TCU Nutrition Exam 3 (Davis)

What are proteins made of and how are they arranged?

-Compound of C, H, O, N

-Arranged into animo acids and linked in a chain.

What are Amino Acids?

-Building blocks of protein.

What are Amino Acid properties and how many are there?

-3 properties- all connected to a central carbon.

(4th side of chain varies.)

-20 in total, 9 are considered essential.

Name 3 properties of amino acids.

-Amino group.

-Acid group.

-Hydrogen group.

Give 4 examples of Amino Acids

Glycine,

Alanine,

Aspartic Acid,

Phenylalanine.

How are Amino Acids connected.

-AAs are connected by peptide bonds.

-Shape is folded and tangled depending on specific AAs and their sequence.

What are 4 types of Amino Acids Sequences?

-Dipeptide: 2AA

-Tripeptide: 3AA

-Oligopeptide: 4-10AA

-Polypeptide: >10AA

What is a dipeptide?

2 Amino Acid group

What is a Tripeptide?

3 Amino Acid group

What is a oligopeptide?

4-10 Amino Acid group

What is a polypeptide?

>10 Amino Acid group

How does condensation of two amino acids form a dipeptide?

-An OH group from the acid end of one amino acid and an H atom from the amino group of another join to form a molecule of water.

-A peptide bond forms between the two amino acids creating the dipeptide bond

What is hemoglobin made of?

-Globular hemoglobin protein is made of 4 polypeptide chains.

What is the structure of hemoglobin and how is it determined?

-Shape of each polypeptide chain is determined by an amino acid sequence (primary structure)

that twists into a helix (secondary structure)

and bends itself into a ball shape (tertiary structure).

What is denaturation of a protein and what are examples?

-Disruption of stability.

-Uncoil and lose shape.

-Stomach acid.

-Examples: Cooking an egg, curdling milk, stiffening of egg whites.

Where does digestion of proteins begin and what is the process?

-Begins in the stomach.

-HCL causes pepsinogen (inactive enzyme) to convert to pepsin (active).

-Larger polypeptides are broken down into smaller polypeptides and AA.

-In the small intestine- broken down to AA.

-Transferred to pumps (active transport) which carry them to interior for passage into blood.

-Unused amino acids transported to liver.

-Exogenous enzymes are broken down like any protein.

-Hydrolyzed AA supplements are not as well utilized and absorbed as whole food proteins.

What are the uniquenesses of each person?

-amino acid sequences of proteins

- genes (DNA).

What is Transcription?

-DNA template to make mRNA

What carries the code to ribosomes?

-mRNA

-Ribosomes are protein factories

What is translation?

mRNA specifies sequence of amino acids, tRNA

What are Essential Amino Acids?

-AAs that the body cannot synthesize in adequate amounts.

-Protein in food provides AA for the body to make its own proteins.

-Limiting AA- the all or none law of protein synthesis.

Limiting AA.

-Diet must supply all essential AA in adequate amounts.

-Must be available simultaneously.

What is a High Quality Protein?

-Easily digestible and complete protein.

-Egg protein is the reference protein by which we measure the quality of other protein.

What is Complete protein?

-Provides all AA in relatively the same amounts required by humans.

-Exp. Animal protein, except gelatin.

-Plant protein is variable.

What is an egg protein?

-Has biological value of 100.

-Refers to the amount of N2 retained after it has been digested and absorbed.

What is a poor quality protein?

-Imbalance of AA limits protein synthesis.

-Wastes AA as they are converted to urea.

-Carbons are metabolized for energy.

In protein metabolism (making other compounds) what are examples of this?

-Neurotransmitters (Tyrosine used to make epinephrine and norepinephrine).

-Melanin.

-Thyroxin.

-Tryptophan precursor for niacin and serotonin.

What is maximum protein utilization?

-Suitable AA pattern.

-Digestible.

-Spared by energy from other sources.

-Accompanied by vitamins and minerals to facilitate use.

-Body healthy and equipped to utilize it.

What is nitrogen balance?

-Refers to N2 consumed vs. N2 excreted.

-Important bc protein is needed for growth and maintenance of all body tissues.

-(+) N2 balance in growth and pregnancy.

-(-) N2 balance during sickness, trauma, if bedridden (muscle atrophy), starvation.

-Quantity depends on LBM (muscle is metabolically active).

-Kidney disease is an exception.

-Unused AA due to limiting AA is broken down.

Unused AA being broken down.

-N2 released in the blood as NH3 (Ammonia).

-Cleared by liver and converted to urea.

-Filtered by kidneys and excreted in urine.

Protein Metabolism- Excreting urea.

-Liver releases urea into blood. Kidneys filter urea out of blood.

-Liver disease.

-Kidney disease.

-Protein intake and urea production (water consumption).

What are the roles in the body for Enzymes?

-Proteins that facilitate chemical reactions without being changed.

-Synthetase builds body structures.

-Hydrolyze- break down compounds as in digestion.

How enzymes work?

-The separate compounds, A and B, are attracted to the enzyme's active site, making a reaction likely.

-The enzyme forms a complex with A and B.

-The enzyme is unchanged, but A and B have formed a new compound, AB.

What are the roles in the body for Fluid balance?

-Fluids flow between body compartments.

-Proteins and minerals maintain proper distribution.

What are the roles in the body for Acid-base balance?

-Acts as a buffer preventing acidosis and alkalosis.

-Proteins protect one another by sequestering H2 if too much or releasing if too little.

What are the roles in the body for Antibodies.

-Proteins that act on foreign organisms and protect the body.

Roles in the body: Hormones.

-Messenger molecules secreted by glands in response to changes in the internal environment.

-Insulin and glucagon control blood glucose.

-Thyroxin controls metabolic rate.

What are the roles in the body for Blood clotting?

-Formation of fibrin- a stringy/insoluble mass of protein.

-Vitamin K, calcium also involved.

What are the roles in the body for Transport proteins?

-Move nutrients and other proteins in and out of cells.

-Lipoproteins.

-Can be controlled by hormones.

How do transport proteins work in the body?

-The transport protein picks up sodium from the inside of the cell.

-The protein changes shape and releases sodium outside the cell.

-The transport protein picks up potassium from outside the cell.

-The protein changes shape and releases potassium inside the cell.

What are the roles in the body for Structural forms?

-Collagen- a protein material forming connective tissues as well as formations for bones and teeth.

-Also forms and mends lean tissues (ex. ligaments and tendons).

What are the roles in the body for Visual pigments.

-Opsin- protein of the visual pigments- changes shape in response to light.

What is Opsin?

Protein of the visual pigments, changes shape in response to light.

What are the health effects of protein deficiency?

-Consequences.

-Protein-energy malnutrition.

-Marasmus and kwashiorkor.

What are the health effects of protein with Heart disease?

-Animal-protein intake.

-Homocysteine levels.

-Arginine levels.

What is Protein Energy Malnutrition?

-Most widespread nutrition problem.

-Kwashiorkor.

What is Kwashiorkor when does it occur, and what are symptoms?

Inadequate protein in the presence of adequate food energy.

-Typically reflects sudden and recent food deprivation.

-Common in 18 month-2 year olds.

-Edema - bulging (bloated) belly; limbs and face.

-Loss of appetite.

-Dry, brittle hair, loses color.

-Sores that don't heal.

What is Marasmus when does it occur, and what are symptoms?

-Both Inadequate protein and food energy.

-Very thin- children look elderly.

-Severe deprivation over a long period of time.

-Most common in children 6-18 months old.

-Muscles waste and weaken.

-Impaired brain development.

-Dec. body temperature.

-Protein used for brain, lungs, and heart only.

-GI tract atrophies.

What happens in the case of Protein Excess (too much)?

-Extra work for liver and kidney.

-May provide excess fat and cholesterol and not enough CHO, vitamins, minerals.

-15-20% of kcals should come from protein; no benefit above this amount.

Proteins in foods.

-Body protein is continually broken down.

-AA are not stored.

-Food provides our source of AA.

What is the recommended intake of protein?

0.8g/kg body weight.

Why is there a recommended intake of protein?

-Needed for dietary protein (source of essential amino acids and practical source of nitrogen).

-10-35% of daily energy intake.

What are things Vegetarianism may have to look out for?

-Need complementary proteins to provide all essential AA.

-Health can be sustained by eating a variety of foods as long as energy is adequate.

-Concern with low Ca+, B12, Zn, Fe, Vitamin D.

-Meat replacements.

Why are rice and beans together a great source of complete proteins?

Legumes = Ile and Lys

Grains = Met and Trp

Together = Ile+Lys+Met+Trp = complete protein

In general, legumes provide plenty of isoleucine (Ile) and lysine (Lys) but fall short in Methionine (Met) and tryptophan (Trp). Grains have the opposite strengths and weaknesses, making them a perfect match for legumes.

Health effects of protein.

-Cancer: protein-rich foods; not protein content of diet.

-Osteoporosis: increase in calcium excretion; animal proteins.

-Weight control.

-Kidney disease: acceleration of kidney deterioration.

From Guidelines to Groceries.

-Protein foods: one ounce equals 7 grams of protein.

-Milk and milk products.

-Fruits, vegetables, and grains.

-Read food labels.

Protein Supplements: Protein powders.

-Muscle work vs. protein supplements (athletic performance).

-Whey protein.

-Impact on kidneys.

Amino acid supplements.

-Potential risks associated with intake.

-Lysine and tryptophan.

Who shouldn't use amino acid supplements?

-Pregnant and lactating women.

-Infants, children, adolescents.

-People with mental or physical illness without medical supervision.

-People with inborn errors of metabolism that affect handling of AA.

-People on low protein diets.

What are Chemical Reactions in the Body?

-Energy metabolism (how body obtains and uses energy from food).

-Cells (liver cells).

-Anabolism.

-Catabolism.

Energy-Yielding Pathways.

-Protein, carbohydrate, and fat can be broken down to acetyl CoA.

-Acetyl CoA can enter the TCA cycle.

-Most of the reactions release hydrogen atoms with their electrons, which are carried by coenzymes to the electron transport chain.

-ATP is synthesized.

-Hydrogen atoms react with oxygen to produce water.

Metabolism.

-Sum total of all the chemical reactions that take place in living cells.

-How the body uses foods to meet its needs.

What is energy metabolism?

-All reactions by which the body obtains and uses the energy from food.

Anabolism.

-Reactions in which smaller molecules are put together to build larger ones (consumes energy).

-Glucose to glycogen.

-Glycerol and fatty acids to TG.

-AA to proteins.

Catabolism.

-Reaction where larger molecules are broken down to smaller ones (release energy).

-Glycogen to glucose.

-TG to glycerol and fatty acids.

-Proteins to AA.

Adenosine triphosphate (ATP)

-The body's quick energy molecule.

-Used as energy currency to build body structures, do work, or generate heat.

-Composed of sugar, purine, 3 phosphates (can be broken off when energy is needed).

Capture and Release of Energy by ATP.

-Energy is released when a high-energy phosphate bond in ATP is broken.

-The energy from ATP can be used to do most of the body's work.

-With the loss of a phosphate group, high-energy ATP becomes low-energy ADP.

-Energy is required when a phosphate group is attached to ADP, making ATP.

-ADP needs energy from the breakdown of carbohydrate, fat, and protein to make ATP.

Breaking Down Nutrients for Energy: Digestion.

-Carbohydrates= glucose and other monosaccharides.

-Fats (triglycerides)= glycerol and fatty acids.

-Proteins= amino acids.

Breaking down nutrients for energy.

-Molecules of glucose, glycerol, amino acids, and fatty acids- catabolism= Carbon, nitrogen, oxygen, hydrogen.

Breaking down nutrients for energy: two new compounds.

-Pyruvate.

-Acetyl CoA.

-TCA cycle and electron transport chain.

Pyruvate.

-3-carbon structure.

-Can be used to make glucose.

Acetyl CoA.

-2-carbon stucture.

-Cannot be used to make glucose.

Glucose-to-Pyruvate.

-Process is called Glycolysis.

-2 pyruvate molecules are produced.

-Hydrogen atoms carried to electron transport chain.

-Pyruvate can be converted back to glucose.

Glycolysis.

-Occurs in anaerobic conditions.

-Beings with splitting a 6-carbon glucose compound into 2 interchangeable 3-carbon compounds. These compounds are converted to pyruvate through a series of reactions.

-Any of the monosaccharides can enter the glycolysis pathway at various points.

-Ends with the production of pyruvate.

Pyruvate's options: Quick energy needs.

-Anaerobic.

-Pyruvate to lactate.

-Lactate can be converted back to Glucose through the Cori Cycle.

Pyruvate's options: Slower energy needs.

-Aerobic.

-Pyruvate to acetyl CoA.

Pyruvate-to-Lactate.

-Working muscles break down most of their glucose molecules to pyruvate.

-If cells lack sufficient mitochondria or in the absence of sufficient oxygen, pyruvate can accept the hydrogens from glucose breakdown and become lactate. This conversion frees the coenzymes so that glycolysis can continue.

-Liver enzymes can convert lactate to glucose, but this requires energy.

Pyruvate-to-Acetyl CoA (Aerobic).

-Each pyruvate loses a carbon as carbon dioxide and picks up a molecule of CoA, becoming acetyl CoA.

-Step is not reversible.

-Result from 1 glucose is 2 CO2 and 2 acetyl CoA.

Breakdown of Acetyl CoA.

-Complete oxidation of acetyl CoA is accomplished through the reactions of the TCA cycle and electron transport chain.

-In the TCA cycle, the acetyl CoA carbons are converted to carbon dioxide.

-Each CoA returns to pick up another acetate.

-Net result is that acetyl CoA splits, the carbons combine with oxygen, and the energy originally in the acetyl CoA is stored in ATP and similar compounds.

Glucose-to-Energy Pathway.

-Glucose is completely disassembled to single-carbon fragments, and the fragments are combined with oxygen to form carbon dioxide.

-Much of the energy released is trapped and stored in ATP.

Breaking down nutrients for energy: Glycerol.

-Glycerol can be converted to glucose and pyruvate.

Breaking down nutrients for energy: Fatty acids.

-Fatty acid oxidation.

-2-carbon units at a time then join with CoA.

-Hydrogens and electrons carried to electron transport chain.

Fat breakdown.

-The fatty acid is first activated by coenzyme A.

-As each carbon-carbon bond is cleaved, hydrogens and their electrons are released, and coenzymes pick them up.

-Another CoA joins the chain, and the bond at the second carbon weakens. Acetyl CoA splits off, leaving a fatty acid that is two carbons shorter.

-The shorter fatty acid enters the pathway and the cycle repeats, releasing more hydrogens with their electrons to coenzymes and producing more acetyl CoA. The molecules acetyl CoA enter the TCA cycle, and the coenzymes carry the hydrogens and their electrons to the electron transport chain.

Fats enter the energy pathway.

-Glycerol enters the glycolysis pathway about midway between glucose and pyruvate.

-Fatty acids are broken down into 2-carbon fragments that combine with CoA to form acetyl CoA.

Breaking down nutrients for energy: Amino acids.

-Deamination of amino acids.

-Amino acids-to-energy.

Amino acids-to-energy.

-Several entry points in energy pathway.

-Converted to pyruvate (glucogenic).

-Converted to acetyl CoA (ketogenic).

-Enter TCA cycle directly.

-Amino acids-to-glucose.

Amino Acids enter the Energy Pathway.

-Most amino acids can be converted to pyruvate, which can be used to make glucose; they are glucogenic.

-Some amino acids are converted directly to acetyl CoA; they are ketogenic.

-Some amino acids can enter the TCA cycle direction; they are glucogenic.

Electron transport chain.

-The electrons that bond the hydrogens to the B vitamin coenzymes have a relatively large amount of energy. In a series of reactions that follow, they lose this energy in small amounts, until at the end the electrons with their hydrogens are attached to oxygen to make water.

Glucose Metabolism.

-Glycolysis.

-Glucose can be used for AA when N2 is available.

-Excesses are converted to fat for storage.

Glycolysis.

-Metabolic breakdown of glucose to 2 units of pyruvate (3-carbon compound).

-Can be broken down to acetyl CoA, a building block for fatty acids.

-Some energy is released.

Pyruvate.

-Only the parts of protein and fat that can be converted to pyruvate can provide glucose.

-Those that go directly to acetyl CoA cannot.

Fat Metabolism.

-Glycerol to pyruvate.

-Pyruvate to glucose; pyruvate to acetyl CoA.

-Fatty acid 2 carbon fragments to acetyl CoA.

-Fat cannot make body proteins.

-Readily goes into storage if taken in excess.

Protein Metabolism.

-AA primarily used to build body proteins.

-AA will not enter energy pathway unless there's a shortage of energy or you've eaten in excess.

Protein Metabolism.

-Fairly good source of glucose when CHO is not available.

-Converted to fat for storage if taken in excess.

Excess protein converted to fat storage.

-AA to pyruvate to acetyl CoA to fatty acids to TG.

-Cannot be stored as protein.

-Does not build muscle, but fat.

Excess nitrogen.

-Causes deamination.

-Liver urea to blood to kidneys to urine.

-Water keeps urea in solution as urine. Water needed with high protein diets.

-High protein, low CHO diet weight loss is water.

Excess nitrogen: Deamination.

-Removal of amino (nitrogen-containing) group from an AA.

-Product is NH3 (ammonia).

-NH3 can be used to synthesize non-essential AA.

-Excess combined with CO2 to make urea.

-Urea is basic- build up in blood disturbs acid-base balance.

Urea Synthesis.

-When amino nitrogen is stripped from amino acids, ammonia is produced.

-The liver detoxifies ammonia before releasing it into the bloodstream by combining it with another waste product (CO2) to produce urea.

Urea Excretion.

-The liver and kidneys both play a role in disposing of excess nitrogen.

-A person with liver disease has high blood ammonia.

-A person with kidney disease has high blood urea.

Few hours post meal.

-Body uses glycogen and fat for energy.

-When immediate stores are used- hunger indicates it is time to eat.