Biochemistry Flashcards
Codon that signals initiation of protein synthesis
AUG
Stop codons
UAA
UAG
UGA
Southern blot detects
DNA
Northern blot detects
RNA
Western blot detects
Protein
Dot (slot) detects
RNA, DNA or protein
Purine types and number of rings that they have:
Adenine
Guanine
2 rings
Pyrimidines types and number of rings that they have:
Cytosine
Uracil
One ring
A-T form __ bonds between them:
Two hydrogen bonds
G-C form __ bonds between them:
Three hydrogen bonds
Chemotherapeutic agents that target S phase:
Interfere with DNA Synthesis:
Methotrexate (ectopic pregnancy; dihydrofolate reductase, no thymine + leucovorin)
Capecitadine->5-flurouracil (pyrimidine analog, no thymine)
Cytarabine (AML; pyrimidine analog)
Clabribine (Hairy cell; purine analog). Claudio is a pure hairy man
Azathioprine->6-mercaptopurine (Ulcerative colitis; purine analog)
Hydroxyurea (ribonucleotide reductase)
Chemotherapeutic agents that targets G2 phase:
Bleomycin (forms free radicals that breaks DNA)
Bortezomib
Chemotherapeutic agents that target M phase:
Interfere with microtubules:
Vincristine
Vinblastine
Paclitaxel
Erlibutin
Non cell-cycle specific chemotherapeutic agents:
Affect replication by: Alkaliting (cross link DNA): Cyclophosphamide (+ mesna) Cisplatin (+ amifostine) Busulfan (ablate marrow) Carmustine (glioblastoma) Procarbazine
Intercalating (intercalate within DNA chains):
Doxorubicin (+ dexrazoxane)
Daunorubicin (+ dexrazoxane)
Dactinomycin
Chemotherapeutic agents that target the jump between S and G2 phase:
Etoposide, tenitopiside (inhibit topoisomerase 2)
Iridotecan, topotecan (inhibit topoisomerase 1)
Eucromatine (from less to more condensed)
10 nm chromatin
30 nm chromatin
Loops of 30 nm chromatin attached to scaffolding proteins
Is heterochromatin condensated or non condensated?
Highly condensed
Leading strand characteristics:
Continuous
Moving into/ toward the replication fork
5’—>3’
Lagging strand characteristics:
Discontinuos, series of Okazaki fragments
Moving away from the replication fork
3’—>5’ toward the replication fork
Nalidixic acid mechanism of action:
It is a synthetic quinolone that inhibits DNA gyrase
DNA polymerase gamma function:
Replicates mitochondrial DNA
Single-stranded DNA-binding protein (SSB) function:
Stabilization of unwound template strands
Fluorquinolones mechanism of action:
Inhibit tropoisomerases 2 (DNA gyrase) and 4
Inactivation or deletion of p53 gene is associated with:
Li Fraumeni syndrome and solid tumors
SBLA: sarcoma, breast, brain, leukemia, adrenal
Most DNA repair occurs in ____ phase
G1
Which enzyme is deficient in xeroderma pigmentosa?
Excinuclease (excision endonuclease, an UV specific endonuclease) enzyme deficiency
Lynch syndrome (Hereditary nonpolyposis colorectal cancer) usually results from which mutation and which tumors are associated with it?
Autosomal dominant sd. due to a mutation in genes hML!!H1 and hMS!!H2! Love 1st Sex 2nd!
Increased risk of Colon (proximal colon is always involved), Endometroid (before 50), Ovary and STOMACH ca. CEOS of Merry Lynch
Dx: tumor cells on w. have microsatellite instability on GATA sequence on Ch7 (normally used for testing)
Mechanism of action of Rifampin:
Inhibiting prokaryotic RNA polymerase
Mechanism of action of Actinomycin D:
Chemotherapeutic drug (antitumor antibiotic) also called dactinomycin Binds DNA to prevent transcription, it intercalates DNA
Alpha-amanitin (in certain mushrooms) acts
Inhibiting eukaryotic RNA polymerase 2!!
A cistron is
A gene
Hogness box
Pribnow box
are…
The TATA box
Two example sequences of promoter regions are:
CAAT box (80 bases upstream) and TATA box (25 bases upstream) Binding site for general transcription factors and RNA polymerase 2
Missense mutation definition:
Change leads to a new amino acid
Nonsense mutation definition:
Change leads to a stop codon
Frame-shift versus in-frame mutation:
Frameshift: non triple number of nucleotides are deleted (Duchenne) or inserted (Tay-Sachs) so all aa after the mutation are messed up
In frame: nucleotide substitution (Becker) triplet deletion (CF) or insertion (Huntington, Spinobulbar muscular atrophy)
When does Gray baby syndrome occurs?
In babies with not enough UDP-glucuronyl transferase to metabolize chloramphenicol or inadequate renal excretion
If untreated they die from cardiovascular collapse
Chloramphenicol can also cause aplastic anemia and thrombocytopenia
Cystic fibrosis is normally consequence of
The deletion of phenylalanine at position 580 and generates improper folding
Klein-Waardenburg syndrome is due to
A mutation in a PAX gene
Presents with partial albinism+deafness+aniridia
Menkes disease is due to
A deficient collagen cross-linking due to Cu deficiency (mutation in gene ATP7A)
Sensitivity and specificity of ELISA are:
Sensitivity: high
Specificity: low
Kwashiorkor is due to and presents with:
Protein malnutrition. Presents with edema
Marasmus is due to and presents with:
Chronic deficiency of calories. Does not present with edema
What do statins inhibit in cholesterol synthesis?
3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase
Name 4 facts about the action of Methotrexate
- Antineoplastic
- Interferes with DNA replication in phase S
- Competitively inhibits dihydrofolate reductase
- Deprives the cell of active folate
Competitive inhibitors effect in Km and Vmax:
Increase Km
Do not change Vmax
Noncompetitive inhibitors effect in Km and Vmax:
Decrease Vmax
Do not change Km
GLUT 1 and 3 have a ____ affinity for glucose
High
GLUT 2 has a ____ affinity for glucose
Low
GLUT 1 and 3 are in
Most tissues
GLUT 2 is in
The liver and pancreatic beta-islets
GLUT 4 is in
Skeletal muscle and adipose tissue
Pyruvate kinase deficiency is associated with
Ch1
Hemolytic anemia
Increased 2,3-BPG, low O2 affinity for Hb, high O2 in tissues
Burr cells (echinocytes)
No heinz bodies
Autosomal recessive ♂and♀ (DD. with G6PD that is X-linked ♂ recessive and will have heinz bodies)
Hexokinase/Glucokinase acts
In glycolysis
Phosphorylating glucose to trap it in the cell
Heinz bodies are characteristic from
G6PDH deficiency
Glutathione reductase deficiency
Galactosemia is due to a deficit of one of 2 enzymes:
Galactokinase or
Galactose 1-phosphate uridyltransferase
Clinical picture of galactosemia:
Newborn Cataracts Jaundice Hyperbilirrubinemia Vomiting and diarrhea
Hereditary fructose intolerance is a deficiency of the enzyme:
Aldolase B
Clinical picture of hereditary fructose intolerance:
Starts when baby stops breast feeding Vomiting Lethargy Liver damage, hyperbilirubinemia Hypoglycemia Hyperuricemia Renal proximal tubule defect (Fancony)
Thiamine is
Vitamine B1
Thiamine (vit B1) deficiency may lead to
Beriberi
or
Wernike-Korsakoff syndrome (confusion, ataxia, ophthalmoplegia)
Clinical picture of Wernike-Korsakoff syndrome:
Alcoholic Ataxia Ophthalmoplegia, nystagmus Memory loss and confabulation Cerebral hemorrhage
McArdle disease is a deficiency of
Muscle glycogen phosphorylase
Clinical picture of McArdle disease:
Weak, initial exercise intolerance with cramps
Recovery or ‘second wind’
Possible myoglobinuria
No lactic ac. in venous blood
Pompe disease is a deficiency of:
Lysosomal alpha1,4-glucosidase
Clinical picture of Pompe disease:
Cardiomegaly
Muscle weakness
Death in 2 years
Due to accumulation of glycogen-like material in endosomes
Function of chylomicrons
Transport triglycerides and cholesterol from intestine to tissues
Function of VLDL
Transport triglycerides from liver to tissues
Function of IDL
Pick up cholesterol from HDL to form LDL
Function of LDL
IDL remnant, takes cholesterol from the liver to the peripheral tissues
Function of HDL
Takes cholesterol from peripheral tissues to the liver (reverse cholesterol transport)
Clinical picture of Medium Chain Acyl-Coa Dehydrogenase (MCAD) Deficiency:
Fasting hypoglycemia
Lethargy, coma
C8-C10 acyl carnitines in blood
Episodes after fasting/illness
Tay-Sachs disease is a deficiency of _____ and _____ is accumulated
Hexosaminidase A deficiency
Ganglioside GM2 accumulation
Gaucher disease is a deficiency of_____ and _____ is accumulated
Glucocerebrosidase deficiency
Glucocerebroside accumulation
Niemann-Pick disease is a deficiency of_____ and _____ is accumulated
Sphingomyelinase deficiency
Sphingomyelin accumulation
The most common disorder in the urea cicle is:
Ornithine transcarbamoylase deficiency
Phenylketonuria is a deficiency of:
Enzyme Phenylalanine hydroxylase
Or cofactor Tetrahydrobiopterin (BH4)
Clinical picture of phenylketonuria:
Musty odor
Mental retardation
Pale skin, eye and white hair
Pallor of cathecholaminergic brain structures
Alkaptonuria is a deficiency of the enzyme:
Homogentisate oxidase, that converts tyrosine to fumarate
Clinical picture of Alkaptonuria:
Urine becomes dark
Ochronosis (dark cartilage)
Arthritis
Maple syrup urine disease is a deficiency of:
Branched-chain ketoacid dehydrogenase enzyme
Clinical picture of maple syrup urine disease:
Urine smells like maple syrup Mental retardation Abnormal muscle tone Ketones Metabolic acidosis Hyperammonemia because urea cycle is blocked
Homocystinuria is due to:
Cystathionine synthase enzyme deficiency or affinity loss (B6)
Methionine synthase= homocysteine methyl transferase=Methylenetetrahydrofolate reductase deficiency (B12, folic acid)
Clinical picture of homocystinuria:
Deep vein thrombosis Atherosclerosis Early stroke and MI Ectopic lens (luxates down and in) Marfan-like habitus (loose slender fingers) Mental retardation
Pyridoxine is:
Vitamin B6
Orotic aciduria can be a deficiency of the enzyme ____ or ____
Ornithine transcarbamoylase or OTC (generates hyperammonemia). Carbamoyl phosphate accumulates and backs up to orotic acid. You cannot form citruline
Uridine monophosphate synthase or UMP synthase (generates megaloblastic anemia) because orotic acid accumulates
Lesch-Nyhan syndrome is a deficiency of ___ and the enz. ___ is overactive:
Deficiency of HGPRT enzyme (purine salvage)
You cannot form GMP and IMP so PRPP accumulates and you have an overactive PRPP amidotransferase (de novo purine synthesis)
Clinical picture of Lesch-Nyhan syndrome:
Orange crystals in diapers
Spastic cerebral palsy
Self mutilation
Hyperuricemia
Histone acetylation forms
Euchromatin; Acetylation makes the DNA Active
Deacetylation is the opposite and mutes the DNA
Methylation of DNA forms
Heterochromatin; Methylation Mutes the DNA
Hypomethylation is little methylation
Hypermethylation is a lot of methylation
Mechanism of action of streptomycin:
Binds 30S ribosomal subunit impairing the initiation of protein synthesis
Tocopherol is vitamin
E
Galactosyl beta-1,4-glucose is also called
Lactose
RNA polymerase I mainly produces:
Ribosomal RNA
RNA polymerase II mainly produces:
Messenger RNA
RNA polymerase III mainly produces:
Transfer RNA
Tetracycline acts:
Binding to the 30S subunit of microbial ribosomes preventing the attachment of tRNA (prevents protein synthesis)
Previous administration to which drugs is needed to do a TB test in the treatment of rheumatoid arthritis:
TNF-α inhibitors:
Etarnercept Infliximab Adalimumab Certolizumab Golimumab
They can also cause drug-induced lupus
The enzyme defective in PKU is:
Phenylalanine hydroxylase
Mode of inheritance of Lech Nyhan disease:
X-linked recessive
Mode of inheritance of Marfan sd:
Autosomal dominant
The enzyme lysyl oxidase requires as a cofactor:
Cu
Coenzymes that pyruvate dehydrogenase need to work:
Tender Loving Care For Nancy:
Thiamine pyrophosphate (from thiamine)
Lipoic acid
Coenzyme A (from pantothenic ac)
FAD (from riboFlavin, B2 as FAD gives 2 ATPs)
NAD (from Niacin, B3 as NAD gives 3 ATPs)
Enzymes that require thiamine pyrophosphate (coming from thiamine, B1) to work:
Be APT for thiamine:
Branched chain ketoacid dehydrogenase (Val, Iso->propionyl-CoA; Leu->acetyl-CoA)
Alpha-ketoglutarate dehydrogenase (Alpha-KG->succinyl-CoA)
Pyruvate dehydrogenase (pyruvate->acetyl-CoA)
Transketolase (Ribose5-P->glycolysis)
3 main features of G6PD deficiency are:
Immunodeficiency
Heinz bodies
Hemolytic anemia
Adenyl cyclase is inhibited by:
The alpha part of the Gprot Gi
Liver phosphodiesterase is inhibited by:
Methylxanthines
Phosphofructokinase-2 is inhibited by:
Glucagon phosphorylation
Na/K ATPase is inhibited by:
Ouabain
Digoxin
