Barcode.

Mitochondria are the sites of certain stages of respiration, and therefore are responsible for the production of the energy carrying molecules, ATP, from carbohydrates.

I know, I know, I already fucking know.

My head hits the desk. The recycled textbook line must have been rehearsed on average seventeen times in the past hour like the run-through of a goddamn play, and I wish the teacher would just learn his lines already. Student science graduate, first job and first bunch of kids to fall asleep in front of him, and I know even I could teach the lesson better than this. I’m not the only person here bored only after two months of this ridiculous class, either; Imogen is slumped next to me like a discarded marionette, hair knotted and scribbled all over my arm and I just know she’s begging to drift off to sleep. The only difference between her and I is that I already understand the entire topic, and she doesn’t give a shit.

Because of this, cells with a high metabolic rate have increased numbers of mitochondria, with a larger number of cristae and therefore a larger surface area for respiration. Can anyone give me an example?

I don’t waste precious ATP by raising my hand, because that Irish stutter will give us the answer of muscle cells and epithelial intestinal cells in about three seconds anyway.

A harsh drill cuts Mr Flanagan off mid-mutter and his homework instructions are lost among the hurried screeches of stools on vomit-coloured linoleum. I shut my paper-stuffed folder with a bang and drag it from the table, swinging it dangerously in my palms as I walk towards the exit. The class of my fellow seventeen year olds troops out of Biology Lab 2 and down the stairs, the childish ones among them pushing and shoving year eight students as they race out of the neighbouring Physics room. My aching feet are the last to disgrace the stairway, hand on the rail the only thing stopping me from stumbling headfirst into Imogen ahead. I yawn, shaking scratchy blonde straw from my eyes as it bobs in the breeze from the air-con, and God I wish it was summer. I can almost feel the riverbank pebbles dinting my back and punching my spine, the sun clinging to my skin and clothes as the water rushes past just a few inches from my head. But no, it’s the beginning of January, and the rare beach of stones that stretches along the urban stream is damp and slimy and cold. I already know – I skipped Art to go and see.

“What’re you doing tonight?” Imogen yawns as we step out into the dimming afternoon, breeze nipping at my face like tweezers.

I shrug. “Studying, I suppose. Biology exam’s on Friday, remember? Oh, and they’re taking us out to watch a film or… something.”

“Oh, okay.” Imogen flips her metallic sheen of hair over her shoulder and smiles that china smile, taking my hand. The beam soon shatters when a furious wind whips round her skirt and she squeals, protesting like she does against any form of moderate weather. “Shit, Ollie, It’s fucking freezing.”

“Should’ve brought a coat,” I grin, rubbing her right arm with my palm to try and make her feel warmer. Granted, I hardly ever wear my jacket either, but that’s only because I don’t know where it is most of the time. Imogen prefers to let everyone on the bus to school and in the grounds and in her lessons and in the cafeteria see the way that her latest purchase highlights her waist or her boobs or her thighs, like a walking fashion magazine that’s glued open. Once the wind dies down I raise my hand to twirl a section of her glassy hair between my rough fingers, and I know it only stays perfectly styled and smooth as hell because it dies every morning under the torture of lotions and sprays and straightening irons. Or curlers, if she’s feeling adventurous.

Once we’re out at the front of school, uniformed children are wild to various degrees – younger students are swept up by the wind in the hurry to get away from this old Victorian building, and the elder ones run only because if they don’t they’ll miss their bus. The flock of white shirts and red ties bound by the black-coat-rule are speckled occasionally by sixth-formers – Imogen and I, for example – who are shielded from the skies by more defiant colours. We stop at the fountain in the centre of the path, and I take her other hand as she turns to face me. I lean down to kiss her, peach-flavoured gloss smearing on my own lips, and then she departs with a giggle for her own way home.

When I board the old independently hired minibus, it’s all chatter and squabbling pubescents and meaningless troubles. I flop in the only seat without a neighbour, the one left unused by everyone else, and block out their ignorance with headphones. The bus spits out carbon fumes that immediately smother the back seats of the bus through the cracks in the floorboards and groans as the wheels begin to turn, pulling us up the hill. I close my eyes to the chaos in front of me, and damage my eardrums for the sake of sanity. I feel the bus lurch round corners and fly down red-brick mazes until we’re out of the centre of town, racing farther and farther away from school and communities and people.

It takes on average thirty seven minutes to journey between St James’ Secondary School and Hollingwood House. Of course, it depends on the time of day we set off – in the mornings we have to leave at eight to reach school before the bell at quarter to nine, and at the end of the day we only just miss rush hour and make it back in about thirty minutes. It takes even longer to walk, obviously, and as I glance out of the window when we pull up on the kerb, I almost wish I had, despite the birth of a snowfall in our midst.

I’m the last to leave the bus and the last to step through the front door into the artificial warmth. The primary school kids are already home, unzipped and unbooted and turning their noses up at perfectly sliced apple chunks on plastic plates. Mary smiles at each one of us as we pass her, every child turning left towards the dining room under her the guidance of her sausage arm and her meatball figure - all except me.

Hollingwood isn’t a place that’s afraid of a lick of paint. It’s not somewhere that screams starvation or sorrow or shortage. It’s not a place where you’d find the gruel-fed faces you see in the movies or the care-deprived children shut up in rooms designed for half the number they hold. I climb the rainbow stairs that lead to the smallest children’s bedrooms and in fact, they pass passing disgustingly bright wallpaper tacked with finger-paintings and dappled with multicoloured handprints. My trainers tread on the first floor’s new rugs and carpets, still smelling of the factory glue they stick the underside on with, and my hands reach for a well-dusted oaken handrail as I continue to pass through each narrow hallway crammed with smiles and hugs and mopped up tears.

But this house is what it is. It’s an institution crammed with colour and love to cover up the cold cement that glues its bones together. It’s a tower that grows each time there’s a new arrival, giving the adults an excuse to clean out unused rooms on the appropriate floor and welcome broken souls into the cluster. It’s an excuse for people with hearts two sizes too big to look after the unwanted, the unloved, the uncared for – because it is what it says on the obnoxious sign outside. A children’s home. An orphanage. A drop off site.

I flop down on my bed and lethargically open my textbook.

If synthesis of mitochondria or ATP is prohibited, the cell’s processes slow down and it is unable to do it’s job, leading to eventual shut down.

It lands on the floor with a thud.