it’s a cellular worldthe lipid bilayer of the cell membrane is not permeable to ions,...
Post on 17-Aug-2020
2 Views
Preview:
TRANSCRIPT
It’s A Cellular World
Atoms
Simple molecules
Monomers (sugars, amino acids, nucleotides)
Polymers (starch, glycogen, proteins, DNA, RNA)
Macromolecular assemblies (ribosomes, lipoproteins, membranes)
Cells & Unicellular Organisms
Multicellular Organisms
The Beginning
The primordial soup…
what was in it?
Chemical Elements
6 protons
6 neutrons
Carbon
- -
-
- -
- 6 electrons
Some Key Elements For Organic Molecules
Carbon
- -
-
- -
- 6 electrons
Hydrogen
1 electron
- -
- 7 electrons
Oxygen
8 electrons
-
-
- -
-
- -
- -
-
FYI
6 protons
6 neutrons
1 proton
Nitrogen
-
- -
7 protons
7 neutrons 8 protons
8 neutrons
Natural forces (oxidation, lightning, volcanic activity) create
simple molecules from elements at earth’s surface. Carbon, oxygen,
nitrogen, sulfur, & hydrogen combine to form molecules, e.g.,
carbon dioxide, ammonia, nitrate, acetate, sulfate, phosphate, etc.
In The Beginning
Atoms Bond To Form Simple Molecules
- -
Hydrogen gas (H2)
H-H
A single covalent bond
(sharing 1 pair of electrons)
Oxygen gas (O2)
O=O
A double covalent bond
(sharing 2 pairs of electrons)
Water Is Made With 2 Single Bonds
Water (H2O)
O
H H
Some Molecules Are Polar
(Electrical Charge Distribution Is Uneven)
Electrons are have a negative charge, and
electrons spend more time with the larger oxygen
atom. Therefore, water molecules are polar.
Oxygen
H H
-
- -
-
- - -
- -
-
+
A Molecule of Glucose (a sugar) Is
Made of Carbon, Hydrogen, and
Oxygen Bonded Together In A Ring
C6H12O6
Shorthand Notation
C6H12O6
OH
|
H C H
|
O H
Ionic Bonds
Na+ Cl-
Na+ Cl-
Na+ Cl-
Na+ Cl-
Na+ Cl-
Na+ Cl-
Na+ Cl-
Na+ Cl-
Crystal Lattice of NaCl (table salt)
Salt Dissolves in Water
Na+ Cl-
Na+ Cl-
Na+ Cl-
Na+ Cl-
Na+ Cl-
Na+ Cl-
Na+ Cl-
Na+ Cl-
+ - + - + -
+ - + - + -
+
- +
-
+
- +
-
+
- +
- +
-
+
- +
-
+
- +
-
+
-
+ - + - + -
+ - + - + -
Life Consists of Simple Molecules Combined
to Form Increasingly Complex Molecules
Example: Sugars combine to make disaccharides, starches and glycogen.
• Biological molecules are made from chains &
rings of carbon.
• Single units of biological molecules (monomers)
can join to form increasingly complex molecules
(polymers) with complex shapes.
Simple Sugars Bond to
Form a Disaccharide
+
condensation
hydrolysis (disaccharides)
sucrose
(disaccharide)
The process of splitting a compound into fragments with the
addition of water; a kind of reaction that is used to break down
polymers into simpler units, e.g. starch into glucose.
Hydrolysis
Carbohydrates: Starch, Glycogen, &
Cellulose Are Chains of Sugar Molecules
Proteins, Lipids, & DNA Are Also Polymers
Made From Smaller Building Blocks
• Sugars combine to make disaccharides,
starches, and glycogen.
• Fatty acids make triglycerides, fats, &
phospholipids.
• Strings of nucleotides make RNA & DNA.
• Proteins are chains of amino acids.
Lipids
Fatty substances
Fatty acids
Triglycerides (fat)
Cholesterol
Fatty Acids
• Covalently-linked chains of carbon atoms
• Saturated (all single bonds) & unsaturated (one or more double bonds)
• Monounsaturated fatty acids have 1 double bond
• Polyunsaturated fatty acids have 2-6 double bonds
A Molecule of Fat: A Triglyceride
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H O
O H
H
C
C
C
H
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H O
O H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H O
O H
3 Fatty Acids
Glycerol
backbone
H-
RNA & DNA
Chains of Nucleotides
U
Sugar-phosphate
backbone
Sugar-phosphate
backbone
Nucleotide
Unit
Ribose
(sugar)
Deoxyribose
(sugar)
his
tyr
val
gln
phe
Proteins Are Chains of Amino Acids
Cells Are the Units of Life
From Bacteria to Man
Let’s Build a Cell
Some Molecules Are Polar
(Electrical Charge Distribution Is Uneven)
e.g., Water molecules are polar.
Electrons, which have a negative charge, spend
more time with the larger oxygen atom, so the
oxygen end of the molecule is more negative then
the hydrogen end.
Oxygen
H H
-
- -
-
- - -
- -
-
+
Water Molecules Cling To Each Other
Because + & - Charges Attract
Water is polar.
Hydrogen bonding of water molecules http://biomodel.uah.es/en/water/index.htm
Triglycerides Are Non-Polar
The long hydrocarbon chains are
uncharged and therefore repel water.
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H O
O H
H
C
C
C
H
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H O
O H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H O
O H
3 Fatty Acids
Glycerol
backbone
H-
The Fatty Acid Composition of Some
Common Oils (Fats)
Phospholipids Are Amphipathic
Phospholipids are amphipathic; they have both polar & non-polar parts.
H
C
C
C
H
H
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H O
O H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H O
O H
CH3-N-C-C-O-P-
O
-CH
3
-CH
3
O
O
=
-
+
Choline Phosphate
2 Fatty Acids
polar head
group
non-polar
fatty acid tails
Glycerol
Water
The Polar Head Group Is Attracted To Water, But
The Non-polar Fatty Acid Tails Are Repelled
Polar head
group
Non-polar
fatty acid tails
“Amphipathic” = Dual nature
Phospholipid Molecules Self-Assemble in H20
Polar head
group
Non-polar
fatty acid tails
Polar Forces Cause Phospholipids To Form Bilayers
Water
Oily Layer
Water
Phospholipid Bilayers Can Form
Spherical Structures …
…thus,
providing the
basis for cell
structure.
Lipids: Cholesterol
• Plants have sterols, but they do not have cholesterol.
Only animal cells have cholesterol.
• The ring structure provides compact rigidity; its purpose
is to modify the fluidity of animal cell membranes.
-
Non-polar
(oily ; hydrophobic;
“water fearing”)
Polar
(hydrophilic;
“water loving”)
Cholesterol Has A Small Polar
Portion, But Is Mostly Non-polar
-
Water
Water
Lipid Bilayer
(Cell Membrane)
A Double Layer of Phospholipids & Cholesterol
Forms the Basis of the Cell Membrane
his
tyr
val
gln
phe
Proteins Are Chains of Amino Acids
Polar (hydrophilic, i.e., “water loving”
Non-polar (hydrophobic, i.e., “water fearing”)
Proteins May Have Hydrophobic (Non-
polar) & Hydrophilic (Polar) Segments
Val Leu Met Met Met Met Phe Leu Asp Asp His Lys Lys His Glu Val Leu Met Phe
Val Leu Met Met Met Met Phe Leu Asp Asp His Lys His Lys Glu Val Leu Met Phe Asp Asp His Lys Lys His Glu Val Leu Met Met Met Met Phe Leu Asp Asp His
Lys
His
Asp Asp His
Lys Glu Val Leu Met Phe Lys Lys His Glu Val Leu Met Phe folding
His Lys Glu Val Leu Met Phe Lys Lys His Glu Val Leu Met Phe
Val Leu Met Met Met Met Phe Leu Asp Asp Asp Asp His
Lys Lys His Glu
The Hydrophobic Segments of
Proteins Influences How They Fold
Water
Water
The Hydrophobic Segments of
Proteins Also Influences Their
Insertion Into Cell Membranes
Protein Structure
“Receptors,” binding
sites that recognize
chemical signals
Proteins Serve Many Functions
Antibodies –
chains (subunits)
with binding sites
for antigens
Signal
molecule
Protein
receptor Cylindrical tubes to
transport large
molecules across
the cell membrane
Hemoglobin to
transport oxygen
Enzymes that
join or split
other molecules
Peptide
hormones
(insulin)
Collagen fibers
for structure
Fibers that
contract
Chains bound together
to form a sheet
Extracellular Water
Intracellular Water
Extracellular Water
Intracellular Water
A Stereotypical Eukaryotic Cell
Source: http://www.daviddarling.info/encyclopedia/E/eukarycell.html
The Type Of Fat In Your Diet
May Affect Cellular Function
Different Types of Triglycerides (Fats & Oils)
EPA DCHA
Solid at room temperature:
Coconut butter is a fat with mostly saturated fatty acids.
Lard is animal fat, which is rich in saturated fatty acids.
Liquid at room temperature:
Olive oil is a fat with a high amount of oleic acid (18:1, i.e.,
monounsaturated).
Corn oil is a fat with a high amount of linoleic acid (18:2).
Fish oils are fats with unusually long fatty acids (20 or 22
carbon atoms) with 5 or 6 double bonds.
The Fatty Acid Composition of Some
Common Oils (Fats)
Mozaffarian, D. et al. N Engl J Med 2006;354:1601-1613
Structure of Cis and Trans Fatty Acids
Mozaffarian, D. et al. N Engl J Med 2006;354:1601-1613
Potential Physiological Effects of Trans Fatty Acids
Proteins in the Cell Membrane
Serve a Number of Functions
Protein Binding Sites
Protein folding may create “pockets” with a specific shape that can bind other molecules, like a lock that accepts a specific key. This enables them to serve:
As receptors that recognize signal molecules (e.g. hormones).
A defensive function to recognize foreign molecules.
As enzymes that can bind cellular molecules and then break them down or combine them with other molecules to effect synthesis.
These highly specific binding sites enable proteins to function as:
Receptors that recognize signal molecules (e.g. hormones).
Receptors that trigger defensive responses
Antibodies that tag foreign molecules
Enzymes that can bind cellular molecules and then break them down or combine them with other molecules to effect synthesis.
Almost All The Activities of Cells
Are Controlled By Proteins
• Proteins can change shape & properties when another molecule binds to them, causing things to happen.
• Enzymes & channel proteins, act as little programmed chemical robots.
Simple Sugars Bond to
Form a Disaccharide
+
condensation
hydrolysis (disaccharides)
sucrose
(disaccharide)
The process of splitting a compound into fragments with the
addition of water; a kind of reaction that is used to break down
polymers into simpler units, e.g. starch into glucose.
Hydrolysis
Some Enzymes Break Substrates
Apart & Others Combine Them
Transport of Substances Across the Cell Membrane
The lipid bilayer is
permeable to water and
small, uncharged
molecules (e.g. oxygen
[O2] and carbon dioxide
[CO2]
Simple
diffusion
Facilitated
diffusion
Active
transport
Energy
Transmembrane
proteins create a water-
filled pore through which
ions and small
molecules like glucose
can pass by diffusion.
The lipid bilayer of the cell membrane is not permeable to ions,
water-soluble molecules like glucose, or large molecules like
protein or DNA.
Some transmembrane
proteins use ATP energy
to actively transport ions
and small molecules
against a concentration
gradient.
Muscle Fibers Are Made of Proteins
Cell Membrane – A Fluid Mosaic
Atoms
Simple molecules
Monomers (sugars, amino acids, nucleotides)
Polymers (starch, glycogen, proteins, DNA, RNA)
Macromolecular assemblies (ribosomes, lipoproteins, membranes)
Cells & Unicellular Organisms
Multicellular Organisms
A “Typical” Eukaryotic
Cell and Its Organelles
Mitochondria:
convert sugar,
starch, fat into
cellular energy.
Nucleus: DNA,
RNA synthesis.
Rough endoplasmic
reticulum & ribosomes:
protein synthesis.
Muscle Cells
Endothelial Cells
Intestinal Cells
Pancreatic Cells
Gallbladder Cells
Nerve Cells
White Blood Cells
Bone Cells
On A Scale From 1 To 10,000
1 m 10
m
.1 m .01
m
.001
m
.0001
m
viruses bacteria
History of the Evolution of Life
Levels of Organization
Atoms
Molecules
Macromolecules
Organelle
Cells
Tissues
Organs
Organ
systems
Organism
top related