Chapter 2- Cells
Cells
Protosomes is the living substance of the cell and includes:
a) Cytoplasm
b) Karyoplasm
The karyoplasm simply forms the contents of the nucleus.
The cytoplasm involves the contents of the cell excluding the nucleus.
The plasma membrane (plasmalemma) separates the cytoplasm from its extracellular
environment.
Cytoplasm is mainly H2O, and various organic and inorganic substances are dissolved or
suspended. The fluid suspension in the cytosol.
Plasma Membrane (Plasmalemma)
Chapter 3: Metabolism
Metabolism
Glycolysis
A total of 9 steps are involved in taking a glucose molecule into 2 molecules of pyruvate.
Glycolysis occurs in the cytosol. Each step is catalyzed by an enzyme. We have a net gain of
2 ATP. This represents anaerobic respiration. Anaerobic metabolism is the only energy
source in the mammalian red blood cells.
In the absence of O2, such as in muscle that is fatigued, the end product in the human body is
lactate.
Step 1: Is endergonic, thus nonspontaneous. The reaction is driven by coupling it with a
reaction that is exergonic, namely ATP hydrolysis.
,Once phosphorylated, the molecule cannot leave the cell. It is destined to go forward. We have
an irreversible step at the start of the pathway.
Glycolysis has a three-part strategy:
1) It phosphorylates glucose, forming glucose-6-phosphate
2) It converts low energy phosphates to high energy phosphates
3) It used high energy phosphates to convert ADP to ATP
A kinase will catalyze the transfer of a phosphate group from a high energy molecule such as
ATP.
Glucose: C6H12O6… an aldohexose
Fructose: C6H12O6… a ketohexose
If you see NAD+, NADH, FAD, FADH2… you are most likely dealing with dehydrogenase.
Since an ATP is transferred, a kinase is involved. This is called the substrate-level
phosphorylation. In substrate level phosphorylation, we see the formation of ATP or GTP by
the direct transfer of a phosphoryl group (PO3) to ADP or GDP from another phosphorylated
compound.
If O2 is lacking, lactate and NAD+ is made.
Pyruvate is reduced; NADH is oxidized.
The Krebs Cycle or TCA Cycle
The Krebs cycle is also called TCA cycle.
It occurs in the matrix of the mitochondria and represents aerobic respiration.
If O2 is present, pyruvate combines with a molecule called Coenzyme A.
In the matrix, this is called an oxidative decarboxylation-CO2 is lost by pyruvate
The TCA cycle dismantles acetyl groups converting them into CO2 and H+ and H+ into the
electron transport chain to produce ATP.
Succinic dehydrogenase is part of the inner mitochondrial membrane
Chapter 4: Acid-Base Balance
,Blood pH is approximately 7.4
Below 7.35= Acidosis
Above 7.45= Alkalosis
In Acidosis, we see a depression of CNS synaptic transmission. Disorientation and coma can
result. Death soon follows.
In Alkalosis, we see hyperexcitability in CNS and PNS with extreme nervousness and spasm
of the muscle. Death can result if untreated.
The pH balance can be easily upset. CO2, lactic acid, ketone bodies, etc. can all contribute to
lowering the blood pH.
Three main mechanisms can help maintain pH:
1) Buffers
2) CO2 removal by the lungs
3) H+ removal by the kidneys
Buffer
A buffer helps maintain pH. Buffers can release or gain H+. If a small amount of OH- ions are
introduced into the a buffer solution, the conjugate acid will react with it. If a small amount of
hydronium ion is added, the conjugate base reacts with it. These buffers act as “sponges”.
The principle intracellular buffer is the phosphate buffer.
The principle blood buffer is bicarbonate.
Acidosis and Alkalosis can be classified as respiratory or metabolic.
Respiratory Alkalosis
pH > 7.45
Loss of CO2 occurs…hyperventilation!!
When CO2 levels increase, the respiratory center in the brain tells you to breath more rapidly.
, This happens in cases of severe anxiety, early stages of aspirin overdose, O2 deficiency in high
altitude (The rising CO2 and H+ ions are sensed by chemoreceptors in the carotid artery and
the brain receives the message).
Respiratory Acidosis
pH <7.35
Here we interfere with H+ loss.
People with Emphysema will hypoventilate and the CO2 loss is hindered. If CO2 is not
removed from the lungs fast enough, it “backs up” and H+ will not be removed by HCO3-.
Airway obstruction, or if a drug is given that depresses the respiratory center, Asthma and
pneumonia too!
Metabolic Acidosis
pH <7.35
This may be due to loss of HCO3- ions through kidney dysfunction or severe diarrhea.
Laxative abuse as well.
Accumulation of metabolic acids such as seen in diabetes mellitus…think ketone bodies!
Coma and death could result.
Metabolic Alkalosis
pH >7.45
This occurs when loss of acids seen. Repeated vomiting of gastric contents, or if you take to
much antacids
Chapter 5: Enzymes
Enzymes
Most enzymes are proteins in nature and function as biological catalysts
They act as catalysts (lower the energy of activation)
Cells
Protosomes is the living substance of the cell and includes:
a) Cytoplasm
b) Karyoplasm
The karyoplasm simply forms the contents of the nucleus.
The cytoplasm involves the contents of the cell excluding the nucleus.
The plasma membrane (plasmalemma) separates the cytoplasm from its extracellular
environment.
Cytoplasm is mainly H2O, and various organic and inorganic substances are dissolved or
suspended. The fluid suspension in the cytosol.
Plasma Membrane (Plasmalemma)
Chapter 3: Metabolism
Metabolism
Glycolysis
A total of 9 steps are involved in taking a glucose molecule into 2 molecules of pyruvate.
Glycolysis occurs in the cytosol. Each step is catalyzed by an enzyme. We have a net gain of
2 ATP. This represents anaerobic respiration. Anaerobic metabolism is the only energy
source in the mammalian red blood cells.
In the absence of O2, such as in muscle that is fatigued, the end product in the human body is
lactate.
Step 1: Is endergonic, thus nonspontaneous. The reaction is driven by coupling it with a
reaction that is exergonic, namely ATP hydrolysis.
,Once phosphorylated, the molecule cannot leave the cell. It is destined to go forward. We have
an irreversible step at the start of the pathway.
Glycolysis has a three-part strategy:
1) It phosphorylates glucose, forming glucose-6-phosphate
2) It converts low energy phosphates to high energy phosphates
3) It used high energy phosphates to convert ADP to ATP
A kinase will catalyze the transfer of a phosphate group from a high energy molecule such as
ATP.
Glucose: C6H12O6… an aldohexose
Fructose: C6H12O6… a ketohexose
If you see NAD+, NADH, FAD, FADH2… you are most likely dealing with dehydrogenase.
Since an ATP is transferred, a kinase is involved. This is called the substrate-level
phosphorylation. In substrate level phosphorylation, we see the formation of ATP or GTP by
the direct transfer of a phosphoryl group (PO3) to ADP or GDP from another phosphorylated
compound.
If O2 is lacking, lactate and NAD+ is made.
Pyruvate is reduced; NADH is oxidized.
The Krebs Cycle or TCA Cycle
The Krebs cycle is also called TCA cycle.
It occurs in the matrix of the mitochondria and represents aerobic respiration.
If O2 is present, pyruvate combines with a molecule called Coenzyme A.
In the matrix, this is called an oxidative decarboxylation-CO2 is lost by pyruvate
The TCA cycle dismantles acetyl groups converting them into CO2 and H+ and H+ into the
electron transport chain to produce ATP.
Succinic dehydrogenase is part of the inner mitochondrial membrane
Chapter 4: Acid-Base Balance
,Blood pH is approximately 7.4
Below 7.35= Acidosis
Above 7.45= Alkalosis
In Acidosis, we see a depression of CNS synaptic transmission. Disorientation and coma can
result. Death soon follows.
In Alkalosis, we see hyperexcitability in CNS and PNS with extreme nervousness and spasm
of the muscle. Death can result if untreated.
The pH balance can be easily upset. CO2, lactic acid, ketone bodies, etc. can all contribute to
lowering the blood pH.
Three main mechanisms can help maintain pH:
1) Buffers
2) CO2 removal by the lungs
3) H+ removal by the kidneys
Buffer
A buffer helps maintain pH. Buffers can release or gain H+. If a small amount of OH- ions are
introduced into the a buffer solution, the conjugate acid will react with it. If a small amount of
hydronium ion is added, the conjugate base reacts with it. These buffers act as “sponges”.
The principle intracellular buffer is the phosphate buffer.
The principle blood buffer is bicarbonate.
Acidosis and Alkalosis can be classified as respiratory or metabolic.
Respiratory Alkalosis
pH > 7.45
Loss of CO2 occurs…hyperventilation!!
When CO2 levels increase, the respiratory center in the brain tells you to breath more rapidly.
, This happens in cases of severe anxiety, early stages of aspirin overdose, O2 deficiency in high
altitude (The rising CO2 and H+ ions are sensed by chemoreceptors in the carotid artery and
the brain receives the message).
Respiratory Acidosis
pH <7.35
Here we interfere with H+ loss.
People with Emphysema will hypoventilate and the CO2 loss is hindered. If CO2 is not
removed from the lungs fast enough, it “backs up” and H+ will not be removed by HCO3-.
Airway obstruction, or if a drug is given that depresses the respiratory center, Asthma and
pneumonia too!
Metabolic Acidosis
pH <7.35
This may be due to loss of HCO3- ions through kidney dysfunction or severe diarrhea.
Laxative abuse as well.
Accumulation of metabolic acids such as seen in diabetes mellitus…think ketone bodies!
Coma and death could result.
Metabolic Alkalosis
pH >7.45
This occurs when loss of acids seen. Repeated vomiting of gastric contents, or if you take to
much antacids
Chapter 5: Enzymes
Enzymes
Most enzymes are proteins in nature and function as biological catalysts
They act as catalysts (lower the energy of activation)
