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BIOLOGY 2B03 (285)
Kim Dej (39)
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Biology 2B03 Introduction.docx

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Department
Biology
Course
BIOLOGY 2B03
Professor
Kim Dej
Semester
Fall

Description
Biology 2B03 Introduction: Cell Biology [email protected] Dr. Kimberley Dej [email protected] Alison Cowie Lectures posted to A2L the Friday before that weeks classes MSAF: Contact Alison Cowie ([email protected]) Cannot use it for anything worth 30% or more Each of tests focus on material up until that test Some information is cumulative What is a cell? Smallest unit of life An autonomous biological unit Smallest living unit Individual cells can grow, reproduce, process information, respond to stimuli, communicate, carry out chemical reactions Individual cells carry hereditary material Individual cells are surrounded by plasma membranes Classification of living organisms: eukaryotes or prokaryotes Prokaryotes: single celled bacteria and cyanobacteria Have hereditary information but is not bound by a nucleus Cell or organism that lacks a membrane bound discrete nucleus and other subcellular compartments Eukaryotes: These comprise all multicellular plants and animals. Fungi (multicellular molds an unicellular yeast) Protozoans (unicellular) Have a nucleus with the hereditary material bound in a membrane Have lots of different organelles Every organelle has a specific function Prokaryotic cells have a simple internal organization See ppt image The nucleoid consists of a single circular DNA molecular and it is not enclosed within its own membrane Reproduce by a simplified cell division (fission) Prokaryotes may be unicellular or exist as colonies. Is a colony the same as a multicellular organism? In prokaryotes we see colonies Examples: eubacteria (lactococcus lactis) or a colony of archeabacteria (methanosarcina) Eukaryotic cells have a complex internal organization Eukaryotes contain a membrane bound nucleus containing (most of) the genetic material of the cell: Activities are compartmentalized; an extensive internal membrane enclose various compartments= organelles Despite their apparent differences, the two cell types have a lot in common They both have cytoplasm Plasma membrane Both carry genetic material: have DNA based chromosomes The same sorts of basic building blocks Both have selectively permeable plasma membranes that separate the interior of the cell from the exterior of the cell Both contain ribosomes that translate genetic information into proteins Essential metabolic reactions are the same Evolutionary related to each other We share many biochemical pathways with all organisms, even though we look very different from one another The proteins in different cells are often chemically similar and functionally identical Functional systems were selected for a purpose Eukaryotic cells are much larger and complex than prokaryotic cells Eukaryotic: 10-100 micrometers Prokaryotic: 1-5 micrometers The cytoplasm of eukaryotic cells: Large complex collection of membrane bound organelles that increase the efficiency of functions Division of labor: organelles that reside in the cytoplasm Review the functions of the organelles Eukaryotes: Red, red blood cells, White, white blood cells and green, platelets Cells to Tissues: Organisms demonstrate multicellularity Requires extracellular glue Simplest: single cells embedded in a jelly of protein and polysaccharide (extracellular matrix) Colonial single celled alga Multicelular Organisms consist of interacting cells Integration of cellular activity into tissues Communication between cells Development of organisms by growth DNA: hereditary information RNA: transport DNA to RNA to Protein Proteins: working molecules of the cell coded in genes protein structure determines function Remember: proteins are dynamic! Proteins show emergent properties in the cell Module 1: amino acids and their properties Protein architecture What is a protein? 3D structure: linkage of amino acids What are the functions of proteins? Things that give the cell shape: structure Trans-membrane proteins Moving things: transport around the cell Protein catalysts or enzymes: could be allosteric: function changes with shape Regulatory proteins: hormones (signaling pathways) Sensors for environmental changes and mechanisms for relaying this information to the cell Gene regulation Molecular motors Organelle identity and function There is great diversity in the structure of proteins Structure determines function Specificity of protein function If you change the shape, the function will disappear Proteins are composed of amino acids Amino acids are attached in a linear array to create the primary structure of the protein: a polypeptide Amino end (N-terminus) and carboxyl end (C-terminus) Read from left to right Covalent bond in amino acid linkages: amino acid residue 20 different amino acids are incorporated into newly synthesized polypeptide What is an amino acid? Monomeric building blocks of proteins All 20 amino acids have same general structure Consist of four components attached to a central carbon, the a carbon Variable R group (or side chain) It is the properties of the side chains (R) that affect protein structure and function Shape will e determined by the side groups Side Chains differ in: Size Shape Charge Hydrophobicity Reactivity o These properties can all have an effect on the conformation of the whole protein Amino acids are classified into groups based upon solubility in water or polarity of the side chain Solubility refers to a physical property of a molecule that can transiently bond with water through hydrogen bonding This is thermodynamically favorable A hydrophilic molecule: r portion of a molecule is one that is typically charge polarized and capable of hydrogen bonding with water A hydrophobic molecule are not electrically polarized and unable to form hydrogen bonds Non-polar side chains: hydrophobic amino acids Water insoluble (or only slightly soluble) amino acids Hydrophobic amino acid Tend to be on interior of proteins Often aggregate within core of a protein What sorts of molecules are hydrophobic?
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