MCQ Flashcards
Is insulin important during the fed state?
Yes
Why is insulin important during the fed state?
Insulin stimulates glycogenesis
How is the acetylcholine receptor opened?
Rotation of the pore helices
What is a potent activator of PFK-1 in liver cells?
F-2,6-bisP
Does complete oxidation of one molecule of palmitate provide more or less molecules of ATP than complete oxidation of one molecule of glucose?
Palmitate produces more
Are ketone bodies beneficial for the brain?
Yes
What oxidises very long chain fatty acids?
Peroxisomes
What difference can be observed in the circulating fatty acid levels of individuals with type 2 diabetes?
Elevated levels
What do proteins destined for the plasma membrane pass through?
Endoplasmic reticulum and Golgi apparatus
What does manose-6-phosphate do to soluble proteins?
Directs them to lysosomes
What would genomic amplification of the c-MYC gene likely lead to?
Development of cancer
Are inherited single allele mutations in tumour suppressor genes linked to susceptibility to cancer?
Yes
What happens to the melting temperature of DNA as length increases?
It increases
What do histone undergo in their N-terminal sequences?
Post-translational modifications
What does the binding of the glucocorticoid receptor to its ligand result in?
Translocation of the glucocorticoid receptor to the nucleus
What is transcription termination coupled to in eukaryotes?
mRNA polyadenylation
Why does the core RNA polymerase terminate transcription at rho-independent sites in prokaryotes?
Due to a GC-rich hairpin and a run of U nucleotides in the RNA
What is the significance of the Pribnow box at -10 in prokaryotes?
Important determinant of the start site of transcription
What is TFIID?
A complex of TATA binding protein (TBP) and a number of other
general transcription factors called TAFs
What impact will increasing concentration of BH3 only proteins have on a cell?
Make the cell more likely to undergo apoptosis
What does the spindle assemble checkpoint do?
Monitors the proper attachment of chromosomes to microtubules during mitosis
What is the action of Humira in rheumatoid arthritis?
Blocks the action of TNFα on its receptor
How are human antibodies created from transgenic mice?
Mice are derived from embryonic stem cells engineered to include the human antibody loci in their genome
Does a plasmid produce a circular recombinant molecule in the host cell?
Yes
Does a bacterial artificial chromosome produce a circular recombinant molecule in the host cell?
Yes
Does a yeast artificial chromosome produce a circular recombinant molecule in the host cell?
No
Does a cosmid produce a circular recombinant molecule in the host cell?
Yes
Does a P1-derived artificial chromosome produce a circular recombinant molecule in the host cell?
Yes
Are coding or non-coding regions of genes more conserved between different animal species?
Coding regions are more conserved
How many introns do mammalian mitochondrial genes have?
Few or none
Are mammalian genes distributed evenly across the genome?
No
Is the one gene-one protein assumption true or false?
False
What do mutations in genes that are imprinted often alter?
Foetal growth
How is mild anaemia of sickle cell trait characterised at the molecular level?
A deleterious gain of function
What is the high rate of de novo mutations in Duchenne muscular dystrophy likely related to?
The large size of the dystrophin gene
Are most copies of rare mutant alleles found more often in homozygotes or heterozygotes?
Heterozygotes
What allows us to predict that male tortoiseshell cats will be sterile?
X-inactivation
What hormone is produced by alpha cells in the isle of langehans?
Glucagon
What is adrenaline?
A catecholamine derived from tyrosine (the amino acid)
What does insulin stimulate muscle to convert glucose into?
Glycogen
What do serine proteases use to stabilise the tetrahedral intermediate?
Oxyanion hole
What is the amino acid residue at the active site of HIV protease that mediates target cleavage?
Aspartic acid
What is targeted by sarin to inhibit acetylcholinesterase?
Serine
What intracellular messenger releases Ca2+ from the endoplasmic reticulum?
Inositol-1,4,5-trisphosphate (IP3)
What signal stimulates synthesis of phosphatidylinositol-3,4,5-trisphosphate (PIP3)?
Insulin
What is released from a G protein when it is activated by a receptor?
GDP
What sequence ensure nascent soluble proteins are retained in the endoplasmic reticulum?
KDEL
What mediates vesicular transport between endoplasmic reticulum and the Golgi apparatus?
COP II vesicle
What mediates the first step in cholesterol uptake?
LDL receptor
What chemical interaction holds strands together in a DNA double helix?
Hydrogen bonds
What chemical moiety is at the 3’- end of a linear DNA molecule?
Hydroxyl
What aromatic base is normally paired with guanine?
Cytosine
Is cytosine acidic or basic?
Basic
Is cytosine aromatic?
Yes
What is a telomere?
The DNA region at each end of a chromosome
What enzyme initiates nucleic acid synthesis in DNA replication?
Primase
What is a transposon?
A mobile genetic element
What is a distinguishing feature of a lariat?
2’-5’ phosphodiester bond
What part of the antibody is involved in interaction with receptors on effector cells of the immune system?
Fc
What is CDR?
A hypervariable loop joining two beta strands
What defines the binding specificity of an antibody?
CDR (a hypervariable loop joining two beta strands)
What technique involves separation of the products of transcription based upon their lengths, followed by transfer on to a membrane support to allow interrogation with a labelled DNA or cDNA probe?
Northern blotting
What is cDNA library construction?
A preparation of a bank of clones from a tissue or a developmental stage that allows further investigation of the genes expressed through sequence analysis or hybridisation to locus specific probes
What is restriction fragment length polymorphism analysis?
Digestion of nucleic acids and comparison of the product sizes following gel separation to identify allele specific patterns
What is a de novo loss of several adjacent loci from one chromosome, which results in a disease phenotype, an example of?
Contiguous gene deletion syndrome
What phenomenon is important for normal development which is often impaired in clinical conditions such as Prader-Willi syndrome?
Imprinting
Does muscle require insulin for efficient uptakes and metabolism of glucose?
Yes
Does fat require insulin for efficient uptakes and metabolism of glucose?
Yes
Does the brain require insulin for efficient uptakes and metabolism of glucose?
No
Does the pancreas require insulin for efficient uptakes and metabolism of glucose?
No
Does the liver require insulin for efficient uptakes and metabolism of glucose?
No
How are serine and alanine similar?
Serine is alanine with another hydroxyl group
How are tyrosine and phenylalanine similar?
Tyrosine is phenylalanine with another hydroxyl group
What do the amino acid pairs serine+alanine and tyrosine+phenylalanine have in common?
Alanine + -OH = Serine
Phenylalanine + -OH = Tyrosine
Is glucose a reducing sugar?
Yes
What molecules link to form maltose?
2 α-D-glucose molecules
Does starch or glycogen contain more α-1,6 branches?
Glycogen
What is cellulose formed from?
A chain of β-D-glucose molecules
Are sugars added to proteins in the endoplasmic reticulum?
Yes
Where do the side chains point in a β-sheet?
Above and below the plane of the sheet
In regular secondary structures, what are all the backbone C=O and N-H atoms forming?
Hydrogen bonds
How many of the backbone C=O and N-H atoms form hydrogen bonds in regular secondary structures?
All of them
What is an α-helical hairpin mainly held together by?
Hydrophobic interactions
In an α-helix, do the side chains point towards the C-terminus?
No
What does the Φ angle describe?
Rotation around the bond between the Cα and N atoms
What angle describes the rotation around the bond between Cα and N atoms?
Φ
What is involved in the humanisation of a murine antibody?
The CDR loops of the murine antibody are grafted onto a human framework
Does 1,3-bisphosphoglycerate formation from glyceraldehyde-3-phosphate require ATP?
No
Is glucokinase inhibited by glucose-6-phosphate?
No
Is the reaction catalysed by aldolase during glycolysis essentially irreversible?
No
Does glycerol phosphate formation from dihydroxyacetone phosphate requires NAD+?
No
Does AMP interact with glycogen phosphorylase?
Yes, AMP activates glycogen phosphorylase
Can more glycogen be stored in liver or muscle?
Muscle
How does glucose influence phosphorylation of liver glycogen phosphorylase?
Promotes it
What promotes phosphorylation of liver glycogen phosphorylase?
Glucose
What reaction does glucose promote in liver glycogen phosphorylase?
Phosphorylation of liver glycogen phosphorylase
In liver cells, is the NAD+/NADH ratio lower in the mitochondria or the cytosol?
Mitochondria
What reduces pyruvate kinase activity in the liver?
The action of glucagon
Do liver tissues use ketone bodies?
No
What is the effect of ethanol metabolism in the liver?
It slows down gluconeogenesis
How many protons does complex IV pump for each pair of electrons transferred to oxygen?
2 protons
Which complexes in the electron transport chain contain tightly-bound iron-sulphur proteins that transfer single electrons?
Complexes I, II, III
If the associated entropy change is positive, what will happen as long as the temperature exceeds a certain threshold?
An endothermic chemical reaction will spontaneously proceed
What condition must be met for an endothermic chemical reaction to spontaneously proceed if the associated entropy change is positive?
Temperature exceeds threshold value
What conditions must be met in order for an endothermic chemical reaction to spontaneously proceed?
The associated entropy change is positive
Temperatures exceeds threshold value
What do G-protein-coupled receptors promote?
GDP release from G proteins
Do G-protein-couple receptors bind ATP?
No
Does the activation of G-protein-coupled receptors require phosphorylation of tyrosine residues?
No
Do G-protein-coupled receptors allow ions to pass freely across the plasma membrane?
No
Which has a larger phosphorylation potential, adenosine triphosphate or phosphocreatine?
Phosphocreatine
How are newly synthesised insulin receptors targeted to the plasma membrane?
Via the Golgi apparatus
What cell type do adenocarcinomas originate in?
Glandular epithelial cells
Is there a correlation between genome size and organism complexity?
No
What do the majority of repeat sequences in our genome derive from?
Transposable elements
What do bacteria rely on in DNA mismatch repair?
DNA methylation
What do bacteria rely on DNA methylation for?
DNA mismatch repair
Is DNA methylation inherited in a Mendelian fashion?
No
How is ubiquitin linked to lysine in proteins?
Covalently via a multi-step process
Are most genes in mammals spliced or not?
Spliced
Is RNA splicing common in yeast?
No, it’s rare
What does canonical splicing require?
Large ribonucleoprotein
During RNA splicing, what does the branch point region base pair with?
US snRNA
During RNA splicing, what does US snRNA pair with?
The branch point region base
What does alternative splicing increase?
The diversity of the proteome
What increases the diversity of the proteome?
Alternative splicing
In prokaryotes, does splicing require a unique lariat structure to form?
No
What do cells with unrepaired DNA usually undergo?
Apoptosis
What does phosphorylation of Cdc6 help prevent?
Re-replication of DNA
Can cells with unrepaired DNA damage become senescent?
Yes
What effect does cleaving have on a caspase?
Activated when cleaved
What caspase cleaves Bid?
Caspase 8
Is caspase 7 an initiator caspase?
No
Is caspase 8 part of the extrinsic pathway of apoptosis?
Yes
What residues to caspases primarily cleave substrates at?
DEVD residues
What does giemsa-banding reflect?
Chromatin condensation
How often will an aneuploid karyotype be abnormal?
Always
How many chromosomes does the mouse karyotype have?
40
How does the position of the centromere vary for a given chromosome?
Stays constant
What regulates mammalian X inactivation?
Non-coding RNA
What proposed random X inactivation?
Mary Lyon’s 1961 paper
Which is the heterogametic sex in birds?
Female
Is the human Y chromosome gene-rich?
No
What is the FMR1 gene influenced by?
Trinucleotide repeat expansion
What have genome-wide association studies usually identified?
Low risk disease variants
What is Down’s syndrome generally caused by?
Meiotic defects
Why is trisomy 21 common in Down’s syndrome?
This chromosome is small and the effects of the increased gene dosage are therefore less serious
Is the risk of Down’s syndrome correlated to maternal age?
Yes, risk increases with maternal age
Is Down’s syndrome usually congenital?
Yes
Do individuals with Down’s syndrome have a lower incidence of dementia?
No, they have a higher incidence of dementia
What is biotin a cofactor for?
Acetyl CoA carboxylase
What is a cofactor of acetyl CoA carboxylase?
Biotin
What is pantothenate involved in?
Transfer of 2-carbon units
What is involved in the transfer of 2-carbon units?
Pantothenate
What is an electron carrier in cytochrome C?
Haem
Is haem found in cytochrome C?
Yes, it acts as an electron carrier
What modular domain binds proline-rich sequences?
SH3
What nucleotide exchange factor induces conformational change in Ras and release of GDP?
Sos
What transcription factor is activated by the MAP kinase pathway?
Fos
What enzyme is inhibited via phosphorylation during starvation, thus promoting gluconeogenesis?
Pyruvate dehydrogenase
What amino acid provides an important connection between the citric acid cycle and the urea cycle?
Aspartic acid
What metabolite inhibits de novo fat synthesis by activating a kinase?
AMP
What is an IP3 receptor?
An ion channel
What inactivates the signalling properties of cyclic AMP?
Phosphodiesterase
What conserved protein domain binds to phosphotyrosine residues?
SH2 domain
What is activated by genomic amplification in neuroblastoma?
N-Myc
What tumour virus protein is responsible for binding to and inactivating p53?
Human papilloma virus E6
What regulates c-Src?
Intramolecular tyrosines with a phosphotyrosine?
What is a centromere?
The region of attachment between two sister chromatids
What function effect is achieved by X-chromosome inactivation?
Dosage compensation
What is a T-loop?
A DNA structure formed by telomeres
What enzyme unwinds the parental DNA in replication?
DNA helicase
What is the proof reading activity of DNA polymerases?
3’-5’ exonuclease
What step is required in the maturation of bacterial Okazaki fragments?
Nick translation
What is the template of transcription in eukaryotes?
Genomic DNA
What is histone acetylase?
A chromatin-modifying enzyme
What is an enhancer in transcriptional control?
A cis-regulatory element that can be located far from the gene locus
What is a mosaic?
Individual composed of cells with different genotypes
What is chiasma?
Point where exchange of genetic information occurs between homologous non-sister chromatids
What is the chi-squared test?
Statistical method for determining the significance of observed outcomes against expected results
What do glucagon, adrenaline and vasopressin all stimulate?
Cell signalling cascades using cAMP as a common intracellular signal transduction molecule
What common intracellular signal transduction molecule do glucagon, adrenaline and vasopressin all use when stimulating cell signalling cascades?
cAMP
What regulates protein kinase A catalytic activity?
Binding to cAMP
What repulsion is required for calcium ion flow through voltage-gated calcium channels?
Ion-ion repulsion
What do voltage-gated calcium channels open in response to?
Plasma membrane depolarisation
How many binding sites do voltage-gated calcium channels have for calcium ions?
2
How can the response of voltage-gated calcium channels to membrane potential be modified?
Phosphorylation
Can disaccharides have reducing ends?
Yes
How many chiral centres do glucose and galactose differ at?
1
What chiral centre do glucose and galactose differ at?
Carbon 4
What bond is the α-1,6 branchpoint in glycogen?
Glycosidic bond
How many epitopes does a monoclonal antibody typically recognise on the target antigen?
1
How many domains do IgG class antibodies contain?
12 immunoglobulin domains held together by disulphide bonds
What allows the antigen binding arms of a single antigen to bind to two antigens?
The hinge region
What does the hinge region allow?
The binding arms of a single antigen to bind to two antigens
What mediates effector functions of antibodies?
The constant domains
What do the constant domains mediate?
Effector function of antibodies
What permits the variable domain to form the antigen binding site?
Sequence diversity in three loops
What does sequence diversity in three loops allow the variable domain to do?
Form the antigen binding site
Does secondary structure always maximise side chain hydrogen bonds?
No
What proteins have no disulphide bonds?
Intracellular proteins
Is disulphide bonding necessary for all tertiary structures?
No, intracellular proteins have none
What sort of protein is haemoglobin?
Globular
What makes up the Greek key motif?
4 β-sheets
Do cofactors provide functionality?
Yes, ie carrying electrons and oxygen
What connects the two nucleotides contained by NAD and FAD?
5’-5’ phosphodiester bonds
What is tetrahydrofolate essential for?
Adenine production
What vitamin is the precursor for a cofactor essential for acyl transfer?
Pantothenate
What is the cofactor pantothenate is a precursor for essential for?
Acyl transfer
What is MLH1 essential in?
Eukaryotic mismatch repair system -> proof reading -> error frequency x100 increase
Do inherited single allele mutations in tumour suppressor genes confer susceptibility to cancer?
Yes
What is glucokinase also known as?
Hexokinase IV
What is hexokinase IV?
Glucokinase
Is hexokinase inhibited by its product?
Yes
Is glucokinase inhibited by its product?
No
Is hexokinase IV inhibited by its product?
No
What is the ΔG·’ for the glycolytic reaction catalysed by fructose bisphosphate aldolase?
Highly endergonic
How many carbons does acetyl have?
2
Is DNA or RNA more stable at alkaline pH?
DNA
Can RNA hybridise with DNA?
Yes
What does cytosine demethylation produce?
Uracil
Are histones basic or acidic?
Basic
Can histone tails undergo chemical modifications?
Yes
What do chromatin remodellers use for activity?
ATP
What does heterochromatin largely consist of?
Repetitive DNA
What does histone H! bind to?
Inter-nucleosomal DNA
How does DNA replication proceed from the DNA origin?
Bidirectionally
What is primase?
A DNA-dependent RNA polymerase
How can flux regulation through a pathway be controlled?
Enzyme expression levels
What does allosteric control provide?
Rapid regulation of pathways, usually from intracellular cues
What prevents accumulation of the products of a given pathway?
Feedback inhibition
What inactivates pyruvate dehydrogenase?
Phosphorylation
What is the impact of increased concentrations of ATP on citrate synthase?
Inactivates citrate synthase
What does the liver take up from the blood stream following exercise?
Lactate
What takes up lactate from the blood stream after exercise?
Liver
What is the toxic mechanism of dinitrophenol (DNP)?
Uncoupling agent that dissipates the chemiosmotic gradient
Does sex chromosome dimorphism occur in birds?
Yes
Does sex chromosome dimorphism occur in mammals?
Yes
Does sex chromosome dimorphism occur in Drosophila?
Yes
In mammals what is the heterogametic sex?
Male
In birds, what is the heterogametic sex?
Female
What does an IRES facilitate?
CAP-independent translation in eukaryotes
What facilitates CAP-independent translation in eukaryotes?
IRES
Why does RNA polymerase terminate transcription at rho-independent site in prokaryotes?
Due to a GC-rich hairpin followed by a run of U nucleotides
Is RNA polymerase II transcription highly regulated?
Yes
What is an important determinant of the transcription start site in prokaryotes?
Pribnow box
What is TFIID a complex of?
TATA-binding protein (TBP) and other general transcription factors (TAFs)
What inhibits degradation of cyclic AMP?
Caffeine
What stimulates protein kinase C activity?
Diacylglycerol
What protein is strongly associated with an inherited predisposition to cancer?
Retinoblastoma (look for tumour suppressors)
What protein is associated with the development of B-cell lymphoma in chickens infected with the avian leukosis virus?
MYC
What protein is strongly associated with tumour angiogenesis?
Vascular endothelial growth factor (VEGF)
What are indels frequently caused by?
Polymerase slippage
What can unbalanced structural variants cause?
Copy number variant
What are transitions and transversions examples of?
Single nucleotide variant
What type of repair is coupled to DNA synthesis?
Mismatch repair
What is translesion synthesis?
A type of DNA polymerase-dependent DNA repair
What type of repair is associated with meiosis?
Homologous recombination
What is the peak absorption wavelength of DNA?
260nm
What correlates inversely with DNA sequence complexity?
Speed of strand reannealing
What assay is used to detect a specific RNA in a nucleic acid sample?
Northern blot
What is Turner syndrome?
A sex chromosome aneuploidy condition in females
What is Klinefelter syndrome?
A sex chromosome aneuploidy condition in males
What is Angelman syndrome caused by?
Paternal uniparental disomy for chromosome 15
What method of cell death usually doesn’t induce inflammation?
Apoptosis
What caspase does pyroptosis often depend on?
Caspase 1
What induces ferroptosis?
Toxic lipid peroxides
What allosteric modulator regulates the balance between glycolysis and gluconeogenesis acting on PFK1?
Fructose-2,6-bisphosphate
What is the product of hexokinase?
Glucose-6-phosphate
What is an intermediate in the citric acid cycle and gluconeogenesis?
Oxaloacetate
How many ATP molecules are produced from the oxidation of FADH2?
1.5
How many ATP molecules are produced from the complete oxidation of acetyl CoA?
10
How many ATP molecules are produced from the complete oxidation of palmitoyl-CoA?
108
Is tyrosine aromatic?
Yes
Is tryptophan aromatic?
Yes
Is phenylalanine aromatic?
Yes
Is threonine aromatic?
No
Can serine be phosphorylated?
Yes
Can threonine be phosphorylated?
Yes
Can tyrosine be phosphorylated?
Yes
Can phenylalanine be phosphorylated?
No
What charge are lysine sidechains at pH6?
Positive
What charge are arginine sidechains at pH6?
Positive
What charge are histidine sidechains at pH6?
Positive
Does aspartic acid have positively charged sidechains at pH6?
No
Where do secondary structures correspond to on a Ramachandran plot?
2 separate areas
What conditions are needed to favour ketone body formation in liver cells?
High ATP levels
High NADH levels
Less active pyruvate dehydrogenase
High acetyl-CoA levels
What can ligand-gated ion channels be classified as?
Allosteric receptors
Why do SNARE proteins wind around each other?
To force inbound vesicles closer to target organelle membranes
What direction does RNA synthesis proceed in?
5’-3’
What would make a cell more likely to undergo apoptosis?
Release of cytochrome C from the mitochondria
What would make a cell less likely to undergo apoptosis?
Increasing Bcl2 concentration
Is it only pro-apoptotic Bcl2 family proteins that have BH3 domains?
No
What do Bax and Bak form in the outer mitochondrial membrane?
Pores
Is Mcl-1 pro-apoptotic?
No, Mcl-1 is anti-apoptotic
What caspase can cleave Bid?
Caspase 8
Is Bcl2 a tumour suppressor gene or an oncogene?
Oncogene
What does it mean if a meiotic recombination frequency of 50% is observed?
The two genes are likely to be located on different chromosomes
If the heterogametic sex of a species is female, what is the sex of the parthenogenetic offspring?
Male
Have twin studies shown that genetic factors have a greater role in schizophrenia than in parkison disease?
Yes
What equations allows calculation of the genotype frequencies if you know the phenotype frequencies?
Hardy-Weinberg equation
Can some oncogenes be characterised by single point mutation?
Yes
Does the Bcl2 protein promote cell death?
No
When is the v-src protein activated?
Following truncation of its extreme carboxy terminus
What gene is involved in chromosomal translocations characteristic of non-AIDS Burkitt’s lymphoma?
c-myc
What would a point mutation of the intracellular domain of the epidermal growth factor receptor do?
Contribute significantly to the development of cancer
Does Magnetic Resonance require ionizing radiation?
No
Does Magnetic Resonance require a static magnetic field?
Yes
What can Magnetic Resonance be used for?
3D anatomical images
Does Magnetic Resonance provide poor soft-tissue contrast?
No, provides excellent soft-tissue contrast
Is Magnetic Resonance a relatively insensitive technique?
Only without hyperpolarization
What is a PET experiment?
A positron emitting tracer is injected in the patient and gamma radiation is detected from positron-electron annihilation
What percentage of the mitochondrial genome makes functional gene products?
95%
How are mutations in mitochondrial DNA inherited?
Maternally
What are cells with a mixed population of mutant and normal mitochondria known as?
Heteroplasmic
What can be used to determine total protein concentration in a solution?
Bradford assay
What technique relies on purification on the basis of charge?
Ion exchange chromatography
What is isothermal calorimetry used to do?
Measure heat changes when two molecules interact
What domain in Grb2 binds to the active receptor tyrosine kinase?
SH2 domain
What protein switches off small G proteins?
GTPase activating protein
What protein kinase is activated by binding to an active small G protein?
Raf
What enzyme catalyses the hydrolysis of triacylglycerol to diacylglycerol in fat cells?
Adipose triglyceride lipase
What amino acid is directly involved with the urea cycle?
Arginine
What activates phosphorylase kinase?
Calcium ions
What inhibits carnitine acyltransferase I?
Malonyl-CoA
What activates acetyl CoA-carboxylase?
Citrate
What protein is associated with pancreatic cancer?
K-Ras
What kinase promotes cell survival?
Akt
What scaffold protein directs intracellular co-localization of protein kinase A and other proteins?
AKAP
What enzyme hydrolyses phosphatidylinositol-4,5-bisphosphate to generate IP3 and diacylglycerol?
PLC
What activates PKA?
Binding of cAMP
What is a distinguishing feature of a mRNA 5’ CAP in eukaryotes?
5’-5’ nucleotide bond
What is an RNA mediated mechanism for inhibiting gene expression?
RNAi
What is the catalytic core of the spliceosome?
U2 and U6 snRNAs
What amino acid forms an isopeptide bond between ubiquitin and a target protein
Internal lysine
What is essential for the degradation of long-lived proteins?
Lysosome
What is the E3 enzyme?
The ubiquitin ligase
What is the ubiquitin ligase?
The E3 enzyme
What is a euchromatin?
A gene rich region of DNA
What is RNA-dependent DNA polymerase
A reverse transcriptase
What is Leber Hereditary Optic Neuropathy (LHON)?
A mitochondrial disease with matrilineal inheritance
What is complete insensitivity syndrome?
XY individuals developing as phenotypic females
What is chronic myeloid leukaemia commonly caused by?
The presence of the Philadelphia chromosome translocation
What does presence of the Philadelphia chromosome translocation often cause?
Chronic myeloid leukaemia
What is nuchal translucency?
An ultrasound test contributing to prenatal down syndrome diagnosis
What is the initiator of dosage compensation in female mammals?
Xist non-coding RNA
What occurs when a new population is established by a small number of individuals from a larger population?
Founder effect
During the onset of type 2 diabetes, are blood glucose levels likely to be below 7mM?
No, above 7mM
May ketone bodies be present in the blood during onset of type 2 diabetes?
Yes
Is the level of insulin in the blood usually low or undetectable during the onset of type 2 diabetes?
No, often very high
Is uptake of glucose into fat cells responsive to insulin during onset of type 2 diabetes?
Poor responsive
May glucose be present in the urine during the onset of type 2 diabetes?
Yes
Which is stronger, the bonding between two strands of an anti-parallel β-sheet or parallel β-sheet?
Anti-parallel β-sheet
Why is the bonding between two strands of an anti-parallel β-sheet stronger than two strands of a parallel β-sheet?
Because of the orientation of the hydrogen bonds
How can the linkage between two strands of an anti-parallel β-sheet be accommodated?
A short structural loop called a hairpin
On their own, what are β-sheet and α-helices held together exclusively by?
Hydrogen bonds
What causes scurvy?
Reduced hydroxylation of proline residues, weakening collagen fibres
Does glucokinase or muscle hexokinase have a higher km for glucose?
Glucokinase
How is genetic diversity altering the peptide sequence of constant domains achieved?
Recombination
What is haem?
A prosthetic group
How does oxygen bond to an iron ion in oxy-haemoglobin?
Coordinated within a porphyrin ring
Kinetically, how does haemoglobin bind to oxygen?
With sigmoidal binding kinetics
Where does fatty acid synthesis occur?
In the cytosol
What happens to most acetyl-coA in the liver?
Converted into ketone bodies
What is insulin made up of?
2 polypeptides
Where is insulin produced?
Pancreatic beta cells
Does insulin promote glycogen synthesis in muscle?
Yes
Do allosteric enzymes obey Michaelis-Menton kinetics?
No
Do non-allosteric enzymes obey Michaelis-Menton kinetics?
Yes
What do competitive inhibitors do to km and vmax?
Affect km, vmax unchanged
What do non-competitive inhibitors do to km and vmax?
Decrease vmax, km unchanged
What does the serine protease oxyanion hole do?
Stabilise the transition state
What residue do Asp proteases have in their active site?
Aspartic acid residues
Can enzymes form covalent bonds with reaction intermediates?
Yes
What joins sugar molecules in disaccharides?
Glycosidic bonds
What allows the protein backbone to fold?
Rotation around the α-carbon
Are phosphodiester bonds present in DNA or RNA?
In both
Is L-deoxyribose a building block of DNA?
No, D-deoxyribose is the most naturally occurring one
Do all sugars have a reducing end?
No
What domains binds to polyproline epitopes?
SH3 domains
What do SH2 domains recognise?
Phosphorylated tyrosines
How does Sos activate Ras proteins?
Promoting guanine nucleotide exchange
What do transcription factors use to recognise specific DNA sequences?
Hydrogen bonds to base pairs down wide groove and sometimes narrow grooves
What explains the expansion of gas in a vacuum?
Second law of thermodynamics
How can changes in relative concentrations of ATP, ADP and AMP be followed in vivo?
Using 31P nuclear magnetic resonance spectroscopy
Does phosphoenolpyruvate have a small or large phosphorylation potential?
It has one of the highest
Will the standard free energy change for the hydrolysis of the activated carrier acetyl coenzyme A be positive or negative?
Negative
For the reaction A + B ⇌ C + D, is the change in Gibbs free energy under non-standard non-equilibrium conditions is given by: ΔG = ΔGo’ – RT ln {( [A] × [B] ) / ( [C] × [D] )}?
Yes
For the reaction A + B ⇌ C + D, what is the change in Gibbs free energy under non-standard non-equilibrium conditions given by?
ΔG = ΔGo’ – RT ln {( [A] × [B] ) / ( [C] × [D] )}
ΔG = ΔGo’ + RT ln {( [C] × [D] ) / ( [B] × [A] )}
Do skeletal muscles contain glucose-6-phosphate?
No
Do adipocytes contain glycerol kinase?
No
Do skeletal muscles contain acetyl-CoA carboxylase?
Yes
Do liver cells contain succinyl-CoA:aceoacetate CoA transferase?
No
Does heart muscle or skeletal muscle cells contain fructose-1,6-bisphosphatase?
Skeletal muscle does, heart muscle doesn’t
What causes phenylketonuria?
Failure to breakdown phenylalanine
How can leucine and lysine be metabolised?
Only as ketone bodies
What is excess ammonia in tissues added to?
Glutamate
What carries ammonia from skeletal muscle to the liver?
Alanine
What is the activated form of the extender unit in fatty acid synthesis?
Malonyle CoA
How does citrate influence acetyl-CoA carboxylase?
Citrate is an allosteric activator
Where are fatty acids synthesised?
Cytoplasm
How many molecules of CO2 are lost in each extension reaction of fatty acid synthesis?
1
Do all G protein-coupled receptors stimulate formation of cyclic AMP?
Some, not all
How many transmembrane domains do G protein-coupled receptors have?
7
What do G protein-coupled receptors stimulate?
Release of GDP from G proteins
What is the nucleus surrounded by?
A double membrane
Do nuclear pores allow proteins to pass?
Yes
Is the lumen of lysosomes acidic or basic?
Acidic
What do the endoplasmic reticulum and nuclear envelope form?
A continuous membrane system
Can mitochondria synthesise proteins?
Yes
What direction does nucleosomal DNA form a spiral in?
Left-handed spiral
Where does eukaryotic DNA replication start?
Multiple origins
What do DNA polymerases require for nucleotide polymerisation?
A primer and a template
What is primase?
A DNA-dependent RNA polymerase
What is DNA polymerase I 3’-to-5’ exonuclease activity important for?
Proof reading
What is DNA polymerase I 5’-to-3’ exonuclease activity important for?
Nick translation
What do nuclear hormone receptors form on DNA?
Homo- or hetero- dimers
What does activation of the glucocorticoid receptor by cortisol binding involve?
Dissociation of glucocorticoid from Hsp90
What are nuclear hormone receptors?
Specific DNA-binding transcription factors
Can nuclear hormones influence transcription?
Yes, they can activate and/or repress transcription
Where is the mRNA GMP cap methylated?
Position 7
What does the poly(A) tail protect RNA from?
3’ to 5’ exonucleases
What does splicing remove?
Introns
What is required for splicing?
mRNA cap
Does the Ras protein become oncogenic following truncation?
No
How does the retinoblastoma protein control the cell cycle?
Inhibiting E2F proteins
What is an increase in copy number of the N-myc gene associated with in children?
Childhood neuroblastoma
How many somatic mutations do most human cancers have?
1,000-30,000
What does the Hardy-Weinberg Law assume?
Mating is random
There is no selection
There is no mutation
There is no genetic drift
Do genetics play a greater role in schizophrenia or Parkinson’s disease?
Schizophrenia
What is often used for the treatment of malignant melanoma?
Drugs that inhibit the mutant B-RAF oncogene
What do tumour initiating cells (cancer stem cells) contribute to?
Resistance against radiation therapy
Can cells with unrepaired DNA damage become senescent?
Yes
What happens during a PET experiment?
Gamma radiation is detected from positron-electron annihilation
Why is arganine so basic?
Has a guanido group?
What amino acid has a sidechain that attaches to sugars in N-linked oligosaccharides?
Asparagine
Is phenylalanine hydrophobic or aromatic?
Both
Where is succinate dehydrogenase located?
Inner mitochondrial membrane
What is an allosteric activator of pyruvate carboxylase?
Acetyl-CoA
What is an allosteric activator of glycogen phosphorylase?
5’- adenosine monophosphate
What imports proteins from the cytosol in a fully folded state?
Nucleus
What conveys proteins from the Golgi apparatus to the endoplasmic reticulum?
COP I vesicles
Where are sugar residues first attached to proteins?
Endoplasmic reticulum lumen
What has EF-hands that bind Ca2+?
Calmodulin
What inhibits degradation of cyclic AMP?
Caffeine
What stimulates release of Ca2+ from the endoplasmic reticulum?
Isonitol-1,4,5-triphosphate (IP3)
What are transposons?
Mobile genetic elements?
What is replicative transposition?
Chromosomal rearrangement that increases genome size
What is a physical measure of DNA complexity?
Annealing rate
What is the peak wavelength of ultraviolet absorbance of DNA?
260nm
How much DNA is in the human nucleus?
6pg
What promotes CAP-independent protein translation?
IRES
What signal facilitates digestion in lysosomes?
KFERQ
What enzyme is involved in targeted protein degradation?
Ubiquitin ligase
What is an oncogene?
Dominantly acting cancer gene
What is a spontaneous deamination of 5-methylcytosine?
Endogenous mutational process
What is a translocation involving chromosome 1 and chromosome 5?
Structural variation
What is an explanation for the high frequency of heterozygous carriers of the HbS autosomal recessive allele for sickle-cell disease in Africa?
Balancing selection
What is array-based genomic hybridisation?
Molecular cytogenic method for determining copy number variation in a test sample compared to a reference sample
What is variable penetrance?
Less than 100% of individuals with a particular genotype display the expected phenotype
What is fMRI?
A method of measuring brain activity using MRI that is sensitive to changes in blood flow and levels of oxygen
What is FDG?
A PET tracer that is an analogue for glucose
How might inhibitors of phosphotyrosine phosphatases be expected in principal to impact cells responsiveness to insulin?
Increase it
What increases the phosphorylase enzyme activity of glycogen phosphorylase b?
Phosphorylation of glycogen phosphorylase b at serine 14
Binding of 5’AMP to phosphorylase b
What is oxidised and reduced in the electron transport chain?
Everything up to complex 3 is reduced
Everything after complex 3 is oxidised
Complex III of the electron transport chain is inhibited by antimycin. What would happen to the redox state of copper and cytochrome a if antimycin was added to mitochondria that were oxidising NADH?
Copper and cytochrome a both become more oxidised
What is the net yield of ATP when glycogen is utilised by contracting muscle?
3 ATP
How does carbon derived from carbohydrate and fatty acids enter the citric acid cycle?
Condensation of acetyl-CoA with oxaloacetate
What is the absorbance of a compound at a given wavelength equal to?
Its concentration x the width of the sample cuvette x the molar absorbance coefficient
Can amino acids be glucogenic?
Most are
What can some amino acids be metabolised to to contribute to fatty acid synthesis under appropriate conditions?
Acetyl-CoA and acetoacetate
What sort of molecule is urea?
Highly soluble, uncharged
What is required as a cofactor by an enzyme that post-translationally modifies collagen?
Ascorbic acid
Where do collagen molecules assemble before being secreted?
In the endoplasmic reticulum of fibroblast cells
What is the primary sequence of collagen composed of?
Many repeats of the sequence glycine-X-Y where X and Y are often proline and hydroxyproline
What is the carbonyl oxygen of each peptide bond hydrogen bonded to?
The amide nitrogen of the amino acid 4 residues towards the C-terminus
Can protein alpha helices be amphipathic?
Yes
Are protein alpha helices right or left handed?
Right handed
Do protein alpha helices tend to maximise hydrogen bonding?
Yes
What two amino acids are never found in proteins?
Citrulline
Ornithine
What amino acid is involved in the hydrophobic interaction between insulin and its receptor?
Phenylalanine
What amino acid is involved in disulphide formation between the A and B chains of insulin
Cysteine
What amino acid is involved in a site for regulatory phosphorylation by the kinase activity of the insulin receptor?
Tyrosine
Where must insulin be injected?
A site of slow release, ie fat pads but absolutely not a blood vessel
What is a recently-developed drug treatment of type 2 diabetes?
Stimulation of the response to the insulin receptor by thiazolidinediones
What would be the affect of CO2 reacting with α-amino groups and introducing negative charges that stabilise deoxyhaemoglobin?
Altered affinity of oxygen for haemoglobin
How is iron coordinated in haemoglobin?
By N atoms, 4 from the haem ring and one as an axial ligand from histidine
What changes occur when oxygen binds to haemoglobin?
O2 binding allows iron to move into the plane of the haem ring accompanied by α-helix movements that lead to a more open structure
What metabolic process corresponds with the synthesis of malonyl-CoA?
Fatty acid synthesis
What metabolic process corresponds with the donation of the CoA group from succinyl-CoA to a 4-carbon acceptor?
Ketone body utilisation
What metabolic process corresponds with the synthesis of glutamate?
Transamination
What intracellular enzyme is activated as a result of phosphorylation by protein kinase A and which cleaves its substrate into two products that are both released into the blood for use by other tissues?
Triacylglycerol lipase
What enzyme’s activity is increased during gluconeogenesis as a result of a fall in the concentration of a potent inhibitor in response to glucagon activity?
Fructose-1,6-bisphosphate
What enzyme is require for fatty acid synthesis, is activated by insulin, and inhibited by glucagon via phosphorylation of the enzyme protein at different sites?
Acetyl-CoA carboxylase and fatty acid synthase, but acetyl-CoA is a regulatory point for fatty acid synthesis
Where are fatty acids released from during fasting?
Adipose tissue
Where are chylomicrons synthesised following the ingestion of a high-fat meal?
Gut epithelium
Where is urea synthesised?
Liver
What ligand is required for the activation of calmodulin?
Calcium
What is a regulator of cytosolic guanylyl cyclase?
Nitrous oxide (NO)
What is produced by membrane bound and cytosolic guanylyl cyclase?
3’5’ cyclic GMP
What enzyme class catalyses geometric or structural changes within one molecule?
Isomerase
What enzyme class catalyses oxido-reduction reactions?
Dehydrogenase
What enzyme class catalyses bond breaking by means other than hydrolysis and oxidation?
Lyase
What is the concentration of the substrate at which the enzyme velocity is half maximal?
Km
What is the gradient of the straight line obtained from a Lineweaver-Burk plot?
Km/Vmax
What is the intercept on the X axis of a Lineweaver-Burk plot?
-1/Km
What guanine nucleotide-binding protein can regulate intracellular vesicle fusion?
Rab
What protein is folded in the endoplasmic reticulum and stored in secretory granules?
Insulin
What structural coat protein is required for the exit of transport vesicles from the endoplasmic reticulum?
Cop II
What amino acid is most positively charged?
Arginine
What amino acids are positively charged, from most to least?
Arginine
Lysine
Histidine
What amino acids are negatively charged?
Aspartic acid
Glutamic acid
What amino acids have hydrophobic side chains?
Tryptophan
Tyrosine
Phenylalanine
Methionine
Leucine
Isoleucine
Valine
Alanine
What amino acids have uncharged side chains?
Serine
Threonine
Asparagine
Glutamine
Tyrosine
Cysteine
Proline
Glycine
What amino acids have polar uncharged side chains?
Tyrosine
Serine
Threonine
Asparagine
Glutamine
What is Arg?
Arginine
What is His?
Histidine
What is Lys?
Lysine
What is Asp?
Aspartic acid
What is Glu?
Glutamic acid
What is Trp?
Tryptophan
What is Tyr?
Tyrosine
What is Phe?
Phenylalanine
What is Met?
Methionine
What is Leu?
Leucine
What is Ile?
Isoleucine
What is Val?
Valine
What is Ala
Alanine
What is Ser?
Serine
What is Thr?
Threonine
What is Asn?
Asparagine
What is Gln?
Glutamine
What is Cys?
Cysteine
What is Pro?
Proline
What is Gly?
Glycine
What process converts glycogen to glucose?
Glycogenolysis
What process converts glucose to glycogen?
Glycogenesis
What process converts glucose to pyruvate?
Glycolysis
What process converts pyruvate to glucose?
Gluconeogenesis
What process converts protein to amino acids?
Proteolysis
What converts triacylglycerol to fatty acids?
Lypolysis
What process converts fatty acids to triacylglycerol?
Esterification
What is the conversion of fatty acids to acetyl CoA?
Beta oxidation
What is the conversion of acetyl CoA to fatty acids?
Lipogenesis
What is the conversion of ketone bodies to acetyl CoA?
Ketolysis
What is the conversion of acetyl CoA to ketone bodies?
Ketogenesis
What cyclin-dependent kinases are in G1?
CDK4
CDK6
What cyclin-dependent kinases are in G1/S?
CDK2
What cyclin-dependent kinases are in S?
CDK2
What cyclin-dependent kinases are in M?
CDK1
What cyclins are present in G1?
Cyclin D1, D2, D3
What cyclins are present in G1/S?
Cyclin E
What cyclins are present in S?
Cyclin A
What cyclins are present in M?
Cyclin B
What inhibits CDK2?
P21
P27
What does isocitrate dehydrogenase catalyse?
The decarboxylation of isocitrate to alpha-ketoglutarate
What cofactor is used by aminotransferases?
Vitamin B6
What do fish excrete nitrogen as?
Ammonium ions
What is glycosylation of proteins catalysed by?
Cytosolic enzymes
Does an enzyme with a high km have a low or high affinity for its substrate?
Low
What does the PH domain bind to?
Inositol phospholipids
What does PTB domain bind to?
Phosphorylated tyrosines
What is required to initiate fatty acid synthesis?
Acetyl CoA
Malonyl CoA
NADPH
What can be added or removed from proteins in the Golgi apparatus?
Add or remove sugar
Add sulphate groups
Add phosphate
What is the TTAGGG repeat associated with?
Telomeres
Where is purifying selection strongest?
Non-coding regions of genomes
What does APC/C CDH1 degrade?
Securin and cyclins from S and M
What is the cofactor of succinate dehydrogenase?
FAD+
What is the cofactor of the E1 component of PDH complex?
Thiamine Pyrophosphate
What inhibits phosphofructokinase 1?
ATP
Citrate
What liberates iron from Fe-S clusters?
Superoxide
What accepts electrons from complex 1?
Ubiquinone
What converts succinate to fumarate?
Succinate dehydrogenase subunit A
What accepts electrons from the conversion of succinate to fumarate?
Succinate dehydrogenase subunit B
What is dideoxynucleotide (ddNTP)?
A chain terminating nucleotide used in Sanger sequencing
What is the difference between type 1 and type 2 topoisomerases?
Type 1 cleave one dna strand
Type 2 cleave two dna strands
What is a cluster of defined alleles inherited together?
Haplotype
What enzyme regulates centrosome duplication?
CDK2
What enzyme is required to remove sister chromatid cohesion?
Separase
