Cell StructureCell StructureChapter 3Chapter 3

BiologyBiology

Mr. GilbertsonMr. Gilbertson

Cytoskeleton

A network of proteins that are constantly changing to meet the needs of the cell.

Long threads or fibers that crisscross the entire cell as shown in the diagram to the right.

Three types are shown:

MICROTUBULES ANDMICROTUBULES ANDMICROFILAMENTSMICROFILAMENTS

MICROTUBULES ANDMICROTUBULES ANDMICROFILAMENTSMICROFILAMENTS

• MICROTUBULES– LONG SLENDER PROTEIN TUBES– ACT AS TRACKS FOR MOVEMENT OF ORGANELLES– SPINDLE FIBERS AID IN MOVEMENT OF CHROMOSOMES

IN MITOSIS ASSOCIATED WITH THE CENTROSOME (CENTRIOLES)

• INTERMEDIATE FIBERS– SMALLER THAN MICROTUBULES AND SERVE FOR

STRENGTH

• MICROFILAMENTS– FINE PROTEIN THREADS– HELP MOVE CELLULAR MATERIALS THROUGH

CYTOPLASMIC STREAMING– HELP WITH MUSCLE CONTRACTIONS

CENTRIOLESIMPORTANT IN CELL DIVISION

EUGLENA WITH EUGLENA WITH FLAGELLUMFLAGELLUM

EUGLENA WITH EUGLENA WITH FLAGELLUMFLAGELLUM

CELLULAR CELLULAR LOCOMOTIONLOCOMOTION

MICROTUBULESMICROTUBULES

CELLULAR LOCOMOTIONCELLULAR LOCOMOTION• CILIA

– EXTEND FROM SURFACE OF CELL

– SHORT HAIRLIKE EXTENSIONS THAT COVER THE SURFACE OF SOME CELLS ALLOW MOVEMENT OF CELL

– MAY ALSO LINE THE SURFACE OF SOME ORGANS TO MOVE FLUIDS AND MUCUS

• FLAGELLA– LONG WHIPLIKE STRUCTURES

– OCCUR SINGLY OR IN PAIRS

– BY WHIPPING BACK AND FORTH SOME UNICELLULAR ORGANISMS ARE ABLE TO MOVE

– TAIL OF A SPERM CELL IS AN EXAMPLE

• SIMILARITIES– EACH IS COMPOSED OF NINE PAIRS OF MICROTUBULES IN

A CIRCLE AND AN ADDITIONAL PAIR RUNNING DOWN THE CENTER (9 + 2 ARRANGEMENT)

CYTOPLASMCYTOPLASM

• JELLY-LIKE MATERIAL FOUND INSIDE THE CELL

• PROTOPLASM DIVIDED INTO– CYTOPLASM OUTSIDE NUCLEUS

– NUCLEOPLASM WITHIN NUCLEUS

• CYTOPLASMIC STREAMING– CONSTANT MOTION OF PARTICLES AND

ORGANELLES

– MOST APPARENT IN PLANT AND PROTIST CELLS

CYTOPLASMCYTOPLASMCYTOPLASMCYTOPLASM

THE NUCLEUSTHE NUCLEUSWITH NUCLEOPLASMWITH NUCLEOPLASM

THE NUCLEUSTHE NUCLEUSTHE NUCLEUSTHE NUCLEUS• CONTROL CENTER OF THE CELL

• SITE OF NUCLEIC ACID SYNTHESIS

• DIRECTS ACTIVITIES OF CELL

• SURROUNDED BY A DOUBLE MEMBRANE KNOWN AS THE NUCLEAR ENVELOPE

• FILLED WITH NUCLEOPLASM RICH IN PROTEIN AND NUCLEIC ACIDS

• CONTAINS FINE STRANDS CALLED CHROMATIN

NUCLEUSNUCLEUSNUCLEUSNUCLEUS

PRIMARY FUNCTIONSPRIMARY FUNCTIONS

1)1)PROTECT DNA FROM PROTECT DNA FROM LYSOSOMES AND LYSOSOMES AND ENZYMES IN THE ENZYMES IN THE CYTOPLASMCYTOPLASM2)2)MAKE DNA AVAILABLE MAKE DNA AVAILABLE AT THE PROPER TIME AT THE PROPER TIME TO TURN GENES ON AND TO TURN GENES ON AND OFFOFF

NUCLEAR MEMBRANE

NUCLEAR MEMBRANENUCLEAR MEMBRANE

• ALSO KNOWN AS THE NUCLEAR ENVELOPE

• DOUBLE MEMBRANE SURROUNDING THE NUCLEUS

• NUCLEAR PORES ALLOW THE PASSAGE OF MATERIALS (RNA) FROM THE NUCLEOPLASM TO THE CYTOPLASM AND BACK

NUCLEOLUSNUCLEOLUS CHROMATINCHROMATIN

NUCLEOLUS AND NUCLEOLUS AND CHROMATINCHROMATIN

• NUCLEOLUS– FOUND WITHIN THE NUCLEUS

– MAYBE MORE THAN ONE

– CONTAINS PARTIALLY ASSEMBLED RIBOSOMES AND mRNA TO BE USED DURING CELL DIVISION

• CHROMATIN– DURING CELL DIVISION CHROMATIN CONDENSES

AND COILS TO FORM CHROMOSOMES

– MOSTLY COMPOSED OF DNA WITH ASSOCIATED PROTECTIVE PROTEINS

ORGANELLESORGANELLESORGANELLESORGANELLES“LITTLE ORGANS”

EACH HAS A SPECIFIC FUNCTION NECESSARY TO

THE OVERALL SUCCESS OF THE CELL

RIBOSOMESRIBOSOMES• MOST NUMEROUS OF CELLS

ORGANELLES• SITE OF PROTEIN SYNTHESIS• ROUGHLY SPHERICAL IN SHAPE• 15 TO 20 NANOMETERS IN DIAMETER• COMPOSED OF THREE AMINO ACIDS

AND OVER 50 PROTEINS• MAY BE FREE FLOATING IN

CYTOPLASM OR ATTACHED TO THE ENDOPLASMIC RETICULUM

ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM• MEMBRANE SYSTEM OF FOLDED SACS AND

TUNNELS

• ROUGH ER - COVERED WITH RIBOSOMES

• SMOOTH ER– FEW IF ANY RIBOSOMES

– FUNCTIONS PRIMARILY AS AN INTERCELLULAR HIGHWAY OR

– STORAGE AREA FOR PROTEINS PRIOR TO EXPORT FROM THE CELL

• RELATIVE AMOUNTS OF EACH VARY FROM ONE CELL TO ANOTHER

• GLANDS GENERALLY HAVE MORE ROUGH ER AND LESS SMOOTH ER

ROUGH ENDOPLASMID ROUGH ENDOPLASMID RETICULUMRETICULUM

GOLGI APPARATUSGOLGI APPARATUS

GOLGI BODYGOLGI BODYGOLGI BODYGOLGI BODY

GOLGI APPARATUSGOLGI APPARATUS• PROCESSING, PACKAGING, AND SECRETING

ORGANELLE• CONSISTS OF A STACK OF FLATTENED SACS

FILLED WITH FLUID AND DISSOLVED OR SUSPENDED SUBSTANCES

• WORKS WITH ER AND RIBOSOMES– PROTEIN IS SYNTHESIZED ON RIBOSOME– PASSES TO INTERIOR OF THE ER MEMBRANE– MOVES TO THE SMOOTH ER WHERE IT IS ENCLOSED

IN A VESICLE– VESICLE MIGRATES AND FUSES WITH A GOLGI SAC– CONTENTS OF GOLGI SAC ARE MODIFIED AS THE

PASS FROM ONE SAC TO ANOTHER– FINALLY THE COMPLETED PURIFIED PROTEIN

FILLED SAC FORMS A VESICLE WHICH MOVES TO THE CELL MEMBRANE AND DISCHARGES ITS CONTENTS

MITOCHONDRIAMITOCHONDRIA

MITOCHONDRIAMITOCHONDRIA

MITOCHONDRIONMITOCHONDRIONMITOCHONDRIONMITOCHONDRION

MITOCHONDRIAMITOCHONDRIA• “POWERHOUSE” OF THE CELL

• SITE OF CELLULAR RESPIRATION AND RELEASE ENERGY FOR USE BY CELL

• CAN GROW, DIVIDE, OR FUSE WITH ONE ANOTHER

• HAS A DOUBLE MEMBRANE SYSTEM – OUTER MEMBRANE IS SMOOTH AND SERVES AS BOUNDARY

– INNER MEMBRANE HAS MANY LONG FOLDS CALLED CRISTAE WHERE REACTIONS OF RESPIRATION OCCUR

• ATP IS FORMED HERE

• HAVE THEIR OWN DNA – CAN ONLY BE FORMED BY THE DIVISION OF EXISTING

MITOCHONDRION

– MAY HAVE DEVELOPED FROM PROKARYOTE CELLS LIVING AS SYMBIONTS

– SOUGHT PROTECTION AND PROVIDED ENERGY

LYSOSOMESLYSOSOMES

LYSOSOMESLYSOSOMES• CONTAIN DIGESTIVE ENZYMES

• SMALL ROUGHLY SPHERICAL WITH A SINGLE MEMBRANE

• EXIST PRIMARILY IN ANIMAL AND FUNGAL CELLS

• FOUR FUNCTIONS– AUTOLYSIS - DESTRUCTION OF DEAD CELLS

– AUTOPHAGIA - DEATH OF UNNECESSARY CELLS DURING DEVELOPMENT LIKE BETWEEN FINGERS AND TOES

– PHAGOCYTOSIS - ENGULFING AND DIGESTION OF BACTERIA OR VIRUS PARTICLES

– INTRACELLULAR DIGESTION - THE BREAKDOWN OF MOLECULES AND MATERIALS WITHIN THE CYTOPLASM THUS ALLOWING BASIC MATERIALS TO BE “RECYCLED”

VESSICLESVESSICLESVESSICLESVESSICLES

VESSICLESVESSICLESSMALL BODIES FOUND IN MANY

CELLS WHICH CONTAIN

SPECIFIC MATERIALS SUCH AS

PROTEINS OR LIQUIDS

PRIMARY FUNCTION IS STORAGE

OF NECESSARY MATERIALS

PLANT vs. ANIMALPLANT vs. ANIMALCELLSCELLS

PLANT vs. ANIMALPLANT vs. ANIMALCELLSCELLS

MOST OF THE PARTS OF THE

CELL DESCRIBED THUS FAR

ARE FOUND IN BOTH PLANT

AND ANIMAL CELLS

COMPARISON OF PLANT COMPARISON OF PLANT AND ANIMAL CELLSAND ANIMAL CELLS

COMPARISON OF PLANT COMPARISON OF PLANT AND ANIMAL CELLSAND ANIMAL CELLS

• ANIMAL CELLS– NO CELL WALL

– NO CHLOROPLASTS

– SMALL VACUOLES

– LYSOSOMES OFTEN PRESENT

– CILIA AND FLAGELLA MAY BE PRESENT

– SIZE BETWEEN 10 AND 20 MICROMETERS

• PLANT CELLS– HAVE CELL WALL

– HAVE CHLOROPLASTS

– HAVE LARGE WATER VACUOLE

– LYSOSOMES USUALLY ABSENT

– CILIA AND FLAGELLA USUALLY ABSENT EXCEPT IN REPRODUCTIVE CELLS

– SIZE BETWEEN 30 AND 50 MICROMETERS

PLANT CELLPLANT CELL

CELL WALLCELL WALL

CELL WALLCELL WALL• RIGID COVERING OF A PLANT CELL• COMPOSED PRIMARILY OF CELLULOSE• EMBEDDED IN PECTIN AND LIGNIN

(HARDENING AGENTS)• PORES ALLOW IONS AND MOLECULES

TO PASS FROM ONE CELL TO ANOTHER• PRIMARY WALLS - FORMED DURING

CELL GROWTH • SECONDARY WALL - FORMED AFTER

ALL GROWTH HAS CEASED

Cell WallCell Wall• Varies among different types of organismsVaries among different types of organisms• In plants it is composed of cellulose fibers In plants it is composed of cellulose fibers

imbedded in a polysaccharide and protein imbedded in a polysaccharide and protein matrix.matrix.

• In eubacteria it is composed of peptidoglycan a In eubacteria it is composed of peptidoglycan a polymer of sugars cross-linked by short polymer of sugars cross-linked by short polypeptides.polypeptides.

• In fungi it is composed of chitin a In fungi it is composed of chitin a polysaccharidepolysaccharide

• Composition of the cell wall is used in Composition of the cell wall is used in classification.classification.

CELL WALLCELL WALL

PRIMARY WALLPRIMARY WALL

SECONDARY WALLSECONDARY WALL

MIDDLE LAMELLAMIDDLE LAMELLA

CELL WALLCELL WALLFORMATIONFORMATION

• MIDDLE LAMELLA IS FIRST TO FORM – INTERCELLULAR LAYER MADE OF PECTIN ENZYME USED IN

MAKING JAMS AND JELLIES

• NEXT PRIMARY WALL FORMS BETWEEN MIDDLE LAMELLA AND CELL MEMBRANE

– CELLULOSE FIBERS ARE LAID DOWN IN LAYERS - ALL IN THE SAME DIRECTION

– ALLOWS CELL TO GROW IN THE OTHER DIRECTION AT RIGHT ANGLES TO THE MOST RECENTLY DEPOSITED LAYER

– PROTECTS CELL YET ALLOWS THE CELL TO GROW

• AFTER GROWTH CEASES THE SECONDARY WALL IS FORMED

– FORMED WHEN CELLULOSE AND LIGNIN FIBERS ARE INTERWOVEN

– NO FURTHER GROWTH IS POSSIBLE

– PRIMARY FUNCTION IS TO STRENGTHEN THE CELL MAKING IT “WOODY”

WATER VACUOLEWATER VACUOLE

VACUOLEVACUOLE• FOUND IN ALL PLANTS• VACUOLES STORE ENZYMES AND

WASTES• WATER VACUOLE MAY OCCUPY AS

MUCH AS 90% OF THE VOLUME OF A MATURE PLANT CELL

• MAY BE USED TO STORE TOXIC MATERIALS THAT MUST BE KEPT AWAY FROM THE REST OF THE CYTOPLASM

• USED TO MAINTAIN CELL SHAPE AND RIGIDITY THROUGH TURGOR PRESSURE

PLASTIDSPLASTIDSCHLOROPLASTS

CHLOROPLASTSCHLOROPLASTS• SITE OF PHOTOSYNTHESIS• CONTAIN THE PIGMENT CHLOROPHYLL• MOST IMPORTANT OF ALL

ORGANELLES (FOOD MAKING AND OXYGEN PRODUCTION)

• RESPONSIBLE FOR THE GREEN COLOR OF PLANTS

• SINGLE OUTER MEMBRANE AND INNER THYLAKOID MEMBRANE

• DIVIDED INTO GRANA AND STROMA

PLASTIDSPLASTIDSLEUCOPLASTS CHROMOPLAST

LEUCOPLASTS ANDLEUCOPLASTS ANDCHROMOPLASTSCHROMOPLASTS

• CHROMOPLASTS– SYNTHESIZE AND STORE PIGMENTS

– SOME PIGMENTS ARE INVOLVED IN PHOTOSYNTHESIS

– OTHERS GIVE COLOR TO PLANT STRUCTURES SUCH AS FLOWER PETALS

• LEUCOPLASTS– FOUND IN MOST PLANTS

– COLORLESS BODIES

– STORE STARCH GRANULES, PROTEINS, AND LIPIDS

– FOUND IN STORAGE ORGANS LIKE TUBERS

CELLULAR CELLULAR ORGANIZATIONORGANIZATION

• UNICELLULAR - ONE CELLEDUNICELLULAR - ONE CELLED• MULTICELLULAR - MANY CELLS MULTICELLULAR - MANY CELLS

LIVING TOGETHER DEPENDING ON LIVING TOGETHER DEPENDING ON EACH OTHEREACH OTHER

• COLONIAL - MANY CELLS LIVING COLONIAL - MANY CELLS LIVING TOGETHER ONLY LOOSELY TOGETHER ONLY LOOSELY DEPENDENT ON THE OTHER CELLS IN DEPENDENT ON THE OTHER CELLS IN THE COLONY, PRIMARILY FOR THE COLONY, PRIMARILY FOR REPRODUCTION.REPRODUCTION.