The cell is
the smallest living thing that can grow and multiply independently. All
multi-cellular organisms, like humans, grew from a single cell after
conception. An adult person is built up by about 75.000.000.000.000
cells. There are hundreds of different types of cells, differing in
features like shape, colour, and function. They also have certain things
in common, e.g. the fact that they have a nucleus and a
cell membrane. Cells are filled with a liquid called cytoplasm
in which we find organelles like the mitochondria
and ribosomes. Also, many nutrients, gasses, ions, etcetera are
dissolved in the cytoplasm. The most important macromolecules in
cells are sugars, fats, proteins, DNA, and RNA.
Name three specific molecules you find in cells. Answer
Proteins play a very important role in life and the processes in your body. Your hair and nails are made of protein, your body defends itself with antibodies (which are proteins), your laundry detergent is full of proteins that break down stains, proteins in your eyes enable you to see, etcetera.
Name a few examples of proteins with these functions:
All living matter contains protein fulfilling very diverse but essential roles. Proteins are macromolecules consisting of amino acids. Each amino acid has a central carbon atom (the Cα), an amino group, a carboxyl group (the acidic group) and a side chain. The recurring sequence of ...-NH-Cα-CO-NH-Cα-CO-... is called the backbone of the protein.
Mark
the following parts of amino acids in the figure on the left: the Cα,
the amino group, de carboxyl group, and the side chain. Answer
This figure is a simplified representation of an amino acid, the
charges are left out. In the body, amino acids occur as zwitterions,
molecules with a positive and a negative charge(here: NH3+ en COO-).
Two amino acids can be linked with a peptide bond. In the process
of linking one H2O molecule is removed.
Mark the peptide bond in the figure below. Answer
Three or more amino acids linked together are called a polypeptide or a protein. More about that in the exercises on the next page.
