Week 1 -YR1 Lecture 1H - Molecules of Life 2021 PDF

Molecules of Life Dr Morven Cameron [email protected] Lipids Carbohydrates Proteins Collagen Phospholipid Molecules of Life Nucleotides Dr Morven Cameron [email protected] ATP Glucose Lipids Carbohydrates Proteins Collagen Phospholipid Molecules of Life Glucose Nucleic acid...

Molecules of Life Dr Morven Cameron [email protected] Lipids Carbohydrates Proteins Collagen Phospholipid Molecules of Life Nucleotides Dr Morven Cameron [email protected] ATP Glucose Lipids Carbohydrates Proteins Collagen Phospholipid Molecules of Life Glucose Nucleic acids Dr Morven Cameron [email protected] ATP Learning outcomes Identify the role that nucleic acids, carbohydrates, lipids and proteins have as building blocks for cellular structures, cellular interactions and as signalling molecules. Recall that polymers are formed by dehydration reactions; monomers are recovered by hydrolysis of polymers Molecules of Life Nucleic acids – DNA – RNA – ATP, GTP (nucleoside triphosphates) Proteins – Globular – enzymes, hormones – Fibrous – connective tissue, bone, hair – Membrane – neuronal receptors, cell adhesion molecules Carbohydrates – Glucose – Glycogen Lipids – Phospholipids – Fatty acids – Cholesterol Monomers à Polymers Nucleotide à DNA, RNA (nucleic acids) Amino acids à polypeptides, proteins Monosaccharides à polysaccharides, carbohydrates Lipids are a bit different. condensation reaction Formation via dehydration synthesis, breakdown via hydrolysis. water breaking down Dehydration synthesis Dehydration synthesis – Removal of a water molecule between two reacting molecules forming a new covalent bond in the process. Hydrolysis Hydrolysis – Addition of a water molecule to a polymer to break a bond within a polymer to form the monomers. Dehydration & hydrolysis https://www.youtube.com/watch?v=ZMTeqZLXBSo Molecules of Life Nucleic acids – DNA – RNA – ATP, GTP (nucleoside triphosphates) Proteins – Globular – enzymes, hormones – Fibrous – connective tissue, bone, hair – Membrane – neuronal receptors, cell adhesion molecules Carbohydrates – Glucose – Glycogen Lipids – Phospholipids – Fatty acids – Cholesterol Monomer - nucleotide Adenine Thymine Guanine Cytosine Uracil Deoxyribose Nucleic Acid – DNA Ribose Nucleic Acid - RNA DNA RNA Nucleic acids - DNA ATP & GTP ATP sometimes called the energy “currency” of the cell – Generated in the mitochondria – Important for: – – – – – Muscle contraction Maintenance of membrane potential Assembly of complex molecules Cellular transport etc. GTP – – – – Signal transduction within the cell Synthesis of RNA and DNA Protein synthesis Gluconeogenesis guanine ATP & GTP Adenine Nucleic acids - DNA Nucleic acids - RNA Uracil takes the place of thymine – pairs with adenine during transcription. Nucleic acids - structure DNA molecules form a double helix. – Also forms tertiary structures – chromatin. RNA molecules are singlestranded. – Can form many different structures. tRNA rRNA Molecules of Life Nucleic acids – DNA – RNA – ATP, GTP (nucleoside triphosphates) Proteins – Globular – enzymes, hormones – Fibrous – connective tissue, bone, hair – Membrane – neuronal receptors, cell adhesion molecules Carbohydrates – Glucose – Glycogen Lipids – Phospholipids – Fatty acids – Cholesterol Monomer – amino acid 20 different types Monomer – amino acids Amino acid monomers link to form polypetides via _______ type of reaction??? Peptide bonds. Typically “peptides” are 2-50 amino acids, proteins are > 50 amino acids. Additionally, proteins will have tertiary and/or quaternary structures. Amino acids 20 types directly coded for by the genetic code. Amino acid – side chains Charged side chains polar side chains non-polar side chains Protein structure Post-translational modifications Change the structure and function of the coded protein. Lots of protein misfolding diseases result from inappropriate posttranslational modifications. Post-translational modifications Protein structure 1:56 min https://www.youtube.com/watch?v=qBRFIMcxZNM Amino acids Amino acids Breakdown: – Oxidised to urea and CO2 – Amino group enters the urea cycle. – Keto acid enters to Krebs cycle. Different protein functions human growth hormone Globular – enzymes, hormones Fibrous – connective tissue, bone, hair Membrane – neuronal receptors, cell adhesion molecules Molecules of Life Nucleic acids – DNA – RNA – ATP, GTP (nucleoside triphosphates) Proteins – Globular – enzymes, hormones – Fibrous – connective tissue, bone, hair – Membrane – neuronal receptors, cell adhesion molecules Carbohydrates – Glucose – Glycogen Lipids – Phospholipids – Fatty acids – Cholesterol Carbohydrates A carbohydrate is a biological molecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen– oxygen atom ratio of 2:1. Monomer - monosaccarides Glucose, fructose and galactose. Ribose and deoxyribose. Monomer - monosaccharides Glucose, fructose and galactose. Ribose and deoxyribose. Disaccharides Common: sucrose (table sugar), lactose (in milk) and maltose. 2 monosaccharides joined by ________. Polysaccharides Cellulose – main constituent of cell walls. – Humans can’t digest. Starch – Potatoes – Wheat Glycogen – How humans store excess glucose. Polysaccharides Glycogen Glucose is stored in animal tissues by the process of glycogenesis Easily converted back to glucose to provide energy for cellular respiration. Can be stored in muscle for immediate access. Molecules of Life Nucleic acids – DNA – RNA – ATP, GTP (nucleoside triphosphates) Proteins – Globular – enzymes, hormones – Fibrous – connective tissue, bone, hair – Membrane – neuronal receptors, cell adhesion molecules Carbohydrates – Glucose – Glycogen Lipids – Phospholipids – Fatty acids – Cholesterol Lipids Non-polar molecules – hydrophobic 3 main types: – Triglycerides – Phospholipids – Cholesterol Lipids Non-polar molecules – hydrophobic Fats - made up of a glycerol and fatty acids. – Triglycerides Fatty acid Triglycerides Functions: – long term energy storage – adipose tissue – insulation/protective cushion Can be saturated or unsaturated – Solid fat vs oil Phospholipids Glycerol, two fatty acid chains and a phosphate group. Amphipathic Major constituent of cell membranes. Bilayer spontaneously forms when placed in water. Phospholipids Glycerol, two fatty acid chains and a phosphate group. Amphipathic Major constituent of cell membranes. Bilayer spontaneously forms when placed in water. Form liposomes – important for drug delivery. Cell membranes More unsaturated fatty acids – more fluid the membrane. Cholesterol – Also amphipathic – Help to maintain membrane fluidity at lower temperatures. – Facilitates cell signalling. – Can make up ~20% of the mass of the cell membrane. “The Cell” Cooper and Hausman 7th ed Cholesterol Polar head group coupled to a steroid ring structure, and hydrocarbon tail. Precursor for key steroid hormones: – Testosterone & estrogen Steroid hormones - examples Hormones that can diffuse through the lipid bilayer. – Sex steroids – Testosterone – Estrogen – Corticosteroids – Cortisol – Aldosterone Others Four main “molecules of life” – – – – Nucleic acids Proteins Carbohydrates Lipids Other molecules that play a role in physiology? – – – – Metal ions – Na+, K+, Ca2+, Mg2+ Iron in blood. Zinc – important in protein folding Many, many more…. Questions?