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Physical Properties
• Due to the polar nature of water
• Hydrogen bond- weak attraction
between hydrogen on adjacent
molecules such as water
H H
O
H H
O
Hydrogen bond
Water and it’s importance to Life
• Life evolved in water
• Water’s unique properties have
made life as we know it possible
Physical Properties
• Heat of vaporization- amount of
energy that is released or gained
when changing state from liquid
to gas or back
Physical Properties
• High Specific Heat- the amount of
heat absorbed or released when
water changes temperature by
one degree C. ( 1 cal. )
Ice Floats
• As a liquid water’s hydrogen bonds
continuously break and reform
• As a solid four molecules form hydrogen
bonds creating crystals with open
channels and thus fewer molecules per
area.
Physical Properties
• Water reaches maximum density
at 4 degrees C.
• Water is a universal solvent due
to it’s polar nature
Evaluate the importance of the
following and explain the
property of water responsible.
•
•
•
•
•
Cytoplasm is 98 % water
Ice Floats
Lake effect temperature moderation
Evaporative Cooling
Spring-Fall Overturn
Most Abundant Chemicals in
Life
•
•
•
•
Carbon
Oxygen
Hydrogen
Nitrogen
96 %
• Ca, P, K, S, Na, Cl, Mg > 4 %
Carbon is special
• Tetrahedral structure- four valence
electrons shared
• Covalent bonds - stability
Carbon is Special
• Variations are possible in
carbon molecules that provide
diversity
• Isomers are possible
structural- differ in structure
same chemical
formula
geometric-differ in spatial
relationship
enantiomers-mirror images
of each other
Condensation Synthesis
A
+
B
A
B
+ H2 O
A and B could be monosaccharides or amino acids
Hydrolysis
+ H2O
+
Addition of water breaks the bond
Polymers
Polymers are repeating units of monomers.
They are very important to Biology.
They are made or synthesized by the removal of
water called CONDENSATION SYNTHESIS
They are broken down by the addition of water or
HYDROLYSIS
Classes of Biomolecules
• Carbohydrates- used for energy and
structures( building living organisms)
• Lipids- used for energy storage,
communication and structures
• Proteins- used for a variety of life
functions
• Nucleic Acids-the instructions for
building life
Carbohydrates
• Three common forms
– Monosaccharides
– Disaccharides
– Polysaccharides
Carbohydrates
• Monosaccharides- single sugars or
simple sugars,ex. Glucose (
C6H12O6)
• Disaccharides- double sugar, ex.
Sucrose
• Polysaccharides- polymers of
glucose such as: 1. Starch 2.
Cellulose 3. Glycogen 4. Chitin
Review
• What will happen here?
AOH + HB = ?
And here: CH2OH
CH2OH
O
OH
O
H
OH
OH
H
OH
OH
OH
H2O
OH
OH
Dehydration Synthesis
or a Condensation Reaction
A + B = AB + H2O
CH2OH
CH2OH
O
O
O
OH
OH
OH
OH
H2O
OH
OH
Review
• What will happen here?
AB + H2O = ?
And here: CH2OH
CH2OH
O
H2O
O
O
OH
OH
OH
OH
OH
OH
Hydrolysis or Reaction
AB + H2O = AOH + HB
Molecules have been HYDROLIZED!
CH2OH
CH2OH
O
O
OH
OH
OH
OH
OH
OH
OH
OH
Glucose
Glucose has
a chemical
formula
of C6H12O6
CH2OH
C
OH
O
H
OH
C
H
OH
H
C
C
H
OH
C
H
FRUCTOSE
O
CH2OH
CH2OH
C
C
HO H
C
OH
H H
C
OH
Disaccharides
• Sucrose and Lactose
• 2 monosaccharides bonded together
CH2OH
CH2OH
O
O
O
OH
OH
OH
OH
OH
Alpha or
Beta?
OH
Polysaccharides
• 3 or more Monosaccharides bonded
together
CH2OH
CH2OH
O
CH2OH
O OH
O
O
OH
OH
OH
O
OH
OH
OH
OH
Polysaccharide
•
•
•
•
Starch-storage in plants
Cellulose-structural part of plant cell wall
Glycogen- storage in animals, liver
Chitin – structural component for
arthropods, exoskeleton. Also found in
fungi.
Polysaccharides – Starch
• Plants use it as energy storage
• Difficult for humans to break down
– Ex. Avoid a high starch diet
polysaccharides
Glucose
monomers
Polysaccharides – Cellulose
(B 1, 4 linkage)
• Long fibers
• Up to 15,000 Glucose units per strand
• Most abundant biological substance on
earth
– Ex. Cotton, Trees, Paper
• Why is cellulose so strong?
• Why can’t humans breakdown cellulose
and cows can?
Polysaccharides – Glycogen
• Animals use it as energy storage
• Lots and lots of it in the liver
• Forms huge branched storage units which
allow for easy break down for energy
Other polysaccharides
• Chitin
– Found in the exoskeleton of insects, and
arthropods
• Ex. Crabs, lobsters, grasshoppers
• Pectin
– Found in plant cell walls
– Provides rigidity
• Heteropolymers
– Glycoproteins and peptidoglycans
Protein
Polymers of amino acids
With 20 natural amino acids there
are a variety of proteins
Amino Acids
The building blocks of protein
H
H
H
O
N -C - C
OH
R
R- there are twenty different R groups possible
Alanine
Glycine
NH2-CH-COOH
CH3
NH2-CH2-COOH
Peptide bond- is a bond between amino
acids
a molecule of water is removed
Protein Structure
1. Primary- order of the amino acids
2. Secondary- hydrogen bonds cause pleats and helix
3. Tertiary- folds and loops create shape by R
Group bonds
4. Quaternary-interaction of several proteins
A protein with secondary
structure
A protein with Tertiary Structure
Lipids
• Large molecules that do NOT have an
affinity for water; not soluble in.
• May have hydrophobic-water fearing and
hydrophilic-water loving parts.
Triglycerides
hydrophilic
hydrophobic
Types of Lipids
• Made of hydrocarbons • Triglycerides- fats, waxes, and
oils(saturated all single bonds C-C,
unsaturated have double C=C bonds
• Phospholipids- attached phosphate
replaces one of the hydrocarbon tails
• Steroids- Ring Forms of Hydrocarbons
cholesterol and some hormones
Triglycerides
• Saturated fats- single bonds
make this a solid at room
temperature and more difficult
to digest.
Unsatured Fats
• Triglycerides that contain
double bonds (
dehydrogenated) are liquids at
room temp and more
digestable
Nucleic Acids
• Made of monomers called
nucleotides
• DNAdeoxyribonucleicacid
• RNA- ribonucleic acid
• These molecules carry all
DNA Basic Composition
• DNA is made up of nucleotides
• Nucleotides are made of
…………...Deoxyribose sugar
……………Phosphate
……………Base
bases are guanine,cytosine, thymine and
adenine
RESPIRATION
C
A
T
A
B
O
L
I
S
M
SYNTHESIS
ATP SYNTHESIS
FROM ADP + Pi
A
N
A
B
O
L
I
S
M
Free Energy
• Ability to do work in the cell or ecosystem.
Energy Transfer
•
•
•
•
ATP formation
+
G
ENDERGONIC
Stores energy
in phosphate
bond
• ATP breakdown
•-
G
• EXERGONIC
• Releases
energy between
phosphates
Enzyme Characteristics
• Lower the activation
energy
• Speed up the rate of a
reaction
• Act as catalysts
• Are proteins
(occasionally RNA)
Enzyme Characteristics
• Conformation or shape is
most important feature (
Lock and Key Hypothesis)
• Substrate Specific
• Do NOT become part of
reaction
Enzyme activity.
7
pH
Enzyme activity.
7
pH
Enzyme activity.
10
Temperature o C
Enzyme activity.
10
30
Temperature o C
Active site
Allosteric site
substrate
products
Cofactors
• Non protein helpers for enzyme activity
• May bind to active site tightly or loosely
• Many are inorganic such as zinc or iron
• If organic they are called Coenzymes
Allosteric site
• Regulatory site other than the
active site.
Competitive Inhibitor
substrate
inhibitor
Enzyme-Substrate
Complex
Enzyme
Noncompetitive Inhibitor
Allosteric Regulation
Active site
activator
Active
conformation
Inactive
form
Allosteric
site
inhibitor
Feedback inhibition
• Product may cause negative
feedback (act to inhibit, disrupt
conformation)
• Reactants may cause positive
feedback ( act to preserve enzyme
conformation)
Initial Enzyme a
substance
Enzyme b
- feedback
Enzyme c
End
product
Prokaryotic Cells
• Lack a nucleus
• Lack membrane bound organells
• Include bacteria and other Monerans
Eukaryotic Cells
• Have a nucleus
• Have membrane bound organells
• Plants, Animals, Fungi, and Protists have
these cell types
Organells Membrane Bound ( endomembrane)
Nucleus
Endoplasmic reticulum (rough)
Endoplasmic reticulum ( smooth )
Golgi apparatus
Lysosome
Vacuoles
Vesicles
Peroxisome ( single membrane)
Mitochoindria
Chloroplasts
Non membrane bound organells
Nucleolus
Microtubules
Microfilaments
Centrioles
Cilia
Flagella
Nucleus
• Chromatin- DNA organized with
protein (histone)
• Controls Protein Synthesis
• Double Membrane with pores
may be continious with ER
• Nucleolus- made of and
synthesizes RNA
Endoplasmic Reticulum
• Rough ER- contains ribosome
for protein synthesis
• Smooth ER- lacks ribosomes,
synthesis of lipids, metabolism
of carbohydrates,
detoxification of drugs and
poisons
Muscle ER- calcium ion transfer
ER and protein synthesis and
Transport Vesicles
• Export Proteins – become enclsed in
vesicle of the ER Pinch closed
Especially secretory proteins ( glycoproteins
)
E R..
Golgi Apparatus
• Manufacture, storage shipping , and
packaging secretion products
• Cis
• Trans
• Vesicles
trans
cis
Phospholipids are amphipathic have
both hydrophobic
and hydrophilic portions
hydrophilic
hydrophobic
Membrane Fluidity
• Unsaturated hydrocarbons in
the phospholipids make it flow
laterally
• Cholesterol maintains some
rigidity at low temperatures
and prevents too much fluidity
at high
Membrane proteins
• Integral-penetrate
into or through
the lipid bilayer
• used for transport
• Peripheral proteinattach to the
surface of the lipid
layer
• used for- receptors,
recognition(carbohy
drates attached)
Permeablility
• What passes
through easily
• Oxygen
• Carbon dioxide
• water
• What does not
pass through
easily
• ions
• proteins
• carbohydrates
Transport
• Passive
• Requires no
expenditure of ATP
• Moves from high to
low
• Can be facilitativeaided by protein
conformation
change
• Gatted channels
• Active
• Requires ATP
energy
• Generally moves
from low to high
• Gatted channels
• Na-K pump
• Proton Pumps
• Phagocytosis or
Pinocytosis
Solutions
• Homogeneous-same throughout
• solvent- what you are dissolving into
• solute- what you dissolve
solution
SOLUTE
*
*
*
*
SOLVENT
*
Hypertonic
.5M
glucose
.5M glucose
Distilled water
1.5 M glucose
Water Balance
• Plasmolysis( plasmolyzed) plant cell
shrinks or looses water
• Flacid -plant cell gains water and looses at
same rate
• Turgid- Plant cell gains
Plasmolysis
• Membrane shrinks due to water loss
• Restricted to cells with walls
• Occurs in a Hypertonic environment
Facilitated Diffusion
• Proteins make movement of polar
molecules, ions, or larger compounds
possible by providing a passage.
• Often protein changes conformation
• NO ATP required
• Movement from high to low
concentration
Active Transport
• Sodium Potasium Pump
• Proton pumps
Membrane Potential
• Voltage across a membrane
• -50 to-200 millivolts
• Electrochemical gradientscombination of ion potential
and electric charge difference
Gated Channels
• Chemical or electrical impulses cause
them to change shape-OPEN
Na-K Pump
• Membrane Potential-voltage difference
across a membrane
• Chemical Gradient-difference in
concentration of solute across a
membrane
• Electro-chemical Gradientcombination of the above ex.
• Na+,K+, Cl-(8.13)
Exocytosis and Endocytosis
• Phagocytosis- engulf
pseudopodia
• Pinocytosis- gulps
• Receptor mediated pinocytosis
Signal Transduction
• Binding of extracellular
molecule to receptor protein
see model on pg. 156
Campbell
Cell types determine cycle
• Prokaryotes- binary
fission circular
chromosome
attaches to inner
membrane.
Replication is
followed by
reattachment at two
sites.
No spindle fibers
• Eukaryotes-have a
larger genome and
nuclear genetic
material must be
carried on several
chromosomes by
specialized
structures.
Can be Confusing?
Chomosomes
Chromatids
Sister
chromatids
Homologous
chromosomes
Centromere
Centrosome
Centrioles
Kinetochore
Nonkinetochore
Chromosomes
chromatid
Sister chromatid
centromere
Chromosome Number is
fixed in each species
Diploid Number
Monoploid (haploid)
2n
n
46 in humans
23 in humans
Somatic Cells-body
cells
Gametes-egg, sperm,
pollen.
Cell Cycle
Events in the growth, development and
reproduction of the cell.
Go cells have stopped dividing or have lost
the potential to divide.
G1- gap or growth after cell division. Cell
grows in size. this stage contains the
RESTRICTION point
S- synthesis of new DNA from existing
template(replication)
G2- gap 2 or growth prior to cell division
M- mitosis or chromosome division
C- cytokinesis or cell division
Interphase= G1, S, and G2
Control of Cell Cycle
Restriction point- go/no go control during G1
G0 - a non-dividing stage for a cell
Growth Factors-compounds which regulate growth
and division. Ex.PDGF platelet derived growth factor
Density-dependent inhibition- crowding inhibits cell
division.
Adhesiveness- cells ECM causes them to stick together
Metastasis-cells(cancerous) migrate
Cell Clock Regulators
• Proteins ( enzymes) regulate cell
cycle
• Produced by internal cell clock
genes
• Protooncogenes- cause cells to
divide
• Tumor suppressor genes- prevent
cell division
Cancer and the Cell Cycle
• Normal Cells
• Adhesive
• Contact
inhibition
• Cancer cells
• Lost
adhesiveness
• Lost contact
inhibition
Principles of Heredity
• Alternative versions of genes
(alleles) account for variations in a
trait.
• For each character, an organism
inherits two alleles, one from each
parent.
• If alleles differ, then the dominant will
be fully expressed over the
recessive.
• The two alleles segregate (separate)
during gamete formation.
Crossing over
During prophase of meiosis
homologous pairs may exchange
genetic material.
New Genetic Combinations
• Recombination during fertilization brings
together two sets of genetic instructions
• Meiosis-crossing over brings about new
combinations
• Random genetic mutation can result in
random genetic change
Electron Carriers
NAD+ nicotinamide adenine
dinucleotide
NAD+ When oxidized
NADH +2 H+ When reduced
FAD or FADH2
Types of Respiration
• Anaerobic-without oxygen 1. Alcoholic
fermentaion 2.Acetic Acid fermentaion 3.
Lactic Acid fermentaion
• Aerobic-with oxygen
• ALL OF THESE BEGIN WITH THE
ANAEROBIC PROCESS OF
GLYCOLYSIS
GLYCOLYSIS
Glucose is made ready to
metabolize by addition of phosphates
and then it is broken down into
2- 3 carbon compounds (PYRUVATE)
This yields a net gain of 2 ATP
ACETYL COA FRORMATION
• Pyruvate is converted into a 2
Carbon compound and added to
an enzyme
• CO2 is released
Kreb’s Cycle
• Breaks C-H-O bonds
• Energy is transferred via carriers
to other steps
• CO2 released
• Some small amount of ATP is
produced
Electron Transport
• Hydrogen Pathway- pumps H
ions
• Electron Transfer
• Chemiosmosis- H ions flow
through ATP syntase proteins to
make ATP from ADP + P
Substrate level phosphorylation
• ATP is formed as a direct
transfer of
electrons from the substrate to as
ADP + P ATP
Oxidative phosphorylation
• Electrons made available in
metabolism are transferred to
oxygen and ATP is produced in
the process. Chemiosmosis
Fermentation generates ATP by substrate
level phosphorylation.
It is anaerobic
Three Types:
AlcoholicLactic Acid-
2 Ethanol +2CO2+NAD
2NAD+2Lactate
Photosynthesis
CO2+H2O
light
CnH2n0n+O2
Light- measured as an absorption spectrum,
the wavelengths that are most important
are different for different types of autotrophs
Light rxn.
H2O
Dark rxn. CO2
light
PS1
NADP
H
Calvin
Calvin Cycle
Cycle
Thylakoid
PS2
Photolysis
and Photophosphorylation
O2
ATP
Stroma
CnHnOn
Visible Spectrum
Reflected
Absorbed
Absorbed
680-700
Primary
acceptor
NADP+ + 2H
-e
NADPH
pq
Cytochrome
complex
Photosystem I
P700
pc
Chl
a
700nm LIGHT
Photosystem II
P680
680nm
Photosystem I
• Also known as P700receives electrons from
those released in PSII to
replace photoexcited
electrons uses light at far
end of the red wavelength
• PSI 700
• PSII 680 the II in PSII H2O
Photosystem II
• P680
• due to an association with
different proteins
• this system utilizes different
wavelengths
• causes water to split capturing
it’s electron
• it then transfers the electron to
PSII chlorophyll molecules
Noncyclic Electron Flow
Water is split (photolysis) and electrons
pass continuously from water to NADP+.
Primary electron acceptors pass
photoexcited electron to the electron
transport chain(Pq), (Pc), cytochromes.
.
Uses both PSI and PSII
Generates O2, NADPH, and ATP
Cyclic Electron Flow
Excited Electrons pass through the
electron transport
chain from P700 (PS I ) and return to
the starting point.
Uses only PSI
Only ATP is generated
3CO2
RuBP
3ATP
Carbon Fixation
rubisco
Calvin
Cycle
6ATP
6ADP
6NADPH
3ADP
6NADP
Regeneration RuBP
G3P--Glucose
Photorespiration
CO2 can act as a limiting factor.
In cases where there is not sufficient
Carbon dioxide plants will combine
oxygen with RuBP to form compounds
that are broken down into CO2
Adaptations for Photosynthesis
• C4 Plants
• CAM plants
• CO2 is added to PEP
phosphophenolpyruvat
e
• stored in BUNDLE
SHEATH CELLS near
veins of leaf
• example- Corn
• in hot dry areas plants
must close stomates
• CO2 taken in at night is
stored as an acid
Discovery of DNA
1. Frederick Griffith
– Was studying Streptococcus Pneumonia
– Smooth vs. Rough Strains
– Smooth had a mucous coat and were
pathogenic (caused pneumonia)
– Rough were non-pathogenic
– Conducted an experiment with mice
– Found out that the Rough bacteria
became transgenic
Discovery of DNA
2. Avery, McCarty and MacLeod
– What was the genetic material in Griffith’s
experiment?
– Purified the heat–killed S-bacteria
•
Into DNA, RNA, and Protein
– Mixed each with the R cells to see which
one transformed
Discovery of DNA
3. Hershey-Chase Experiment
– Studied viruses that infect bacterial cells
– Bacteriophages
– Protein or DNA responsible for take-charge
actions of the virus?
– Tagged the Protein with radioactive S
•
Why?
– Tagged the DNA with radioactive P
•
Why?
The Structure of DNA:
a double helix?
•
Chargaff’s Nucleic Acid Ratios
1. Measured the base compositions of
several species
2. Percentage of each base present
•
Human DNA
1. A = 30% and T = 29%
2. G = 20% and C = 19%
The Structure of DNA:
a double helix?
• Rosalind Franklin and Maurice Wilkins use XRay diffraction to view structure
• Watson and Crick propose a double helix
using their X-Ray pictures
DNA Double Helix
DNA: Three Parts
• DNA is made up of nucleotides
• Nucleotides are made of
– Deoxyribose sugar
– Phosphate
– Base
• Guanine, Cytosine, Thymine and Adenine
DNA: The Deoxyribose Sugar
DNA: The Phosphate
DNA: The Nitrogenous Bases
• Purines
• Adenine and Guanine
• Double Ring Structure
• Pyrimidines
• Thymine and Cytosine
• Single Ring Structure
Single Stranded DNA
Nucleotides can only
be added to the 3’ end
of the nucleotide and
therefore addition of
new nucleotides is
always 5’-----> 3’
DNA is
anti-parallel!!
DNA STRUCTURE
How does it know to pair up?
• ADENINE ALWAYS
PAIRS WITH
THYMINE
• Two hydrogen
bonds
• GUANINE ALWAYS
PAIRS WITH
CYTOSINE
• Three hydrogen
bonds
Why do they pair up?
• Double helix had a
uniform diameter
• Purine + Purine
– = too wide
• Pyrimidine + Pyrimidine
– = too narrow
• Purine + Pyrimidine
– = fits the x-ray data
One last look
Why does
it twist?
DNA Replication
Meselson-Stahl demonstrate the
Semiconservative Replication
of DNA using radioactive nitrogen
Why must DNA Replicate?
• Species Survival
– DNA must replicate BEFORE cell division
• Synthesis during Interphase
• All genes must be present in the
daughter cells
Origins of Replication
• Sites along DNA that contain specific
nucleotides are recognized by specific
proteins that initiate process
• In eukaryotes there are hundreds of
thousands of such points
• Form replication bubbles
How does DNA Replicate?
•
•
•
•
•
Hydrogen bonds break, forming bubbles
Enzymes unwind and unzip
Free nucleotides in the nucleus start
process of complementary base pairing
Nucleotides are fused together by DNA
Polymerase only 5’ to 3’
Results in two identical double helixes
Replication Steps
• DNA helicase enzymes open double
strand
• DNA uncoils and unzips exposing the
DNA template
• Primase adds a RNA primer as binding
proteins hold strands together
• DNA polymerase attaches to template
at replication fork
• Nucleoside triphosphates add bases
pairing A-T and G-C as new strand is
added to a 3’ end, primer removed
replication3
How does DNA Replicate?
How does DNA Replicate?
Leading Strand is Continuous
• A single RNA primers initiates the addition
of nucleotides to the 3’ end of the leading
strand
Lagging Strand
• Must wait for replication fork to open and
then add primer
• Form Okazaki fragments
• RNA is removed only after addition of
about 100 to 200 nucleotides
• Fragments are joined by a ligase enzyme (
DNA glue)
DNA Replication
The result
• DNA Replication results in TWO double
helixes. DNA unwinds and unzips, and
new daughter strands form, each
complementary to an old parental
strand.
RNA - Structure
• “Ribonucleic Acid” – different from
DNA
• Always Single Stranded
• Ribose Sugar Base Unit
• Phosphate group (same in DNA)
• Nitrogenous Bases
– Cytosine always pairs with Guanine
– BUT! Adenine always pairs with URACIL
• (different in DNA!!!!!)
Four kinds of RNA
• Ribosomal RNA
• Messenger RNA
• Transfer RNA
• snRNA ribozyme in spliceosome
rRNA
•
•
Ribosomal RNA or rRNA
•
represents about 70% of cellular RNA
•
joins with Ribosomal proteins to make the cellular
organelle: RIBOSOMES
FUNCTION – As a manufactured ribosome,
supplies a location for tRNA to join with
mRNA to synthesize a protein
mRNA
2. Messenger RNA or mRNA
•
•
•
•
•
represents about 10% of cellular RNA
contains the sequence of bases coding for a
particular amino acid sequence in a
polypeptide chain
removal of non-coding, internal sequences
(introns)
modification of the 5' base (cap)
addition of adenines to 3' end (poly A tail)
FUNCTION – reads the DNA code (base
sequence) and becomes a copy that is
read at the ribosome to make a protein
hn RNA
• Pre-mRNA contains intronsnon-coding regions as well as
exons-coding regions
Processing mRNA
• Deletion of introns
• Join exons
• Add cap ( GTP) and poly A tail
RNA splicing
• Spliceosome-several
snurps
• snRNPs small nuclear
Ribonucleoproteins-splicing
enzyme( cuts and glues)
Transcription
•
•
DNA unzips at the locus of the gene
being coded
mRNA makes a copy of the gene
•
•
Then…
mRNA is enzymatically modified
– A cap and a tail are added
•
it then leaves the nucleus and finds a
ribosome (composed of rRNA and
protein)
tRNA
•
•
•
•
•
Transfer RNA or tRNA
represents about 20% of cellular RNA
each tRNA molecule is specific for one amino
acid
there is an enzyme for each amino acid which
recognizes the amino acid and its specific
tRNA and joins the two together
the specific joining of tRNA to amino acid is
the only place where the “genetic code"
applies
FUNCTION – Pairs with Amino Acids and
delivers them to ribosomes at the right
time to synthesize a protein
Protein Synthesis
• Why should cells do this?
– Cells would not be able to grow and change without
proteins.
– Proteins are found everywhere:
• As enzymes, cell membranes, muscles, heart, blood…
• What happens when proteins are not made
correctly or not made at all?
– Ex. Cystic Fibrosis
• What part of DNA holds the code for the protein?
PROTEIN SYNTHESIS
Everyone is involved
• Transcription
DNA, mRNA
• Translation
mRNA, rRNA and tRNA
Pre-Translation
• mRNA binds to the ribosome
• Meanwhile, tRNAs are attaching to their
amino acids using tRNA Transferase
• Free tRNAs, with their amino acids
attached, circulate in the cytoplasm and
match up with the triplet codes in the
mRNA
Translation
Initiation
• The first tRNA enters the ribosome at the A
site
• The second tRNA enters the ribosome (at
the P site) and the amino acids are bonded
together = PEPTIDE BOND
Elongation
• Both tRNAs shift in one direction and make
room for the next tRNA to enter the
ribosome
• this pattern continues until the protein is
complete
Quick Definitions
A-site – aminoacyl-tRNA binding site
P-site – peptidyl-tRNA binding site
Triplet code – DNA
Codon – RNA
Anti-codon - tRNA
Introns – removed from initial mRNA
Exons – bonded together to make the
finished mRNA product for translation
Polyribosomes – more than one ribosome
reading the mRNA at one time
Codons and anti-codons
Triplet code on DNA
TAC
mRNA copies it: CODON
AUG
tRNA carries the ANTICODON
UAC
The Genetic code reads the codon
AUG, the amino acid:
Methionine
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45 different anti-codons exist
AUG is always the initiation codon
GTP supplies energy needed to synthesize
protein
initiator tRNA always carries Methionine first!
Initiation factors - proteins that bring all parts
together (mRNA, small subunit, large subunit,
and tRNAs)
Genetic Code
• Interprets what the DNA triplet code reads
• Is written in both DNA base language A, G,
C, T or RNA base language A, G, C, U
• Determines the order for Amino Acids
• Is universal within all species
• Reads the same as the anti-codon (on
tRNA) except T is now U
Genetic Code
Gene Regulation
Control of gene expression occurs at four levels
in human cells:
Transcription and posttranscription control
(nucleus)
Translation and posttranslation control
(cytoplasm)
• Various cells express different genes
• Genes can be turned on or off
• Genes respond to activity outside of the cell
• Control of transcription is most important
regulatory mechanism (binding factors and
enhancers) Presence of TF determines
specialization
DNA Technology
•
Biotechnology or genetic engineering
– the use of natural biological systems
to produce a product desired by
human beings
Examples include:
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Gene Cloning
DNA Amplification
Transgenic Organisms
Gene Therapy
Chromosome Mapping and Sequencing
Gene Cloning
Gene Cloning
• Recombinant DNA – DNA from two different
sources (human and E. coli)
• Plasmid – circular DNA used to transport the
gene into the organism
• Enzymes needed – Restriction and Ligase
• Host cell – usually bacteria, wall must
become competent in order for the bacteria to
uptake the plasmid
• Restriction enzyme cleaves DNA and allows
for DNA fragment to insert at the sticky ends
• Vector – method of transporting a gene (virus,
plasmid)
pVIB lux genes
2 genes to produce LUCIFERASE
Aldehyde (energy source)
synthesis
several genes
Regulatory genes to turn of and on
DNA Amplification
Polymerase Chain Reaction – PCR
• Used to make multiple copies of the
same gene
• Copies can be examined to see if they
match any other sources
• Prevents constant extraction from the
organism and better results
Other Technologies
• Recombinant DNA - gene
splicing
• Transgenic organism- an
organism that contains another
organism’s DNA
Transgenic Organisms
• Transgenic – possessing gene(s) from another
organism
• Gene Pharming – Using transgenic farm animals
to produce pharmaceuticals
ex. CF, cancer, blood clots
• Genetically altering crops to be resistant to
insects and produce larger
http://biology.about.com/science/biology/gi/dynamic/offsite.htm?site=http://abcnews.go.co
m/sections/science/DailyNews/gmcorn%5Fbutterflies000821.html
• Suicide Genes
• Insulin
Gene Therapy
• Delivering the defective gene to the cells
that need it to produce a protein
• Familial hypercholesteremia
• SCID – severe combined
immunodeficiency syndrome (missing
maturation enzyme for T and B cells)
Chromosome Mapping
• 100,000 human genes
• RFLPs – Restriction Fragment Length
Polymorphisms – used to probe a
region of DNA – visible under a
microscope
• Restriction enzymes – sequence AA
• Specific base digestion
– CF LAB
Human Genome Project
• HGP – due for completion in 2002
• Already sequenced the Fruit Fly and E.
Coli
Gene Therapy
• Delivering the defective gene to the cells
that need it to produce a protein
• Cystic Fibrosis
• Vector – method of transporting a gene
(virus, plasmid)
– Mechanical - usually a laboratory tool
used (inoculating loop)
– Biological - part or whole of an organism
(bacteria)
Chromosome Mapping
• 30,000 human genes
• RFLPs – Restriction Fragment Length
Polymorphisms – used to tag a region
of DNA – visible under a microscope
• Restriction enzymes – sequence AA
• Specific base digestion
Sanger Method of DNA Sequencing
1.
Heat DNA Strands until they
separate
2. Add nucleotides and DNA
Polymerase
3. Add Dedeoxynucleotides (A, T, G,
and C) at different time periods to stop
replication
4. Place fragments in to Gel
Electrophoresis
5. Allow to migrate and read the Base
Sequence
Electrophoresis
Human Genome Project
• HGP – due for completion in 2002
• Already sequenced the Fruit Fly and E.
Coli
• The ultimate goal of HGP is to associate
human traits and inherited diseases with
particular genes.
• It promises to revolutionize both
therapeutic and preventive medicine
techniques for many human diseases.
Human Genome Project
• Genome - the complete collection of an
organism's genetic material.
• The human genome is composed of an
estimated 30,000
• A single human chromosome may contain
more than 250 million DNA base pairs,
and it is estimated that the entire human
genome consists of about 3 billion base
pairs.
DNA Fingerprinting
• Treat suspects’ blood with the same
restriction enzyme
• Place sample in Gel Electrophoresis
• Allow samples to migrate
• Compare the suspects with the blood
found at the crime scene
• Used in Criminal Trials: OJ Simpson
– OJ – DNA was an exact match yet he was
found not guilty?