Clicker Q5-1: Which biological molecule is this? A. Phospholipid B. Triacylglycerol (fat) C. Carbohydrate D. Amino acidPep$de&bond!Fig.%5'18&Amino&end&(N/terminus)!Pep$de&bond!Carboxyl&end&(C/terminus)!(a)!(b)!Amino acids are connected via peptide bond Polypeptide synthesis: N => C directionFig.%5'21g&Collagen!Hemoglobin!How a protein assumes its correct shape? (shape = function) - Folding of a polypeptide: 1. Primary 2. Secondary 3. Tertiary - Some proteins consists of two or more polypeptides: Quaternary structureFig.%5'21a&Amino&acid&subunits!+H3N&&&Amino&end!25!20!15!10!5!1!Primary&Structure!Fig.%5'21c&Secondary&Structure!β&pleated&sheet!Examples&of&amino&acid&subunits! α helix!Hydrogen%bonds%between%O%and%H%atoms%in%the%backbone%of%the%polypep?de%Fig.%5'21f&Hydrophobic%interac?ons%and%van%der%Waals%interac?ons!Disulfide%bridge!Ionic%bond!Hydrogen%bond!Tertiary structure: interactions between the R-groupsFig.%5'21g&Polypep$de&chain!β&Chains!Heme!Iron!α&Chains!Collagen!Hemoglobin!Quaternary&Structure:&associa$on&of&several&polypep$des&Clicker Q5-2 Which of the amino acids below would most likely reside in the membrane-anchoring domain of a membrane-embedded protein? Phenylalanine%Serine% Lysine%A. Phenylalanine B. Serine C. LysineNUCLEIC ACIDS: store and transmit hereditary information. • Two types: 1) DEOXYRIBONUCLEIC ACID (DNA) • The permanent blueprint that passes genetic information from one cell to the next and from generation to generation. 2) RIBONUCLEIC ACID (RNA) • Genes are transcribed into MESSENGER RNA (mRNA) that are temporary blueprints for the construction of proteins.1%2%3%%%%%%%%Synthesis%of%%%%%%%%%%%%%mRNA%in%the%nucleus%Movement%of%%mRNA%into%cytoplasm%%%%%%%%%%%via%nuclear%pore%Synthesis%of%protein%NUCLEUS%CYTOPLASM%DNA&mRNA&Ribosome%Amino%acids%Polypep$de&mRNA&DNA&&&&&&&&&&&&&&& & &&RNA&&&&&&&&&&&&&& & &&PROTEIN&(polypep$de)&Transcrip$on&Transla$on&Fig.%5.26%The&structure&of&a&nucleo$de:&three&major&components&RiboseNucleic acid is a chain of nucleotides, connected by phosphodiester bonds phosphodiester&bond%linking%between%the%3’carbon%of%one%nucleo?de%and%the%5’%carbon%of%the%other%The sequence of a nucleic acid is always written in 5’ to 3’ directionPHOSPHODIESTER&BONDS%•%%%Direc$onality:&& &•&new&nucleo$des&are&added&at&3’/OH&& &•&sequence&is&“read”&in&5’&///>&3’&direc$on&3’&C&5’&C&phosphodiester&bond&3’&end&5’&end&+%phosphate%of%next%nucleo?de…%OH&3&4&5&2&1&A. NUCLEOTIDES Two types of sugars: 1) DEOXYRIBOSE 2) RIBOSE 2’C has H 2’C has -OH In DNA In RNA O%H&2’&H% H%H%H%HOCH2%OH%OH%O%OH&2’&H% H%H%H%HOCH2%OH%OH%A. NUCLEOTIDES&Two&families&of&nitrogenous&bases:&1)&&PYRIMIDINES&(1&ring):&&Cytosine&(C) &&&Thymine&(T)&&Uracil&&&&&&(U)&2)&&PURINES&(2&rings):&&Adenine&(A) &&&Guanine&(G) &&CH%CH%Uracil%(in%RNA)%U%Nitrogenous&bases%%Pyrimidines%C%N%N%C%O%H%NH2%CH%CH%O%C%N%H%CH%HN%C%O%C%CH3%N%HN%C%C%H%O%O%Cytosine%C%Thymine%(in%DNA)%T%N%HC%N%C%C%N%C%CH%N%NH2%O%N%HC%N%H%H%C%C%N%NH%C%NH2%Adenine%A%Guanine%G%Purines%CH%CH%Uracil%(in%RNA)%U%&Pyrimidines&&Purines&Fig. 5.28 The DNA Double Helix 3’%end%Sugar'phosphate%backbone%Base%pair%(joined%by%hydrogen%bonding)%Old%strands%Nucleo?de%about%to%be%%added%to%a%%new%strand%A%3’%end%3’%end%5’%end%New%strands%%3’%end%5’%end%5’%end%Antiparallel helix Stabilized by: 1) H-bonding between bases that pair between opposite chains. 3) Van der Waals interactions between stacked bases. Replica?on%Clicker question The following nucleotide is: A. Purine, deoxyribonucleotide B. Purine, ribonucleotide C. Pyrimidine, deoxyribonucleotide D. Pyrimidine, ribonucleotideCellular Architecture. Organelles • Reading for Wed, Fri lectures: Chapter 6Figure 6.2 The size range of cells Nucleus%Most%bacteria%Measurements&1%cen?meter%(cm)%=%10'2%meter%(m)%=%0.4%inch%1%millimeter%(mm)%=%10–3%m%1%micrometer%(µm)%=%10–3%mm%=%10'6%m%1%nanometer%(nm)%=%10–3%µm%=%10'%9%m%10%m%1%m%0.1%m%1%cm%1%mm%100%µm%10%µm%1%µm%100%nm%10%nm%1%nm%0.1%nm%Human%height%Length%of%some%nerve%and%%muscle%cells%Chicken%egg%Frog%egg%Most%plant%and%animal%cells%Mitochondrion%Smallest%bacteria%Viruses%Ribosomes%Proteins%Lipids%Small%molecules%Atoms%Unaided&eye&Lightµscope&Electronµscope&nucleus%Most%bacteria%•&Most&eukaryo$c&cells&are&10/100&µm.&•&Cells&need&to&be&small&to&keep&a&high&&&&&SURFACE&/&VOLUME&ra$o.&&&&&If&too&large,&cells&could¬&move&nutrients&&&&or&waste&IN&/&OUT&fast&enough.&•&Larger&animals&have&more&c ells,&&&&¬&bigger&cells.&Phase/contrast.%Enhances%contrast%%in%unstained%cells%by%amplifying%%varia?ons%in%density.%How&do&we&study&cells:&Microscopy&50 µm Lightµscopy%(live%or%fixed%cells)%Electronµscopy%(fixed%cells)%Fluorescence.%Shows%loca?ons%of%specific%molecules%tagged%with%fluorescent%dyes%or%an?bodies.%50%µm%1%µm%Scanning&electronµscopy&shows%a%3D%image%of%the%surface.%Transmission&electronµscopy&shows%ultrastructure%of%organ elles%in %thi n%sec?on .%Two&types&of&cells:&A.&PROKARYOTIC&CELL&Membrane%Cytoplasm%1%µm B.&EUKARYOTIC&CELL&Cytoplasm%Membrane%I.&Architecture&of&the&cell&“before&nucleus”&“true&nucleus”&Plasma&membrane&/&boundary%of
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