What are cells?

Cells are the smallest unit of life. All organisms are made up of cells, and cells are often referred to as the ‘building blocks of life’. A cell is the smallest unit of life that can replicate independently, and cells are often called the “building blocks of life”. The study of cells is called cell biology.

In recent years, technological advances have allowed scientists to observe and analyse human cells in exceptional detail to better understand the mechanisms underlying cell biology.

What’s inside a cell?

Animal (and human) cells contain five key features; they are:

Nucleus – the so-called ‘head’ of the cell; the nucleus contains the cell’s genetic information and controls its activities.

Cytoplasm – where chemical reactions occur.

Cell membrane – the outside of the cell; the membrane is responsible for deciding which substances may enter and leave the cell.

Mitochondria – the energy hub of the cell.

Ribosomes – where protein synthesis occurs.

What do cells do?

Many cells are specialised to enable them to carry out particular functions within the body. Sperm cells, for example, have a number of features that are specially adapted to making reaching the egg a little easier. They have a long tail that allows them to swim quickly through the female’s body, and a middle section that’s packed with energy-providing mitochondria. Red blood cells are required to deliver haemoglobin to the various cells in the body. They are round in the shape, giving them a large surface area and ample space to carry plenty of haemoglobin.

What can go wrong?

Sadly, cell design isn’t flawless. Occasionally, mutations in a person’s gene code can result in the production of cells that aren’t entirely suited to their prescribed roles. Mutated genes are often inherited from one’s parents. Sickle Cell Anaemia is an inherited disease. It affects the body’s ability to produce red blood cells and deliver haemoglobin around the body. Instead of being round in shape, the cells produced are sickle-shaped; as such, they have a smaller surface area and are less able to deliver haemoglobin.

Mutations

Cancer cells emerge when the genes responsible for controlling cell division are irrevocably damaged. Many mutations are caused by the environment and exposure to radiation or chemicals. Exposure to tobacco smoke is a risk factor for many types of cancer, including lung, mouth and throat, and more than 90% of all lung cancer cases can be attributed to tobacco smoking. Mutations can also occur naturally over time due to the presence of errors in DNA transcription; the more times a cell is allowed to divide, the more errors it is likely to produce, making age a significant risk factor for cancerous mutations.

The Hayflick Limit

The Hayflick limit is the number of times a normal human cell can divide before cell division stops. A cell’s Hayflick limit corresponds directly to the length of the telomere region at the end of the cell’s DNA. With each division, some of the telomeres at the end of the strand fail to divide and are lost; over time, all of the telomeres will be lost, and the cell will cease to divide.

Cancer cells do not have a Hayflick limit; unlike other cells, cancer cells contain an enzyme called telomerase that maintains telomere length and ultimately prevents the cell from reaching its Hayflick limit. Cells that don’t have a Hayflick limit have the potential to divide infinitely.

Author Bio:

Simon Hopes is a renowned author and social media enthusiast. Bitplane is one of the companies at the forefront of medical imaging research; thanks to their technologies, scientists are now able to view cells in real-time and in perfect 3D.