Lecture 2 Cells and Macromolecules PDF

Lecture 2 Cells and Macromolecules BIO206 Introductory Cell & Molecular Biology Instructor: Ichiro Inamoto University of Toronto Mississauga 1 Table of contents 2.1 Prokaryotic and Eukaryotic cells 3 2.2 Macromolecule...

Lecture 2 Cells and Macromolecules BIO206 Introductory Cell & Molecular Biology Instructor: Ichiro Inamoto University of Toronto Mississauga 1 Table of contents 2.1 Prokaryotic and Eukaryotic cells 3 2.2 Macromolecules of Life 11 2  Lecture 2.1 Prokaryotic and Eukaryotic cells 3  Two major classifications of cells Prokaryotes and Eukaryotes 'karyon' = kernel / nut (nuclei looked like kernels to early scientists) 'pro' = before 'eu' = true Prokaryote: without kernels, "cells without defined nucleus" Eukaryotes: with kernels, “cells with a true nucleus” 4  Two major classifications of cells Prokaryotes Lack membrane bound nucleus Lack membrane-bound organelles Smaller than eukaryotes Mostly single celled Bacteria and Archaea Eukaryotes Has membrane bound nucleus Has other membrane bound organelles that compartmentalize biochemical reactions Larger than prokaryotes Single or multicellular Protista, Fungi, Plants, Animals 5  General structure of a prokaryote Prokaryotes Lack membrane bound nucleus Lack membrane-bound organelles Smaller than eukaryotes Mostly single celled Bacteria and Archaea Prokaryote structures Plasma membrane cell wall cytoplasm nucleoid ribosomes internal membranes inclusion bodies flagella 6  General structure of a eukaryote Eukaryotes animal cell Has membrane bound nucleus Has other membrane bound organelles that compartmentalize biochemical reactions Larger than prokaryotes Single or multicellular Protista, Fungi, Plants, Animals plant cell 7 Portion of a Eukaryotic Liver Cell E. coli 8 Eukaryotic Organelles Rough endoplasmic reticulum RER E. coli 9  Tree of life Grows in unusual and /or extreme environments Protista, Fungi, Plants, Animals Most bacteria including photosynthetic organisms Evolutionary relationship between three domains of life, constructed based on ribosomal DNA analysis 10  Lecture 2.2 Macromolecules of Life 11 What are cells made of? Cell is the fundamental unit of life A sack made out of lipid membranes, filled with aqueous solution containing various organic and inorganic molecules macromolecules (nucleic acids, proteins, carbohydrates, lipids) variety of other organic metabolites inorganic ions water organelles (for eukaryotic cells) Inside an E. coli cell, Original illustration by David S. Goodsell 12 Hornus S. et al., (2013) PLoS ONE 8(1): e53609. doi:10.1371/ journal.pone.0053609  Macromolecules Macromolecules are the major structural, enzymatic and regulatory component of all cells across the domains of life Four types of macromolecules exist Each type of macromolecule is a polymerized version of their corresponding building block For example, nucleic acid is a macromolecule made of polymerized nucleotides 13  Macromolecules monomer polymer Sugars polymerize to become polysaccharides Amino acids polymerize to become polypeptides polypeptide Nucleotides polymerize to become nucleic acids Polysaccharides, polypeptides and nucleic acids polymerize via covalent bonding 14  Examples of macromolecule functions Polysaccharides are used as cellular structures, energy storage, etc. Proteins (functional, folded versions of polypeptides) are used as catalysts, cellular structures, etc. Nucleotides are used as storage of genetic material, catalysts, etc. 15  Lipids generate membranes in aqueous environment Fatty acids 'polymerize' via hydrophobic/hydrophilic interactions and not by covalent bonding Fatty acids have a hydrophilic 'head' connected to a hydrophobic 'tail' hydrophilic (polar) head wants to interact with other polar molecules such as water hydrophobic (non-polar) tail wants to interact with other hydrophobic molecules Single unit of a fatty acid 16  Lipids generate membranes in aqueous environment Fatty acids 'polymerize' via hydrophobic/hydrophilic interactions and not by covalent bonding Fatty acids have a hydrophilic 'head' connected to a hydrophobic 'tail' H2O H2O H2O Phospholipid bilayer hydrophilic head interacts with water In aqueous environment, fatty acids form a double- hydrophobic tail faces away from layered structure water and interacts with themselves heads line up, facing (hydrophobic core) water tails form the hydrophobic core hydrophilic head interacts with water 17 H2O H2O H2O  Lipids generate membranes in aqueous environment The plasma membrane (which defines the boundaries of a cell) is made out of phospholipid bilayer H2O H2O H2O Phospholipid bilayer In aqueous environment, fatty acids form a double- layered structure heads line up, facing water tails form the hydrophobic core 18 H2O H2O H2O  R strain cells Genetic information is stored in DNA Streptococcus pneumoniae Purify S strain DNA bacterial pathogen ‘Smooth (S)’ strain causes pneumonia Add S strain DNA ‘Rough (R)’ strain does not cause pneumonia to R strain Extract and purify different macromolecules from the S strain and transfer it to the R strain R strain gets converted to S strain The R strain which received DNA of S strain gets converted to an S train 19  Genetic information is stored in DNA Streptococcus pneumoniae bacterial pathogen ‘Smooth (S)’ strain causes pneumonia ‘Rough (R)’ strain does not cause pneumonia Extract and purify different macromolecules from the S strain and transfer it to the R strain The R strain which received DNA of S strain gets converted to an S train R strains which received other molecules of the S train does not get converted 20  Genetic information is stored in DNA All cells store hereditary information in the same linear chemical code: DNA DNA is a blueprint for the cell How does the cell use this blueprint to organize itself? 21