BCHEM LE6 (2024) Flashcards
- Transporter of lipid that is lowest in density but largest in size. It contains the highest percentage of lipid and the smallest of protein.
A. Chylomicron
B. VLDL
C. LDL
D. HDL
Chylomicron
- Which of the following is true about plasma lipoproteins?
A. They are held together by covalent bonds.
B. They are composed of a neutral lipid core surrounded by esterified cholesterol.
C. They have varied protein to lipid ratio.
D. The principal lipid carried by lipoprotein particles are chylomicrons.
They have varied protein to lipid ratio.
- This apoprotein is found in the particles released by the intestinal mucosal cells called “nascent” chylomicrons.
A. Apo CII
B. Apo B48
C. Apo B100
D. Apo C
Apo B48
- This apoprotein is found in the particles released by the intestinal mucosal cells called “nascent” chylomicrons.
A. Apo CII
B. Apo B48
C. Apo B100
D. Apo C
Apo B48
- Which of the following proteins are the major carriers of triacylglycerols?
A. VLDL and LDL
B. Chylomicrons and VLDL
C. Chylomicrons and LDL
D. VLDL and HDL
Chylomicrons and VLDL
- As the lipid-to-protein ratio decreases, particles become smaller and more dense in the following order:
A. Chylomicron > HDL > VLDL > LDL
B. Chylomicron > VLDL > LDL > HDL
C. HDL > LDL > VLDL > Chylomicron
D. HDL > LDL > VLDL > Chylomicron
Chylomicron > VLDL > LDL > HDL
- Which statement is correct?
A. A marked decrease in triacylglycerol produces turbidity in plasma.
B. Because chylomicrons are the most dense, they form a supranate.
C. Increased turbidity can result from an increase in chylomicrons or VLDL.
D. Plasma lipoproteins transport the highly-soluble lipids.
Increased turbidity can result from an increase in chylomicrons or VLDL.
- This apolipoprotein antagonizes ApoE and is known to inhibit lipoprotein lipids.
A. ApoB
B. ApoC-I
C. ApoC-III
D. ApoC-II
ApoC-III
- In the exogenous pathway, this apoprotein activates lipoprotein lipase which catalyzes the hydrolysis of triacylglycerols.
A. Apo E
B. Apo C
C. Apo B48
D. Apo A8
Apo C
- Site of action of hormone sensitive lipase that degrades stored triacylglycerols activated by cAMP-dependent protein kinase:
A. Stomach
B. Pancreas
C. Adipocytes
D. Liver
Adipocytes
- They are composed predominantly of triacylglycerol and they carry this lipid to the peripheral tissues from the liver:
A. Chylomicron
B. VLDL
C. LDL
D. HDL
VLDL
- Its primary function is to provide cholesterol to the peripheral tissues by depositing cholesterol in the membranes of the cells.
A. Chylomicron
B. VLDL
C. LDL
D. HDL
LDL
- Nascent triglyceride-rich very low density lipoproteins are secreted from the:
A. Intestinal mucosal cells
B. Liver
C. Stomach
D. Pancreas
Liver
- Which of the following is true about metabolism of low density lipoproteins?
A. LDL receptors are positively charged glycoprotein molecules that are clustered in pits on cell membranes.
B. After binding, the LDL undergo a process called exocytosis.
C. The pH of the contents of the endosomes increases allowing separation of the LDL from its receptor where receptors migrate to one side of the endosome and the LDLS stay free within the lumen of the vesicle.
D. The receptors can be recycled whereas the lipoprotein remnants in the vesicles are degraded by lysosomal enzymes releasing cholesterol, fatty acids, amino acids and phospholipids.
The receptors can be recycled whereas the lipoprotein remnants in the vesicles are degraded by lysosomal enzymes releasing cholesterol, fatty acids, amino acids and phospholipids.
- The initiating step in the modification of ApoB involves which process?
A. Peroxidation of polyunsaturated fatty acids in the LDL lipids.
B. Regulation of modified LDL taken up by macrophages.
C. Acetylation of apolipoprotein B.
D. Oxidation of circulating macrophages with low levels of scavenger receptor activity.
Peroxidation of polyunsaturated fatty acids in the LDL lipids.
- Which of the following is not correct about HDL’s?
A. HDL particles are synthesized in the liver and are released into the bloodstream by endocytosis.
B. Newly secreted HDL are disc-shaped particles containing predominantly unesterified cholesterol, phopholipid and a number of lipoproteins.
C. They are excellent acceptors of unesterified cholesterol from the surface of cell membranes and from other circulating lipoproteins.
D. The only mechanism for removing cholesteryl ester from HDL in the plasma is through transfer to VLDL.
HDL particles are synthesized in the liver and are released into the bloodstream by endocytosis.
- This transferes cholesterol from HDL to VLDL and triacylglycerols from VLDL to HDL.
A. Lipoprotein lipase (LPL)
B. Cholesteryl ester transfer protein (CETP)
C. Hepatic lipase (HPL)
D. CURL
Cholesteryl ester transfer protein (CETP)
- Familial hypercholesterolemia is usually secondary to a deficiency in:
A. ApoCII
B. ApoB48
C. ApoB100
D. ApoCIII
ApoCII
- Which of the following comprises metabolic syndrome?
A. Elevated HDL, hypertension, elevated blood sugar, obesity
B. Elevated LDL, hypertension, elevated blood sugar, obesity
C. Elevated HDL, hypertension, elevated triglycerides, obesity
D. Elevated LDL, hypotension, elevated blood sugar, obesity
Elevated LDL, hypertension, elevated blood sugar, obesity
- Which functions of the apoproteins refer to solubilisation of lipids?
A. Enzymatic
B. Esterification
C. Structural
D. Recognition
Structural
- GT, a 3-month old female, was brought in to your clinic for consult. She was born via home delivery from Cagayan. On work-up, she had abnormal red blood cell morphology and neurologic symptoms. This can be a lipoprotein abnormality secondary to:
A. Absence of normal LDL
B. Absence of normal HDL
C. Lack of ApoC proteins
D. Lack of ApoA proteins
Absence of normal LDL
- They are excellent acceptors of unesterified cholesterol, both from the surface of the cell membranes and from other circulating lipoproteins.
A. Chylomicron
B. VLDL
C. LDL
D. HDL
HDL
- Activates lecithin cholesterol acyltransferase (LCAT), which esterifies tissue cholesterol picked up by HDL.
A. ApoB
B. ApoC-I
C. ApoC-II
D. ApoA-1
ApoA-1
- They are endocytosed by target cells with receptors and degraded, releasing cholesterol, which decreases further uptake of cholesterol.
A. Chylomicron
B. VLDL
C. LDL
D. HDL
LDL
- Which of the following lipids is NOT part of a lipoprotein?
A. Phospholipids
B. Triacylglycerols
C. Esterified cholesterol
D. Unesterified cholesterol
Esterified cholesterol
- Which of the following is abundantly present in the white matter of the brain?
A. Galactocerebroside
B. Glucocerebrosides
C. Triacylglycerols
D. Gangliosides
Galactocerebroside
- Which of the following is NOT a glycerophospholipid?
A. Cardiolipin
B. Plasmalogen
C. Lecithin
D. Sphingomyelin
Sphingomyelin
- Which of the following phospholipids acts as a precursor for the generation of inositides?
A. Phosphatidyl choline
B. Phosphatidyl inositol
C. Phosphatidyl serine
D. Phosphatidyl ethanolamine
Phosphatidyl inositol
- Which type of special lipid serves as the receptor for choleragen in the intestinal cells?
A. GM2 ganglioside
B. GM1 ganglioside
C. Sphingomyelin
D. Galactocerebroside
GM1 ganglioside
- Which of the following is an intermediate both for the synthesis of phospholipids and triacylglycerols?
A. Diacylglycerol
B. Cholesterol
C. Choline
D. Inositol
Diacylglycerol
- A 3-year old child was brought to the medical center and found to have hepatosplenomegaly and mental retardation. Biopsy reveals accumulation of sphingomyelin. What is the nature of the disease?
A. Gaucher’s
B. Niemann Pick’s
C. Krabbe’s
D. Tay Sach’s
Niemann Pick’s
- Among the following special lipids, which is a glycerophospholipid?
A. Cardiolipin
B. Galactosyl ceramide
C. GM2
D. Sphingomyelin
Cardiolipin
- The enzymes that is deficient in Niemann Pick’s disease?
A. Glucocerebrosidase
B. Hexosaminidase A
C. Sphingomyelinase
D. b-galactocerebrosidase
Sphingomyelinase
- Among the following special lipids, which is a sphingophospholipid?
A. Cardiolipin
B. Plasmalogen
C. Lecithin
D. Sphingomyelin
Sphingomyelin
- Which of the following phospholipids acts as a lipotropic agent?
A. Phosphatidyl choline
B. Phosphatidyl inositol
C. Phosphatidyl serine
D. Cardiolipin
Phosphatidyl choline
- What are the components of a galactocerebroside?
A. Sphingosine + fatty acid + galactose
B. Glycerol + fatty acids + phosphoric acid + galactose
C. Glycerol + fatty acids + phosphoric acid + nitrogenous base + galactose
D. Sphingosine + fatty acid + phosphoric acid + galactose
Sphingosine + fatty acid + galactose
- What is the major component of the lung surfactant?
A. Dipalmitoyllecithin
B. Dipalmitoylphospatidyl serine
C. Dipalmitoylcephalin
D. Dipalmitoylphosphatidyl inositol
Dipalmitoyllecithin
- Ethanolamine is the nitrogenous base of which phospholipid?
A. Cardiolipin
B. Phosphatidyl inositol
C. Lecithin
D. Cephalin
Cephalin
- What is the significance of L:S ratio determination of amniotic fluid in a pregnant female?
A. Fetal heart rate
B. Fetal lung maturity
C. Fetal head size
D. Expected date of delivery
Fetal lung maturity
- What are the components of ceramide?
A. Sphingosine + fatty acid
B. Glycerol + fatty acid + phosphoric acid
C. Glycerol + fatty acid + phosphoric acid + nitrogenous base
D. Sphingosine + fatty acids + phosphoric acid
Sphingosine + fatty acid
- Sphingosine is not part of the special lipid:
A. Cerebrosides
B. Gangliosides
C. Sphingomyelin
D. Plasmalogen
Plasmalogen
- How many sugar moieties are present in GM1?
A. One
B. Three
C. Four
D. Two
Four
- What does the letter M in GM2 represent?
A. Sialic acid residues
B. N-acetyl galactose residues
C. Glucose residues
D. N-acetyl glucosamine residues
Sialic acid residues
- In eukaryotes, cardiolipin is synthesized from the condensation of:
A. Serine + CDP–DAG
B. Phosphatidyl glycerol + CDP–DAG
C. Removal of carbon dioxide
D. Head group exchange
Phosphatidyl glycerol + CDP–DAG
- What is the second messenger utilized in the regulation of the cytidyl transferase enzyme used in the synthesis of phospholipids?
A. cGMP
B. IP3
C. 1,2-DAG
D. cAMP
cAMP
- What is the predominating hormone in the cells when cytidyl transferase enzyme is active?
A. Insulin
B. Glucagon
C. Adrenaline
D. Thyroxine
Insulin
- What ganglioside accumulates in Tay Sach’s disease?
A. GM1
B. GM2
C. GT3
D. GD2
GM2
- What is the enzyme deficient in generalized gangliosidosis?
A. b-galactosidase
B. Hexosaminidase A
C. Arylsulfatase A
D. b-glucosidase
b-galactosidase
- In Fabry’s disease, this globoside accumulation can lead to end-stage renal disease:
A. Ceramide trihexoside
B. Lactosyl ceramide
C. Galactosyl ceramide
D. Glycosyl ceramide
Ceramide trihexoside
- This is a glucosylceramide lipidoses that results from a deficiency of b-glucosidase:
A. Faber’s disease
B. Fabry’s disease
C. Gaucher’s disease
D. Niemann Pick disease
Gaucher’s disease
- True about the non-template strand except:
A. Also termed coding strand
B. Strand that is transcribed
C. Corresponds exactly to the sequence of RNA primary transcript except T for U
D. None
Strand that is transcribed
- The product of DNA transcription is called:
A. Mature mRNA
B. Introns
C. Exons
D. Primary transcript
Primary transcript
- Nonprotein coding RNA that participates in mRNA splicing:
A. snRNA
B. miRNA
C. siRNA
D. IncRNA
snRNA
- The most abundant of all types of RNA comprising about 80% of the total:
A. mRNA
B. tRNA
C. rRNA
D. snRNA
rRNA
- Similaritiesof DNA and RNA synthesis include the following except:
A. The general steps of initiation, elongation and termination with 5’ to 3’ polarity
B. Large with multicomponent initiation complexes
C. Adherence to Watson-Crick base-pairing principles
D. Both have highly active efficient proofreading function
Both have highly active efficient proofreading function
- This includes the promoter, RNA-coding region, and a terminator.
A. Transcription unit
B. Primary transcript
C. 5’ flanking sequences
D. 3’ flanking sequences
Transcription unit
- The RNA polymerase that has intermediate sensitivity to α-amanitin.
A. Pol I
B. Pol II
C. Pol III
D. Pol IV
Pol III
- The major product/products of RNA polymerase I is:
A. rRNA
B. mRNA, IncRNA, miRNA, snRNA
C. tRNA, 5s RNA
D. 45S RNA
rRNA
- RNA polymerase attaches to this site to start the initiation process.
A. Guanosine triphosphate cap
B. Enhancer
C. Promoter
D. Primer
Promoter
- All nucleotides downstream of the site of transcription termination are termed.
A. 5’ flanking sequences
B. 3’ flanking sequences
C. Pre-initiation complex
D. Closed complex
3’ flanking sequences
- The type of RNA polymerase that catalyzes the synthesis of mRNA.
A. Pol I
B. Pol II
C. Pol III
D. Pol IV
Pol II
- The TATA box in eukaryotes is located:
A. 10 bp upstream from the transcription start site (TSS)
B. 35 bp upstream from the TSS
C. 25-30 bp upstream from TSS
D. 5 bp upstream from TSS
25-30 bp upstream from TSS
- The termination protein is also called:
A. Psi factor
B. Rho factor
C. Sigma factor
D. Alpha factor
Rho factor
- In some mRNA encoding genes that lack a consensus TATA box, this directs the RNAP II transcription machinery to the promoter:
A. Downstream promoter element
B. Enhancers
C. General transcription factors
D. Primer
Downstream promoter element
- The general transcription factor (GTF) that binds to the TATA box promoter element.
A. TFIIA
B. TFIIB
C. TFIIC
D. TFIID
TFIID
- Phosphorylation of Pol II results to:
A. Increased activity
B. Reduced activity
C. No change
D. Inactivity
Increased activity
- On certain eukaryotic genes, transcription machinery cannot access the promoter because they are wrapped in:
A. Spliceosomes
B. Ribosomes
C. Nucleosomes
D. Ribozymes
Nucleosomes
- Processing of mRNA primarily occurs in the:
A. Cytoplasm
B. Ribosomes
C. Nucleus
D. Nucleolus
Nucleus
- The RNA sequence that appears in mature RNAs
A. Exons
B. Introns
C. Cap
D. Tail
Exons
- Intervening sequences of DNA that neither appear in mature mRNA nor contribute to the genetic information.
A. Exons
B. Introns
C. Cap
D. Tail
Introns
- Removal of intervening sequences and splicing together of final sequences are done by:
A. Spliceosome
B. Nucleosome
C. Ribosome
D. None
Spliceosome
- In mammalian cells, the three rRNA molecules are transcribed as part of this single large precursor molecule.
A. 45S
B. 40S
C. 32S
D. 24S
45S
- The precursor rRNA molecule is processed in the:
A. Nucleus
B. Nucleolus
C. Ribosome
D. Mitochondria
Nucleolus
- At the 5’-end, mRNA molecules are capped with
A. Poly (A) tail
B. TATA cap
C. 7-methylguanosine cap
D. GCCT tail
7-methylguanosine cap
- Represents a molecular link between transcription, elongation complexes, RNA splicing and nuclear export:
A. SAGA
B. P/CAF
C. TREX
D. CTD
TREX
- This is the first stage in expression of genetic information:
A. Replication
B. DNA synthesis
C. Translation
D. Transcription
Transcription
- Which statement does not hold true for DNA?
A. It is the repository of genetic information
B. In prokaryotic cells, the DNA is found associated with various type of protein called nucleoprotein
C. Prokaryotic cells, which lack nuclei, have a single chromosome
D. In prokaryotes, the DNA-protein complex is present in non-membrane bound region known as nucleoid
In prokaryotic cells, the DNA is found associated with various type of protein called nucleoprotein
- Which is NOT a characteristic of the structure of DNA?
A. DNA is a polymer of deoxyribonuclease monophosphates (dNMPs) covalently linked by 3‘→5’-phosphodiester bonds
B. DNA only exists as a double stranded molecule
C. Has two strands that wind around each other forming a double helix
D. The DNA contains four monomeric deoxynucleotide units
DNA only exists as a double stranded molecule
- Thymine is present in:
A. DNA
B. RNA
C. DNA and RNA
D. Neither DNA nor RNA
DNA
- G-C bonds in DNA are:
A. Always equal to the number of A-T bonds in a single DNA strand
B. Held together by 2 hydrogen bonds
C. Linked together by sharing of electrons
D. More resistant to denaturation than A-T bonds
More resistant to denaturation than A-T bonds
- In the DNA double helix;
A. The chains are paired in a parallel manner
B. The 5’-end of one strand is paired with the 3’-end of the same strand
C. The hydrophilic deoxyribose–phosphate backbone of each chain is on the outside of the molecule
D. The hydrophillic bases are stacked inside
The hydrophilic deoxyribose–phosphate backbone of each chain is on the outside of the molecule
- Which of the following bases is not normally seen in RNA?
A. Adenine
B. Uracil
C. Thymine
D. Guanine
Thymine
- Which of these is referred to as a linker histone?
A. H1
B. H2
C. H3
D. H4
H1
- The chemical nature of RNA differs from that of DNA:
A. Ribonucleic acid (RNA) is a polymer of purine and pyrimidine ribonucleotides linked together by 3→5’-phosphodiester bonds analogous to those in DNA
B. In RNA, the sugar moiety to which the phosphates and purine and pyrimidine bases are attached is the 2’-deoxyribose of DNA rather than ribose
C. The pyrimidine components of RNA are similar to those of DNA
D. Both DNA and RNA can be hydrolyzed by alkali to
2’→3’ cyclic diesters of the mononucleotides
Ribonucleic acid (RNA) is a polymer of purine and pyrimidine ribonucleotides linked together by 3→5’-phosphodiester bonds analogous to those in DNA
- The following statement is TRUE with regards to tRNA structure and function:
A. It has an anticodon arm which binds to a specific amino acid
B. It needs to be activated by the attachment of a nucleic acid
C. It is a single-stranded molecule bound by intrachain bridges
D. It bridges the gap between DNA and RNA synthesis
It is a single-stranded molecule bound by intrachain bridges
- In the 3’ → 5’ phosphodiester bonds:
A. Join the 3’ hydroxyl group of the deoxypentose of one nucleotide to the 5’ hydroxyl group of deoxypentose of an adjacent nucleotide through a methyl group
B. The resulting long branched chain has polarity that are not attached to other nucleotides
C. The 5’ end of the chain has a free phosphate attached to it
D. The bases located along the resulting deoxyribose-phosphate backbone are by convention always written in sequence from 3’ to 5’ end of chain
The 5’ end of the chain has a free phosphate attached to it
- In the DNA double helix;
A. The two chains are coiled around a common axis called the Helical Axis
B. The overall structure resembles a twisted ladder
C. The spatial relationship between the two strands in the helix creates a major (wide) groove and a minor (narrow) groove
D. All of the above
All of the above
- True of Chargaff Rule except:
A. In any sample of dsDNA molecules, the concentration of deoxyadenosine nucleotides equals that of thymidine nucleotides
B. The concentration of deoxyguanosine nucleotides equals that of deoxycytidine nucleotides
C. The concentration of deoxyadenosine nucleotides equals that of Uracil nucleotides
D. None of the above
The concentration of deoxyadenosine nucleotides equals that of Uracil nucleotides
- The following statement is false;
A. The double helix structure is disrupted by alterations in the pH of the DNA solution
B. Heat denatures the DNA strands
C. Phosphodiester bonds are broken by heat treatment
D. None of the above
C. Phosphodiester bonds are broken by heat treatment
- Which statement is not true?
A. The single stranded DNA has a higher relative absorbance at at 260 nm wavelength than does double stranded DNA
B. The melting temperature (Tm) is affected by the number of hydrogen bonds between bases
C. DNA that contains high concentrations of Adenine and Thymine denatures at a lower temperature than Guanine and Cytosine-rich DNA
D. There are three hydrogen bonds between Adenine and Thymine but only two between Guanine and Cytosine
There are three hydrogen bonds between Adenine and Thymine but only two between Guanine and Cytosine
- Which is the most tissue-specific and species-specific of the histones?
A. H1
B. H2
C. H3
D. H4
H1
- Among the major structural forms of DNA, which has the planes of the base pairs tilted 20O away from the perpendicular to the helical axis?
A. A form
B. B form
C. C form
D. Z form
A form
- This structural form of DNA has a left-handed helix that contains about 12 base pairs per turn.
A. A form
B. B form
C. C form
D. Z form
Z form
- True of the B form DNA that is usually found under physiologic conditions.
A. It is a right-handed helix with ten residues per 360° turn of the helix
B. B. The planes of the bases are parallel to the helical axis
C. C. The width of the double helix is measured at 34 Å, and the distance spanned by one complete turn of the double helix is 20 Å
D. D. One turn of B-DNA includes 10 base pairs, so the rise is therefore 34 Å per base pair
It is a right-handed helix with ten residues per 360° turn of the helix
- Which among major types of RNA that participate in the process of protein synthesis make up about 80% of the total RNA in the cell?
A. Ribosomal RNA (rRNA)
B. Transfer RNA (tRNA)
C. Messenger RNA (mRNA)
D. Noncoding RNA (ncRNA)
Ribosomal RNA (rRNA)
- The two strands of the DNA double-stranded helix are held in register by this bond:
A. Hydrogen bonds
B. van der Waals
C. Hydrophobic interactions
D. All of the above
All of the above
- Which of these histones is not a part of the nucleosome core?
A. H1
B. H2A
C. H2B
D. H3
H1
- The sugar moiety to which the phosphates and purine and pyrimidine bases are attached is a ribose.
A. DNA
B. RNA
C. Both DNA and RNA
D. Neither
RNA
- Can be hydrolysed by alkali to 2’,3’ cyclic diesters of the mononucleotides.
A. DNA
B. RNA
C. Both DNA and RNA
D. Neither
RNA
- Capable of folding back on itself like a hairpin and this acquiring double-stranded characteristics.
A. DNA
B. RNA
C. Both DNA and RNA
D. Neither
RNA
