ch03 lecture(carbon)[1]

8/14/2019 ch03 lecture(Carbon)[1]

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Carbon Compounds in Cells

Chapter 3


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Importance of Carbon

Carbon permeates the world of lifefrom

the energy-requiring activities andstructural organization of cells, to physical

and chemical conditions that span the

globe and influence ecosystems

everywhere.


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Humans and Global Warming

Fossil fuels are rich in carbon

Use of fossil fuels releases CO2 intoatmosphere

Increased CO2 may contribute to globalwarming


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Organic Compounds

Hydrogen and other elements

covalently bonded to carbon

Carbohydrates

Lipids

ProteinsNucleic Acids


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Carbons Bonding Behavior

Outer shell of

carbon has 4

electrons; can hold

8

Each carbon atom

can form covalentbonds with up to 4

atoms


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Methane: Simplest Organic

Compound

Structural formula

Ball-and-stick

model

Space-filling

model

HH

H

H

C

Figure 3.2Page 36


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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


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Hemoglobin Molecular Models

Ball-and-stick model Space-filling model

Ribbon modelFigure 3.3Page 37


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Functional Groups

Atoms or clusters of atoms that are

covalently bonded to carbon backbone

Give organic compounds their different

properties


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Question 1

1. How many single bonds does a carbon

form? What is the hybrid model that

applies? SP, SP2, or SP3 ?


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Answer 1

How many single bonds does a carbon

form? What is the hybrid model that

applies? SP, SP2, or SP3 ?

Four bonds; SP3


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Examples of Functional Groups

Methyl group - CH3

Hydroxyl group - OH

Amino group - NH3+

Carboxyl group - COOH

Phosphate group - PO4-

Sulfhydryl group - SHMemorize!


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Question 2

2. Name three functional groups and give

their formulas.


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Answer 2

2. Name three functional groups and give their formulas.

Methyl group - CH 3

Hydroxyl group - OH

Amino group - NH 3+

Carboxyl group - COOH

Phosphate group - PO 4-

Sulfhydryl group - SH


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Types of Reactions (Stopped 17

aug 07)

Functional group transfer

Electron transfer

Rearrangement

Condensation

Cleavage


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Condensation Reactions

Form polymers from subunits

Enzymes remove -OH from one molecule,H from another, form bond between two

molecules

Discarded atoms can join to form water


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Figure 3.7aPage 39

enzyme action at functional groups

Condensation



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Hydrolysis

A type of cleavage reaction

Breaks polymers into smaller units

Enzymes split molecules into two or moreparts

An -OH group and an H atom derived from

water are attached at exposed sites


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Figure 3.7bPage 39

Hydrolysis


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Carbohydrates

Monosaccharides

(simple sugars)

Oligosaccharides(short-chain carbohydrates)

Polysaccharides(complex carbohydrates)


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Monosaccharides

Simplest

carbohydrates

Most are sweettasting, water

soluble

Most have 5- or 6-carbon backbone

Structure of glucose


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Disaccharides

Type of

oligosaccharide

Twomonosaccharides

covalently bonded

Formed bycondensation

reaction

+ H2O

glucose fructose

sucrose

Figure 3.8bPage 40


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Polysaccharides

Straight or

branched chains of

many sugarmonomers

Most common are

composed entirelyof glucose

Starch chain

Figure 3.9Page 40


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Cellulose & Starch

Differences in bonding patterns betweenmonomers yield different properties

amylose (a starch)cellulose

Figure 3.10Page 41


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Glycogen

Sugar storage form in animals

Large stores in muscle and liver cells

Figure 3.10Page 41


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Chitin

Polysaccharide

Nitrogen-containing groups attached to

glucose monomers

Structural material for hard parts of

invertebrates, cell walls of many fungi


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Question 3

3. Name a common disaccharide. What are

its components (two sugars).


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Answer 3

3. Name a common disaccharide. What are

its components (two sugars).

Sucrose. Glucose and fructose are its

component sugars.


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Question 4

4. Compare and contrast the meanings of:

disaccharide and polysaccharide


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Answer 4

4. Compare and contrast the meanings of:

disaccharide and polysaccharide.

The former is composed of only 2

simple sugars. The later may be made

up of 100s or 1000s of simple sugars.


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Most include fatty acids

Fats

Phospholipids

Waxes

Sterols and their derivatives have no fatty

acids

Tend to be insoluble in water

Lipids


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Fatty Acids

Carboxyl group at one

end

Carbon backbone

Saturated or

unsaturated

linolenic

acidstearic acid oleic acidFigure 3.12Page 42


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Fats

Fatty acid(s)

attached to glycerol Triglycerides are

most common

Figure 3.13Page 42


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Phospholipids

Main component of

cell membranes

Hydrophobic tails

Hydrophilic head

Fig. 3.14a,b

Page 43


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Question 5

5. What are three categories of fatty acid

lipids?


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Answer 5

5. What are three categories of fatty acid

lipids?

Fats

Phospholipids

Waxes


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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


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Waxes

Long-chain fatty acids linked to

long-chain alcohols or carbon rings

Firm consistency, repel water

Important in water-proofing


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Question 6

6. What are the characteristics of sterols?

Give an example.


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Answer 6

6. What are the characteristics of sterols?

Give an example.

No fatty acids

Rigid backbone of four fused-together

carbon rings

Cholesterol - most common type in

animals


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Question 7

7. Describe waxes. Why are they

important?


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Answer 7

7. Describe waxes. Why are they

important?

Long-chain fatty acids linked to long-

chain alcohols or carbon rings

Firm consistency, repel water

Important in water-proofing


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Amino Acid Structure

Amino

group

Carboxyl

group

R group

Figure 3.16

Page 44

Figure 3.17Page 44

tryptophan

(trp)


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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


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Peptide bond forms.

Water forms as a by-product.

Another peptide bond forms.




newly forming

polypeptide chain




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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-


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Second and Third Levels

Hydrogen bonding

produces helix or

sheet

Domain formation

Secondarystructure

Tertiary structure

Figure 3.19aPage 46


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Fourth Level Structure

Some proteins

are made up of

more than one

polypeptide

chain

HLA-A2 quaternary structureFigure 3.20Page 47


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Hemoglobin

alpha chain

beta chain alpha chain

beta chain


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One Wrong Amino Acid

Single amino acid change in beta chain

can cause sickle-cell anemia

HbS

valine histidine leucine proline threonine glutamatevaline

Fig. 3.21c,dPage 48


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Sickle Cell Anemia

Caused by two mutated copies (HbS) of

Hb gene

Low oxygen causes red blood cells to

clump

Clumping prevents normal blood flow

Over time, may damage tissues and

organs throughout the body


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Myostatin

Myostatin is a regulatory protein inhibitsmuscle growth.

One inactive myostatin gene will increasemuscle mass and reduce muscle fat.

Two inactive myostatin genes will have adramatic effect on both muscle size andfat content.


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Myostatin Gene Inactivated
http://images.search.yahoo.com/search/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3Dcattle%2B%2Bmyostatin%26ei%3DUTF-8%26fr%3Dmy-vert-img-top%26x%3Dwrt&w=665&h=337&imgurl=fig.cox.miami.edu%2F%7Ecmallery%2F150%2Fneuro%2Fbelgian.blue.jpg&rurl=http%3A%2F%2Ffig.cox.miami.edu%2F%7Ecmallery%2F150%2Fneuro%2Fmuscle.htm&size=22.2kB&name=belgian.blue.jpg&p=cattle++myostatin&type=jpeg&no=7&tt=33&oid=4b4c18a25cf2c1e4&ei=UTF-8


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Belgium Blue Breed


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Beef Fat Content

Meat from cattle having

no copies of the inactive

myostatin gene.
http://www.ars.usda.gov/is/graphics/photos/jul04/k11279-1.htmhttp://www.ars.usda.gov/is/graphics/photos/jul04/k11279-1.htm


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One Inactive Myostatin Gene

Meat from cattle having

one copy of the inactive

myostatin gene.


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Two Inactive Myostatin Genes

Meat from cattle having two

copies of the inactive myostatin

gene.

http://www.ars.usda.gov/is/AR/archive/jul04/beef0704.htm

"MIGHTY MOUSE" GENE


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MIGHTY MOUSE GENEWORKS THE SAME WAY IN

PEOPLE Sequencing the myostatin gene from the boy and his mother, who had been a professional athlete, revealed a single change in the building blocks of the gene's DNA. Surprisingly, the change was not in the gene regions that correspond to the resulting protein, but in the intervening

regions that are used only to create protein-making instructions, thus changing the gene's protein-building message.

http://www.hopkinsmedicine.org/Press_releases/2004/06_23_04.html

Loss of Myostatin Gene Builds


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oss o yostat Ge e u dsMuscle in Humans

June 24, 2004Loss of Myostatin Gene Builds Musclein Humans

A research team funded by MDA has discovered anaturally occurring genetic change (mutation) in humansthat dramatically increases muscle size and strength.The mutation is in the gene for a protein calledmyostatin that normally acts to slow muscle growth.When this gene is inactivated, restraints on muscle

growth are lifted.

http://www.mdausa.org/research/040624myostatin.html


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Double Muscled German Boy

The researchers, led by Markus Scheulke of Charite University Medical Center in Berlin, identified a mutation in both copies of the myostatin gene in a 4-year

old child who had been noted to have unusually well-developed musculature from the time of birth. At 4, the child was reportedly able to hold two 3-kilogram (6.5-pound) weights in his outstretched

arms. His mother, a former professional athlete, was found to have a single copy of the same mutation.

http://www.ast-ss.com/blog/img/myostatin_boy.jpg


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Myostatin Serum Levels

http://fig.cox.miami.edu/~cmallery/150/neuro/myostatin.htm

Measurement of myostatin

levels in the patient's serum

by electrophoretic

analysis showed absence

of the myostatin pepetidein the child compared to

wild type organisms


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Selection?


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Sugar

At least onephosphate group

Nitrogen-

containing base

Nucleotide Structure

ATP

Figure 3.23a

Page 50


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Nucleotide Functions

Energy carriers

Coenzymes

Chemical messengers

Building blocks for nucleic

acids


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DNA

Double-stranded

Sugar-phosphate

backbone Covalent bonds in

backbone

H bonds betweenbases

Figure 3.25

Page 51


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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

ch03 lecture(carbon)[1]

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