Unit 2: Metabolism and Survival Flashcards
What is a metabolic pathway?
a metabolic pathway is an intergrated and controlled pathway of enzyme catalysed reactions within a cell
what kind of steps do metabolic pathways have?
revirsable and irreversible steps, and alternative routes
catabolic pathways
the breakdown of large molecules into smaller molecules, releasing energy
anabolic pathways
build up (biosynthesis) large molecules from small molecules, require energy
connection between catabolic and anabolic pathways
the energy released from the catabolic pathways is transferred to the anabolic pathways
fermentation in animals equation
glucose –> pyruvate –(reversiable - oxygen is produced) —> lactate
fermentation in plants and yeast equation
glucose –> pyruvate –> ethanol and CO2
what happens when metabolic pathways are modified?
they can contain alternative routes, so that steps can be passed
when are alternative routes used by a cell?
when a cell has a plentiful supply of sugar
what controls the entry and exist of substances in a cell?
the cell membrane
describe the fluid mosaic model
- a double layer that is constantly moving
- it is made up of phospholipid molecules and proteins
how do large molecules cross the cell membrane?
they depend on protein carrier molecules
what do transport proteins contain?
pores or channels
where are protein pumps/carrier molecules found
on the cell membrane
what do protein pumps do?
transfer specific ions across the membrane
what is the role of protein pores/channels?
to allow specific substances to diffuse across the membrane
how do protein pumps work
actively pump ions in and out of their cell
do protein pumps pump against or with the concentration gradient?
against the concentration gradient
what do protein pumps require for active trasport of ions/molecules?
energy
how do protein pumps get energy?
from respiration
what are protein pumps affect by?
the availability of oxygen, food, and temperature
where are enzymes embedded?
in membranes
what is the relationship between enzymes and metabolic pathways?
metabolic pathways are controlled by the presence or absence of enzymes, regulating the rate of reaction
what is the meaning of enzymes that are continually expressed?
the enzymes are always present in the cell
what is the result of the absence of catalysts?
most reactions in biological systems would take place too slowly to produce products at an adequate place for metabolising organisms
connection between catalysts and enzymes
enzymes are biological catalysts
what do catalysts do?
increase/speed up chemical reactions
what are the shapes of enzymes?
they are globular proteins
what are the three qualities of enzymes as catalysts?
- lowers the activation energy
- speeds up the rate of reaction
- takes part in but is unchange by the reaction
what is activation energy?
the energy required to break thhe bonds of the reactants to produce products
when do the bonds of reactants break?
when the reactants have obsorbed enough energy to make them stable
2 steps of induced fit
- substrate binds to the enzyme at the active site
- binding of the substrate induces the enzyme’s active site to change shape so that there is an exact fit once a substrate is bound
after what process can reactions occur?
after induced fit has occured
what happens to the active site when a reaction involved two or more substrates?
The shape of the active site helps orientate the reactants in the correct position so a reaction can take place
what are the 5 stages of the substrate bonding to the active site?
- the substrate molecules have a high affinity for the active site
- the active site holds the reactants together in an induced fit
- the chemical bonds in the reactants are weakened, the activation energy is lowered
- the products now have a low affinity for the active site and are released
- the active site the enzyme is free to repeat the process
what is the third stage of the substrate bonding to the active site?
the chemical bonds in the reactants are weekend, the activation energy is lowered
what is the fifth stage of the substrate bonding to the active site?
the active site the enzyme is free to repeat the process
what is the second stage of the substrate bonding to the active site?
the active site holds the reactants together in an induced fit
what is the forth stage of the substrate bonding to the active site?
the products now have a low affinity for the active site and are released
what is the first stage of the substrate bonding to the active site?
the substrate molecules have a high affinity for the active site
high affinity
a strong sense of attraction of two substances
low affinity
a weak sense of attraction of two substances
what is the result of low substrate concentration on the product(s)?
low product concentration
what is the result of high substrate concentration on the product(s)?
more product formation, increased rate of reaction
what is the result of a further increase in substrate concentration?
maximum product formation, max. rate of reaction
what is the result of excess substrate concentration?
no further increase in product formation, max. rate maintained
(max rate of reaction) despite the increasing substrate concentration, there is ……..
no further increase in product formation
example of a metabolic pathway
metabolite W –> metabolite X –> metabolite Y –> metabolite Z
arrows: enzymes
when are enzymes activated in metabolic pathways?
when the metabolites become available
what are most enzyme reactions?
reversible
what is always maintained during enzyme catalysed metabolic pathways?
balance is always maintained
how do enzyme inhibitors affect the rate of reaction?
it decreases the rate of reaction
competitive inhibitors
molecules that will compete with the normal substrate for the reaction
compare the shapes of normal substrates with competitive inhibitors
the competitive inhibitors are similar in shape to the normal substrates
what happens when the substrate concentration is low?
(in relation to inhibitors)
the inhibitors successfully compete for the active site
what happens when substrate concentration is low?
(in relation to products formed)
fewer substrate molecuels are converted into products and the rate of reaction is reduced
when are the effect of the competitive inhibitors overcame?
when the high concentration of substance molecules compete successfully for the active site of enzymes
when is maximum reaction rate achieved?
at high substance concentration
what do competitive inhabitors compete with?
the usual substrate
what do the competitive inhabitors compete for?
the oppurtunity to bind with the active site of enzymes
how can the effect of competitive inhabitors be reversed?
increasing the substance concentration
biosynthesis
Build up of large molecules
Bring about the breakdown of large molecules into smaller ones, releasing energy
Catabolic pathways
Bring about the buildup of large molecules from small molecules, require energy
Anabolic pathways
Example of catabolic pathway
Respiration
Example of anabolic pathway
Protein synthesis
What type of metabolic pathway is respiration an example of
Catabolic
What type of metabolic pathway is protein synthesis an example of
Anabolic
Where do metabolic pathways happen?
The cell cytoplasm
What are metabolic pathways sped up by?
Enzymes – biological catalysts
what are metabolic pathways controlled by?
Enzymes
When would alternative route be used in metabolic pathways?
When cells have a plentiful supply of sugar
Does diffusion require energy
No – it is passive
What is the name of the movement of molecules from a high concentration to a low concentration?
diffusion
diffusion
the movement of molecules from a high concentration to a low concentration
only ____ _____ molecules can diffuse through protein pores
very small
how do large molecules move across the membrane?
through protein molecules
what do transport protein molecules contain?
pores/channels
protein channels only allow ________ substances to diffuse across the membrane
specific
what are protein pumps also known as?
carrier molecules
where are protein pumps located?
on the cell membrane
what do protein pumps do?
transfer specific ions across the membrane
what structure transfers specific ions across the membrane
protein pumps
do protein pumps require energy?
yes, it is active transport
where do protein pumps source their energy from?
respiration
what three things are protein pumps affected by?
- availability of oxygen
- availability of food
- temperature
without what would most reactions in biological systems would take place too slowly to produce products at an adequate place for metabolising organisms
catalysts
enzymes ________ the rate of reaction by ____________ the activation energy
increase, lowering
what happens after induced fit has occurred?
chemical reaction
first step of induced fit
- substrate binds to the enzyme at the active site
second step of induced fit
binding of the substrate induces the enzyme’s active site to change shape so that there is an exact fit once a substrate is bound
stage 1 of substrate binding to active site
- the substrate molecules have a high affinity for the active site
stage 2 of substrate binding to active site
- the active site holds the reactants together in an induced fit
stage 3 of substrate binding to active site
- the chemical bonds in the reactants are weekend, the activation energy is lowered
stage 4 of substrate binding to active site
- the products now have a low affinity for the active site and are released from the active site
stage 5 of substrate binding to active site
- the active site the enzyme is free to repeat the process
a strong sense of attraction of two substances
high affinity
a weak sense of attraction of two substances
low affinity
low product concentration
low substrate concentration
more product formation, increased reaction rate
high substrate concentration
max. product formation, max rate of reaction
further increase in substrate concentration
no further increase in product formation, maximum reaction rate maintained
excess substrate concentration
metabolite W –> metabolite X –> metabolite Y –> metabolite Z
arrows: enzymes
what happens when metabolite W becomes available?
enzyme 1 is activated and converts W to Z
metabolite W –> metabolite X –> metabolite Y –> metabolite Z
arrows: enzymes
what happens when metabolite x becomes available?
enzyme 2 is activated and converts X to Y
where do non competitive inhibitors attach to on enzymes?
a position away from the active site
what effect does a non competitive inhibitor have on the active site?
changes the shape
What do noncompetitive inhibitor prevent the substrate from doing
Binding to the active site
What is the effect of non-competitive inhibitor is on product formation?
Stops the formation of product as induced fit cannot be achieved
What effect do noncompetitor inhibitors have on reaction rate?
Reduce the reactionary
Add to high substrate concentration, all enzyme active sites are ______
occupied
can max reaction rate ever be achieved with a non competitive inhibitor?
no, it cannot be overcome by increasing substrate concentration
what do non competitive inhibitors do
prevent bound substrate being converted into product
compare without inhibitor, with competitive inhibitor, and non competitive
Substrate can normally bind to active site of an enzyme
competitive inhibitor mimics substrate and competes for active site
noncompetitive inhibitor alters conformation of enzymes so active site is no longer fully functional
When does feedback inhibition occur
When an end product in the metabolic pathway reaches a critical concentration
What does feedback inhibition prevent
Wasteful conversion and accumulation
Cellular respiration
A series of biochemical reactions that allow a cell to generate energy
A series of biochemical reactions that allow a cell to generate energy
Cellular respiration
Cellular respiration
A series of biochemical reactions that allow a cell to generate energy
In human cells, reactions occur to convert glucose into —-
Adenosine triphosphate
Full name of ATP
Adenosine triphosphate
What is ATP
Energy rich molecule
What kind of reaction is respiration
Catabolic
Describe how respiration is catabolic
It is the break down of large nutrient molecules into smaller ones and releases energy used to drive other reactions
It is the break down of large nutrient molecules into smaller ones and releases energy used to drive other reactions
How respiration is catabolic
Word equation for aerobic respiration in animals
Glucose and oxygen —> carbon dioxide + water + energy
Glucose and oxygen —> carbon dioxide + water + energy
Word equation for aerobic respiration in animals
What are carbs broken down into during aerobic respiration
Smaller glucose molecules
What does the breakdown of carbs produce
Energy
What happens when glucose enters the cell
It is burnt
What is the process called when glucose is burnt
Combustion
Where does combustion happen in a cell
Mitochondria
What happens to glucose in the mitochondria
It is burnt - combustion
Reactants of aerobic respiration
Oxygen and glucose
Oxygen and glucose
Reactants of aerobic respiration
Waste products of aerobic respiration
Carbon dioxide and water
What happens to the waste products of aerobic respiration
They are carried by the blood to the alveoli into the air (out of the body)
They are carried by the blood to the alveoli into the air (out of the body)
What happens to the waste products of aerobic respiration
As you get closer to the ribose, the phosphate bonds hold ____ energy
Less
As you get closer to the ribose, the _______ bonds hold less energy
Phosphate
Three parts of ATP molecule
(left to right)
Adenosine, ribose, three Phosphates
Adenosine, ribose, three Phosphates
Three parts of ATP molecule
(left to right)
When is energy held in an ATP molecule released
When the bond attaching the terminal phosphate molecule is broken by enzyme activity
When the bond attaching the terminal phosphate molecule is broken by enzyme activity
When is energy held in an ATP molecule released
What is the terminal phosphate
The phosphate molecule furthest from the ribose
What does ATP become when you break the terminal phosphate
ADP adenosine diphosphate
ADP adenosine diphosphate
What does ATP become when you break the terminal phosphate
What is required to regenerate ATP from ADP and Pi
Energy
What does ADP act as
The link between catabolic and anabolic reactions
What acts as the link between catabolic and anabolic reactions
ADP
What is ATP
The carrier and regulation-storage unit of energy
The carrier and regulation-storage unit of energy
What is ATP
What can ATP be used for (examples)
Muscle cell contractions
Cell division
Protein synthesis
Transmission of nerve impulses
Muscle cell contractions
Cell division
Protein synthesis
Transmission of nerve impulses
What can ATP be used for (examples)
Phosphorylation
An enzyme-controlled process by which a phosphate group is added to a molecule
An enzyme-controlled process by which a phosphate group is added to a molecule
Phosphorylation
ATP is not ….
Stored
Example of phosphorylation
The formation of high energy molecule, ATP
The formation of high energy molecule, ATP
Example of phosphorylation
What is ATP used for
To transfer energy to cellular processes which require energy
To transfer energy to cellular processes which require energy
What is ATP used for
When does phosphorylation also occur
When phosphate and energy are transferred from ATP to the molecules of a reactant in a metabolic pathway making them more reactive
When phosphate and energy are transferred from ATP to the molecules of a reactant in a metabolic pathway making them more reactive
When does phosphorylation also occur
Glycolysis
The breakdown of glucose to pyruvate in the cytoplasm
The breakdown of glucose to pyruvate in the cytoplasm
Glycolysis
Where do all chemical reactions happen
The cytoplasm
Three points on glycolysis
Occurs in the cytoplasm
A molecule of glucose is broken down into pyruvate
Enzyme controlled steps
Stage 1 of glycolysis
Energy investment stage, 2 ATP molecules used
Energy investment stage, 2 ATP molecules used
Stage 1 of glycolysis
Stage 2 of glycolysis
Energy pay off stage, 4 ATP molecules produced
Energy pay off stage, 4 ATP molecules produced
Stage 2 of glycolysis
What is ATP required for in relation to glycolysis
For the phosphorylation of glucose and intermediates during the energy investment stage
For the phosphorylation of glucose and intermediates during the energy investment stage
What is ATP required for in relation to glycolysis
what is the net gain of glycolysis
2 ATP molecules
What does coenzyme NAD do
During glycolysis, Picks up hydrogen ions released by a dehydrogenase enzyme
During glycolysis, Picks up hydrogen ions released by a dehydrogenase enzyme
What does coenzyme NAD do
In glycolysis, what releases hydrogen ions
Dehydrogenase enzyme
During glycolysis, what does dehydrogenase enzyme release
Hydrogen ions
What was the end product of glycolysis
Pyruvate
how many carbons foes an acetyl group have
2
what is NADH made up of
H+ ions and NAD
In the citric acid cycle, what does acetyl group of coenzyme A combine with?
oxaloacetate
In the citric acid cycle, what does oxaloacetate combine with?
the acetyl group of coenzyme A
in the citric acid cycle, what does the combination of coenzyme A and oxaloacetate form?
citrate
what is citrate made up of?
coenzyme A and oxaloacetate
where does the breakdown of glucose to pyruvate occur
cytoplasm
where does the further breakdown of pyruvate occur
mitchondria
what is the second stage of respiration
the citric acid cycle
what stage in the citric acid cycle in respiration
stage 2
where does the citric acid cycle happen
the matrix of the mitochondrion
what cycle occurs in the matrix of the mitochondrion
the citric acid cycle
what is required for the phosphorylation of glucose and intermediates during stage 1 of glycolysis
ATP
what is pyruvate broken down into in aerobic conditions
an acetyl group
what does the combination of an acetyl group and coenzyme A produce
acetyl coenzyme A
what is acetyl coenzyme A made up of
acetyl group and coenzyme A
the breakdown of what produces an acetyl group
pyruvate
in what conditions does the breakdown of pyruvate into an acetyl group occur
aerobic conditions
what happens in the citric acid cycle
A) the acetyl group combines with coenzyme A to form acetyl coenzyme A
B) the acetyl group from acetyl coenzyme A combines with oxloacetate to form citrate
C) during enzyme controlled steps, citrate is gradually converted back into oxloacetate
—> resulting in the generation of ATP and release of carbon dioxide.
D) H+ ions and electrons are passed to the coenzyme NAD to form NADH
E)NADH passes its H+ ions to the electron transport chain
A) the acetyl group combines with coenzyme A to form acetyl coenzyme A
B) the acetyl group from acetyl coenzyme A combines with oxloacetate to form citrate
C) during enzyme controlled steps, citrate is gradually converted back into oxloacetate
—> resulting in the generation of ATP and release of carbon dioxide.
D) H+ ions and electrons are passed to the coenzyme NAD to form NADH
E) NADH passes its H+ ions to the electron transport chain
stages of the citric acid cycle
part A of the citric acid cycle
the acetyl group combines with coenzyme A to form acetyl coenzyme A
part B of the citric acid cycle
the acetyl group from acetyl coenzyme A combines with oxloacetate to form citrate
the acetyl group from acetyl coenzyme A combines with oxloacetate to form citrate
part B of the citric acid cycle
the acetyl group combines with coenzyme A to form acetyl coenzyme A
part A of the citric acid cycle
what do dehydrogenase enzymes do
remove hydrogen ions and electrons and pass them to the coenzyme NAD, forming NADH
remove hydrogen ions and electrons and pass them to the coenzyme NAD, forming NADH
what dehydrogenase enzyme does
when does dehydrogenase enzymes remove hydrogen ions and electrons
glycolysis and the citric acid cycle
in the citric acid cycle, what gets passed to the electron transport system chain
the hydrogen ions and electrons from NADH
what is part B of the citric acid cycle controlled by
enzymes
what is formed in part B of the citric acid cycle
citrate
what is produced in the conversion of citrate into oxaloacetate
ATP and carbon dioxide
what do dehydrogenase enzymes do in the citric acid cycle
remove H+ ions from the respiratory substrate along with associated electrons
what enzyme removes H+ ions from the respiratory substrate along with associated electrons
dehydrogenase enzymes
in the citric acid cycle, what are passed to the coenzyme NAD
H+ ions and electrons
in the citric acid cycle, what are H+ ions and electrons passed to (to form NADH)
coenzyme NAD
what do coenzyme NAD and H ions and electrons form in the citric acid cycle
NADH
what is NADH made up of
coenzyme NAD and H+ ions
what happens to NADH when it is formed
its passed to the electron transport chain
what is passed to the electron transport chain when it is formed
NADH
where is the electron transport chain
the inner mitochondrial membrane
what is the electron transport chain
a series of carrier proteins attached to the inner mitochondrial membrane
a series of carrier proteins attached to the inner mitochondrial membrane
the electron transport chain
in the electron transport chain, where does the NADH come from
the glycolysis and the citric acid cycle
what is produced in glycolysis and the citric acid cycle
NADH
what does NADH do
release electrons and pass them on to the electron transport system
what releases electrons and pass them on to the electron transport system
NADH
what do electrons release as they go through the electron transport chain
energy