• RNA is made in cells by copying DNA using RNA polymerase
  • RNA is broken down by action of RNAses
  • Some viruses such as HIV, measles and flu virus, use RNA as genetic material
  • The role of RNA in the cell is central to the central dogma

Gene Expression

  • Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as transfer RNA or small nuclear RNA genes, the product is a functional RNA.
  • Genes closely spaced
  • Organized in operons
  • Operons transcribed/translated when needed – inducible
  • Simple promoter elements
  • Simple control

Lac Operon

  • The lac operon is an operon required for the transport and metabolism of lactose in Escherichia coli and many other enteric bacteria.


  • Chromatin is a complex of DNA and protein found in eukaryotic cells. Its primary function is packaging very long DNA molecules into a more compact, denser shape, which prevents the strands from becoming tangled and plays important roles in reinforcing the DNA during cell division, preventing DNA damage, and regulating gene expression and DNA replication. During mitosis and meiosis, chromatin facilitates proper segregation of the chromosomes in anaphase; the characteristic shapes of chromosomes visible during this stage are the result of DNA being coiled into highly condensed networks of chromatin.


  • A nucleosome is a fundamental unit of chromatin structure.


  • Ribonucleic acid is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and DNA are nucleic acids, and, along with lipids, proteins and carbohydrates, constitute the four major macromolecules essential for all known forms of life.


  • Epigenetics is the study of heritable phenotype changes that do not involve alterations in the DNA sequence. The Greek prefix epi- in epigenetics implies features that are “on top of” or “in addition to” the traditional genetic basis for inheritance.

Transcription Factors

  • Transcription factors are proteins involved in the process of converting, or transcribing, DNA into RNA. Transcription factors include a wide number of proteins, excluding RNA polymerase, that initiate and regulate the transcription of genes.

RNA Processing

  • RNA processing refers to any modification made to RNA between its transcription and its final function in the cell. These processing steps include the removal of extra sections of RNA, specific modifications of RNA bases, and modifications of the ends of the RNA.

RNA Splicing

  • RNA splicing is a form of RNA processing in which a newly made precursor messenger RNA transcript is transformed into a mature messenger RNA. During splicing, introns are removed and exons are joined together.

Catalytic RNA

  • Catalytic RNAs are involved in a number of biological processes, including RNA processing and protein synthesis. Discovery of catalytic RNA contributed to the hypothesis of an ‘RNA world’, describing the origin of life as starting from RNA.

Genetic Code

  • The genetic code is the set of rules used by living cells to translate information encoded within genetic material into proteins.

Aminoacyl tRNA synthetase

  • An aminoacyl-tRNA synthetase, also called tRNA-ligase, is an enzyme that attaches the appropriate amino acid onto its tRNA. It does so by catalyzing the esterification of a specific cognate amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA.


  • From greek “koola” (glue) “gen” (producing
  • Boiling hooves to make glue
  • Medical uses in treating bones and skin
  • Most abundant protein in the body
  • 25% to 30% of all body protein by weight
  • Synthesis decreases with age

Collagen I

  • Type I collagen is the most abundant collagen of the human body. It forms large, eosinophilic fibers known as collagen fibers.

Collagen II

  • Type II collagen is the basis for articular cartilage and hyaline cartilage, formed by homotrimers of collagen, type II, alpha 1 chains. It makes up 50% of all protein in cartilage and 85–90% of collagen of articular cartilage. Type II collagen does form fibrils.

Collagen III

  • Type III collagen is a fibrillar collagen, and it consists of only one collagen α chain, in contrast to most other collagens. It is a homotrimer containing three α1(III) chains supercoiled around each other in a right-handed triple helix.

Collagen IV

  • Collagen IV is a type of collagen found primarily in the basal lamina. The collagen IV C4 domain at the C-terminus is not removed in post-translational processing, and the fibers link head-to-head, rather than in parallel.

Collagen V

  • Type V collagen is a fibrillar collagen. Type V collagen is essential for fibrillation of types I and III collagen, and consequently for optimal fibrillary formation and tissue quality. Type V collagen contributes to the bone matrix; corneal stroma; and the interstitial matrix of muscles, liver, lungs, and placenta.


  • Hydroxyproline is a neutral heterocyclic protein amino acid. It is found in collagen and as such it is common in many gelatin products. Hydroxyproline is mostly used as a diagnostic marker of bone turnover and liver fibrosis.

Lysyl Hydroxylase

  • Lysyl hydroxylases are alpha-ketoglutarate-dependent hydroxylases enzymes that catalyze the hydroxylation of lysine to hydroxylysine. Lysyl hydroxylases require iron and vitamin C as cofactors for their oxidation activity. It takes place following collagen synthesis in the cisternae of the rough endoplasmic reticulum.

Lysyl Oxidase

  • Lysyl oxidase, also known as protein-lysine 6-oxidase, is an enzyme that, in humans, is encoded by the LOX gene. It catalyzes the conversion of lysine molecules into highly reactive aldehydes that form cross-links in extracellular matrix proteins


  • Scurvy is the name for a vitamin C deficiency. It can lead to anemia, debility, exhaustion, spontaneous bleeding, pain in the limbs, and especially the legs, swelling in some parts of the body, and sometimes ulceration of the gums and loss of teeth.