Cell Organelles

Structures and Functions

Provincial exam diagram

http://www.botany.com/uwc.ac.za/sci_ed/std8/cells/er.htm

Cell Membrane

STRUCTURE• Phospholipid bilayer• Contains cholesterol, glycoprotiensFUNCTIONS• Provides protection• Selective permeability• Cell recognition & receptor proteins• Import & Export (endo/exocytosis)

Cytoskeleton

STRUCTURE:protein filaments & microtubules found throughout the cytoplasm

FUNCTIONS:maintains cell shape

transport within the cell - movement of vesicles and organelles

Mitochondria

STRUCTURE:double membrane bound organellematrix (inner space) & cristae (convolutions of inner membrane)

FUNCTIONS:production of ATP (site of cellular respiration)

Mitochondria Structure

Provincial exam diagram!

Smooth Endoplasmic Reticulum

STRUCTURE:• Network of tubules, extension of

nuclear membranes• Lack ribosomes

Smooth Endoplasmic Reticulum

FUNCTIONS• Package proteins for transport within cell• Synthesis of membrane phospholipids• Synthesize lipids, triglycerides, steroids• Large surface area for chemical reactions• Detoxify drugs in liver cells

Diagram: Smooth ER

http://cellbio.utmb.edu/cellbio/cit3.htm

Rough Endoplasmic Reticulum

STRUCTURE:

• Network of tubules (membranous)• Ribosomes on surface

Rough Endoplasmic Reticulum

• Production of proteins at ribosomes- enzymes & hormones

• Transport to smooth ER for modifications & packaging

Provincial Exam Diagram!

RIBOSOMESMade of rRNA & protein - 2 subunitsFound free (floating in cytoplasm) or

bound (attached to ER)FUNCTIONS:Site of protein synthesis –

polypeptides, enzymesReads RNA code, translates into

amino acid sequence - protein

Ribosome Structure

Liver Cell Polyribosomes

Polyribosomes

Structure:

Many ribosomes grouped together, ribosome cluster

Functions:

Work together to read one strand of RNA - increases speed & # of proteins produced

Polyribosomes

GOLGI BODIES• Stacked flat sacs• Accept vesicles on one side and

produce vesicles on the otherFUNCTION:Modification of proteins and lipidsStorage and packaging of moleculesPOST OFFICE OF CELL

Golgi Apparatus

Vesicles

• Membrane bound sac, liquid filled• Formed from pinching off of membrane of ER, Golgi body, cell membrane

• Can contain proteins, lipids

FUNCTION:

Shipping containers – transport of materials around or out of cell

Vacuoles

• Membrane bound sac• Contains liquids or solids• Larger than vesicles

Vacuole

FUNCTION:Plant cells – large fluid filled vacuoles maintain structure

Storage within cellFood & Contractile vacuoles

Lysosomes

• Membrane bound sacs • Contain digestive enzymes• Manufactured by the Golgi apparatusFUNCTION:Garbage disposalBreakdown bacteria entering cell,

worn out organelles, intracellular digestion

                

Nucleus

STRUCTURE• Bound by a double porous

membrane• Contains chromatin: DNA &

proteins wound together• Contains RNA

Nucleus

FUNCTION• Stores genetic information• Controls cell division• Directs functioning of cell (provides

template for RNA - protein synthesis)

Nucleolus

• Found within the nucleus• Cluster of RNA

• Produces ribosomes

Nuclear Envelope

• Double membrane (4 phospholipid layers)

• Contains nuclear poresFUNCTION:Protection of nuclear contentsAllows communication with cell via

RNA molecules (through nuclear pores)

Chromosomes

• Double stranded DNA molecules• Found in nucleus

Genetic blueprint in basesCell division (mitosis), RNA

transcription

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Plant Cells

Cell Wall

Structure:

Composed of cellulose

Located outside of cell membrane

Function:

Provides structure, protection, rigidity to plant cells (not found in animal cells)

Permeable

Cell Wall

Chloroplast

Structure:

Double membrane bound organelle

Stroma: space within chloroplast

Thylakoid stacks: where reactions occur - contain chlorophyll

Function:

Site of PHOTOSYNTHESIS within plant cells (produces glucose)

Chloroplast

Chloroplast