• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

Card Range To Study



Play button


Play button




Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

90 Cards in this Set

  • Front
  • Back
What comprise the monomers that we use to make polypeptides?
Amino acids
How are proteins made generically?
Transcription and translation
How are amino acids used for energy production in our bodies?
They contain C-C bonds which can be fed into the TCA cycle directly or indirectly.
What must happen first before an amino acid can continue on in being used for energy production?
The amino group must be removed, this converts it from an alpha amino acid to an alpha-keto acid, stripping off the amine group which becomes ammonia which is toxic to our bodies.
How is ammonia removed from our bodies?
Urea cycle disguises the ammonia and it is excreted in the urine.
What are the two important components of Nitrogen metabolism?
1.) Amino acid pool

2.) Protein turnover
What is the Amino acid pool?
The "Pool" of individual amino acids in the body excluding AA's in proteins.

They come from:
-Dietary AA's
-Tissue AA's from degradations of proteins in the body
Describe the amino acid pool at any given time.
Amino acid pool is approx 100g coming from:
-Body protein catab. 400g/d
-Dietary protein. 100g/d
-De Novo synth. Variable

New body protein is about 300-400g/d
AA's used for energy metabolism is variable
FA synthesis
Special products. 30g/d
Neurotransmitters (GABA)
For a 70kg male, what amount is protein?
Approx 12kg. Of that 12kg, about 400g (3.3%) is broken down and replaced each day
What happens to protein turnover with age?
Synthesis of protein is greater than catabolism, same is true for anabolic situations such as weightlifting
Some specific proteins have higher turnover rates due to shorter t1/2's, why have turnover at all?
Protein turnover allows a cell to be adaptable to new situation/environments, Adaptability increases survival.
Because there are protein turnover rates, there must be regulation. Turnover (degradation) is stimulated by what?
Ubiquitin (a small protein)
-binds to protein molecule

Proteins with many Pro-Glut-Ser-Threo (PEST) sequences are rapidly degraded
Amino acids may be used for energy, what is the typical percentage of our energy coming from Amino acids/proteins?
20%, remembering that the primary need for proteins (AA's) is for protein synthesis.
Americans eat approx. how much protein/day compared to the RDA?
100g/day, RDA is 56g. We eat about 2x recommended allowance.
What does a low protein diet lead to?
Shortages in essential amino acids, leads to increased protein catabolism, and can lead to Kwashiorkor in extreme instances.
Where does protein digestion begin?
Stomach. HCL secreted by parietal cells activates pepsinogen produced by Chief cells under the direction of Gastrin and CN X (Vagus).
Where does most protein digestion occur?
Small intestine. Protein digestion only begins in the stomach.
What enzymes participate in protein digestion in the small intestine?
Pancreatic enzymes:

Small intestine:
Where is aminopeptidase found in the small intestine?
It is found lining the mucosal cells forming the lumen of the small intestine.
What is the function of aminopeptidase on protein structure?
Acts on the N-terminus of proteins and clips off single AA's and short peptide fragments.
What form are pancreatic enzymes found in prior to entering the duodenum?
Proenzymes or zymogens which are the inactive precursors of these enzymes which if activated in the pancreas will digest the pancreatic tissue--->major problems.
What are the inactive forms of the pancreatic enzymes?

They are cleaved by Enteropeptidase to their active forms.
What happens to AA's and peptides that are cleaved from polypeptides?
They are transported into the mucosal cells of the small intestine and any remaining peptide bonds are hydrolyzed. Only single AA's leave mucosal cells and enter circulation via hepatic portal circulation.
.What is the cost to transport AA's across the mucosal cell membrane?
AA pumps (at least 7 known) pump specific AA's across the membrane and cost ATP per AA.
After entering circulation individual AA's lose their amine group to become alpha-keto acids, what are the two ways the amine group is removed?
1.) Transamination (majority)

2.) Oxidative Deamination
-liver, kidney. Produces alpha keto acid and ammonia.
What are transaminases?
A group of enzymes specific for one or a few AA's used in transamination.
Which AA's are not substates for at least 1 transaminase?
Lysine & Threonine
What is true for all Aminotransferases?
Alpha-ketoglutarate is the amine "acceptor", products being Glutamate, and an alpha-keto acid. (The NH3 is transferred from the AA to alpha keto glutarate which becomes glutamate)
What cofactor does Transaminase require?
Pyridoxal-PO4 from Vitamin B6.
What are two examples of Transaminases?
Alanine Aminotransferase
-Also called GPT (glutamate-pyruvate transaminase). Alanine gives its NH3 to apha-KG and becomes Pyruvate.

Aspartate Aminotransferase
-Also called GDT (Glut-OAA transaminase)
-The EXCEPTION to the rule.
Whats important to know about Alanine aminotransferase in muscle tissue?
The reaction runs from right to left, this is creating alpha-KG and Alanine; protein breakdown occuring. High levels of Alanine in blood.
What is the action of Aspartate aminotransferase?
Removes the NH3 group from Glutamine (which becomes Alph-KG) and transfers it to OAA which becomes Aspartate.
What AA is needed for Urea synthesis?
What is the function of Glutamate DH?
Acts quickly on Glutamate produced by transaminases converting it to Alpha-KG + NH3+ (reversible rxn)
What regulates Glutamate DH activity?
Stimulated by:

Inhibited by:
*Inhibiting AA metabolism when energy supply is good.
What are the electron carriers for Glutamate DH?
Plants we eat contain some D-Amino acids, how do we process these?
Our bodies use D-Amino Acid Oxidase to convert D-AA's to Alpha-Keto acids + NH4+
Whats important about the transaminase and glutamate dh rxns?
They are reversible so they are employed in AA synthesis as well as catabolism.
What are the two direct deamination rxns?
Serine---->Pyruvate + NH4
Serine dehydratase

Threonine-->Alpha-Ketobutyral + NH4 via Threonine Dehydratase.
How do we get rid of nitrogen?
Consuming the ammonia (NH4) and producing Urea which can circulate in the blood and be removed in the kidneys.
What are the nitrogenous compounds found in urine and their approx percentages?
Urea (86%)
Creatinine (5%)
NH4+ (3%)
Other (6%)
What are they primary forms of nitrogenous waste in birds/reptiles and fish?
Birds/Reptiles (Uric Acid)

Fish (Ammonia, excreted all the time)
What are the steps of the Urea cycle?
Arginine + Fumarate
What are the enzymes used in the Urea cycle?
Arginase (produces urea)
Ornithine transcarbamylase
Argininosuccinate Synthase
Where is Carbamoyl-PO4 made?
C02 + NH4 + 2 ATP + H2O------> via carbamoyl phosphate synthase yields?
2 ADP + Pi
3 H+
What is the rate limiting enzyme for the formation of Urea?
Carbamoyl Phosphate synthase
What is the rate limiting enzyme for the formation of Urea?
Carbamoyl Phosphate synthase
Where in the body is Urea produced?
What amino acid are other amino acids converted to frequently for use by the body?
Why don't we want ammonia in the blood & tissues?
It is highly toxic in small amounts. Transported as Urea or Glutamine
Does ammonia ever accumulate "inside" the body?
No, ammonia is immediately dumped into the urine which is technically outside the body in a storage space.
The ketogenic amino acids are?
What is important to know about ketogenic amino acids?
Their carbons only enter at AcCoA, can be used for Ketone production but not for gluconeogenesis (remembering pyruvate is 3 carbons) They enter as 2-C's therefore as AcCoA.
What is important to know about Glucogenic amino acids?
Carbons can be used for gluconeogenesis. They enter with 3 C's
What are the Glucogenic amino acids?
Most amino acids are, with the exception of Lysine/Leucine.
Which are the amino acids with "mixed" catabolism (ie. Ketogenic/Glucogenic)
May enter as either AcCoA or other points compatible with gluconeogenesis.
What is the mnemonic for the essential amino acids?
HAL=Basic-Hist, Arg, Lys
ALL=Ketogenic only
Which amino acids can be converted to Pyruvate and then AcCoA for TCA?
Which amino acids can be converted directly to AcCoA for TCA?
Which amino acids enter TCA as alpha-ketoglutarate?
Which amino acids enter TCA as Succynl CoA?
Which amino acids enter TCA as Fumarate?
Which amino acids enter TCA as OAA?
What is important about the pathways of amino acid catabolism?
They are also reversible so that amino acid synthesis can be run in the other direction.
What does PVT TIM HALL stand for?
The essential amino acids. Phenylalanine, Valine, Tryptophan, Threonine, Isoleucine, Methionine, Histidine, Arginine, Lysine, Leucine.
What is methinonine converted to during catabolism?
Methionine to S-Adenosylmethionine (SAM)
What is SAM (S-adenosylmethionine) important for in AA catabolism?
Its an important CH3 (methyl) donor to the "One carbon pool" for synthesis of various compounds.
In addition to SAM, name another important one carbon pool carrier?
Folic acid (Folate), its activated, carbon carrying form is THF (Tetrahydrofolate)
What are the special products produced from amino acids?
What are porphyrins?
Web-like structures that bind Iron (Fe2+, Fe3+) for redox rxns.

Made from Glycine, Succinyl CoA
What is a porphyrin complexed with a metal?
Where does Heme synthesis occur?
Bone marrow
What is the typical lifespan of an RBC?
120 days
Describe the breakdown of Hemes.
Destroyed RBC-->Heme-->Biliverdin-->Bilirubin-->Bound to albumin-->Secreted in bile.
What is the function of Heme oxigenase?
Converts heme to biliveridin, requires (1) NADPH
What is the function of Biliverdin reductase?
Converts Biliverdin to Bilirubin using (1) NADPH
What is the ultimate fate of Heme?
It is processed and secreted into bile.
What is jaundice?
Higher than normal levels of bilirubin in blood
What are the 4 types of jaundice?
Premature Newborn
What is hemolytic jaundice?
High RBC death; sickle cell, malaria
What causes obstructive jaundice?
Bile ducts are blocked, possibly by gallstones.
What is Hepatocellular jaundice?
Liver damage such as cirrhosis, hepatitis.
Why are newborns sometimes jaundiced?
Premature babies are frequently jaundiced because their liver is not fully developed and functional.
What is creatine?
A phosphate bond acceptor. Made from glycine and arginine. Its breakdown product is creatinine. Increased levels of creatine in urine=kidney malfunction.
What is important to know about histamine as far as our amino acid lecture is concerned?
Regulates H+ secretion by the stomach.

Results from removal of the COO- from Histidine.

Involved in allergy & inflammation rxns.
What is important to know about Serotonin?
Its 5-OH-Tryptamine
Made from tryptophan
Neruotransmitter in CNS & gut (enteric nervous system)
What are catecholamines?
Neurotransmitters of the CNS/PNS/Sympathetic autonomic systems. Made from tyrosine & phenylalanine
-Dopamine (DA)
-Norepinephrine (NE)
-Epinephrine (EPI)
What are the breakdown products of NE and EPI? What enzymes are responsible?
Homovanillic acid and Vanylmandelic acid.

-Monoaminie oxidase
-Catecholamine-O- methyl transferase
What is melanin?
Skin pigment made from Tyrosine.

Albinism is absent or low