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CELL ORGANELLESMS. GAYNOR
AP BIOLOGY / CHAPTER 6 (PART 2)
ORGANELLESORGANELLESVery smallPerform various functions for cellFound in the cytoplasmMay or may not be membrane-
bound
BASIC ANIMAL BASIC ANIMAL CELL ORGANELLESCELL ORGANELLES
Nucleolus
Nucleus
Nuclear envelope
Ribosome (attached)Ribosome (free)
Cell Membrane
Rough endoplasmic reticulum
Golgi apparatus
Mitochondrion
Smooth endoplasmicreticulum
Centrioles
BASIC PLANT CELL BASIC PLANT CELL ORGANELLESORGANELLES
CELL OR PLASMA CELL OR PLASMA MEMBRANEMEMBRANE
STRUCTURE Made of double layer (bilayer) of:
phospholipids and proteins Surrounds outside of ALL cellsFUNCTION (JOB) Controls what enters or leaves the cell
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel Lipid bilayer
Carbohydratechains
6
PHOSPHOLIPIDSPHOSPHOLIPIDSHeads contain glycerol &
phosphate and are hydrophilic (attract water)
Tails are made of fatty acids and are hydrophobic (repel water)
Make up a bilayer where tails point inward toward each other
Can move laterally to allow small molecules (O2, CO2, & H2O to enter)
CELL MEMBRANE IN CELL MEMBRANE IN PLANTSPLANTS
7
ADDITIONAL FUNCTION IN PLANTS:
• Pushes out against
the cell wall to maintain cell shape and protect
Cell membrane
CELL WALLCELL WALLSTRUCTURE• Found in:• plants
• Made of cellulose• Fungi
• Made of chitin• Bacteria
• Made of peptidoglycan
FUNCTION (JOB)• Protect• Maintain shape
Cell wall
PLANT CELL WALLPLANT CELL WALL
Two layers of cell wallTwo layers of cell wallPrimary Cell WallPrimary Cell Wall
(Outer )(Outer )CelluloseCellulose onlyonly
Secondary Cell WallSecondary Cell Wall (Inner)(Inner)Cellulose & LigninCellulose & Lignin
Cell membrane is Cell membrane is innermost layerinnermost layer
CYTOPLASM OF A CYTOPLASM OF A CELL CELL
STRUCTURE• Jelly-like substance• Mostly water
• aqueous solutionFUNCTION (JOB)• Provides a solution
for chemical reactions to take place in
• Holds organelles in place
cytoplasm
NUCLEUSNUCLEUSSTRUCTURE• Contains the DNA in
chromosomes• Bounded by a
nuclear envelope (membrane) with pores
• Usually the largest organelle
FUNCTION (JOB)• Controls the normal
activities of the cell
12
NUCLEAR ENVELOPENUCLEAR ENVELOPEDouble membrane
surrounding nucleusAlso called nuclear membraneContains nuclear pores for
materials to enter & leave nucleus
Connected to the rough ER
Nuclear pores
13
INSIDE THE NUCLEUS The genetic material (DNA) is
found
DNA is spread out And appears as
CHROMATINin non-dividing cells
(NOT TIGHTLY COILED)
DNA is condensed & wrapped around proteins forming
as CHROMOSOMES in dividing cells
(TIGHTLY COILED)
WHAT DOES DNA DO?WHAT DOES DNA DO?DNA is the hereditary
material of the cell
Genes that make up the DNA molecule code for different
proteins
NUCLEOLUSSTRUCTUREInside nucleusInside nucleusCell may have Cell may have 1 to 31 to 3
nucleolinucleoliDisappearsDisappears when cell when cell
dividesdividesFUNCTION (JOB)Makes ribosomes Makes ribosomes
(ribosomal subunits)(ribosomal subunits) 15
CYTOSKELETONCYTOSKELETONSTRUCTURE Made of proteins Microfilaments are
threadlike & made of ACTIN Microtubules are tubelike &
made of TUBULIN
FUNCTION (JOB) Network of fibers that help
cell maintain cell shape Also help move organelles
around
17
Table 6.1
STRUCTURE Bean shapeDOUBLE membrane Has its own DNA Folded inner membrane
called CRISTAE (increases surface areafor more chemical reactions)
Interior called MATRIX
MMITOCHONDRIONITOCHONDRION(PLURAL = (PLURAL =
MITOCHONDRIA)MITOCHONDRIA)
19
FUNCTION (JOB)“Powerhouse” of cellMakes cellular energy
(ATP)More active cells like
muscle cells have MORE mitochondria
Site of CELLULAR RESPIRATION (burning glucose)
MITOCHONDRION (CON’T)MITOCHONDRION (CON’T)
INTERESTING FACT INTERESTING FACT ------
Mitochondria Come from cytoplasm in the EGG cell during fertilization
Therefore …You inherit your
mitochondria from your mother!
CHLCHLOORROOPLAPLASTSSTS
STRUCTUREBean shapeDOUBLE membraneSacs (“coins”) called
ThylakoidsThylakoids stack called
Granum (pl. =grana)Stroma – gel in middleHas its own DNA
FUNCTION (JOB)Found only in autotrophsCarries out
photosynthesis
RIBRIBOSOMESOSOMESSTRUCTUREMade of PROTEINS and rRNAFUNCTION (JOB)Make proteinsamino acids to make proteinsProcess called TRANSLATION
RIBOSOMES (CON’T)RIBOSOMES (CON’T)
Can be attached to Rough ER (proteins made
exit cell)
OR
Be free (unattached) in the
cytoplasm
(proteins made stay INSIDE cell)
ROUGH ENDOPLASMIC ROUGH ENDOPLASMIC RETICULUM (RER)RETICULUM (RER)
STRUCTUREHas ribosomes on
its surfaceFUNCTION (JOB) Helps to make
proteins for export out of cell
SMOOTH ENDOPLASMIC SMOOTH ENDOPLASMIC RETICULUM (SER)RETICULUM (SER)
STRUCTUREHas NO ribosomes on
its surfaceUsually attached to RERFUNCTION (JOB)Makes lipids
(membranes)Regulates calcium
(muscles)Destroys toxins (Liver) 25
ENDOMEMBRANE SYSTEM
Includes nuclear membrane connected to ER connected to cell membrane
(transport)
GOLGI APPARATUS GOLGI APPARATUS (BODIES)(BODIES)
STRUCTUREStacks of flat sacsLooks like pancakes
with syrup drips“Pankcakes” NOT
connectedFUNCTION (JOB)• Modify• Sort• Package • molecules from ER for
storage OR transport in in transport vesiclestransport vesicles
Transport vesicle
“syrup bubble”
GOLGI BODIESGOLGI BODIESflattened sacsflattened sacsHave a reHave a recceiving eiving
side (side (ccis face) & a is face) & a shipping or shipping or ttransporting side ransporting side ((ttrans face)rans face)Receive proteins Receive proteins
made by ERmade by ERTransport vesicles Transport vesicles
with modified with modified proteins pinch offproteins pinch off
Transport
vesicle
CIS
TRANS
Membrane proteins and lipidsAre synthesized in the ER and Golgi apparatus
ER
Figure 7.10
Transmembraneglycoproteins
Secretoryprotein
Glycolipid
Golgiapparatus
Vesicle
Transmembraneglycoprotein
Membrane glycolipid
Plasma membrane:Cytoplasmic face
Extracellular face
Secretedprotein
4
1
2
3
CILIA & FLAGELLACILIA & FLAGELLAFUNCTION (JOB) of FlagellaMoves WHOLE cells
FUNCTION (JOB) of CiliaMoves fluids or small particles across cell surface
CILIA & FLAGELLACILIA & FLAGELLASTRUCTUREMade of protein
tubes called microtubules
Cilia Shorter more numerousFlagella Longer fewer (usually 1-3)
CENTRIOLESCENTRIOLES
STRUCTURE Found only in animal cells
inside CENTROSOMES Paired structures near
nucleus (“t” shape” Made of microtubules
FUNCTION (JOB) Appear during cell division Help to pull chromosome
pairs apart to opposite ends of the cell
CENTRIOLES & THE MITOTIC CENTRIOLES & THE MITOTIC SPINDLESPINDLE
**Made of MICROTUBULES (Tubulin)
LYSOLYSOSOMESSOMESSTRUCTURE They have a low pH Contain Contain hydrolytichydrolytic
digestive enzymesdigestive enzymes
FUNCTION (JOB) Break down Break down food, bacteria &food, bacteria &
old cell partsold cell parts Lyse & Lyse & release enzymesrelease enzymes to to
break down/recycle cell break down/recycle cell partsparts
Programmed forProgrammed for cell death cell death (APOPTOSIS)(APOPTOSIS)
Think= “Think= “LysoLysol” cleanerl” cleaner (a) Phagocytosis: lysosome digesting food
1 µm
Lysosome containsactive hydrolytic
enzymes
Food vacuole fuses with lysosome
Hydrolyticenzymes digestfood particles
Digestion
Food vacuole
Plasma membraneLysosome
Digestiveenzymes
Lysosome
Nucleus
VACUOLESVACUOLESSTRUCTUREFluid filled sacks
for storageSmall or absent
in animal cellsPlant cells have
a large Central Vacuole
Surrounded by a membrane called a TONOPLAST
No vacuoles in bacterial cells
36
VACUOLES VACUOLES (CON’T)(CON’T)
FUNCTION (JOB)In plants, vacuoles
store Cell SapIncludes storage of
sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes
CONTRACTILE VACUOLECONTRACTILE VACUOLESTRUCTUREFound in FRESHWATERunicellular protists like
parameciaFUNCTION (JOB)Regulate water intake by
pumping out excess (homeostasis)
Keeps the cell from lysing (bursting)
PEROXISOMESFUNCTION (JOB) Produce hydrogen peroxide (H2O2) and convert it to water H2O2 is also toxic to a cell, and an enzyme made by the
peroxisome can break down H2O2
ChloroplastPeroxisome
Mitochondrion
1 µm
Figure 6.19
INTRACELLULAR JUNCTIONS
ANIMALS: Tight junctions: btw
neighboring cells; prevents leakage between cells
Desmosomes: riveted, anchoring junction; strong sheets of cells
Gap junctions: cytoplasmic channels; allows passage of materials or current between cells
INTRACELLULAR JUNCTIONSPLANTS: Plasmodesmata: cell wall “holes”; water
and solute passage in plants Similar to GAP JUNCTIONS in animals
NOW…LET’S PRACTICE
LIMITS Diffusion limits cell size
Movement from higher [ ] to lower [ ]Larger the distance, slower the diffusion rateA cell 20 cm would require months for
nutrients to get to the centerDNA limits cell size
larger cells need more DNA…Needs more of everything!
Most cells have just one nucleolus
Surface area to volume ratio limits sizeVolume increase
more rapidly than surface area.
Cell size doubles, 8x as much volume, but
only 4x as much surface area
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