Upload
338460
View
219
Download
0
Embed Size (px)
Citation preview
8/14/2019 Chap 4 - Marcomolecules
1/36
CHAPTER 4
CELLULAR CHEMICAL COMPOUNDS
8/14/2019 Chap 4 - Marcomolecules
2/36
Cellular chemical compounds
Four main classes of large biological molecules:
carbohydrates, lipids, proteins and nucleic acids
also called macromolecules
They are chain-like molecules called polymers : a
long molecules consisting of many similar or identical
building blocks linked by covalent bonds.
The repeating units that serve as the building blocks
of a polymer are small molecules called monomers.
8/14/2019 Chap 4 - Marcomolecules
3/36
Carbohydrates
The most important source of energy in a cell
General formula : CnH2n On
Consists of carbon, hydrogen and oxygen 1:2:1
Include both sugars and polymers of sugars
Simplest carbohydrates : monosaccharides
Double sugars : disaccharides consisting of two
monosaccharides joined by a condensation reaction
Macromolecules : oligosaccharides consisting two to tenunits of monosaccharides
polysaccharides - consisting more than ten
units of monosaccharides
8/14/2019 Chap 4 - Marcomolecules
4/36
Monosaccharides
Few groups: trioses (C3H6O3), pentose (C5H10 O5) and
hexoses (C6H12 O6)
Example : Hexose - Glucose (C6H12 O6)
Act as reducing agents in Benedict and Fehling Tests.
2 groups : aldose and ketose depending on the location
of the carbonyl group
Example : Glucose is an aldose and fructose is a structural
isomer of glucose is a ketose
Characteristics : sweet, water-soluble and can crystallize
8/14/2019 Chap 4 - Marcomolecules
5/36
8/14/2019 Chap 4 - Marcomolecules
6/36
Oligosaccharides
Consists of two or more units of monosaccharides
Disaccharide (important oligosaccharides)
Consists of two monosaccharides joined by a glycosidic linkage a
covalent bond formed between two molecules by a condensation
reaction
Example:
Glucose + glucose Maltose(Malt sugar in brewing beer)
Glucose + fructose Sucrose(Table sugar)
Glucose + galactose Lactose(sugar in milk)
Characteristics : sweet, water-soluble and can crystallize
8/14/2019 Chap 4 - Marcomolecules
7/36
Condensation reaction to form disaccharide - sucrose
+ H2O
8/14/2019 Chap 4 - Marcomolecules
8/36
Polysaccharides
Macromolecules, polymers with a few hundred to
a few thousand monosaccharides joined by
glycosidic linkages through condensation
reaction
General formula : (C6H12 O6)n
Serve as storage material, hydrolyzed to provide
sugar for cells and building material
Characteristics : not sweet, insoluble in water
and cannot crystallize
8/14/2019 Chap 4 - Marcomolecules
9/36
Starch
Storage in plants. Consists entirely of glucose
monomers. Plants store starch as granules within
cellular structures called plastids which include
chloroplasts.
8/14/2019 Chap 4 - Marcomolecules
10/36
Glycogen
Similar to amylopectin but more extensively
branched. Storage polysaccharide in human andother vertebrates mainly in liver and muscle cells.
8/14/2019 Chap 4 - Marcomolecules
11/36
Protein
Consists of C, H, O and N and occasionally S made up of thousands of polypeptides chains
Basic unit for polypeptide is amino acid connected bypeptide bonds
Amino acid monomers side chain
R carbon
H O
N C C
H OH
amino H carboxylgroup group
the physical and chemical properties of the side chain
determine the unique characteristics of a particular amino
8/14/2019 Chap 4 - Marcomolecules
12/36
Functions of protein:
a. Building new tissues and replacing dead, injuredor damaged tissues
b. Producing enzymes, antibodies, hemoglobin,
carotene and hormones
c. Produce energy by breaking down protein to
carbohydrates
d. Forming muscles
Sources of protein:
Meat, eggs, milk, fish and beans
8/14/2019 Chap 4 - Marcomolecules
13/36
Formation of Amino
acid polymers
Condensation
H
H
OH
OH
8/14/2019 Chap 4 - Marcomolecules
14/36
Level of Protein Structure
The Primary Structure of Protein
Example : Transthyretin a
globular protein found in the
blood that transport vitamin A
and a particular thyroid hormonethroughout the body
Four identical polypeptide chains
make it composed of 127 amino
acids
8/14/2019 Chap 4 - Marcomolecules
15/36
The Secondary Structure of
Protein
Composed of coils andfolds of polypeptide protein
Hydrogen bonds linked the
repeating constituents of
the polypeptide backbone. Two types:
helix human hair pleated sheet spider
silk
8/14/2019 Chap 4 - Marcomolecules
16/36
The Tertiary Structure of
Protein
Holds by a few type ofbonds:
Hydrophobic
interaction
Van der Waals
interaction
Ionic bond
Disulfide bridge
Example:Cytokines, Interleukins,
Human growth
hormones
8/14/2019 Chap 4 - Marcomolecules
17/36
The Quaternary Structure of Proteins
Include overall protein structure that results from the
aggregation of these polypeptide subunits Example :
Hemoglobin : consists of four polypeptide subunits, two of
one kind ( chains) and two of another kind ( chains)
8/14/2019 Chap 4 - Marcomolecules
18/36
Review: the four levels of protein structure
8/14/2019 Chap 4 - Marcomolecules
19/36
8/14/2019 Chap 4 - Marcomolecules
20/36
Lipid
Consists of C, H and O and sometimes P
Types of lipid : fats, phospholipids and steroids
Characteristics : insoluble in water but soluble in organic
solvent; at room temperature, lipid exists in two forms: liquid
(oil) and solid (fat)
Fats
Form from smaller molecules by dehydration reactions
Constructed from glycerol and fatty acids
Fat molecule = three fatty acids join to a glycerol (ester
linkage)
Fat is also called triacylglycerol : three fatty acids + one
glycerol
8/14/2019 Chap 4 - Marcomolecules
21/36
8/14/2019 Chap 4 - Marcomolecules
22/36
Fatty acids vary in length and in the number and locations of
double bonds
2 types : saturated and unsaturated fats
Saturated fatty acid : No double bonds between carbon atoms
composing the chain, it is saturated with hydrogen
Unsaturated fatty acid : has one or more double bonds, form
by the removal of hydrogen atoms from the carbon skeleton
8/14/2019 Chap 4 - Marcomolecules
23/36
Saturated fat
Mostly animal fats
Solid at room temperature Example : butter
Unsaturated fat
Mostly from plants and fishes
Liquid at room temperature
Example : Olive oil, cod liver oil
The kinks where the cis double bond are located
prevent the molecule from packing closely enough
to solidify at room temperature
8/14/2019 Chap 4 - Marcomolecules
24/36
Function of fats:
a. Release twice the energy for each gram ofburned fat, compared to carbohydrates.
b. Act as heat insulators, for example adipose
tissue under the skin
c. Provide protection against injuries or
concussion to internal organs for example fats
around kidneyd. Act as the soluble site for fat-soluble vitamins
like vitamins A, D, E and K.
8/14/2019 Chap 4 - Marcomolecules
25/36
Power from animal fat, soybeans, or other forms of biodiesel fuel
Designed by Craig Loomes Design Group Ltd
8/14/2019 Chap 4 - Marcomolecules
26/36
Phospholipids
Similar to fat but only has two fatty acids attached to glycerol
The third hydroxyl group of glycerol is joined to a phosphate
group which has a negative electrical charge
Additional small molecules usually charged or polar can be
linked to the phosphate group to form a variety of phospholipids
8/14/2019 Chap 4 - Marcomolecules
27/36
Nucleic Acid
Two types of nucleic acids : deoxyribonucleic acid (DNA) and
ribonucleic acid (RNA)
These molecules enable living organisms to reproduce their
complex components from one generation to the next
DNA provides directions for its own replication, directs RNAsynthesis and control protein synthesis
DNA is the genetic material that organisms inherit from their
parents
Each chromosome contains one long DNA molecule
DNA encoded the information that program all the cells
activities
8/14/2019 Chap 4 - Marcomolecules
28/36
The human genome has
approximately 3 billion
base pairs of DNA
arranged into 46chromosomes (23 pairs of
chromosomes including a
pair of sex chromosome)
DNA was first isolated by
the Swiss physician
Friedrich Miescher in 1869
In 1953, James Watson
and Francis Crick
suggestedthe first
accurate model of DNA
structure
8/14/2019 Chap 4 - Marcomolecules
29/36
The Structure of Nucleic Acids
Nucleic acids are macromolecules that exists as
polymers called polynucleotides
Each polynucleotides consists of monomers called
nucleotides
Nucleotides composed of three parts :a nitrogenous base a
pentose (five-carbon sugar)
a phosphate group
Nucleotides are joined by covalent bonds called
phosphodiester linkage
Nucleotide monomers
8/14/2019 Chap 4 - Marcomolecules
30/36
Nucleotide monomers
Phosphodiester linkage
8/14/2019 Chap 4 - Marcomolecules
31/36
Nucleotide Polymers
Nucleotides are joined by covalent bonds called phosphodiester
linkage between the OH group on the 3 carbon of one nucleotideand the phosphate on the 5 carbon of the next
The two free ends of the polymers : phosphate attached to a 5
carbon (5 end) and a hydroxyl group on a 3 carbon (3 end)
5C
3C
5C
3C
Phosphodiester
linkage
8/14/2019 Chap 4 - Marcomolecules
32/36
Base pairing:
8/14/2019 Chap 4 - Marcomolecules
33/36
Base pairing:
In DNA
Adenine(A) Thymine(T)
Guanine(G) Cytosine(C
In RNA
Adenine(A) Uracil (U)
Guanine(G) Cytosine(C
8/14/2019 Chap 4 - Marcomolecules
34/36
Differences between DNA and RNA
Characteristics DNA RNA
1. Pentose group(sugar)
Deoxyribonucleicacid Ribonucleic acid
2. Nitrogenousbase
Adenine, Thymine,Guanine and
Cytosine
Adenine, Urasil,Guanine and
Cytosine3. Structure Longer chain,
double strandedShorter chain, canbe either double(only virus) or singlestrand
Urasil replace Thymine in RNA; but the other nitrogen bases
no changeUrasil = un-meth lated form of Th mine
8/14/2019 Chap 4 - Marcomolecules
35/36
Functions of DNA/RNA
DNA:
Containing genetic information = genes
Synthesis of RNA as well
Genes have coding that help in protein synthesis by RNA
Can be inherited from parents to offsprings; genetic relationship
RNA:
Responsible for protein synthesis
RNA
8/14/2019 Chap 4 - Marcomolecules
36/36
RNA
3
Transfer RNA
(tRNA)
3
Messenger RNA
(mRNA)
Ribosomal RNA
(rRNA)
Messenger RNA
Carries
informationspecifying amino
acid sequences of
proteins from DNA
to ribosomes
Transfer RNA
The RNA that moves
amino acids to theribosome to be
placed in the order
prescribed by the
messenger RNA
Ribosomal RNA
RNA that
constructed theribosomal subunit;
Helping in protein
synthesis