Lecture: Metabolism Flashcards
What is metabolism?
Metabolism refers to all chemical reactions that occur in the body.
What is catabolism?
Catabolism is a type of metabolism: the breaking down of complex molecules into simpler forms.
Why type of reaction is catabolism?
Catabolism is an exergonic reaction (energy, or ATP, is released).
What is anabolism?
Anabolism is a type of metabolism: the building of simple molecules into more complex molecules.
What type of reaction is anabolism?
Anabolism is an endergonic reaction (energy, or ATP, is used).
How is ATP used in catabolism?
Catabolic reactions transfer energy from complex molecules to ATP.
How is ATP used in anabolism?
Anabolic reactions transfer energy from ATP to complex molecules.
What is oxidation?
Oxidation is the removal of electrons. It results in a decrease in potential energy. There is also a loss of H+.
Oxidation Is
Loss of electrons
What is reduction?
Reduction is the addition of electrons. It results in an increase in potential energy. There is also a gain of H+.
Reduction Is
Gain of electrons
What are the two main mechanisms of ATP generation?
- substrate level phosphorylation 2. oxidative phosphorylation
What is substrate level phosphorylation?
the generation of ATP by transferring a high-energy phosphate group from a substrate to ADP.
What is oxidative phosphorylation?
the generation of ATP by removing electrons from organic compounds and passing them through the electron transport chain.
What are the breakdown products of carbohydrate metabolism used for?
- ATP production
- amino acid synthesis
- glycogen synthesis (process called glycogenesis)
- triglyceride synthesis (process called lipogenesis)
Before glucose can be used by the body, it must first enter the body cells by passing through the plasma membrane and entering the cytosol. What are the two methods this occurs?
- secondary active transport
2. facilitated diffusion
How does glucose enter the cell through secondary active transport?
glucose enters cells through Na+ glucose symporters.
How does glucose enter the cell through facilitated diffusion?
glucose enters cells by being transported on GluT molecules.
Where does secondary active transport of glucose mainly occur in the body?
mainly occurs in the GI tract.
Where does facilitated diffusion of glucose mainly occur in the body?
in most body cells besides the GI tract.
What is cellular respiration?
the oxidation of glucose to produce ATP.
What are the four steps in cellular respiration?
- glycolysis
- formation of acetyl coenzyme A
- the Krebs Cycle
- the electron transport chain reactions
Where does glycolysis occur?
In the cytosol of the cell.
What is the energy net gain in glycolysis?
2 ATP molecules, 2 NADH + H+
What are the end products in glycolysis?
2 pyruvic acids
Where does the formation of acetyl coenzyme A occur?
in the mitochondrial matrix.
What is the net energy gain in the formation of acetyl coenzyme A?
2 NADH + H+
What are other products released in the formation of acetyl coenzyme A?
2 CO2
Where does the Krebs Cycle occur?
mitochondrial matrix
What is the net energy gain in the Krebs Cycle?
6 NADH + H+, 2 FADH2, 2 ATP
What are other products released in the Krebs Cycle?
4 CO2 (or 6 total now)
Where do electron chain reactions occur?
within the inner membrane of the mitochondria.
What is the net energy gain in electron chain reactions?
book says 28, ppt says 32-34 ATP
What is the total amount of ATP produced at the end of cellular respiration?
30-32 ATP per glucose molecule
What is glycogenesis?
formation of glycogen for glucose storage
What hormone stimulate glycogenesis?
Insulin stimulate glycogenesis (glucose storage).
What is glycogenolysis?
glucose release.
What hormone stimulates glycogenolysis?
Glucagon and epinephrine stimulate glycogenolysis.
What is gluconeogenesis?
the process of glucose forming from fats and proteins.
What hormone stimulates gluconeogenesis?
Cortisol and glucagon stimulate gluconeogenesis.
What must occur to lipids before they can be transported in the blood? Why?
Lipids must be combined with proteins to form Lipoprotiens. This is because most lipids are insoluble in water/blood.
What are the four classes of lipoproteins?
- chylomicrons
- very-low-density lipoproteins (VLDL’s)
- low-density lipoproteins (LDL’s)
- high-density lipoproteins (HDL’s)
What are chylomicrons and what do they do?
a type of lipoprotein that transports dietary (ingested) lipids from small intestine to adipose tissue for storage.
What do very-low-density lipoproteins (VLDL’s) do?
carry triglycerides from the liver to muscle and adipose tissue.
What do low-density lipoproteins (LDL’s) do?
deliver cholesterol to body cells. They provide up to 75% of the body’s cholesterol. This is “bad” because it can block arterial walls.
What do high-density lipoproteins (HDL’s) do?
remove excess cholesterol from body cells and transport it to the liver to make bile.
What are the two sources of cholesterol for the body?
- food
2. hepatocytes
What is “good” cholesterol?
high-density lipoproteins (HDL’s)
What is “bad” cholesterol?
low-density lipoproteins (LDL’s)
In an adult, what should the total cholesterol (TC) be?
less than 200 mg/dL.
In an adult, what should the total low-density lipoprotein (LDL) count be?
less than 130 mg/dL.
In an adult, what should the total high-density lipoprotein count be?
greater than 40 mg/dL.
In an adult, what should the total triglyceride count be?
between 10 and 190 mg/dL.
What is lipolysis?
lipid catabolism; triglycerides are split into fatty acids and glycerol. They are then released from adipose tissue.
What hormones stimulate lipolysis?
Epinephrine and norepinephrine stimulate lipolysis.
Cortisol, thyroid hormones, and insulin-like growth factors also play a part.
What is beta oxidation?
fatty acid catabolism, turned into acetyl coA for the krebs cycle
What is lipogenesis?
lipid anabolism; the formation of lipids by the liver and adipose cells rom glucose and amino acids.
What hormones stimulate lipogenesis?
Insulin
When does lipogenesis occur?
when individuals consume more calories than are needed to satisfy their ATP needs.
Unlike carbs/ triglycerides, proteins are not stored for future use. What happens to proteins instead?
- oxidized to produce ATP
2. synthesized to new proteins
What are proteins often times used for?
- enzymes
- transportation
- antibodies
- hormones
- collagen, elastin, keratin (structurally)
What is protein catabolism?
the conversion of amino acids into fatty acids, ketone bodies, and glucose by hapatocytes.
What hormone stimulates protein catabolism?
Cortisol
Before amino acids can enter the Krebs Cycle, what must occur?
deamination (removal of their amino group).
What is protein anabolism?
the formation of peptide bonds between amino acids to produce new proteins.
Where is protein anabolism carried out?
on the ribosomes (directed by DNA and RNA) of almost every cell.
What hormones stimulate protein anabolism?
Insulin-like growth factors, thyroid hormones (T3 and T4), insulin, estrogen, and testosterone
How many amino acids are in the body?
20
What are essential amino acids, and how many are there?
10
What are nonessential amino acids, and how many are there?
Nonessential amino acids are synthesized (formed) in the body. There are 10.
What are the three key molecules in metabolism?
- glucose 6-phosphate
- pyruvic acid
- acetyl coenzyme A
What are the four roles of glucose 6-phosphate?
- synthesis of glycogen
- release of glucose into the bloodstream
- synthesis of nucleic acids
- glycolysis
Explain synthesis of nucleic acids:
Glucose 6-phosphate is used by cells to make substances needed for the formation of DNA and RNA.
Explain glycolysis:
Most body cells carry out glycolysis- producing ATP anaerobically. Glucose 6-phosphate is converted to pyruvic acid.
What are the three roles of pyruvic acid?
- production of lactic acid
- production of alanine
- gluconeogenesis
Explain production of lactic acid
When oxygen is in short supply in a tissue, pyruvic acid is changed to lactic acid.
Explain production of alanine
Amino groups are sometimes added to pyruvic acid to produce alanine.
Explain gluconeogenesis
Pyruvic acid can be converted to oxaloacetic acid and can be used to form glucose 6-phosphate.
What are the three roles of acetyl coenzyme A?
- begins the Krebs Cycle and electron transport chain: by conversion from pyruvic acid.
- entry into the Krebs Cycle
- synthesis of lipids
Explain the synthesis of lipids:
Because pyruvic acid can be converted to acetyl coenzyme A, carbohydrates can be turned into triglycerides.
What does regulation of metabolic reactions depend on? Regulation of metabolic reactions depends both
- chemical environment within body cells (such as levels of ATP and oxygen)
- signals from the nervous and endocrine systems.
What occurs during the absorptive state?
ingested nutrients enter the blood and lymph from the GI tract.
How do ingested nutrients enter the blood from the GI tract during the absorptive phase?
- facilitated diffusion of glucose into cells
- active transport of amino acids into cells
- glycogenesis
- Protein synthesis
- Lipogenesis
Around how long does it take to absorb a meal?
~4 hours
What occurs during the postabsorptive state?
Absorption is complete and the ATP needs of the body are satisfied by nutrients already present in the body. Normal blood glucose levels are maintained.
How does the body maintain normal blood glucose levels during the post absorptive state?
by converting glycogen in the liver and skeletal muscle to glucose via: -glycogenolysis -lipolysis -protein breakdown -gluconeogenesis
What is the definition of fasting?
going without food for many hours or a few days.
What is the definition of starvation?
going without food for weeks or months.
What are the main events that occur in fasting and starvation?
gluconeogenesis, the use of amino acids, lipolysis of triglycerides, and ketogenesis increases.
What is metabolic rate?
Metabolic rate is the overall rate at which metabolic reactions use energy.
What is basal metabolic rate?
the measurement of metabolic rate when the body is in a quiet, resting, and fasting condition.
What are the factors the affect metabolic rate?
-exercise-hormones-nervous system-body temperature-ingestion of food-age-gender climate -sleep -malnutrition -pregnancy
Where is the body’s “thermostat”?
in the preoptic area of the hypothalamus; the anterior portion of the hypothalamus.
In thermoregulation, if the body temperature is increased, what occurs within the body to decrease the raised temperature?
vasodilation occurs, the metabolic rate decreases, and evaporation of perspiration occurs.
In thermoregulation, if the body temperature is decreased, what occurs within the body to increase the lowered temperature?
vasoconstriction occurs, there is a release of epinephrine and norepinephrine, thyroid hormones are stimulated, and shivering occurs.
What are the main sources of nutrition?
- Water
- Carbohydrates
- Lipids
- Proteins
5 minerals - Vitamins
What percent of calories should come from carbohydrates?
50%-60% of calories should come from carbohydrates.
What are minerals?
inorganic elements concentrated mostly in skeleton.
What is the general function of minerals?
regulate enzymatic reactions.
What are vitamins?
organic elements that must be ingested with food.
What is the general function of vitamins?
Vitamins serve as coenzymes.
What are the essential functions of a cell?
- Metabolic turnover
- Growth and cell division
- Special processes, such as secretion, contraction, and the propagation
Carbohydrate + Amylase = ?
Glucose
Protein + Trypsin = ?
Amino Acid
Lipid + Lipase = ?
Fayy acid + glycerin
How do nutrients enter circulation?
Through the hepatic portal vein into circulation
What mechanism allows cells to receive essential nutrients?
Na+K+ pump (Sodium potassium pump)
What is a normal blood glucose level?
80-100mg/100ml
What is a nutrient pool?
The source of substrates for catabolism and anabolism (building blocks of cellular energy)
What happens to blood sugar levels if you eat a lot of carbohydrates?
300-400mg/100ml
What is 1 way energy from catabolism is used in metabolism?
Synthesization of high-energy compounds
an “uphill” process that forms new chemical bonds
Anabolism
What is excess glucose and where is it stored?
Glycogen is stored in the liver
4 functions of organic compounds
- structural maintenance 2. Support growth 3. Produce secretions 4. Store nutrient reserves
What is most abundant storage carbohydrate
Glycogen
An organic compound composed of a branched chain of glucose molecules
Glycogen
What is the most abundant storage lipids
Triglycerides
An organic compound composed primarily of fatty acids
Triglycerides
How many kcal in 1 gram of Carbs?
4kcal
How many kcal in 1 gram of fat?
9kcal
How many kcal in 1 gram of protein?
4kcal
Most abundant organic components in body
Protein
Which organic compound Perform many vital cellular functions?
Protein
How many calories does a resting person need?
2000kcal
How much does glucose and cal does the brain need?
120g of glucose, 480 calories
One molecule of glucose nets how much ATP?
36 molecules of ATP…
What are aerobic Reactions
aerobic metabolism or cellular respiration
Where do aerobic reactions occur?
in mitochondria, consume oxygen, and produce ATP
What is a calorie in science?
The amount of heat required to raise the temp of 1 g of water by 1 C degree
What is pyruvic acid?
Pyruvic acid can be made from glucose through glycolysis, converted back to carbohydrates
What is the ionized form of pyruvic acid?
Pyruvate
What is an enzyme?
A protein catalyst, works in a specific temp and ph, to create a specific reaction
What do the mitochondria use to create ATP?
Mitochondria use oxygen to break down pyruvic acid
What is significant about the outer mitochondrial membrane?
large-diameter pores that allow pyruvic acid molecules to permeate
What is the chemical formula of glucose?
C6H12O6
What is significant about the inner mitochondrial membrane?
Contains carrier protein that move pyruvic acid into mitochondrial matrix
What cells have their own DNA?
Mitochondria
What separates outer and inner membranes of the mitochondria?
the Intermembrane space
How is mitochondrial DNA passed down?
From the mother
What is the function of the citric acid cycle?
remove hydrogen atoms from organic molecules and transfer them to coenzymes
What temp constitutes a fever?
37.2C (99F)
What is ATP?
Adenosine triphosphate, the source of all energy in your body
What is Pyrexia?
Usually temporary raised body temperature
How does the body temp change at night?
Falls 1-2 degrees at night
When does body temperature peak?
During day or early evening
What tissue is an insulator?
Adipose Tissue
What causes variations in thermal response?
- Body weight 2. Weight distribution 3. Relative weights of tissues types 4. Natural cycles
Where does the Electron Transport Chain take place?
Inner membrane of mitochondria
What is the ATP outcome of glycolisis?
4-1=2 ATP
Is glycolysis aerobic or aerobic?
Anerobic
What is oxidation?
The removal of hydrogen atoms (The addition of elections)
What is reduction?
The addition of hydrogen atoms (The loss of electrions)
What is the waste product when hydrogen is removed form glucose?
CO2
What is another term for aerobic metabolism?
Cellular respiration
What is the end product of Glycolysis?
Pyruvate
What does the preparatory action of Glycolysis produce?
Pyruvate into Coenzyme A
Where does Co-enzyme A go after its produced?
Into the TCA cycle and produces NADH
What process produces more than 90% of ATP used by body
Oxidative Phosphorylation and the ETS
How ATP is the electron transport chain responsible for?
32 molecules of ATP
How ATP is the TCA cycle responsible for?
2 molecules of ATP
How much ATP is glycolysis responsible for?
2 molecules of ATP
Which parts of the cycle are metabolism aerobic?
TCA + electron transport chain
Which parts of the metabolism cycle are anerobic?
Glycolysis
Where does the The Electron Transport System (ETS) occur?
in inner mitochondrial membrane
How do electrons move?
series of oxidation–reduction reactions
What do electrons eventually combine with an form?
combine with oxygen to form water
What is the intermediary of oxidation-reduction reaction?
Coenzymes
How many steps are in Glycolysis?
7
What controls the 7 steps of Glycolysis?
7 distinct enzymes
Reduction _____ energy
Gains
Oxidation _____ energy
Loses
What is another name for the Electron Transport System?
The respiratory chain
What is a cytochrome?
electron transfer agents in many metabolic pathways, especially cellular respiration.
What are the precursor of Gluconeogenesis?
Lactic acid, Glycerol + Amino Acids and glycogen stores
Where is glycogen stored?
Skeletel muscle and liver
What does an ion pump do?
Create concentration gradient for H+ across inner membrane Concentration gradient provides energy to convert ADP to ATP
What is an ion channel?
Channels of the inner membrane that permit diffusion of H+
How many different proteins does the body synthesize?
100k-140k
Where are cellular proteins recycled?
Cytosol
During protein recycling what bonds are broken to free amino acids?
Peptide bonds
What is the chemical compound representing the amine group?
NH2
What is Chemiosmosis?
Ion channels and coupling factors use kinetic energy of hydrogen ions to generate ATP
What are the 2 hormones that contribute to the metabolism?
Insulin and glucagon
What are the 6 significant minerals in metabolism?
- Sodium 2. Potassium 3. Chloride 4. Calcium 5. Phosphorus 6. Magnesium
Which ion is greater INSIDE the cytoplasm, and which is greater outside?
Inside: Potassium Outside: Sodium
What 2 things does Oxidative Phosphorylation require?
Electrons and oxygen
How do cells obtain oxygen during Oxidative Phosphorylation
by diffusion from extracellular fluid
What mineral is a major cation inside cytoplasm?
Potassium
What mineral is a major cation inside body fluids?
Sodium
What mineral is essential for muscle and neuron function and bone structure?
Calcium
What mineral is a cofactor of enzyme required for normal membrane function
Magnesium
Which vitamins are fat soluble?
A, D, E, K
Which vitamins are water soluble?
B, components of coenzymes
How are fat soluble vitamins absorbed?
Along the digestive tract along with lipids of micelles
Which vitamin is a comment of visual pigment retinal?
A
Which vitamin helps in blood coagulation?
K + Calcium
Which Vitamin is required for bone growth, calcium and P absorption?
D
What happens if there is Vitamin A defficiency?
Retarded growth, nigh blindness, deterioration of epithelial membranes
What is the effect of excess A?
Liver damage, paling, CNS effects
What happens if there is Vitamin D defficiency?
rickets, skeletal deteriotation
What are the different types of B vitamins?
B1, B6, B12
What is fructose intolerance
when cells on the surface of the intestines aren’t able to break down fructose efficiently. Causes nausea, bloating, and malabsorption of other vitamins.
What is galactosemia
genetic metabolic disorder that affects an individual’s ability to metabolize the sugar galactose (convulsions, jaundice, fatigue, vomiting)
What is maple sugar urine disease?
An inherited metabolic disorder causing an inability to break down the amino acids leucine, isoleucine, and valine
What is phenylketornuria?
an inherited inability to metabolize phenylalanine (plant protein) that causes brain and nerve damage
What is gout?
defective metabolism of uric acid causes arthritis
What happens when glucose and lipid reserves are inadequate?
Liver cells breakdown internal proteins + absorb additional amino acids from the blood
