One of the most fundamental functions of full folded proteins or speeding up chemical reactions
take place when reactants collide in precise orientations
if the reaction has enough kinetic energy to overcome repulsions between their negatively-charged electrons, chemical bonds may form However most chemical reactions are non productive
brings substrates together in precise orientations so the electrons involved in the reaction can interact.
Do enzymes affect the amount of kinetic energy?
must have kinetic energy for the reaction to proceed
brought together in very specific positions that facilitate reactions.
Very specific in which reactions they catalyze
The specificity of an enzyme is related to the structure of its active site
The site where the enzyme binds its substrate
R-groups in Active sites of enzymes
R-groups in the active sit may form short-lived covalent bonds that assist with the transfer of atoms or groups of atoms form one reactant to another.
some enzymes require these to function normally. These are either metal ions or small organic molecules called co enzymes.
most enzymes are regulated by molecules that are not part of the enzyme itself.
occurs when a molecule similar in size and shape to the substrate competes with the substrate for binding to the enzyme's active site
occurs when a molecule causes a change in enzyme shape by binding to the enzyme at a location other than the active site.
What limits the rate of catalysis?
the rate of product formation increases linearly for a given increase in substrate concentration at low substrate concentrations. At high substrate concentrations the reaction rate levels out, or saturates
all enzymes show this type of saturation kinetics
high substrate affinity:achieves maximum reaction rate rapidly as substrate concentration increases.
Low substrate affinity: achieves maximum rate only after reaching high substrate concentrations
What factors make an enzyme function best?
function best at specific temperatures and pH ranges.
temperature affects the movement of substrates and enzymes
pH affects the enzyme's shape and reactivity
Was the first "living" entity a protein?
some say that the first self-replicating molecule on Earth was a protein
Amino acids were abundant in prebiotic soup
Proteins are the most efficient catalysts known
The first self-replicating molecules had to act as catalysts for the assembly and polymerization of their copies
First self-replicator probably needed to have a mold or template-something not found in proteins
Nucleic Acid is what?
is a polymer of nucleotide building blocks
can for ribonucleic acids(RNA)
or Deoxyribonucleic acid (DNA)
What are Nucleotides compose of?
sugar group( 5 carbon sugar)
What does a phosphate group do?
provides a critical linkage site for nucleotide polymerization
unique because it gives nucleic acids an overall negative electrical charge
Sugar group & special properties
pentose sugar called ribose in RNA and deoxyribose in DNA
on RNA there is a OH group on the 2 prong carbon which give the molecule special properties
on DNA there is only a H group linked to the 2 prime carbon
give unique chemical properties to nucleotides
Pyrimidine bases- are C, U, T with only one ring
Purine-A, G and have 2 rings
U is found only in RNA and T is only in DNA
formation of a special covalent bond called a phosphodiester bond
this takes place between the phosphate group on the 5' carbon of one nucleotide and the -OH group on the 3' carbon of another nucleotide
formed via condensation reactions
Enzyme- catalyzed polymerization
happens in the cell and requires the addition of two extra phosphate groups to the nucleotide building blocks.
Nucleic acid polymers consist of a back bone. What is special about the backbone?
alternating sugar and phosphate group contributed to successive nucleotides in the chain
Nitrogenous bases jut out and away from the backbone to establish the primary structure
sequence of nucleotide letters
The sugar-phosphate backbone of a nucleic acid is _________?
one end has an unlinked 5' carbon, and the other end has an unlinked 3' carbon
How are sequences written and why?
Written 5'--> 3'
because this reflects the mechanism by which nucleotide are added to a growing nucleic acid molecule
Austrian biochemist, established two empirical rules for DNA in 1950
the total number of purines and pyrimidines is the same
the numbers of A's and T's are equal, and the numbers of C's and G's are equal
British Chemist and biologist, produced the raw x-ray crystallographic data that was used to devise the helical structure of DNA
New Zealand molecular biologist Devised methods for producing and photographing crystals of DNA. He also was the first to suggest DNA forms a helix
James Watson and Francis Crick
American and British molecular biologist, respectively, determined in 1953 that
DNA consist of two antiparallel nucleic acid strands that twist upon each other to form a double helix
the hydrophilic sugar-phosphate backbones of both nucleic acids face the exterior of the DNA molecule, and purine-pyrimidine pairs of nitrogenous bases face the interior
DNA strands form complementary base pairs A-T and G-C
The DNA double helix has two types of grooves that differ in size major & minor grooves
DNA's important features
Strict adherence to base pairing rules allows one strand to be "read" from the other. i.e. the strands are complementary to each other
Base pairing rules are H bonding chemistry cause the two strands to run in opposite direction i.e. the stands are anti parallel
How does DNA replicate?
Complementary base pairing provides a simple mechanism for DNA replications. i.e. each strand can serve as a template for the formation of a new complementary strand
requires two main steps
Separation of the double helix to expose the strands so that each may function as a template
Hydrogen bonding of deoxyribonucleic building blocks with complementary bases on the template strands, followed by phosphodiester bond formation b/w adjacent nucleotides to form the complementary strand
What is the result of DNA replication?
Both template strands have been copied perfectly to form two new double helices(daughter molecules)
Each new double helix consist of one strand from the original(parent) DNA molecules and one new strand.
Is DNA a catalytic molecule?
DNA's stability makes it good for genetic information
DNA is less reactive than RNA therefore is more resistant to chemical degradation. The resistance is largely attributed to the lack of hydroxyl group at the 2' position of the ribose sugars in each nucleotide
Stable molecules make bad catalysts
Some think RNA was first molecule not DNA
hydrated hydrocarbon composed of carbon, hydrogen, and oxygen atoms arranged as (CH2O)N
repeating chains of hydrated carbon form monosaccharides, or simple sugars, that are the building blocks of carbohydrates.
The structures of simple sugars differ in several key ways that help biologist and chemist define sugar building blocks
Triose-3 carbon atoms
Pentose- 5 carbon atoms
Hexose- 6 carbon atoms
What are the different locations of carbonyl group in Monosaccharides ?
Aldose sugars- have a carbonyl group at the end of the monosaccharides that forms a highly reactive aldehyde
Ketose sugars- have a carbonyl group in the middle of the monosaccharide that forms a reactive ketone
Spatial arrangement of Monosaccharides atoms
most of the carbon atoms in simple sugars are chiral centers- the same groups of atoms can be linked to these carbons in different orientations
The arrangement of the hydroxyl group at each chiral carbon atom defines the type of simple sugar.
Linear vs. Ring
dissolved in water at pH 7 or in solid form glucose(and many other hexoses) from six-membered rings called hemiacetals
the cyclization process produces two different forms or anomers of glucose
What is a polysaccharide?
polymeric carbonhydrates that are formed through condensation reactions b/w the hydroxyl groups on seperate monosaccharides. the condensation reactions produce special covalent bonds called GLYCOSIDIC LINKAGES
The monomers joined by ______ ______ can be ______ or _____________.
glycosidic linkages identical different
The glycosidic linkage can form between any ______ ______ _____, so the location and ______ of these bonds _____ _____.
two hydroxyl groups
Did polysaccharides have a role in the origin of life?
had little role in the origin of life because they lack the structural and chemical complexity of molecules that are able to catalyze chemical reactions
Functions of Carbohydrates
serve as building blocks in the synthesis of other molecules
indicate cell identity
Store chemical energy
Provide cells with fibrous structural materials
What do polysacchrides do instead of store information?
they display information on the outer surfaces of cells
present in the form of glycoprotiens and glycolipids
What is the definition Glycoprotiens and glycolipids
sugars that have been joined to proteins and lipids, respectively by strong covalent bonds.
What are glycoprotiens key for?
they are key for identification badges that function in cell-cell recognition and cell-cell signaling
Glycolipids help cells identify what?
regulate and overall fluidity of their membranes.
"outside" the cell locations
"internal" cell locations
Early in history of earth, KE of sunlight and heat were converted into chemical engergy when atmospheric __ ,___ ,___ were combined via covalent bonds to form ___ and ____.
CO2 CH4 NH3 H2CO HCN
Chemical energy is trapped in ______ ______ of sugars that are _____ via ______________.
covalent bonds produced photosynthesis
What does the energy locked in the covalent bonds of Carbs allow them to do?
participate in exergonic(energy releasing) chemical reaction that yield ATP
When is the energy cycle completed for carbohydrates?
when organisms use ATP to drive endergonic (energy requiring) reactions and perform cell work.
What do carbohydrates contain a lot of and what do they do?
contain a large amount of C-H bonds Yields energy for ATP production
Carbohydrates stored in plants for energy (potatoes)
energy storage, stored sugars in animals (liver and muscles)
What are starch and glycogen made out of?
alpha-glucose monomers joined by alpha-1, 4- glycosidic linkages. These linkages cause the sugar chains to form distinct helical structures
Branching occurs when in a starch or glycogen?
forms when glycosidic linkages form b/w carbon-1 of a glucose monomer on one strand and carbon-6 of a glucose monomer on another strand
Can starch be branched?
can be branched or unbranched
amylose is branched
amylopectin is unbranched
What does the enzyme amylase and phosphorylase do?
catalyze the hydrolysis of alpha-glycosidic linkages in glycogen and starch, respectively. The released glucose subunits then can be used for ATP production
What about structural carbohydrates?
have Beta-1, 4-glycosidic linkages that are difficult to hydrolyze-few enzymes have active sites that accommodate their geometry or have the reactive groups necessary
How do structural carbohydrates form?
form in long strands with bonds between adjacent strands.
may be organized into fibers or layered in sheets to give cells and organisms great strength and elasticity.
is a polymer of B-glucose monomers linked by B-1, 4-glycosidic linkages. It is found in plant cell walls
is a polymer of N-acteylglucosamine monomers linked by B-1, 4-glycosidic linkages. it is found in fungal cell walls and insect and crustacean exoskeleton
made up of two types of monosaccharides linked by B-1 and 4-glycosidic linkages. each monomer is cross linked to a chain of amino acids. and peptide bonds link the amino acid chains of adjacent strands. It is a component of bacterial cell walls
Want to see the other 68 Flashcards in Ch 3-7?JOIN TODAY FOR FREE!