Cell Structure and Function - Cell Biology (PDF)

LU | Faculty of Sciences Cell Structure and Function - Cell Biology - By Reem Dakhil M1 Biochemistry and founder of Unbeatable Chapter 1 Cell Biology Birth Definitions – Cell doctrine  Cell Biology vs Cytology Cell Biology...

LU | Faculty of Sciences Cell Structure and Function - Cell Biology - By Reem Dakhil M1 Biochemistry and founder of Unbeatable Chapter 1 Cell Biology Birth Definitions – Cell doctrine  Cell Biology vs Cytology Cell Biology Cytology The study of cells and their The study of cells and their components structurally and components structurally functionally  The Cell Doctrine Unit Division Organism Fundamental unit of Cells divide Cells + their products structure & function = organism Life Double-life Basis of life continuity One for its own, (mitosis – meiosis – one for the organism fertilization)  Chapter 2 Molecular Components of cells Inorganic and Organic Compounds What atoms and molecules are found in our cells?  Atomic level 96% 4% Very low C, H, N, O Na, K, Cl, S, P Trace elements Most abundant atoms B, F, Mn, Fe, Co, Cu, Zn, Se, I…  Molecular Level Organic molecules “Biomolecules” Inorganic molecules Proteins Water Carbohydrates Mineral salts Lipids Nucleic acids 1. Water  Basis of cell life  Most abundant  Electrically neutral  Extremely polar: partially (-) O & partially (+) H  Forms Hydrogen bonds (with H2O or with other molecules) & ionic bonds (solubilizes salts)  H2O is found free or interacting with molecules  2. Mineral Salts  Found dissolved & ionized by water (due to water polarity)  [ ] inside cell ≠ [ ] interstitial fluid  Balance in [ ] is essential for: membrane permeability, nerve impulse, muscle contraction, cell division …  Metal ions are essential for the activity of certain proteins (muscle contraction, O2 transfer, intercellular signaling…)  3. Organic Compounds Molecules Macromolecules +Vitamins amino acids proteins needed at low [ ] monosaccharaides polysaccharides can be carbs (vit. C) fatty acids lipids or lipids (vit. A, E, D) nucleotides DNA, RNA  I. Proteins 1. Introduction  Most abundant organic molecules  Most diverse (encoded by genes)  diversity in functions  Unbranched polymers of aminoacids  I. Proteins 2. Function ~ All functions for cell & organism life Morphology – cell’s molecular identity (HLA, blood groups) – gene expression & DNA replication – storage & transportation – intercellular & organ communication – immunity – senses – cell cycle – muscle contraction * but they are not energetic molecules  I. Proteins 3. Diverse Chemical Composition Although diverse, but chemically: proteins are a homogeneous class (1 unbranched chain of aa) They differ by number & sequence of aa, which are identical for a protein type Diverse sequences  diverse 3D structures  diverse functions  I. Proteins 4. The Amino Acids  Made of: C, H, N, O, S  Cα linked to: NH3, COOH, H, and side chain R  They differ by R only  4 groups: - Non-polar (Alkyl, benzyl) - Polar uncharged (NH2, CO, OH) - Polar positive / basic (NH3+) - Polar negative / acidic (COO-)  20 types, 9 of them are essential aa (can’t be synthesized by cells, must be supplied by diet)  Only L-stereoisomers form polypeptides  I. Proteins 4. The Amino Acids  All aa are soluble in water (due to amino & carboxyl groups) BUT not all proteins/peptides are soluble in water  aa ionization depends on: pH & R  Zwitterions: aa with uncharged R and ionized groups (NH2 & COOH) at pH=7  I. Proteins 5. Polypeptide  I. Proteins 5. Polypeptide  Linear unbranched chain of aa joined by covalent bonds “peptide bonds”  Formed by ribosome; digested by proteases  Reaction: nucleophile attack between NH2 of aa (n) & COOH of aa (n-1)  “amide bond” CO – NH  H2O is eliminated  Backbone: repeating N – Cα – C  polarized: N-terminus (Amino terminus NH2) & C-terminus (Carboxy terminus COOH)  I. Proteins 6. Polypeptide Flexibility Extended groups (R, H, =O) are not in the same plane, they rotate in different directions  confers flexibility  helps folding to adopt 3D conformations  Thanks! Do you have any questions? [email protected] +961 78 823 798 @reem.yd CREDITS: This presentation template was created by Slidesgo, and includes icons by Flaticon, and infographics & images by Freepik