Rough endoplasmic reticulum
A network of membranes within a cell which has ribosomes attached to it. They are important in the synthesis and transportation of proteins.
Messenger RNA
The molecule which transcribes the DNA code and carries it out of the nucleus through the pores in the nuclear membrane to the ribosomes in the cytoplasm which synthesise the required proteins
Digestion
Breaking down the large insoluble food molecules into small soluble molecules
Vesicle
Small sac that stores or transports substances inside a cell
Nucleus
The part of a cell that controls the cell function and contains the chromosomes.
Gene
A short piece of DNA which is responsible for the inheritance of a particular characteristic. It codes for the production of a specific protein. Genes occupy a fixed position, called a locus, on a particular DNA molecule.
DNA
Deoxyribonucleic acid. This is the molecule which contains the genetic code. It coils up tightly inside chromosomes. DNA is a double helix made from two strands which are joined together by pairs of bases.
Islets of Langerhans
The pancreas has two functions: to make hormones (endocrine) and to produce enzymes for digestion (exocrine).
The islets of Langerhans make the hormones insulin and glucagon. The alpha cells (stained red) make the glucagon and the beta cells (green) produce insulin. Nuclei are stained blue.
The islets make up only just over 2% of the pancreatic tissue
Alpha and beta cells in the islets of Langerhans. Source: Masur
Specialised cells
Beta cells are specialised to produce insulin. They have a well-developed rough endoplasmic reticulum, to produce the protein hormone. This is then stored in cytoplasmic vesicles before it is secreted. The process requires energy and beta cells contain many mitochondria to provide ATP.
Roll over the image to see the parts of the cell involved in insulin production.
Protein synthesis
Insulin is a protein and there are several stages in its production. The animation shows the process of protein synthesis. When insulin is being produced, it is the insulin gene in the nucleus that is transcribed into messenger RNA.
Question 5
