Lecture Carbon Molecules, Proteins, And DNA

8/2/2019 Lecture Carbon Molecules, Proteins, And DNA

1/24

Carbon Molecules,

Proteins, and DNA

Emphasis: Proteins and DNA


2/24

Importance of Carbon

Carbon permeates the world of lifefrom theenergy-requiring activities and structural

organization of cells, to physical and chemicalconditions that span the globe and influenceecosystems everywhere.


3/24

Organic Compounds

Hydrogen and other elementscovalently bonded to carbon

Carbohydrates

Lipids

Proteins

Nucleic Acids


4/24

Carbons Bonding Behavior

Outer shell of carbonhas 4 electrons; canhold 8

Each carbon atomcan form covalentbonds with up to 4

atoms


5/24

Methane: Simplest Organic

Compound

Structural formula

Ball-and-stickmodel

Space-fillingmodel

HH

H

H

C

Figure 3.2Pa e 36


6/24

Bonding Arrangements

Carbon atoms canform chains or rings

Other atoms projectfrom the carbonbackbone

Glucose(ball-and-stick model)

In-text figurePage 36


7/24

Hemoglobin Molecular Models

Ball-and-stick model Space-filling model

Ribbon modelFigure 3.3Pa e 37


8/24

Functional Groups

Atoms or clusters of atoms that are covalentlybonded to carbon backbone

Give organic compounds their differentproperties


9/24

Examples of Functional Groups

Methyl group - CH3

Hydroxyl group - OHAmino group - NH3

+

Carboxyl group - COOH

Phosphate group - PO4-

Sulfhydryl group - SH

Memorize!


10/24

Condensation Reactions

Form polymers from subunits

Enzymes remove -OH from one molecule, H

from another, form bond between twomolecules

Discarded atoms can join to form water


11/24

Amino Acid Structure

Aminogroup

Carboxylgroup

R group

tryptophan(trp)

Radical

Amino group

Acid

Central carbon


12/24

Protein Synthesis

Peptide bond

Condensation reaction links amino group of one

amino acid with carboxyl group of next

Water forms as a by-product

Fig. 3.18aPa e 45


13/24

Peptide bond forms.Water forms as a by-product.

Another peptide bond forms.Water forms as a by-product.


newly formingpolypeptide chain



14/24

Primary Structure

Sequence of amino acids

Unique for each protein

Two linked amino acids = dipeptide

Three or more = polypeptide

Backbone of polypeptide has N atoms:

-N-C-C-N-C-C-N-C-C-N-


15/24

Second and Third Levels

Hydrogen bonding

produces helix or

sheet

Domain formation

Secondarystructure

Tertiary structure

Figure 3.19aPa e 46


16/24

Fourth Level Structure

Some proteins are

made up of more

than one

polypeptide chain

HLA-A2 quaternary structureFigure 3.20Pa e 47


17/24

Hemoglobin

alpha chain

beta chain alpha chain

beta chain


18/24

One Wrong Amino Acid

Single amino acid change in beta chain cancause sickle-cell anemia

HbS

valine histidine leucine proline threonine glutamatevaline

Fig. 3.21c,dPa e 48


19/24

Sickle Cell Anemia

Caused by two mutated copies (HbS) of Hbgene

Low oxygen causes red blood cells to clump

Clumping prevents normal blood flow

Over time, may damage tissues and organsthroughout the body

The gene defect is a known mutation of asingle nucleotide (A to T) of the -globingene, which results in glutamic acid beingsubstituted by valineat position 6.

http://en.wikipedia.org/wiki/Sickle-cell_disease


20/24

Sugar

At least one

phosphate group

Nitrogen-containing

base

Nucleotide Structure

ATP

Figure 3.23a

Page 50


21/24

Nucleotide Functions

Energy carriers

Coenzymes

Chemical messengers

Building blocks for nucleic

acids


22/24

DNA

Double-stranded

Sugar-phosphatebackbone

Covalent bonds inbackbone

H bonds between

bases


23/24

DNA Structure Video

http://www.youtube.com/watch?v=qy8dk5iS1f0
http://www.youtube.com/watch?v=qy8dk5iS1f0http://www.youtube.com/watch?v=qy8dk5iS1f0http://www.youtube.com/watch?v=qy8dk5iS1f0http://www.youtube.com/watch?v=qy8dk5iS1f0


24/24

RNA

Usually single strands

Four types of nucleotides

Unlike DNA, contains the base uracil in place of

thymine

Three types are key players in protein synthesis

Documents

Lecture Carbon Molecules, Proteins, And DNA