studystack 2 Flashcards
Amino acid catabolism produces what toxic product?
Ammonia
When does negative nitrogen balance occur?
Dietary Deficiency (starvation) Catabolic stress (ex. infection)
What 3 cofactors are required for amino acid synthesis?
Pyridoxal phosphate Tetrahydrofolate Tetrahydrobiopterin (BH4)
When pyruvate is transaminated, what does it synthesize?
Alanine
When oxaloacetate is transaminated, what does it synthesize?
Aspartate
When alpha-ketoglutarate is transaminated, what does it synthesize?
Glutamate
What forms alanine by transamination?
Pyruvate
What forms aspartate by transamination?
Oxaloacetate
What forms glutamate by transamination?
alpha-ketoglutarate
Where is arginine generated?
Urea cycle
Where does Cysteine get its S?
Methionine
What is pyridoxal phosphate (PLP) synthesized from?
Vitamin B6
What are two mechanisms through which nitrogen is removed from amino acids?
Transamination
Deamination
What enzyme is involved in the oxaloacetate –> aspartate reaction?
AST
What is the function of glutamate dehydrogenase?
It deaminates glutamate, resulting in alpha-ketoglutarate and ammonia.
Where does the deamination of glutamate by glutamate dehydrogenase take place?
Liver
What enzyme is involved in the deamination of glutamate into alpha-ketoglutarate and ammonia?
Glutamate dehydrogenase
What enzyme is involved in the conversion of glutamate + ammonium (NH4+) –> glutamine
Glutamine synthase
What conversion does glutamine synthase catalyze?
glutamate and ammonium –> glutamine
What enzyme is involved in the conversion:glutamine –> glutamate + NH4+?
Glutaminase
In the FASTED state, what do the liver and muscles contribute to amino acid metabolism?
Muscles = provide amino acids for metabolismLiver = uses lots of amino acids in fasted state.
Where does the urea cycle occur?
Liver
What is the enzyme that converts HCO3- + NH4+ –> Carbamoyl phosphate?
CPS1 (carbamoyl phosphate synthase 1)
What is the rate limiting step in the urea cycle?
CPS1 (carbamoyl phosphate synthase 1)
What is the enzyme that converts Ornithine to Citrulline?
OTC (ornithine transcarbomylase)
What is the common source of both of the N’s in urea?
Glutamate
Where do the first two steps of the urea cycle occur?
Mitochondria
In the urea cycle, after the first two steps, where do the following steps occur?
Cytoplasm
What are two products from the urea cycle?
Arginine fumarate
What is the role of NAG in the urea cycle?
It is synthesized by acetyl CoA and glutamate and it STIMULATES CPS1
Ornithine transcarbamoylase deficiency (OTC), the most common cause of urea cycle disorder, is what type of genetic trait?
x-linked
Beginning Product of FA synthesis
Citrate
Shuttle used in FA synthesis
Citrate shuttle
What cofactor is needed in all carboxylases?
Biotin
Location of FA synthesis
Hepatic cytosol
Where do we get NADPH?
Pentose Phosphate Pathway
Large complex of enzymes that binds growing acyl chain and malony CoA in first round.
Fatty Acid Synthase
What are the three types of macromolecular synthesis?
DNA replication (DNA synthesis)
Transcription (RNA synthesis)
Translation (protein synthesis)
What is the basic dogma of biology?
DNA - RNA - protein
Where does prokaryotic replication take place?
In the cytoplasm
Where does eukaryotic replication take place?
In the nucleus during S phase of the cell cycle.
Duplicate chromosomes, so that after mitosis each daughter cell will inherit a complete genome.
DNA Replication
Requirements for DNA replication
DNA polymerase, Mg2+, template, primer, and dNTPs
In what direction does DNA replication occur?
5 to 3 direction
Stage: Ribosomes assembled with mRNA between large and small subunits along with 1st aminoacyl tRNA (Met); tRNa bound to P site of ribosome.
Initiation
Where does B oxidation occur?
Mitochondria
What enzyme combines succinyl-CoA and glycine to start the Heme pathway?
ALA (aminolevulinic acid) synthetase
Rare enzyme deficiency in the heme pathway.
Porphyria
Genetic defect in UDP-glucuronyl Transferase.
Crigler-Najar syndrome
Maximum possible number of hydrogen atoms, single bonds only between carbon atoms, solid at room temperature.
Saturated fats
Has at least one double bond between carbon atoms because hydrogen atoms are missing. Double bond is point of unsaturation, they are unstable. Liquid at room temperature.
Unsaturated fats
An omega-6 fatty acid, precursor of Arachidonic acid.
Linoleic Fatty Acids
Enzyme responsible for catalyzing chain elongation in prokaryotes for both the leading and lagging strands.
DNA Polymerase III
Seals the gap that remains after Pol I removes the RNA primer and replaces it with DNA
DNA ligase
Some polymerases can copy an RNA template into DNA in the process known as ________
Reverse transcription
Hereditary nonpolyposis colorectal cancer (HNPCC), one of the most common inhereted cancers has been shown a defect in this DNA system.
Mismatch
This type of enzyme recognize a misincorporated nucleotide, nicks the strand, and remove sthe misincorporated nucleotide.
Endonucleases
Dihydrofolate reductase inhibitor
Methotrexate
Drug that induces Vitamin B6 deficiency
Isoniazid
Dietary insufficiency of thiamine/impaired intestinal absorption of B1; apathy, memory loss, nystagmus (eyeball motion)
Wernicke-Korsakoff syndrome
In infants, present as tachycardia, vomiting, convulsions, death; adults: dry skin, irritability, disorderly thinking progressive paralysis
Beriberi
Niacin defiency causes
Pellagra: dermatitis, diarrhea, dementia, death
Coenzyme in carboxylation reactions, carrier of activated CO2
Biotin
Selectively stimulates gene expression or specifically repress gene transcription, regulates plasma levels of calcium and phosphorous
Vitamin D
Post translational modification of various blood clotting factors.
Vitamin K
Active form of Vitamin E
a-tocopherol
DNA double helix that have additional twists applied to them that have coiled up upon themselves.
Supercoiling
– heterocyclic compound consisting of pyrimidine fused to a 5 member imidazole ring (adenine and guanine)
Purine
Heterocyclic compounds with nitrogen atoms at positions 1 and 3 of a 6 member ring (thymine, cytosine, uracil).
Pyrimidine
nitrogenous base (attached to 1’ C by B-N-glycosidic bond), a ribose sugar (OH at 2’ C), and a phosphate group (backbone of DNA, attached to 5’ C) – present in RNA molecules
Ribonucleotide
bond is between the 3’ OH group of the deoxyribose/ribose on the last nucleotide and the 5’-phosphate of the dNTP/NTP precurson – basically it is a bond that connects nucleotides in DNA
phosphodiester bond
Linear and single stranded, carries codon information for translation (2%)
mRNA
folded loop structures formed by intra-molecular H-bonding, carries amino acids to ribosomes (16%)
tRNA
Method: Take a single stranded DNA with gene sequence of interest with a fluorescent probe let it anneal to DNA in cell and look for fluorescence.
FISH
complex of DNA and chromosomal proteins (histones)
Chromatin
Rich in lysine and arginine, and as a result carry a positive charge. This makes it easier for negatively charged chromatin to associate.
Histones
Antibiotic drugs that interfere with DNA gyrase
Quinolone
Decondensed and transcriptionally active DNA
Euchromatin
Condensed and transcriptionally inactive DNA
Heterochromatin
Nucleotide that is an analogue of Acyclovir.
Guanine
prevent re-annealing of DNA and prevent hairpin loops from forming
SSB proteins
Drug inhibits bacterial DNA gyrase
Ciprofloxacin
Combines with certain proteins and is involved in RNA processing and gene regulation in eukaryotes
snRNA
3 stop codons
UGA, UAG, UAA
predicts the base pairing of the 5’ anticodon and 3’ codon
Wobble hypothesis
Enzyme that cleave trypsinogen to trypsin.
Enteropeptidase
Where does Urea synthesis begin and end within the cell?
Mitochondria to start, cytoplasm to finish
How much energy is required to run the urea cycle?
4 ATP
