Download Amino Acids

Биологические макромолекулы

Белки

Углеводы

Липиды

Нуклеиновые кислоты
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Organic Compounds

Molecules unique to living systems contain carbon
and hence are organic compounds

They include:

Carbohydrates

Lipids

Proteins

Nucleic Acids
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Carbohydrates

Contain carbon, hydrogen, and oxygen

Their major function is to supply a source of
cellular food

Examples:

Monosaccharides or simple sugars
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Figure 2.14a
Carbohydrates

Disaccharides or double sugars
PLAY
Disaccharides
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Figure 2.14b
Carbohydrates

Polysaccharides or polymers of simple sugars
PLAY
Polysaccharides
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Figure 2.14c
Lipids

Contain C, H, and O, but the proportion of oxygen
in lipids is less than in carbohydrates

Examples:

Neutral fats or triglycerides

Phospholipids

Steroids

Eicosanoids
PLAY
Fats
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Neutral Fats (Triglycerides)

Composed of three fatty acids bonded to a glycerol
molecule
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Figure 2.15a
Other Lipids

Phospholipids – modified triglycerides with two
fatty acid groups and a phosphorus group
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Figure 2.15b
Other Lipids


Steroids – flat molecules with four interlocking
hydrocarbon rings
Eicosanoids – 20-carbon fatty acids found in cell
membranes
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Figure 2.15c
Representative Lipids Found in the Body



Neutral fats – found in subcutaneous tissue and
around organs
Phospholipids – chief component of cell
membranes
Steroids – cholesterol, bile salts, vitamin D, sex
hormones, and adrenal cortical hormones
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Representative Lipids Found in the Body



Fat-soluble vitamins – vitamins A, E, and K
Eicosanoids – prostaglandins, leukotrienes, and
thromboxanes
Lipoproteins – transport fatty acids and cholesterol
in the bloodstream
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Amino Acids

Building blocks of protein, containing an amino
group and a carboxyl group

Amino group NH2

Carboxyl groups COOH
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Amino Acids
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Figure 2.16a–c
Amino Acids
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Figure 2.16d, e
Protein

Macromolecules composed of combinations of 20
types of amino acids bound together with peptide
bonds
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Figure 2.17
Protein

Macromolecules composed of combinations of 20
types of amino acids bound together with peptide
bonds
Peptide bond
H
H
R
O
N
C
C
OH
H
Amino acid
+
H
H
R
O
N
C
C
OH
H
Amino acid
Dehydration H O
2
synthesis
Hydrolysis
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H
H2O
H
R
O
H
R
O
N
C
C
N
C
C
H
H
OH
Dipeptide
Figure 2.17
Protein

Macromolecules composed of combinations of 20
types of amino acids bound together with peptide
bonds
H
H
R
O
N
C
C
OH
H
Amino acid
+
H
H
R
O
N
C
C
OH
H
Amino acid
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Figure 2.17
Protein

Macromolecules composed of combinations of 20
types of amino acids bound together with peptide
bonds
H
H
R
O
N
C
C
OH
H
Amino acid
+
H
H
R
O
N
C
C
Dehydration H O
2
synthesis
OH
H
Amino acid
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 2.17
Protein

Macromolecules composed of combinations of 20
types of amino acids bound together with peptide
bonds
Peptide bond
H
H
R
O
N
C
C
OH
H
Amino acid
+
H
H
R
O
N
C
C
Dehydration H O
2
synthesis
OH
H
Amino acid
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H
H
R
O
H
R
O
N
C
C
N
C
C
H
H
OH
Dipeptide
Figure 2.17
Protein

Macromolecules composed of combinations of 20
types of amino acids bound together with peptide
bonds
Peptide bond
H
H
R
O
H
R
O
N
C
C
N
C
C
H
H
OH
Dipeptide
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 2.17
Protein

Macromolecules composed of combinations of 20
types of amino acids bound together with peptide
bonds
Peptide bond
Hydrolysis
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H
H2O
H
R
O
H
R
O
N
C
C
N
C
C
H
H
OH
Dipeptide
Figure 2.17
Protein

Macromolecules composed of combinations of 20
types of amino acids bound together with peptide
bonds
Peptide bond
H
H
R
O
N
C
C
OH
H
Amino acid
+
H
H
R
O
H
R
O
H
R
O
N
C
C
N
C
C
N
C
C
OH
H
Amino acid
Hydrolysis
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H
H2O
H
H
OH
Dipeptide
Figure 2.17
Protein

Macromolecules composed of combinations of 20
types of amino acids bound together with peptide
bonds
Peptide bond
H
H
R
O
N
C
C
OH
H
Amino acid
+
H
H
R
O
N
C
C
OH
H
Amino acid
Dehydration H O
2
synthesis
Hydrolysis
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
H
H2O
H
R
O
H
R
O
N
C
C
N
C
C
H
H
OH
Dipeptide
Figure 2.17
Structural Levels of Proteins

Primary – amino acid sequence

Secondary – alpha helices or beta pleated sheets
PLAY
Chemistry of Life:
Introduction to Protein Structure
PLAY
Chemistry of Life:
Proteins: Primary Structure
PLAY
Chemistry of Life:
Proteins: Secondary Structure
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Structural Levels of Proteins


Tertiary – superimposed folding of secondary
structures
Quaternary – polypeptide chains linked together in
a specific manner
PLAY
Chemistry of Life:
Proteins: Tertiary Structure
PLAY
Chemistry of Life:
Proteins: Quaternary Structure
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Structural Levels of Proteins
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Figure 2.18a–c
Structural Levels of Proteins
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Figure 2.18b,d,e
Fibrous and Globular Proteins

Fibrous proteins

Extended and strand-like proteins

Examples: keratin, elastin, collagen, and certain
contractile fibers
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Fibrous and Globular Proteins

Globular proteins

Compact, spherical proteins with tertiary and
quaternary structures

Examples: antibodies, hormones, and enzymes
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Protein Denuaturation

Reversible unfolding of proteins due to drops in
pH and/or increased temperature
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Figure 2.19a
Protein Denuaturation

Irreversibly denatured proteins cannot refold and
are formed by extreme pH or temperature changes
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Figure 2.19b
Molecular Chaperones (Chaperonins)

Help other proteins to achieve their functional
three-dimensional shape

Maintain folding integrity

Assist in translocation of proteins across
membranes

Promote the breakdown of damaged or denatured
proteins
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Characteristics of Enzymes

Most are globular proteins that act as biological
catalysts

Holoenzymes consist of an apoenzyme (protein)
and a cofactor (usually an ion)

Enzymes are chemically specific
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Characteristics of Enzymes

Frequently named for the type of reaction they
catalyze

Enzyme names usually end in -ase

Lower activation energy
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Characteristics of Enzymes
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Figure 2.20
Mechanism of Enzyme Action

Enzyme binds with substrate

Product is formed at a lower activation energy

Product is released
PLAY
How Enzymes Work
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Active site
Amino acids
+
Enzyme (E)
Substrates (S)
Enzyme-substrate
complex (E-S)
H2O
Free enzyme (E)
Peptide bond
Internal rearrangements
leading to catalysis
Dipeptide product (P)
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Figure 2.21
Active site
Amino acids
+
Enzyme (E)
Substrates (S)
Enzyme-substrate
complex (E-S)
H2O
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Figure 2.21
Active site
Amino acids
+
Enzyme (E)
Substrates (S)
Enzyme-substrate
complex (E-S)
H2O
Internal rearrangements
leading to catalysis
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Figure 2.21
Active site
Amino acids
+
Enzyme (E)
Substrates (S)
Enzyme-substrate
complex (E-S)
H2O
Free enzyme (E)
Peptide bond
Internal rearrangements
leading to catalysis
Dipeptide product (P)
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Figure 2.21
Nucleic Acids

Composed of carbon, oxygen, hydrogen, nitrogen,
and phosphorus

Their structural unit, the nucleotide, is composed
of N-containing base, a pentose sugar, and a
phosphate group
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Nucleic Acids


Five nitrogen bases contribute to nucleotide
structure – adenine (A), guanine (G), cytosine (C),
thymine (T), and uracil (U)
Two major classes – DNA and RNA
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Deoxyribonucleic Acid (DNA)

Double-stranded helical molecule found in the
nucleus of the cell

Replicates itself before the cell divides, ensuring
genetic continuity

Provides instructions for protein synthesis
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Structure of DNA
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Figure 2.22a
Structure of DNA
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Figure 2.22b
Ribonucleic Acid (RNA)

Single-stranded molecule found in both the
nucleus and the cytoplasm of a cell

Uses the nitrogenous base uracil instead of
thymine

Three varieties of RNA: messenger RNA, transfer
RNA, and ribosomal RNA
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Adenosine Triphosphate (ATP)

Source of immediately usable energy for the cell

Adenine-containing RNA nucleotide with three
phosphate groups
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Adenosine Triphosphate (ATP)
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Figure 2.23
Membrane
protein
Pi
P
Solute
Solute transported
(a) Transport work
ADP
+
Pi
ATP
Relaxed smooth
muscle cell
Contracted smooth
muscle cell
(b) Mechanical work
Pi
X
P
X
Y
+ Y
Reactants
Product made
(c) Chemical work
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Figure 2.24
Membrane
protein
P
Solute
(a) Transport work
ATP
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Figure 2.24
Membrane
protein
Pi
P
Solute
Solute transported
(a) Transport work
ATP
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ADP
+
Pi
Figure 2.24
ATP
Relaxed smooth
muscle cell
(b) Mechanical work
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Figure 2.24
ADP
+
Pi
ATP
Relaxed smooth
muscle cell
Contracted smooth
muscle cell
(b) Mechanical work
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Figure 2.24
ATP
X
P
+ Y
Reactants
(c) Chemical work
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Figure 2.24
ADP
+
Pi
ATP
Pi
X
P
X
Y
+ Y
Reactants
Product made
(c) Chemical work
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 2.24
Membrane
protein
Pi
P
Solute
Solute transported
(a) Transport work
ADP
+
Pi
ATP
Relaxed smooth
muscle cell
Contracted smooth
muscle cell
(b) Mechanical work
Pi
X
P
X
Y
+ Y
Reactants
Product made
(c) Chemical work
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 2.24

МЕТАБОЛИЗМ
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
Catabolism provides the building blocks and
energy for anabolism.
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Figure 5.1

A metabolic pathway is a sequence of
enzymatically catalyzed chemical reactions in a
cell.

Metabolic pathways are determined by enzymes.

Enzymes are encoded by genes.
PLAY
Animation: Metabolic Pathways (Overview)
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Oxidation-Reduction

Oxidation is the removal of electrons.

Reduction is the gain of electrons.

Redox reaction is an oxidation reaction paired with
a reduction reaction.
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Figure 5.9
Oxidation-Reduction

In biological systems, the electrons are often
associated with hydrogen atoms. Biological
oxidations are often dehydrogenations.
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Figure 5.10
The Generation of ATP

ATP is generated by the phosphorylation of ADP.
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The Generation of ATP

Substrate-level phosphorylation is the transfer of a
high-energy PO4– to ADP.
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The Generation of ATP

Energy released from the transfer of electrons
(oxidation) of one compound to another
(reduction) is used to generate ATP by
chemiosmosis.
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The Generation of ATP

Light causes chlorophyll to give up electrons.
Energy released from the transfer of electrons
(oxidation) of chlorophyll through a system of
carrier molecules is used to generate ATP.
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