1. ATP SYNTHASE IMAGES

2. This model shows the structure of ATP. The molecule is composed of three parts: a sugar ribose molecule (red and white), a base molecule made up of carbon and nitrogen atoms (grey and purple), and a string of phosphate atoms (orange). These phosphate groups are essential to the function of ATP. When energy is required, ATP is involved in an enzymatic reaction that results in the loss of a phosphate group and a release of energy to form adenosine diphosphate (ADP). During a resting state, when energy is not required, the reverse reaction takes place to reform ATP from ADP. Credit: Anna Tanczos, Wellcome Images Molecular model of ATP

3. An isolated mitochondrion fractured to reveal its internal structure. The internal membranes (cristae), which are visible, are covered with enzyme complexes involved in the conversion of metabolites into energy. This is a colour-enhanced scanning electron micrograph of a freeze-fractured sample. Credit: Dr David Furness, Wellcome Images BIGPICTUREEDUCATION.COM An isolated mitochondrion

4. This colour-enhanced electron micrograph of cells shows the nuclei in green, mitochondria in red, two lysosomes in brown and large amounts of rough endoplasmic reticulum in white. The horizontal field width of the sample is 10.3 micrometres. Credit: University of Edinburgh, Wellcome Images BIGPICTUREEDUCATION.COM Cells with organelles

5. This colour-enhanced image of part of a kidney cell shows many mitochondria in red, a portion of the nucleus in blue and the cytoplasm in green. The cytoplasm is densely packed with the membranes of the endoplasmic reticulum. Credit: Dr David Furness, Wellcome Images BIGPICTUREEDUCATION.COM Mitochondria in the cell cytoplasm

6. This image shows three mitochondria (shown in blue) fractured to reveal their internal structures. The internal membranes (cristae) are visible and are covered with enzyme complexes involved in the conversion of metabolites into energy. The surrounding cytoplasm is shown in gold. This is a colour- enhanced scanning electron micrograph of a freeze-fractured sample. Credit: Dr David Furness, Wellcome Images BIGPICTUREEDUCATION.COM Three mitochondria surrounded by cytoplasm

7. This transmission electron micrograph shows a mitochondrion in a chick embryo cell. Credit: Professor R Bellairs, Wellcome Images BIGPICTUREEDUCATION.COM TEM of a mitochondrion

8. This colour-enhanced image of a mitochondrion shows the internal membranes (cristae) and enzyme complexes. Credit: Dr David Furness, Wellcome Images BIGPICTUREEDUCATION.COM Mitochondrion

9. A photomicrograph of normal muscle X 63 using an ATP stain. Credit: Wellcome Photo Library, Wellcome Images BIGPICTUREEDUCATION.COM Normal muscle X 63

10. Professor Sir John Walker won the 1997 Nobel Prize in Chemistry (with Paul Boyer and Jens Skou) for his work on the crystallographic analysis of the structure and function of the enzyme ATP synthase. He is shown here in his laboratory at the University of Cambridge. Credit: Anne-Katrin Purkiss, Wellcome Images BIGPICTUREEDUCATION.COM Professor Sir John Walker

11. Reusing our images Images and illustrations All images, unless otherwise indicated, are from Wellcome Images. Contemporary images are free to use for educational purposes (they have a Creative Commons Attribution, Non-commercial, No derivatives licence). Please make sure you credit them as we have done on the site; the format is ‘Creator’s name, Wellcome Images’.Creative Commons Attribution, Non-commercial, No derivatives licence Historical images have a Creative Commons Attribution 4.0 licence: they’re free to use in any way as long as they’re credited to ‘Wellcome Library, London’.Creative Commons Attribution 4.0 licence Flickr images that we have used have a Creative Commons Attribution 4.0 licence, meaning we – and you – are free to use in any way as long as the original owner is credited.Creative Commons Attribution 4.0 licence Cartoon illustrations are © Glen McBeth. We commission Glen to produce these illustrations for ‘Big Picture’. He is happy for teachers and students to use his illustrations in a classroom setting, but for other uses, permission must be sought. We source other images from photo libraries such as Science Photo Library, Corbis and iStock and will acknowledge in an image’s credit if this is the case. We do not hold the rights to these images, so if you would like to reproduce them, you will need to contact the photo library directly. If you’re unsure about whether you can use or republish a piece of content, just get in touch with us at bigpicture@wellcome.ac.uk.bigpicture@wellcome.ac.uk