Orgaic Macromolecules ad the Geetic Code A cell is mostly water. The rest of the cell cosists mostly of carbobased molecules. Orgaic chemistry is the study of carbo compouds. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Carbo ca use its bods to Attach to other carbos. Form a edless diversity of carbo skeletos. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Figure 3.2
Each type of orgaic molecule has a uique threedimesioal shape that defies its fuctio i a orgaism. The molecules of your body recogize oe aother based o their shapes. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Giat Molecules from Smaller Buildig Blocks O a molecular scale, may of life s molecules are gigatic. Biologists call them macromolecules. Examples: DNA, proteis Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Biological Molecules There are four categories of large molecules i cells: Carbohydrates Lipids Proteis Nucleic acids Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Proteis A protei is a polymer costructed from amio acid buildig blocks. Proteis perform most of the tasks the body eeds to fuctio. Behid most cell fuctios, there is a protei. Structural Proteis Receptor Proteis Storage Proteis Cotractile Proteis Trasport Proteis Defesive Proteis Ezymes Hormoal Proteis Sesory Proteis Gee Regulatory Proteis Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
The Moomers: Amio Acids All proteis are costructed from a the same set of 20 kids of amio acids. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Each amio acid cosists of A cetral carbo atom boded to four groups. Three of the groups are idetical i all 20 amio acids, ad each has a distict 4 th group. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Figure 3.20
Proteis as chais A liked chai of amio acids Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Figure 3.21
Your body has tes of thousads of differet kids of proteis. The arragemet of amio acids of ay give protei makes it differet from ay other protei. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Primary structure The specific sequece of amio acids i a protei Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Figure 3.22
A slight chage i the primary structure of a protei affects its ability to fuctio. The substitutio of oe amio acid for aother i hemoglobi causes sickle-cell disease. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Figure 3.23
Nucleic Acids Nucleic acids are iformatio storage molecules. They provide the directios for buildig proteis. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
There are two types of ucleic acids: DNA, deoxyriboucleic acid RNA, riboucleic acid Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
The geetic istructios i DNA Must be traslated from ucleic acid laguage to protei laguage. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Figure 3.25
Nucleic acids are chais of 4 ucleotides: Guaie (G) Thymie (T) Cytosie (C) Adeie (A) Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Figure 3.28b
Now, here is oe of the cetral problems of biology. Much of what is goig o i a cell, as we have see, is carried out by proteis. There are all kids of proteis, depedig o the sequece of their 20 amio acids: Ala-Ala-Gly-Leu-Ser-... Will be etirely differet from Gly-Ala-Leu-Ser-Ala-... Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
The iformatio for the legth ad sequece of each protei must be cotaied i the gees, which are made of DNA. Here agai, a gee is made up of a chai of 4 buildig blocks, called ucleotides: A-G-C-T-C-... C-G-T-A-C-... This sequece of 4 buildig blocs must somehow code for sequece of 20 differet amio acids i proteis. How ca that be doe? Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
To grasp ature s solutio, let s examie a simpler code first Imagie that you take part i a game show. You ad your parter are competig with aother pair of cotestats. Your task is to ivet a code which will allow you, whe the show start, to commuicate with your parter by relyig o the code ad by usig 4 colors to make a series of dots o paper. How will you go about this? Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
How do you express 26 letters i 4 colors? A oe-for-oe code will ot work: Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Let s try 1 color codig for a sigle letter: I this code, dad is: Obviously, this code ca t go very far: With just oe color per letter, we ca oly specify 4 letters but we eed at least 26! a b c d Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs Will ay combiatio of 2 colors be eough for 26 letters? Whe we try, we fid out that oly 16 permutatios are possible? a e i m word ca b f j c g k o d h l p
Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs So, 2 colors per letter: ot eough. How about 3? This is a PARTIAL table. Ca you see how may color combiatios are possible? a e i m q b f j r c g k o s d h l p t
With color triplets the, I ca write ay message i Eglish, codig eve for caps ad puctuatio marks! Now, life is writte by a similar code. DNA is made of a chai of 4 liks or colors (ucleotides) AGCT. Protei is made of a chai of 20 differet liks amio acids. You ca specify ay amio acid you wat, by usig triplets like AAA, AAG, AAG, AAG, AGG,... Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
So the idea is: Triplets of DNA bases which Specify all the amio acids. Are called codos. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
The Geetic Code The geetic code is the set of rules relatig ucleotide sequece to amio acid sequece. Here it is: oe of the greatest scietific breakthroughs of the 20 th cetury: Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs
Figure 10.11
The geetic code is shared by virtually all orgaisms. Copyright 2007 Pearso Educatio Ic., publishig as Pearso Bejami Cummigs