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- Herausgeber: David Fickling Books
- Kategorie: Für Kinder und Jugendliche
- Serie: Explodapedia
- Sprache: Englisch
- Veröffentlichungsjahr: 2023
Joint winner at the Association for Science Education Book of the Year Awards 2023!There are 40,000 genes in every cell of your body. Together, they carry all the instructions needed to make you. Nobody else has exactly the same genes as you do: you are completely unique.Based on up-to-the-minute science, The Gene explores how these tiny tangles of DNA build and operate all living things. See what genes can reveal about you, and find out how today's scientists 'edit' genes. Will these breakthroughs help or harm our future?Grow your knowledge of genes, with the EXPLODAPEDIA!
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Welcome to Explodapedia, the indispensable guide to everything you need to know! This series is packed with in-depth knowledge you can trust; it gives you the tools you need to understand the science behind the wonders of our world. The Gene is a vital chapter of our story, so read on to discover what makes you, you …
‘Extraordinary discoveries are explained in a way everyone can understand.’Sir Paul Nurse, Nobel Prize winner
‘The perfect balance between charm, quirkiness and wonder … for kids and adults alike.’Siddhartha Mukherjee, Pulitzer Prize winner
‘A totally fascinating book, brimming with amazing scientific knowledge and fab illustrations.’ Greg Jenner
‘Successfully blend[s] appealingly humorous drawings … [with] text that combines clarity and accuracy.’Professor Richard Fortey
‘Both accessible and funny … a clever way to introduce … our understanding of all life today.’Professor Venki Ramakrishnan, Nobel Prize winner1
BM: To Andy, whose memory, and genes, live on in me; and now in Beda and Ghyll too.
AA: To Karen, Connor and Spencer – I love what you’ve done with your genes!
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EXPLODAPEDIA: THE GENE First published in 2023 by David Fickling Books, 31 Beaumont Street, Oxford, OX1 2NP
This ebook edition first published in 2023
All rights reserved Text © BEN MARTYNOGA, 2023 Illustrations © MOOSE ALLAIN, 2023
The right of Ben Martynoga and Moose Allain to be identified as the author and illustrator of this work has been asserted in accordance with Section 77 of the Copyright, Designs and Patents Act 1988.
This ebook is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorised distribution or use of this text may be a direct infringement of the author’s and publisher’s rights, and those responsible may be liable in law accordingly.
ISBN 978–1–78845–246–5
Italic type is used in Explodapedia to highlight words that are defined in the glossary when they first appear, to show quoted material and the names of published works. Bold type is used for emphasis.4
Contents
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What Makes You, You
You are exceptional, a genuine one-off, and it’s all thanks to your genes. They make sure nobody else is, or ever will be, quite the same as you.
So, basically, this book is all about YOU. It’s going to help you understand how your genes have shaped every aspect of the way you look, think and feel.
But the story of you isn’t just about what makes you different. Yes, you are absolutely unique … but, like it or not, you’re also almost exactly the same as everyone else on the planet. We’re all humans, because of our genes.
So, what are genes?
The short answer is this: genes are instructions, made from a substance called DNA, that are used to build our bodies and then keep them alive and launch each new generation.
The long answer is that it’s a big and sometimes baffling
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topic: even expert biologists spend a lot of time arguing about what exactly a gene is. So, we’re going to take things one step at a time and gradually build up a clearer picture of the gene. By the end of the book, though, you’ll hopefully see how genes do what seems impossible: they make you virtually identical to everyone else AND entirely individual at the same time.
In fact, genes are completely essential for pretty much everything all living things do. Without genes there’d be absolutely no life on planet Earth.
Look, here’s a gene. Hello there. Can you tell us how you do what you do?
To be fair you’re just a long, wriggly molecule of DNA. There’s no way you could understand quite how important you are to our lives. You probably shouldn’t even be talking to us.
But can you stick around? Maybe you can help us find out more about what genes are and how they work.8
Genes were one of the main things that really got life on Earth started in the first place, about four thousand million years ago, and they’ve been at the very heart of the action ever since. So, believe it or not, some of the genes in your body are practically identical to genes found inside every other creature
you’llever see, from the microscopic bacteria growing between your teeth, to the fly buzzing around that banana in your fruit bowl, to the cat that wants to catch the fly, to the banana itself. Because of your genes, you’ve got a surprising amount in common with all other living things. They’re part of your story too.
Phew. There’s a lot to cover, so let’s start telling the story of you from the very beginning.
Does this picture look familiar?
No? Well, it’s actually a picture of you when you were younger … much younger. You could say it was your first baby snap. You didn’t recognize yourself, because your picture is exactly the same as everyone else’s at that age.
Let’s zoom in a bit:9
Scientists call this a zygote, and that’s all there was to your body in the beginning: a single cell, squishy, round and about as tall and wide as a sheet of paper is thick. But today you’re not just one cell big, you’re formed from trillions of different cells that are all working together to make you. Those cells all look, more or less, like the one on page 9; in fact, all living things are made up of cells that aren’t so very different from this one.
The cells in your body all grew from that zygote, which was formed when an egg cell from your biological* mother was fertilized by a sperm cell from your biological father. When that happened, a bunch of genes that once belonged to your dad and another set of genes from your mum were mixed together to make a completely new set of genes: your genes.
* Your biological parents are the ones who provided the egg and sperm you grew from. They may not be the people you call your parents today, but that’s who we’re referring to in the rest of this section.
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That little zygote may have been small and squishy, but, with its shiny new set of genes, it was a thing of wonder.
It contained all the instructions needed to build and then run an entire, fully formed human: YOU!
Gene instructions work like coded messages. They’re written in a mysterious alphabet made up of just four different letters. Genes are ‘information’ in solid chemical form – genetic information. Living cells contain a stupendous amount of it.
Somehow, all that information was packed away inside a minute cell that could be balanced on the sharp end of a pin. And an entire copy of that genetic information – every last letter of it – is tucked away inside almost every cell in your body today.11
But what does it say? What secret messages are hidden away inside your genes?
Well, if you tried to read the code from scratch, it would look like utter gobbledegook. But, over the years, biologists have got better and better at making sense of it. They’ve discovered that genes are actually chock-full of stories – about things that happened long before you were born, things that are happening to you right now, and things that will happen to you in the future.
And, dear reader, the stories written in your genes aren’t there for entertainment, they can have a massive effect on your life. For example, they can:
• Identify close relatives you never knew you had.
• Predict which illnesses you’ll suffer from decades from now – maybe even when and how you’ll die!
• Predict what your future children might look like, long before they’re born.
These days scientists can’t just read the information stored inside genes. They can also edit genes, erase them and even rewrite them. That means they can make up completely new gene-based stories. So far, they’ve mainly done this with12
non-human living things, such as bacteria, food plants and farm animals. Some of these genetic creations could help us to grow food in new ways, or destroy pollution – but it’s also possible that some of them could harm humans, or the natural world we live in.
However, now it’s even possible to edit and rewrite human genes – including your genes.
You’re right to be concerned. Genes – and the stories they contain – must be handled with great care. Altering them can have vast and truly life-changing effects, for better or for worse. Scientists still have a huge amount to find out about genes. And we do too. So, if we’re going to get to grips with how genes make you, you and how they breathe life into the world, we’d better get on with it.
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CHAPTER 1
From Pea Production to Reproduction
What are Genes for?
The biggest problem with life is … death. All living things will die, eventually, so if they don’t want to go extinct – and frankly, who does? – they simply have to reproduce. Most creatures are very good at this; you could say it’s what they live for. Trees make seeds, birds hatch chicks, flies lay eggs, mould spreads, microbes make more microbes and people have babies. Living things do all this multiplying for themselves – it’s known as reproduction.
Lots of living things, including bacteria and bread yeast, live their lives as single, independent cells. They might reproduce to spread a nasty infection across your tonsils, or to make bread dough rise. Here’s how it happens:14
1. Cell follows gene instructions in order to grow bigger.
2. Cell makes complete copy of all its genes.
3. Cell chops itself in half, making absolutely sure that both new cells end up with a full set of genes.
4. One cell has turned itself into two cells.
This is called cell division and it is the most basic and the most common form of reproduction in the living world.
The cells that make up your body reproduce in the same way. They’re all little living beings in their own right and they are all created by cell division. Whenever part of your body grows or a cut heals, the new cells that are needed get churned out by existing cells that reproduce themselves by cell division.
Lots of plants and fungi, and a smaller number of animals (e.g. starfish and flatworms) use this kind of cell division, called mitosis, to make whole new bodies. If some of their cells bud off, or get broken off accidentally, those cells divide, over and over, eventually making an entire new creature.15
But for animals like us, reproduction is a bit more complicated. As you know, it takes cells from two different people to make a baby: a male sperm and a female egg must fuse themselves – and their genes – together to make a new cell. This is called sexual reproduction. Lots of plants do it in a similar way:
If we skip over the details of how sperm and egg, or pollen and ovum, get mixed together, then the end result of sexual reproduction isn’t all that different from the division of single cells.
The Same, but Different
When a computer copies a file, it makes an absolutely perfect copy. That’s not what living things do.
Sometimes cells make mistakes while copying their genes. And in the case of sexual reproduction, living things mix and reshuffle their gene instructions on purpose.16
It might sound like these errors and intentional mix-ups should cause problems. Sometimes they do – things can go wrong if essential parts of the gene instructions are damaged or destroyed. But overall it’s worth the risk, because living things very often need their next generation to be the same, but different.
Well, the world is always changing. If living things can only ever copy their gene instructions perfectly, they can’t change themselves. And if they can’t change themselves, their old tricks are bound to stop working, sooner or later.
