Metabolism Flashcards
What is the first step of glycolysis?
Glucose enters the cell and is phosphorylated. A molecule of ATP is invested. The product is 6-glucose phosphate.
What is the second step of glycolysis?
Glucose 6-phosphate is rearranged to form fructose 6-phosphate.
What is the 3rd step of glycolysis?
The phosphate group from another ATP is used to produce fructose 1, 6- diphosphate, still a 6 carbon compound (2 ATP are invested at this point.
What is the 4th step of glycolysis?
An enzyme splits the sugar into 2 3-carbon molecules: dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GP)
What is the 5th step of glycolysis?
DHAP is readily converted to GP the reverse reaction may occur.
What is the 6th step of glycolysis?
The next enzyme converts each GP to another 3-carbon compound 1,3-diphosphoglyceric acid. Because each DHAP molecule can be converted to GP and each GP to 1, 3-diphosphoglyceric acid for each initial molecules of glucose. GP is oxidized by the transfer 2 hydrogen atoms to NAD+ to form NADH. The enzyme couples this reaction with the creation of a high-energy bond between sugar and a phosphate group. The 3 carbon sugar now has 3 phosphate groups.
What is the 7th step of glycolysis?
The high energy phosphate group is moved to ADP, forming ATP, the first ATP production of glycolysis. Since step 4 all products are doubled, therefore, this step is actually repays the earlier investment of 2 ATP molecules.
What is the 8th step of glycolysis?
An enzyme relocates the remaining phosphate group of 3-phosphoglyceric acid to form 2-phosphoglyceric acid in preparation for the next step.
What is the 9th step og glycolysis?
By the loss of a water molecule 2-phosphoglyceric acid is converted into phosphoenolpyruvic acid (PEP). In the process, the phosphate bond is upgraded to a high energy bond.
What is the 10th step of glycolysis?
The high energy phosphate bond is transferred from PEP to ADP, forming ATP. For each initial glucose molecule, the result of this step is 2 molecules of ATP and 2 molecules of a 3-carbon compound called pyruvic acid.
What is another name for glycolysis?
Embden-Meyerhof pathway
Phosphorylation
The transferring of phosphate group from a donor to the recipient molecule.
Cellular respiration
ATP generating process in which molecules are oxidized and the final electron acceptor comes from outside the cell and is almost always an inorganic molecule.
Glycolysis
The oxidation of glucose to pyruvic acid, usually the 1st stage in carbohydrate catabolism.
Oxidation
- the removal of electrons from an atom or molecule, a reaction that often produces energy
- the removal of one or more electrons from a substrate. Protons H+ are often removed with electrons
Reduction
a molecule has gained one or more electrons
Redox reaction
- Oxidation and reduction reactions are always coupled; each time a substance is oxidized another is simultaneously reduced.
- oxidation reaction paired with reduction reaction
Metabolism
The sum of all chemical reactions in an organism
Catabolism
The breakdown of complex molecules into monomers; provides energy and building blocks for anabolism
Anabolism
Uses energy and building blocks to build large molecules from monomers.
What links catabolic and anabolic reactions?
energy, catabolic reactions provide energy for anabolic reactions.
Energy+monomers =
macromolecule
during catabolism macromolecules are being broken down into ___________.
monomers and energy
How does catabolism release energy ?
by the oxidation of molecules
Anabolism uses ________
energy to synthesize macromolecules that make up the cell
ATP stores_________.
energy
Energy is released by __________ of ATP.
hydrolysis
ADP + inorganic phosphate+ energy =
ATP
ATP - Energy =
ADP and inorganic phosphate
What are metabolic pathways determined by?
enzymes which are encoded by genes different genes means different proteins (enzymes being made) = different metabolic pathways
Enzymes are encoded by
genes
Catabolic reactions transfer energy from
complex molecules to ATP
Anabolic reactions transfer energy from
ATP to complex molecules
Although microbes can cause disease and food spoilage many metabolic pathways are ____________.
beneficial
The pharmaceutical industry uses microbes such as ______________
bacteria and fungi to make antibiotics
vitamins, vaccines, antibiotics, and enzymes are dirived from ____________.
microbial metabolism
What is the big picture of the function of an enzyme?
they facilitate metabolic reactions
Most living things use __________ to manage energy needs.
ATP
Catabolic reactions couple with _____________.
ATP synthesis
Anabolic reactions couple with _________.
ATP break down
Chemical reactions
Chemical reactions can occur when atoms, ions, and molecules collide
Activation energy
Activation energy is needed to disrupt existing bonds, even in spontaneous reactions
Reaction rate
Reaction rate is the rate of formation of products from reactants.
A reaction rate can be increased by
Enzymes, temperature or pressure
Why does a reaction rate increase when pressure is applied to reactants?
The reactants are in closer proximity to each other which increases the likelihood of a reaction occuring
Why does a reaction rate increase when temperature is increased?
heat will energize the molecules and cause them to move faster; increasing the chances that the molecules will collide and a reaction will occur.
Why do enzymes increase reaction rates?
because they ether bend bonds between molecules allowing substrates to be broken down more easily, or they bring molecules closer together and position them to increase the chances of a chemical reaction.
Enzymes help to increase the likeihood of chemical reactions by _____________.
reducing the activation energy need elicit a chemical reaction. Enzymes are catalysts.
Enzymes
Biological catalysts; specific; not used up in that reaction
What are the components of an enzyme?
Apoenzymes, Cofactors, Holoenzymes
Coenzyme
an organic cofactor
Apoenzyme
inactive protein portion of an enzyme
Cofactor/coenzyme
non-protein agent which activates the enzyme by binding to the Apoenzyme.
Holoenzyme
whole, complete active enzyme. Made up of apoenzyme and cofactor
Examples of Coenzymes
NAD+, NADP+, FAD
The names of enzymes usually end in _________.
-ase
enzymes can be grouped into ____ classes
6; according to the type of chemical reaction they catalyze
Enzymes within the 6 classes are named after _________.
the specific types of reactions they assist
oxidoreductases
enzymes which are involved in oxidation-reduction reactions; oxygen or hydrogen are gained or lost. ex. cytochrome oxidase, lactate dehydrogenase
What are enzymes in oxioreductase class remove hydrogen from substances?
dehydrogenase; those that add electrons to molecular oxygen (O2) are called oxidases
Transferase
responsible for transfer of functional groups amino group, acetyl group or phosphate group ex. Acetate kinase, alanine deaminase
Hydrolase
responsible for hydrolysis (addition of water) ex. lipase and sucrase
Lyase
responsible for removal of groups of atoms without hydrolysis ex. Oxalate decarboxylase and isocitrate lyase
Isomerase
Responsible for rearrangement of atoms in a molecule ex. Glucose-phosphate isomerase, alanine racemase
Ligase
responsible for joining of 2 molecules (usually using energy from the break down of ATP) ex. Acetyl CoA synthase, DNA ligase
How does the mechanism of enzymatic reactions work?
- An enzyme molecule has an active site where it binds the substrate molecule
- The reaction between the substrate molecule and enzyme forms a complex and may temporarily alter the active site slightly
- The enzyme molecule brakes apart the substrate molecule
- 2 end products result from the reaction and are released from the enzyme.
- The enzyme molecule remains unchanged and is recycled.
What are the factors that influence enzyme activity
- Temperature
- pH
- Substrate concentration
- Inhibitors
Enzymes can become __________ by inappropriate pH or temp.
denatured
enzyme activity/ reaction rate increases with temperature until
the enzyme reaches a point where it becomes denatured and can no longer facilitate reactions
why are catabolic and anabolic reactions important?
they allow an organism to grow and reproduce by providing energy and the monomers necessary to build macromolecules
when glucose is transormed into ATP where do the electrons go?
they will be transferred to oxygen
During each chemical reaction in a metabolic pathway there is ___________.
an enzyme facilitating the reaction
What is the energy level of ADP?
low
What is the enegy level of ATP?
high; due to the ustable bonds between the phosphate groups
energy is stored in the bonds between ________.
carbon atoms
sunlight is converted into glucose in plants the glucose in plants then ________.
powers the biochemical reactions of animals
ADP is provided by the ___________.
constant breakdown of ATP.
why ae enzymes needed by living things?
because most chemical reactions are too slow to be compatible with life.
you need 2 things to convert a molecule into another
- activation energy
- enzymes
Enzymes are ___________.
biological catalysts made by living cells to help lower the activation energy of a biochemical reaction
the same enzyme can continue facilitating reactions as long as________.
substrate is available
some enzymes cannot work without ________.
cofactors
Lock and key model
- the shape of the enzyme is specific to its substrate
- Enzymes have a very specific 3 dementional shape
- when you disrupt the 3d shape of an enzyme, you change the shape of the activation site and it can no longer bind with its substrate.
- Denaturation is loss of the enzyme’s 3d structure
When there is low [substrate] enzymes work _______.
slower because substrate molecules are spread out.
Enzymes convert _________ to __________.
- reactions
- products
optimum pH/ Temperature
the temp/ pH at which enzymes best function
when is an enzyme considered denatured?
when it can no longer work
Why do amalyse enzymes stop working when they reach the stomach?
because the pH of the enviornment is too low and causes denaturation.
do all enzymes work at the same pH or temperature?
no, different enzymes have different optimal pH and temperatures
what are the types of inhibitors
- competitive inhibitors
- non-competitive (allosteric) inhibitors