Bio/Biochem Questions Flashcards
when does removal of introns occur?
DNA –> mRNA
pre mRNA processing
electron carriers in the electron transport chain
cytochrome c: 1 electron carrier (cycles between ferrous and ferric state)
Complex I/NADH dehydrogenase complex: 2 electrons to ubiquinone, 4 H+ across the membrane
Complex III: 2 electrons to cytochrome c
Complex IV: 4 electrons from cytochrome c
O2: final electron acceptor, creates 2 molecules of water
what type of primer is most suitable for PCR?
suitable primers have a high GC content and have G or C base pairs at the 5’ and 3’ ends
nondisjunction
failure of homologous chromosomes to separate during anaphase I of meiosis OR the failure of sister chromosomes to separate during anaphase II of meiosis
why would protein synthesis be inhibited by D-alanine?
only L isomers of amino acids are used to form proteins during ribosomal protein synthesis
is growth rate faster under aerobic or anaerobic conditions?
aerobic
a much greater amount of ATP is produced to provide energy for reproduction (net 38 ATP vs net 2 ATP per molecule of glucose)
euchromatin vs heterochromatin
euchromatin is transcriptionally active while heterochromatin is not
actin filaments are
microfilaments
products of fermentation
pyruvic acid and glucose 6 phosphate (and other glycolysis intermediates) can still be produced
lactic acid or ethanol
acetyl coA will not be produced in anaerobic conditions
introduction of which amino acid substitution would result in the largest decrease in the entropic penalty associated with a protein folding into its native conformation?
Leu to Thr substitution at a surface-exposed site
switching a hydrophobic residue for a hydrophilic residue eliminates the entropic penalty associated with ordered water molecules around hydrophobic groups
germ layers
endoderm - epithelial tissues inside the body (digestive and respiratory tracts), bladder, liver, pancreas
mesoderm - bone, muscle, heart and circulatory system, internal sex organs
ectoderm - nervous system, dermis, hair, nails, eyes, ears, mouth, brain
bacterial vs. human cells
humans do not have a cell wall
they differ in ribosome units (eukaryotes have larger subunits) - 80S vs 70S in bacteria
bacterial DNA is circular
both use ATP synthase to make ATP
what hormone triggers ovulation?
luteinizing hormone
if a mutation in an intron affects the expression of an exon, the intron is likely to contain
splice receptor site
alternative splicing leads to changes in exon expressions
mature mRNA is not likely to contain:
introns
promoter sequences
transmembrane proteins are likely to contain:
signal sequence
facilitates transmembrane protein docking at the endoplasmic reticulum
during which step of cellular respiration is NADH neither oxidized nor reduced?
chemiosmosis
where is glomerular filtrate most concentrated?
medullary portion of the collecting duct
function of Na+ K+ ATPase during an action potential
restores resting potential by moving ions against their concentration gradient
3 sodium ions out of the cell, 2 potassium ions into the cell
resting membrane potential
more potassium ions inside than outside, more sodium ions outside than inside
-40 to -90 mV (negative)
to restore resting potential: 3 sodium ions out of the cell, 2 potassium ions into the cell
action potential: depolarization
cell becomes more +
positive ions enter the cell, Na+ enters through voltage-gated sodium channels
cell ends up extra positively charged (not neutral)
action potential: repolarization
cell becomes - again
positive ions leave the cell (Na+ channels close so no new sodium ions can enter, K+ channels open so potassium ions can leave)
action potential: hyperpolarization
after an action potential, cell becomes extra negatively charged because extra potassium ions leave the cell
sodium-potassium pump reestablishes resting potential
what enables a molecule to pass directly through the cell membrane?
small molecule
hydrophobic molecule
planar molecule
ABC transport protein
uses ATP to actively transport antitumor drugs out of the cell
lipid raft
cholesterol or steroid rich domain
the initial filtration step in the glomerulus of the kidney occurs by
passive flow due to pressure difference
blood pressure is the initial driver behind glomerular filtration
insulin in the liver
aids glucose uptake by decreasing the cellular concentration of glucose
where are proteins cleaved after translation?
endomembrane system
leave the ribosome before being cleaved into active form
DNA replication is semiconservative
2 copies of the original molecule are made during replication –> each new molecule will contain 1 original strand and 1 newly synthesized strand
purines and pyrimidines
purines - adenine and guanine, 2 rings
pyrimidines - cystine and thymine/uracil, 1 ring
what happens to an action potential if potassium channels are blocked?
action potential is prolonged
repolarization requires opening of potassium channels so K+ can exit the cell
nuclear localization sequence
allows proteins to be translocated to the nucleus
eg an enzyme that activates expression of a gene activates transcription factors for that gene, and transcription factors are found in the nucleus, so that enzyme would likely contain a nuclear localization sequence
ubiquitination
targets a protein for degradation by a proteasome
posttranslational process
Western blot
analyzes posttranslational modifications of proteins such as histone acetylation
Southern blot
used to detect specific DNA sequences in DNA samples
pretranslational unlike Western blot
relies on palindromic restriction sites eg AAGCTT
vasopressin regulates the insertion of aquaporins into the apical membranes of the epithelial cells of which renal structure?
collecting duct
blood from the small intestine is transported first to the
liver
endosome
facilitates internalization of viral particles by endocytosis
sperm
produced in the seminiferous tubules of the testes
complete maturation and become motile in the epididymis
why add a reducing agent to SDS-PAGE?
reducing agent removes disulfide bonds
allows monomers to run separately
amino acid likely to be phosphorylated
serine
influx of Na+ across the motor end plate
involves ligand-gated ion channel
sodium ion channels bind the ligand acetylcholine to trigger action potential in muscle fibers
the Doppler effect
person hears a higher frequency before passing the source, then a lower frequency after passing the source
f’>f to f’ higher frequency
moving away from observer –> lower frequency
enzyme specific for peptide bonds
proteases and hydrolases
operon containing two genes in a prokaryotic cell
single mRNA transcribed from a single promoter sequence upstream of the first gene in the operon
histone acetylation
typically promotes transcription by modifying chromatin structure
something that inhibits histone acetylation would inhibit transcription by condensing chromatin structure
restriction enzymes recognize
palindromic sequences
complex II is the same as
succinate dehydrogenase
imprinted genes
expressed in a parent-specific manner (eg passed down maternally or paternally) but are not X or Y linked
glomerulus structure
prevents the entry of large molecules such as proteins into the filtrate
filtrate in the nephron
Bowman’s capsule –> proximal tubule –> loop of Henle –> distal tubule –> collecting duct
