D1401-1600 Flashcards
What is the rate-limiting step of the following? • β-Oxidation
Carnitine acyltransferase I
What is the rate-limiting step of the following? • Ketogenolysis
HMG CoA synthase
What is the rate-limiting step of the following? • Cholesterol synthesis
HMG CoA reductase
What direction does RNA polymerase move along the template strand of DNA during transcription?
3’-5’ direction, synthesizing RNA in the 5’-3’ direction
True or false? Histidine activates the histidine operon.
False. Histidine operon is activated when there are low intracellular levels of histidine.
What organ is responsible for the elimination of excess nitrogen from the body?
The kidneys excrete the excess nitrogen from the body as urea in the urine.
What is the only way to increase maximum velocity (Vmax)?
Increase enzyme concentrations
Name the two purine bases found in both DNA and RNA.
Adenine and guanine
What prokaryotic positioning enzyme in translation is blocked by the following? • Tetracycline
EF-Tu and EF-Ts of the 30S ribosomal subunit
What prokaryotic positioning enzyme in translation is blocked by the following? • Erythromycin
EF-G of the 50S subunit
What prokaryotic positioning enzyme in translation is blocked by the following? • Streptomycin
IF-2 of the 30S subunit
True or false? DNA polymerases can correct mistakes, whereas RNA polymerases lack this ability.
True. DNA polymerases have 3’-5’ exonuclease activity for proofreading.
What are the two precursors of heme?
Glycine and succinyl-CoA
What two factors cause PTH to be secreted?
A decrease in Ca2+ and an increase in PO4-
What are the nonoxidative enzymes of the HMP shunt? Are the reactions they catalyze reversible or irreversible?
Transketolase and transaldolase. The reactions they catalyze are reversible.
What are the five AAs that are both ketogenic and glucogenic?
Isoleucine, threonine, tryptophan, tyrosine, and phenylalanine
What artificial sweetener must patients with PKU avoid?
Aspartame
Cri-du-chat syndrome results in a terminal deletion of the short arm of what chromosome?
Chromosome 5
What substrate gets built up in Gaucher’s disease?
Glucosyl cerebroside
What protein prevents ssDNA from reannealing during DNA replication?
Single-strand DNA binding protein
What type of jaundice is seen in Dubin-Johnson syndrome?
Conjugated (direct) hyperbilirubinemia, a transport defect
What type of DNA library is made from the mRNA from a tissue expressing a particular gene?
cDNA libraries are derived from mRNA, are continuous, and contain no introns or regulatory elements.
What is the most common cause of vitamin B6 deficiency?
Isoniazid treatment
What lysosomal enzyme is deficient in • Gaucher’s disease?
Glucocerebrosidase
What lysosomal enzyme is deficient in • Niemann-Pick disease?
Sphingomyelinase
What lysosomal enzyme is deficient in • Tay-Sachs disease?
Hexosaminidase A
What are the three exceptions to the rule of codominant gene expression?
Barr bodies in females, T-cell receptor loci, and immunoglobulin light and heavy chain loci
How many kilocalories per gram are produced from the degradation of fat? CHO? Protein?
9 kcal/g from fat metabolism; 4 kcal/g from both CHO and protein metabolism
What is the only way to increase the Vmax of a reaction?
Increase the concentration of enzymes
From which two substances are phospholipids made?
Diacylglycerols and phosphatidic acid
What intermediate enables propionyl CoA to enter into the TCA cycle?
Succinyl CoA
What vitamin is an important component of rhodopsin?
Vitamin A
What is the term to describe the 5’-3’ sequence of one strand being the same as the opposite 5’-3’ strand?
Palindrome
What gluconeogenic enzyme is absent in muscle, accounting for its inability to use glycogen as a source for blood glucose?
Glucose-6-phosphatase
What is the term for vitamin D deficiency prior to epiphyseal fusion?
Rickets prior to fusion, osteomalacia if the deficiency occurs after epiphyseal fusion.
In what disease is there a genetic absence of UDP-glucuronate transferase, resulting in an increase in free unconjugated bilirubin?
Crigler-Najjar syndrome
What enzyme requires molybdenum as a cofactor?
Xanthine oxidase
At what three sites can the HMP shunt enter into glycolysis?
- Fructose-6-phosphate 2. Glucose-6-phosphate 3. Glyceraldehyde-3-phosphate
What is the term for the pH range where the dissociation of H+ occurs?
pK (think of it as where half is base and half is acid)
What regulates the rate of ketone body formation?
The rate of β-oxidation
What are the eight liver-specific enzymes?
- Fructokinase 2. Glucokinase 3. Glycerol kinase 4. PEPCK 5. Pyruvate carboxylase 6. Galactokinase 7. Fructose-1, 6-bisphosphatase 8. Glucose-6-phosphatase
How many bases upstream is the eukaryotic TATA box promoter?
There are two eukaryotic upstream promoters. The TATA box is -25 base pairs upstream; the CAAT box is -75 bases upstream.
What is needed to initiate translation?
IF and GTP (eIF for eukaryotes)
What part of the 30S ribosome binds to the Shine-Dalgarno sequence?
16S subunit
What component of the ETC is inhibited by the following? • Barbiturates
Complex I
What component of the ETC is inhibited by the following? • Antimycin A
Cytochrome b/c1
What component of the ETC is inhibited by the following? • Cyanide
Cytochrome a/a3
What component of the ETC is inhibited by the following? • Oligomycin
Fo/F1 complex
What component of the ETC is inhibited by the following? • Atractyloside
ATP/ADP Translocase
What component of the ETC is inhibited by the following? • CO
Cytochrome a/a3
What component of the ETC is inhibited by the following? • Rotenone
Complex I
What component of the ETC is inhibited by the following? • Azide
Cytochrome a/a3
What AA is a precursor of the following substances? • Serotonin
Tryptophan
What AA is a precursor of the following substances? • GABA
Glutamate
What AA is a precursor of the following substances? • Histamine
Histidine
What AA is a precursor of the following substances? • Creatine
Glycine/arginine
What AA is a precursor of the following substances? • NAD
Tryptophan
What AA is a precursor of the following substances? • N2O
Arginine
What two enzymes are vitamin B12-dependent
Homocysteine methyl transferase and methylmalonyl CoA transferase
What two post-transcriptional enzymes in collagen synthesis require ascorbic acid to function properly?
Prolyl and lysyl hydroxylases
What three organs participate in production of vitamin D?
- Skin 2. Liver 3. Kidney
What water-soluble-vitamin deficiency is associated with neural tube defects in the fetus?
Folic acid
What phase of Interphase is haploid (N)?
G1 phase; G2 and S phase are diploid (2N).
What neurotransmitter inhibits the optic nerve bipolar cell and shuts off in response to light?
Glutamate
Which of the following—DNA methylating enzymes, scaffolding proteins, histone acetylases, or deacetylases—is a regulator of eukaryotic gene expression?
Histone acetylases is a regulator favoring gene expression. All of the others favor inactivation.
Name the pattern of genetic transmission characterized thus: both M and F affected; no M-to-M transmission; affected M passes trait to all daughters, every generation; affected F passes trait to both sons and daughters; a single mutant allele can produce the disease.
X-linked dominant
What fat-soluble vitamin is connected to selenium metabolism?
Vitamin E
Why are eukaryotes unable to perform transcription and translation at the same time like prokaryotes?
In eukaryotes transcription occurs in the nucleus and translation in the cytoplasm.
What is determined by the secondary structure of an AA?
The folding of an AA chain
What three vitamin deficiencies are associated with homocystinemia?
Folate, vitamin B12, and vitamin B6
If the pH is more acidic than the pI, does the protein carry a net positive or net negative charge?
When the pH is more acidic than the pI, it has a net positive charge, and when the pH is more basic than the pI, it has a net negative charge.
What form of continuous DNA, used in cloning, has no introns or regulatory elements?
cDNA, when it is made from mRNA
What is the start codon, and what does it code for in eukaryotes? Prokaryotes?
The one start codon, AUG, in eukaryotes codes for methionine and in prokaryotes formylmethionine.
What parasite found in raw fish can produce vitamin B12 deficiency?
Diphyllobothrium latum
Methylating uracil produces what pyrimidine base?
Thymine
Name the eukaryotic RNA polymerase based on the following: • Synthesizes tRNA, snRNA, and the 5S rRNA
RNA polymerase III
Name the eukaryotic RNA polymerase based on the following: • Synthesizes hnRNA, mRNA, and snRNA
RNA polymerase II
Name the eukaryotic RNA polymerase based on the following: • Synthesizes 28S, 18S and 5.8S rRNAs
RNA polymerase I
What is the primary screening test used to detect HIV-infected individuals? Confirmatory test?
ELISA is used as a screening test because it is very sensitive; Western blot is used as a confirmatory test because it detects antibodies (protein) to the HIV virus.
How many covalent bonds per purine-pyrimidine base pairing are broken during denaturation of dsDNA?
None. Denaturation of dsDNA breaks hydrogen bonds, not covalent bonds.