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Unlock This CourseAll living things are made up of chemical elements - the basic building blocks of matter. Just like how LEGO bricks can be combined to build amazing structures, elements combine to create the complex molecules that make life possible. But here's the fascinating bit: whilst there are over 100 elements in the periodic table, life mainly uses just a handful of them!
Think about it - your body, a blade of grass, a mushroom and even bacteria all share the same basic chemical ingredients. It's like nature has a favourite recipe that works brilliantly for creating life.
Key Definitions:
About 96% of your body weight comes from just four elements: carbon (18%), oxygen (65%), hydrogen (10%) and nitrogen (3%). These are like the main ingredients in the recipe of life - without them, biological molecules simply cannot exist!
If elements were celebrities, carbon would definitely be the A-lister of biology! Carbon is absolutely essential for life as we know it and here's why it's so special.
Carbon atoms are like the ultimate connectors. Each carbon atom can form four strong bonds with other atoms, including other carbon atoms. This means carbon can create:
Carbon atoms link together to form long chains, like a molecular train. This creates the backbone of many important molecules like fats and proteins.
Carbon atoms can join in circles to form ring structures. These are found in sugars and the bases that make up DNA.
Carbon chains can have branches coming off them, creating complex 3D shapes that are perfect for specific biological functions.
This flexibility means carbon can form millions of different compounds - far more than any other element. It's like having a construction kit with unlimited possibilities!
Both diamond and graphite are made entirely of carbon atoms, but they're completely different! In diamond, each carbon bonds to four others in a 3D structure, making it incredibly hard. In graphite (like in pencils), carbon forms flat sheets that slide over each other, making it soft and slippery. Same element, different arrangements, totally different properties - that's the power of carbon!
Whilst carbon gets the starring role, the other three major elements are equally important supporting actors in the drama of life.
Hydrogen is the simplest and lightest element, with just one proton and one electron. Don't let its simplicity fool you though - it's everywhere in biology!
Oxygen makes up about 21% of the air we breathe and 65% of our body weight. It's essential for:
Nitrogen might only make up 3% of your body, but it's absolutely crucial for life. Here's why:
Beyond the big four, living organisms need several other elements in smaller amounts. These are like the spices in cooking - you don't need much, but they make all the difference!
Essential for DNA, RNA and ATP (the energy currency of cells). Also found in bones and teeth as calcium phosphate. Without phosphorus, cells couldn't store or transfer energy!
Found in some amino acids and helps proteins fold into their correct 3D shapes. It's what gives rotten eggs their distinctive smell, but in proteins, it's essential for proper function!
Some elements are needed in tiny amounts but are still absolutely essential. These trace elements often work as helpers for enzymes or as parts of important molecules.
Essential for haemoglobin in red blood cells. Without iron, you can't transport oxygen around your body efficiently, leading to anaemia.
Found at the centre of chlorophyll molecules in plants. Without magnesium, plants can't photosynthesise and would appear yellow instead of green.
Not just for bones and teeth! Calcium is also essential for muscle contraction and nerve function. Your heart couldn't beat without calcium!
Iron deficiency is the most common nutritional deficiency worldwide. Even though we only need about 18mg of iron per day (that's less than the weight of a paperclip!), without it, people become tired, weak and pale. This shows how crucial even trace amounts of elements can be for proper body function. Good sources of iron include red meat, spinach and fortified cereals.
The magic of life happens when these elements combine in specific ways to create biological molecules. It's like a molecular dance where each element has its own special moves!
Elements don't work alone - they team up to create the four main types of biological molecules:
Understanding elements in biological molecules helps us appreciate how life works at the most basic level. From the carbon in your morning toast to the iron in your blood, these elements are constantly working together to keep you alive and healthy. It's amazing to think that the same elements found in stars are also found in every cell of your body - we truly are made of star stuff!