Mark Bretscher facts for kids

Mark Steven Bretscher (born 8 January 1940) is a British scientist who studies living things. He is a Fellow of the Royal Society, which is a very important honor for scientists. He worked at the Medical Research Council Laboratory of Molecular Biology in Cambridge, United Kingdom. He is now retired.

Early Life and Education

Mark Bretscher was born in Cambridge, England. He went to Abingdon School from 1950 to 1958. After that, he studied Chemistry at Gonville and Caius College, University of Cambridge in 1958. He earned a PhD degree there and became a research fellow.

His Amazing Career

In 1961, Mark Bretscher joined the MRC Laboratory of Molecular Biology. This is a famous research center. He worked there as a student with important scientists like Francis Crick and Sydney Brenner. Later, he spent a year at Stanford University in the United States.

He became a staff member at the MRC Laboratory of Molecular Biology. He led the Cell Biology division from 1986 to 1995. He was also a visiting professor at Harvard University and Stanford University. In 1985, he was chosen as a Fellow of the Royal Society.

Bretscher made big discoveries in three main areas:

• How proteins are made in cells.
• The structure of cell membranes, especially in red blood cells.
• How animal cells move.

Understanding How Proteins Are Made

Mark Bretscher helped us understand how cells build proteins. Proteins are like tiny machines that do many jobs in our bodies.

In his first paper, the word "codon" was used for the first time. A codon is like a secret code word in our genetic code. He also found that the growing protein chain connects to a special molecule called tRNA. tRNA helps carry the building blocks for proteins.

With another scientist, Kjeld Marcker, he found out how protein making starts. They showed that a ribosome, which is like a protein factory in the cell, doesn't need to start at the very beginning of a message. It can find the right starting point even if the message is in a circle. He also suggested that parts of the ribosome move in two steps when making proteins.

Discoveries About Cell Membranes

Mark Bretscher also studied cell membranes. These are the outer layers that protect cells. He focused on human red blood cells.

He found that red blood cells have only two main proteins on their outer surface. These proteins go all the way through the membrane. He also discovered that some fats, called amino phospholipids, are hidden on the inside of the membrane. This showed that the cell membrane is not the same on both sides; it's asymmetrical.

He suggested that this unevenness happens when the membrane is built. He thought that all these fats are made on the inside of the cell. Then, a special "flippase" protein moves some of them to the outside.

With another scientist, Munro, he suggested that the Golgi apparatus helps control cholesterol levels in the cell membrane. Cholesterol makes the membrane stronger and thicker. This helps the cell membrane act as a better barrier. It also helps sort proteins, making sure only the right ones reach the cell's surface.

How Cells Move

Mark Bretscher is a key scientist in understanding how cells move. This process is called cell locomotion. He studied how cells like fibroblasts move.

Most animal cells constantly recycle their outer membrane. This process is called the endocytic cycle. Small parts of the membrane are taken inside the cell. Then, this membrane is processed and sent back to the cell surface.

When cells move, like amoebas, the front of the cell extends forward. The back of the cell then catches up. Bretscher suggested that the cell's front grows by adding new membrane from inside the cell. This membrane is then taken back inside from the rear of the cell.

This creates a flow of membrane from the front of the cell to the back. This flow helps the cell move forward. It's like a "lipid flow" that sweeps things on the cell surface towards the back.

He showed that new membrane is added at the leading edge (the front) of moving cells. He also suggested that the cytoskeleton (the cell's internal support structure) helps move membrane to the front. It also helps shape the new membrane there. In this way, a cell moving on a surface is a bit like a tank, with its surface acting like a tread.

Studies with Dictyostelium discoideum amoebas showed that these fast-moving cells recycle their entire surface every 6 minutes. This supports the idea that cells move by flowing membrane. Some cells can even move without a solid surface, which is strong proof that they move by this flowing membrane process.

His Family and Hobbies

Mark Bretscher's father was Egon Bretscher, a nuclear physicist. Mark is married to Barbara Pearse. His brothers are Anthony Bretscher and Peter Bretscher. He enjoys walking, creating wild gardens, and looking at old English portraits and furniture.

Related Information

• List of Old Abingdonians
• ISBN: 978-1-903435-05-2