MITOCHONDRIA AND CHLOROPLASTS

Structure and function - a review

The Exam Question“Contrast and compare mitochondria and chloroplasts – structure and function. “

Do you know what it means?

• What is the function of a mitochondrion?

• What is the function of a chloroplast?

• How are they similar? How are they different?

Energy Conversion

• Mitochondria convert the chemical energy of reduced carbon compounds into ATP.

• Chloroplasts convert light energy to the energy of reduced carbon compounds

• Fundamental to both processes is an electron transport chain, where energy is passed from compound to compound in coupled oxidation:reduction reactions

Mitochondria2 membranesOuter Membrane - has

large aqueous channels made of a protein called porin - permeable to most small molecules

Inner Membrane - impermeable to ions and small molecules except by specific membrane-transport proteins

Mitochondria

2 compartments• MATRIX - enzymes -TCA

cycle, DNA - several copies, ribosomes, tRNA, etc

• INTERMEMBRANE SPACE

Inner Membrane is folded into cristae,that greatly increase its surface area. This is where you find the Electron Transport Chain (ETC), ATP synthase, transport proteins to allow substances in to matrix

Fig 1-11

Mitochondrial StructureHow many compartments

do mitochondria have?

Which letter corresponds to:

• the matrix? • a crista?• the intermembrane

space?• the outer membrane?• the inner membrane?

Where would you find the DNA? the ribosomes?

C

E

B

A

D

• The ETC is found on the inner membrane

• High energy electrons are passed along the ETC generating a proton gradient across the inner membrane

• H+ gradient drives ATP synthesis

ELECTRON TRANSPORT CHAIN:

Mitochondria have 2 membranesChloroplasts have 3 membranes

There are 3 compartments…what are they?

Chloroplast Thylakoid membrane –

proteins of ETC, ATP synthase

• Inner membrane – membrane transport protein for Rubisco

• Outer membrane - porin

• Stroma – enzymes for Calvin Cycle, chloroplast DNA.

Chloroplasts

Plant Cell

Fig 13-26

Chloroplasts vs Mitochondria

These are mitochondria

So are these

Chloroplasts have different forms too

Thylakoids

Mitochondria

But their structure and function remain linked

Think of 3 similarities between mitochondria and chloroplasts.

Think of 3 ways they are different

NEXT TUTORIAL:• Vesicle Trafficking

• Models of Golgi function

• Receptor-mediated endocytosis

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