Bio 1111ch03 Lecture

7/31/2019 Bio 1111ch03 Lecture

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Carbon Compounds in Cells

Chapter 3



Importance of Carbon

Carbon permeates the world of life—

from the energy-requiring activities and

structural organization of cells, to

physical and chemical conditions that

span the globe and influenceecosystems everywhere.



Humans and Global Warming

• Fossil fuels are rich in carbon

• Use of fossil fuels releases CO2 into

atmosphere

• Increased CO2 may contribute to global

warming



Organic Compounds

Hydrogen and other elements

covalently bonded to carbon

Carbohydrates

Lipids

Proteins

Nucleic Acids



Carbon’s Bonding Behavior

• Outer shell of carbon has 4

electrons; canhold 8

• Each carbon atom

can form covalentbonds with up to 4atoms



Methane: Simplest Organic

Compound

Structural formula

Ball-and-stick

model

Space-filling

model

HH

H

H

C

Figure 3.2Page 36



Bonding Arrangements

• Carbon atoms can

form chains or rings

• Other atoms project

from the carbon

backbone Glucose

(ball-and-stick model)

In-text figurePage 36



Hemoglobin Molecular Models

Ball-and-stick model Space-filling model

Ribbon modelFigure 3.3Page 37



Functional Groups

• Atoms or clusters of atoms that are

covalently bonded to carbon backbone

• Give organic compounds their different

properties



Examples of Functional

GroupsMethyl group - CH3

Hydroxyl group - OH

Amino group - NH3+

Carboxyl group - COOH

Phosphate group - PO3-

Sulfhydryl group - SH



Carbohydrates

Monosaccharides

(simple sugars)

Oligosaccharides

(short-chain carbohydrates)

Polysaccharides

(complex carbohydrates)



• Most include fatty acids

– Fats

– Phospholipids

– Waxes

• Sterols and their derivatives have no

fatty acids

• Tend to be insoluble in water

Lipids



Phospholipids

• Main component of

cell membranes

• Hydrophobic head

• Hydrophilic tails

Fig. 3.14a,b

Page 43



Sterols and Derivatives

• No fatty acids

• Rigid backbone of

four fused-together

carbon rings

• Cholesterol - most

common type in

animalsFigure 3.15aIn-text p43

Cholesterol



Waxes

• Long-chain fatty acids linked to

long-chain alcohols or carbon

rings

• Firm consistency, repel water

• Important in water-proofing



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. 3.18aPage 45



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-



Second and Third Levels

• Hydrogen bonding

produces helix or

sheet

• Domain formation

Secondarystructure

Tertiary structure

Figure 3.19aPage 46



Fourth Level Structure

Some proteins

are made up of more than one

polypeptide

chain

HLA-A2 quaternary structureFigure 3.20Page 47



Hemoglobinalpha chain

beta chain alpha chain

beta chain



• Sugar

• At least one

phosphate group

• Nitrogen-

containing base

Nucleotide Structure

ATP

Figure 3.23a

Page 50



Nucleotide Functions

• Energy carriers

• Coenzymes

• Chemical messengers

•Building blocks for nucleic acids



DNA

• Double-stranded

• Sugar-phosphate

backbone• Covalent bonds in

backbone

• H bonds betweenbases

Figure 3.25

Page 51



RNA

• Usually single strands

• Four types of nucleotides

• Unlike DNA, contains the base uracil in

place of thymine

• Three types are key players in proteinsynthesis

Bio 1111ch03 Lecture

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