Most Biomacromolecules are Polymers... A polymer is a long molecule consisting of many small repeating subunits called monomers. These polymers are built by condensation reactions 3 of the 4 classes of life s organic molecules are polymers: Carbohydrates Proteins Nucleic acids Biomacromolecules: Features
Biomacromolecules Biomacromolecules are very large molecules that play an essential role in the structure and function of cells. Biomacromolecule Sub-units Bond Formed by Condensation Cellular Functions Lipids Lipids are not polymers Fatty Acids & Glycerol Ester linkage Energy storage, phospholipids, signalling molecules Complex carbohydrates Polysaccharides Simple sugar monomers Monosaccharides Glycosidic linkage Energy storage, structral components (eg. cellulose) Nucleic Acids Polynucleotides Nucleotide monomers Phosphodiester linkage Genetic material Proteins Polypeptides Amino Acid monomers Peptide linkage Diverse roles; control and regulation, transport, receptors, structural components Biomacromolecules: Features
Biomacromolecules: Nucleic Acids Nucleic Acids Nucleic acids store genetic information There are two main types Deoxyribonucleic Acid (DNA) Ribonucleic Acid (RNA) DNA is hereditary and directs its own replication DNA also directs synthesis of messenger RNA (mrna) mrna, in turn, controls protein synthesis in ribosomes
Nucleic Acids: Nucleotides Nucleotides Nucleotides are the monomers that make up nucleic acids. A nucleotide has three distinct components; 1. 5 carbon sugar ribose in RNA deoxyribose in DNA 2. negatively charged phosphate group 3. nitrogenous base Adenine (both) Thymine (DNA only) Guanine (both) Cytsosine (both) Uracil (RNA only- takes the place of Thymine)
Nucleotides: Nucleoside Components Nucleoside Components in Detail Nucleoside is a term that refers only to the variable components of a nucleotide; the sugars nitrogenous bases Note the structural differences Pyrimidines have a 6 carbon ring Purines have a 5 and a 6 carbon ring Ribose sugars have a 2' and 3' OH group Deoxyribose sugars have lost an oxygen from their 2' OH group
Biochemical Nomenclature: Prime Hang On- What the Hell is Prime'? Prime was hinted at with carbohydrates...but it has greater significance with regards to nucleic acids. In molecular biology, the prime is used to denote the positions of carbon on a ring. If I refer to carbon number 3, I say 3-prime carbon or write 3' C. glucose
Nucleic Acids: Polynucleotides Nucleic Acids are Polynucleotides A nucleic acid, or polynucleotide, is formed by the joining together of nucleotides by condensation polymerisation. H 2 O The type of covalent bond formed here is called a phosphodiester linkage
Polynucleotides: Assembly Nucleic Acids are Polynucleotides We say that these nucleotides are assembling in a 5' to 3' direction. Is this DNA or RNA?
Nucleic Acids are Polynucleotides Polynucleotides: Assembly
Nucleic Acids: Deoxyribonucleic Acid DNA Structure The DNA molecule has two complementary strands of polynucleotides spiralling about an imaginary axis. The strands are antiparallel- they run in opposite 5' to 3' directions Hydrogen bonds form between complementary nitrogenous bases called base pairs (bp). Remember! A G T C Base pairs
From DNA to RNA: Transcription From DNA to mrna The amino acid sequence of a protein is determined by the nucleotide sequences of the gene that encodes it. The sequence of nucleotides in the DNA of a gene is transcribed into the equivalent sequence in messenger RNA. In RNA, Thymine is replaced with Uracil. Each group of three, called a triplet codon, stands for a specific amino acid. This same genetic code is used by virtually all organisms on the planet. The mrna codons provide instructions for protein assembly.
RNA to Proteins: Translation From RNA to Proteins Messenger RNA (mrna) carries an amino acid sequence to a ribosome. Ribosomes are complexes of protein and ribosomal RNA (rrna). They move along the mrna in a 5' to 3' direction translating the triplet codons. Transfer RNA (trna) uses an anticodon to fetch the required amino acids. Together the ribosome synthesises the protein one amino acid at a time.
Nucleic Acids A Broader Perspective Each somatic cell in the human body has 46 chromosomes over a metre of DNA more than 3 billion base pairs The functional components encoded for by DNA are called genes. The total set of genes for an organism is called the genome, the study of which is called genomics. DNA is passed from parent to offspring. Nucleotide sequences can be assessed to establish kinship. Two closely related species are more similiar in DNA than distantly related species