Any budding Biologist has to understand cells, and there’s no better way to understand cells and what makes them tick, than to draw them! Here are some tips to help you draw a cell that is accurate and complete.
Animal cells (or Eukaryotic cells) and their components are the basic building blocks of life for all animals of the land, air and sea. Though on the face of it many animals are very distinctly different from one another, their cells have many similarities to help them stay alive. Just like the bodies they form, each animal cell has organs (known as organelles) and systems to keep it alive. Even special cells like neurones and Dendritic cells can look totally alien at first glance, but actually contain many of the same things as any other cell!
Size and shape matter
The nucleus of the cell contains all the genetic information that the cell needs to synthesise proteins that make the cell carry out special functions, grow, divide and eventually, die. Having all these important and complicated roles, the nucleus and it’s surrounding nucleolus occupy the largest amount of space in the cell make sure to show that in any drawing. This is also a good reference point for sizing up the rest of your organelles like your Golgi Apparatus and your Ribosomes.
Top Tip: Don’t get caught out by all the scales in biology, from millimetres to micrometers, all the way down to nanometers.
Your generalised animal cell will look a bit like an irregular blob. Animal cells usually aren't that structured shape-wise as they lack a cell wall. It's important to make this distinction as plant cells usually are. You obviously can have specialised animal cell shapes (think neurons) but typically you're going to be drawing an amorphorous blob shape exactly like skin cells or the cells from the inside of your cheeks. Be aware that even though exotic shaped cells may look weird, they still contain the same components. A favorite exam question is to show a picture of a rod or cone cell from eyes and ask what the big black spot in the middle is (hint: it's still a nucleus).
Know your audience
Depending on the intended audience of your illustration, you may want to leave out a few of the organelles listed below. Your average 11-year-old will not have come across mitochondria, much less endoplasmic reticulum of lysosomes. By all means introduce then as an extension or stretch topic, but make sure you're not confusing them with something they won't come across again until sixth form.
Key Stage 2, ages 7-11
Children probably won't have been taught about cells at this stage.
Key Stage 3, ages 11-13
At this age group, students need to be aware of the cell membrane, the cytoplasm and the nucleus.
Key Stage 4, ages 14-16
At this age group, students need to be aware of the cell membrane, the cytoplasm, the nucleus, mitochondria and ribosomes.
Key Stage 5, ages 16-18
Students need to know about cytoplasm, cell membranes, the nucleus, mitochondria, ribosomes, rough and smooth endoplasmic reticulum, golgi apparatus, lysosomes and centrioles. They should also be aware of the lipid bilayer structure of membranes.
Know Your Structures
Not everything in a cell is a tiny blob… Electron microscopes have enabled scientists to see things down to nanometers (that’s 1000th of a cm) in size. This has made it possible to see the finer shapes and structures that exist inside cells. Any good illustration or diagram will take this into account, especially when we’re talking about how structure-function relationships work cells. Many organelles have very distinctive shapes and patterns that are easily recognisable.
Every animal cell should contain the following from biggest to smallest:
Composed of an inner ball of DNA ( called the nucleolus), surrounded by a ‘nuclear envelope’ a spherical shape about 7 micrometers big in diameter that’s covered in tiny holes called pores. The nucleus is densely packed with DNA, RNA and Ribosomes to help transcribe and translate DNA to make proteins.
These are very interestingly shaped organelles, oval shaped capsules with 2 layers to its membrane, the inner layer folds up on itself (like it’s been squished inside). They are rod-shaped organelles around 1 x 3 micrometers big.
0.1-1.2 micrometers big, these vesicles contain lysozyme enzyme at an acidic pH of 4.5 to 5 for destroying faulty proteins and pathogenic material.
Endoplasmic Reticulum, rough and smooth
These are membrane-bound organelles, meaning they are stuck to the membrane. They .2 micrometers thick per layer and are responsible for packaging and dispensing proteins to the outer membrane. The ‘rough’ endoplasmic reticulum refers to the reticulum that is dotted with ribosomes around it’s edges.
Required for production of spindle fibres that are involved in the division of cells, these organelles are composed of microtubules running parallel to one another around a central cavity. Centrioles are paired organelles that have two tubes of microtubules bound at a right angle to one another.
Made up of 7 nanometers thick layers folded on top of one another called cisternae, this organelle is required for transporting proteins and compounds into the cell and assisting them in reaching their target location. Most animal cells contain between 1 and a few of these.
Essentially the cell’s most outer layer that controls what is allowed into and out of the cell. It’s about 7 nanometers thick, made of 2 layers of molecules called phospholipids, long chains of fatty acid molecules with ‘Hydrophilic’ heads.
Top Tip - Take a look at the ‘fluid-mosaic’ membrane theory, to further understand how the proteins and membrane organelles arrange themselves in the membrane.
They are cellular ‘workbenches’ that translate RNA into strings of Amino Acids that fold up to make proteins. They are made up of a type of RNA called rRNA and are 30 nanometer big in total, comprising of two subunits. Given that they're so small though, it's easier to just draw them as tiny dots. Scale trumps detail in this case. They exist all throughout the cell, especially near the nucleus and along the outside of the rough endoplasmic reticulum.
Tiny spheres about 30 nanometers in diameter that contain lots of enzymes that cells need to function.
Test your knowledge of cell structures using this game by Sheppard Software.
Colour is key
Animal cells under the microscope are usually rather colourless (unless stained), but cells are complicated structures with so many moving parts it can be quite hard to distinctly tell different bits apart, especially when telling apart tiny organelles like ribosomes and peroxisomes that can appear to look so similar.
Top Tips: If you use colours, a key is useful to make sure it is clear what each colour corresponds to in your drawings.
If you're going to be super accurate, colour your animal cell components based on what colours they are under the microscope using common stains.
The Nucleus (Indigo)
- Methylene blue - stains animal cells to make nuclei more visible.
- Coomassie blue - stains proteins a brilliant blue.
Cell membranes (Pink)
- Eosin - colours red blood cells, cytoplasmic material, cell membranes, and extracellular structures pink (or red).
- Carmine - colours glycogen red.
- Nile red/Nile blue oxazone - stains intracellular lipid globules red.
- Fuchsin - makes collagen, smooth muscle, or mitochondria bright pink.