Mitochondria & Chloroplast DNA (AQA A Level Biology)

Mitochondria & Chloroplast DNA

Mitochondria

A single mitochondrion is shown – the inner membrane has protein complexes vital for the later stages of aerobic respiration embedded within it

• The site of aerobic respiration within eukaryotic cells, mitochondria are just visible with a light microscope

• Surrounded by double-membrane with the inner membrane folded to form cristae

• The matrix formed by the cristae contains enzymes needed for aerobic respiration, producing ATP

• Small circular pieces of DNA (mitochondrial DNA) and ribosomes are also found in the matrix (needed for replication)

Chloroplast

Chloroplasts are found in the green parts of a plant – the green colour a result of the photosynthetic pigment chlorophyll

• Larger than mitochondria, also surrounded by a double-membrane

• Membrane-bound compartments called thylakoids containing chlorophyll stack to form structures called grana

• Grana are joined together by lamellae (thin and flat thylakoid membranes)

• Chloroplasts are the site of photosynthesis:

  • The light-dependent stage takes place in the thylakoids

  • The light-independent stage (Calvin Cycle) takes place in the stroma

• Also contain small circular pieces of DNA and ribosomes used to synthesise proteins needed in chloroplast replication and photosynthesis