of vesicles with the plasma membrane.