energy organelles & the cytoskeleton section 6.5, 6.6, and 6.7
TRANSCRIPT
Energy Organelles & Energy Organelles & the Cytoskeletonthe Cytoskeleton
Section 6.5, 6.6, and 6.7
Mitochondria & ChloroplastsMitochondria & Chloroplasts
Convert energy to forms the cell can use for work
Mitochondria – site of cellular respiration ◦Found in plants & animals◦Process that makes ATP from food◦Oxygen is needed
Chloroplasts – site of photosynthesis◦Found in plants & algae only◦Convert solar energy to chemical energy
Both enclosed by membranes
Mitochondria & ChloroplastMitochondria & Chloroplast
Membranes are made on free ribosomesContain their own ribosomesContain a small amount of DNA
MitochondriaMitochondria
Found in all Eukaryotic cellsA cell can have hundreds to thousands of
mitochondria depending on its functionMove around, change shape & divideSurrounded by a double membraneOuter membrane smoothInner membrane folding (Cristae)
◦Increases surface areaIntermembrane spaceMatrix
Mitochondria SturctureMitochondria Sturcture
ChloroplastsChloroplasts
Member of the plant organelle group plastids◦Amyloplasts – colorless that store starch in
roots and tubers◦Chromoplasts – pigments that give fruits and
flowers orange & yellow colors◦Chloroplasts – contain the green pigment
chlorophyll
ChloroplastsChloroplasts
Double membrane separated by intermembrane space.
Thylakoids are flattened stacks of sacs like pancakes or poker chips
Each stack is called a granum (grana)Fluid outside the thylakoids is the stroma
(space)Chloroplasts grow, move, & divide
PeroxisomesPeroxisomes
Single membraneContain enzymes that transfer hydrogen
from various substances to oxygen Hydrogen peroxide is produced (H2O2)Functions
◦Break fatty acids down◦Detoxify alcohol
H2O2 is converted to water because it is toxic to the cell
Peroxisome structure (TEM)Peroxisome structure (TEM)
CytoskeletonCytoskeleton
A network of fibers extending throughout the cytoplasm
Plays a role in organizing the structures & activities of the cell, supporting the cell, and maintaining its shape
Composed of three types of structures◦Microtubules◦Microfilaments◦Intermediate filaments
Differ in size
CytoskeletonCytoskeleton
Cytoskeleton - SupportCytoskeleton - Support
Gives support Helps the cell maintain shapeProvides anchorage for organellesCan be dismantled and reassembled in a
new location changing the shape of the cell
Cytoskeleton - MotilityCytoskeleton - Motility
Changes in cell locationMovements of parts of the cellInteraction of cytoskeleton with motor
proteinsExamples:
◦Movements of cilia & flagella◦Muscle cell contraction◦Movement of vesicles on “monorail”◦Cytoplasmic streaming
Motor ProteinsMotor Proteins
Cytoskeleton - RegulationCytoskeleton - Regulation
Cytoskeleton can transmit mechanical forces exerted by extracellular molecules via surface proteins of the cell to the interior and even the nucleus
3 Types of Fibers3 Types of Fibers
Microtubules – thickest of the threeMicrofilaments – thinnest of the threeIntermediate filaments – middle range
size filaments
MicrotubulesMicrotubules
Hollow rodsMade from protein tubulin (alpha & beta)Shape and support the cellServe as tracks for motor proteinsExamples:
◦Guide secretory vesicles from the golgi to the plasma membrane
◦Responsible for the separation of chromosomes during cell division
Centrosomes & CentriolesCentrosomes & Centrioles
Microtubules grow out from centrosomes“Microtubule-organizing center”Animal cells contain a pair of centrioles
found at right angles to each otherEach composed of 9 sets of triplet
microtubules arranged in a ringBefore the cell divides the centrioles
replicateHelp in organizing microtubules but not
essential Plants lack centrioles
Cilia & FlagellaCilia & Flagella
Specialized arrangement of microtubules is responsible for beating of cilia & flagella
Flagella ◦1-2 per cell, undulating motion
Cilia◦Large numbers on cell surface, work like oars
Both are made from 9+2 arrangementDynein arms responsible for bending
movements of cilia & flagella◦Similar to a cat walking up a tree
Motion of Flagella & CiliaMotion of Flagella & Cilia
9+2 arrangement of cilia & 9+2 arrangement of cilia & flagellaflagella
Dynein “walking”Dynein “walking”
Microfilaments (Actin filaments)Microfilaments (Actin filaments)
Solid rodsAlso called actin filaments because they
are built from actin proteinTwisted double chain of actin subunitsFunction is to bear pulling forcesPart of the contractile apparatus of muscle
cellsActin & myosin (thicker than actin)
interact to produce muscle contraction
Role of Microfilaments & motilityRole of Microfilaments & motility
Intermediate FilamentsIntermediate Filaments
Mid size filamentSpecialized for bearing tensionVery diverse (keratins)More permanent fixtures of cells Important in reinforcing the shape of a cell
and fixing the position of certain organelles
Extracellular componentsExtracellular components
Things beyond the plasma membranePlants – cell wallAnimals – Extracellular matrix (ECM)
Plant Cell WallPlant Cell Wall
ProtectsMaintains shape Prevents excess uptake of waterThicker than plasma membraneStrong fibers in a matrix formation like
fiberglass make it extremely strongLayers of cell wall are made that include
pectin (thickening agent in jams & jellies), cellulose, & hardening substances.
Extracellular Matrix of AnimalsExtracellular Matrix of Animals
Glycoproteins – proteins with carbohydrate chains
Collagen – accounts for ½ total protein found in the body
Proteoglycans – Collagen is embedded in Fibronectin – attaches the ECM to integrinsIntegrins – span the membraneImportant communication from the cell to
its surroundings
Extracellular MatrixExtracellular Matrix
Intercellular JunctionsIntercellular Junctions
Plants – PlasmodesmataChannels between cell walls that allow
neighboring cells to communicate with one another
Water & small solutes can pass freely from cell to cell
Plant PlasmodesmataPlant Plasmodesmata
Intercellular JunctionsIntercellular Junctions
Animals ◦Tight junctions – form continuous seals around
the cells – prevent leakage◦Desmosomes – fasten cells together into strong
sheets - anchoring◦Gap junctions – communicating junctions –
provide cytoplasmic channels from one cell to an adjacent cell
Animal cell junctionsAnimal cell junctions
Macrophage eating bacteriaMacrophage eating bacteria