* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Macromolecules: Proteins and Nucleic Acids
Ancestral sequence reconstruction wikipedia , lookup
Magnesium transporter wikipedia , lookup
Molecular evolution wikipedia , lookup
Deoxyribozyme wikipedia , lookup
Ribosomally synthesized and post-translationally modified peptides wikipedia , lookup
Gene expression wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Protein moonlighting wikipedia , lookup
Western blot wikipedia , lookup
Peptide synthesis wikipedia , lookup
Protein–protein interaction wikipedia , lookup
Circular dichroism wikipedia , lookup
Bottromycin wikipedia , lookup
Point mutation wikipedia , lookup
Two-hybrid screening wikipedia , lookup
Nuclear magnetic resonance spectroscopy of proteins wikipedia , lookup
Cell-penetrating peptide wikipedia , lookup
List of types of proteins wikipedia , lookup
Protein (nutrient) wikipedia , lookup
Intrinsically disordered proteins wikipedia , lookup
Metalloprotein wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Protein adsorption wikipedia , lookup
Genetic code wikipedia , lookup
Expanded genetic code wikipedia , lookup
• Some atoms share outer shell electrons with other atoms, forming covalent bonds • Atoms joined together by covalent bonds form molecules • Molecules can be represented in many ways Table 2.8 Life on earth is based on carbon A carbon atom forms four covalent bonds It can join with other carbon atoms to make chains or rings Carbon skeletons vary in many ways Ethane Propane Carbon skeletons vary in length. Butane Isobutane Skeletons may be unbranched or branched. 1-Butene 2-Butene Skeletons may have double bonds, which can vary in location. Cyclohexane Benzene Skeletons may be arranged in rings. 3.6 Forming Macromolecules Fig. 3.17 • An organic molecule consists of a carbon-based core with functional groups attached • Functional groups are the groups of atoms that participate in chemical reactions • A relatively small number of structural patterns underlies life’s structural and functional diversity Ethane Flammable gas Ethanol Makes you drunk 3.6 Forming Macromolecules • Cells make a huge number of large molecules from a small set of small molecules • Most of the large molecules in living things are macromolecules called polymers • Polymers are long chains of smaller molecular units called monomers • Organisms are primarily made of four kinds of macromolecules – – – – Proteins Nucleic acids Carbohydrates Lipids • Macromolecules are made by a process termed dehydration synthesis • Macromolecules are broken down by a process termed hydrolysis Fig. 3.18a Fig. 3.18b H2O HO H HO H2O H HO H Energy HO H Energy HO H HO • Both types of processes require enzymes H 3.7 Proteins Fig. 3.19 • Made up of subunits called amino acids Six amino acids • There are 20 common amino acids, and they fall into one of four general groups Six amino acids Five amino acids Three amino acids Each amino acid contains: – an amino group – a carboxyl group – an R group, which distinguishes each of the 20 different amino acids Amino group Carboxyl (acid) group Amino acids monomers can be linked by peptide bonds Carboxyl group Amino group PEPTIDE BOND Dehydration synthesis Amino acid Amino acid Dipeptide Protein Structure • Determined by the sequence of its amino acids • There are four general levels – Primary – Secondary – Tertiary – Quaternary Fig. 3.21 Levels of protein structure Atoms are shown as balls in this space-filing model. The protein’s shape (yellow) fits into the grooves of DNA. The protein is a “repressor” that inhibits transcription of a gene. Protein Structure • Primary structure – The specific amino acid sequence of a protein • Secondary structure – The initial folding of the amino acid chain by hydrogen bonding • Tertiary structure – The final three-dimensional shape of the protein • Quaternary structure – The spatial arrangement of polypeptides in a multi-component protein More info (not on exam) • A typical protein contains 200–300 amino acids some are much smaller (smallest are peptides) -some much larger (titin a protein in skeletal and cardiac muscle contains 26,926 amino acids in a single chain!) - Protein Structure • Changes in a protein’s environment can cause a protein to denature – It loses its threedimensional structure – And becomes inactive Fig. 3.22 Chaperone Proteins • Help newly-produced proteins to fold properly Fig. 3.25 • Chaperone protein deficiencies may play a role in certain diseases like Alzheimer’s Proteins are the most structurally and functionally diverse of life’s molecules • Proteins are involved in – cellular structure – movement – defense – transport – Communication • Enzymes are proteins, but not all proteins are enzymes A 3.8 Nucleic Acids • Long polymers of repeating subunits termed nucleotides • Nucleic acids such and DNA and RNA serve as the blueprints for proteins • They ultimately control the life of a cell • A nucleotide is composed of three parts – Five-carbon sugar – Nitrogen-containing base – Phosphate Fig. 3.26 The structure of a nucleotide Nitrogenous bases Space-filling model Fig. 3.28 The DNA double helix DNA (Deoxyribonucleic acid) RNA (Ribonucleic acid) Sugar = Deoxyribose Sugar = Ribose Bases = A, G, C, T Bases = A, G, C, U Double-stranded Single-stranded • Stretches of a DNA molecule called genes program the amino acid sequences of proteins – DNA information is transcribed into RNA, a single-stranded nucleic acid – RNA is then translated into the primary structure of proteins more later