Bio-Biochem Flashcards
How does histone acetylation effect gene transcription?
Histone Acetylation = neutral charge, gene activation, DNA uncoiled.
Histone Deacetylation = positive charge, gene silincing, DNA coiled.
What were the results of the Griffith Experiment? How was Griffith’s conclusion further supported bythe evidence of Avery’s results?
Griffith Experiment: R-form (nonpathogenic) bacteria convered to S-form (pathogenic) by some transforming principle
Avery Experiment: Griffith’s transforming principle = DNA. Evidence… - tested (-) on protein detections but (+) on DNA decection tests - ratio of Nitrogen:Phosphorus resembled that of DNA - protein/RNA degrading enzymes —» no effect
Difference between…
- Facultative anaerobe
- Obligate anaerobe
- Aerobe
- Facultative anaerobe: can function either in presence or abscence of oxygen. (perform aerobic or anaerobic respiration)
- Obligate anaerobe: cannot function in the presence of oxygen
- Aerobe: can only function in presence of oxygen
Bacteria Characteristics (pneumococcus):
1.
2.
3.
Bacteria Characteristics (pneumococcus):
- contains organelles (i.e. ribosome, double membrane bound nucleus structure)
- cells larger in diameter than eukaryotic cell
- translation occurs in mitochondria
Menarche & avg. age of onset
Menarche: beggining of menstruation (ages 9-15+)
Klienfelter’s Syndrome:
- genotype?
- genotypic sex?
Klienfelter’s Syndrome:
- genotype: XXY
- Genotypic Sex: Male—»presence of Y chromosome
-
Characteristics:
- infertile
- female secondary sex characteristics
- Aneuploidy
- Examples?
Aneuploidy: abnormal number of chromosomes -
EX; Monosomy X, Trisomy 21/18/13, XXX/XXY/XYY “
What is an RFLP and what is it used for?
Restriction Fragment Length Polymorphisms (RFLPs): used to identify which parent a non-disjoined chromosome comes from.
Assume that ey is X-linked if ey/+ females are crossed with wt males, what are the phenotypes of the progeny?
- (Y) = Y chromosome
- (ey) = small or no eyes (depending on sex & genotype_
- (+) = Normal eyes
Male:
A. (Y/+) —» NORMAL
B. (Y/ey) —» no eyes
Female:
A. (ey/+) —» small eyes
B. (+/+) —» NORMAL
Constitutive vs. Substitution Mutations
Constitutive: ““always active”” mutation—»increase ‘strength’ of binding for weak GAL4 promotor thereby inc. transcription
Substitution: mutation to unstream activiating sequence (UAS) would only dec. efficiency of GAL4 promoter
Hardy-Weinberg Equation
p^2+2pq+q^2=1
p: frequency of wt allele
q: frequency of recessive allele
Is it more practical to compare the entire genome of a wt vs. cancerous cell in order to isolate a mutation? what is a better alternative?
naturally occuring mutations would mask cancer-causing mutations, making it an impractical method for attempting to isolate a mutation.
better alternative = transforming human (hDNA) sequence that upregulates replication & a tag sequence into e. coli then adding this DNA to a mouse cell line.
what are the 3 types of sequencing transfers and what molecules are they used to detect?
Southern Transfer: detection of DNA sequence in DNA samples
- combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization
Northern Transfer: detection of RNA fragments
Western Transfer: detection of proteins”
what codon & AA does the initiator tRNA aminoacyl bind to?
initiator aminoacyl tRNA binds the start codon and transports the AA formylmethionine
Polysomes (Polycistronic mRNA):
- cell type?
- protein translation?
- polycistronic mRNA found in prokaryotic cells.
- contain multiple start codons and proteins are translated separately into many proteins
what organelles are found within a prokaryote?
ribosomes, nucleoid, plasmid, cytoplasm, flagella/pilli, cell wall, and plasma membrane
a non-membrane bound form of CD14 stimulates endothelial cells via interactions w/LPS.
Would CD14 be found in the blood/ECF or the cytoplasm of the endothelial cell?
CD14 would be found within the blood/ECF b/c LPS is released by bacteria in the ECF, therefor CD14 could only interact if its also in ECF.
How does the nuclear envelope confine translation to the cytosol?
Nuclear Envelope: inner (chromosomal DNA & nuclear RNA) & outer (studded w/ribosomes) membrane system
– perforated by nuclear pores (aqueous channel) that are too small for ribosomes (~30nm) to pass through
– pores are capable of expansion if a molecule contains a nuclear import signal
What is the diameter of a nuclear pore, and how does it accomodate the passage of molecules that exceed the size of the pore?
- nuclear pore = ~9nm diameter
- presence of nuclear import signal (containing (+) AA’s) allows nuclear pore to expand to accomodate objects > 9nm
If RNA is injected into a nucleus and later found in the cytosol, and then injected into the cytosol of a 2nd cell, and no RNA was found in the nucleus, where is the receptor most likely located?
nuclear export signal would be found on the nucleoplasmic face
What’s the difference between Gram-positive and gram-negative bacteria?
- *Gram (+):**
- thick peptidoglycan layer
- no LPS
- *Gram (-):**
- Ex: e. coli
- express LPS—»stimulate inflammatory immune response
- thin peptidoglycan layer (network forms double membrane w/periplasmic space)
a phosphatidylethanolamine molecule is formed from which components?
what is the greatest contributing fator as to why integral membrane proteins do not diffuse transversley accross a membrane?
Asymmetric Distribution of Proteins—» integral proteins vary at ECF vs. cytoplasm & hydrophillic regions cannot transverse hydrophobic interior of PM
How many moles of water are required to hydrolyze a peptide bond?
Why is the Na+/K+ ATPase pump more essential (most active) in cells of the Loop of Henle vs. cells in the veins, lungs, or bone marrow?
while viens, lungs, and bone marrow all rely on ion exchange, the LOH employs this mechanism in order to concentrate urine ∴ the Na+ pump is most important at LOH.
what is the purpose of a signal seuence protein domain?
signal sequence domains are required for proteins directed towards secretory pathways
whats the importance of a negative regulator in gene expression?
a negative regulator protein blocks the transcription of a gene when bound, generally by preventing a ligand from binding and activating transcription
Spatial regulation of genes
- type of regulation of gene expression in which a gene is only expressed in a specific location
- Ex: seed storage proteins
temporal regulation of genes
- type of regulation of gene expression in which a gene is only expressed at a specific time in development
- Ex: genes that are only expressed in the light or during flower development
why are certain genes capable of both temporal and spatial regulation of target genes?
nuclear factors vary in different cell types and ∴ confer both temporal and spatial regulation of target genes
Glutamine
- Abbreviations: Gln | Q
- polar
how are different isoforms of proteins expressed?
different isoforms of a protein expressed from single genes through alternative splicing of exons of the primary transcript
angiogenesis
malignant tumors often undergo mutations that propote their growth and the development of blood vessels to feed them
Oncogenesis
- associated w/mutations that occur by randon chance or as a result of mutagenic compounds (i.e. mutagens/carcinogens)
• Ex of Mutagens = UV light, reactive oxygen species, etc.
- dysregulation of gene expression —» oncogenes promote abnormal growth and proliuferation leading to cencer
could higher levels of pro-apoptotic gene expression potentially slow proliferation?
Yes
assuming that a cationic protein is (+) at physiological pH, the primary structure MUST contain…
A. more basic residues than uncharged residues
B. more basic residues than acidic residues
(B) more basic residues than acidic residues
- question asks what MUST be true, ∴ A is incorrrect b/c a protein could have less basic than uncharged residues and still be a cationic protein
For the S156E residue, what AAs are present?
S = serine
E = glutamate
Fight or Flight Response
- activation of the sympathetic nervous system
2. Physiological reactions:
- pupils dialate
- inc. HR
- inc. blood flow to skeletal muscles
3. Hormonal Regulation - Epinephrine/Norepinephrine
Rest & Digest Response
- Activation of parasympathetic nervous system
- Phisiological rxn:
- inc. blood flow to digestive system
- dec. HR
- pupil constriction
Aldostertone
- hormone synthesized in the adrenal cortex - released in response to low BP
- acts on the distal tubule and of the nephron to increase sodium reabsorption in the distal tubule & proximal collecting duct—»favors water reabsorption
- upregulates the Na+/K+ pumps lining the nephron—»pump 3 Na+ into blood/pump 2K+ into the nephron/cell (away from blood)
what is the most effective way to dispose of agar plates and pipette tips that were used in an experiment involving pathogenic bacteria?
place materials into an open metal container and autoclave
Single Crossover
- affect only one arm of each chromosome
Double Crossover
- affect two arms of each chromosome
does lipid synthesis increase or decrease when insulin is released into the bloodstream?
- lipid synthesis would incresae to store incoming glucose
- also would see increased glycogen synth, inc. esterificaiton of FA, & dec. gluconeogenesis
Reduction
- gain of an e-
- decreased oxidation state
- formation of a C-H bond (alkene—»alkane)
- loss of a C–O or C–N bond (or any other electronegative atom and carbon)
If i wanted to use a PET scan to compare the metabolic activity of cancer cells relative to normal ones, which compound should i radioactively label to examine these effects?
pyruvate, acetyl-CoA, ATP, or glucose
glucose—» it’s the onle molecule that would travel through the blood between normal and cancer cells, the other options are all produced intracellularly
are Fungi eukaryotes or prokaryotes?
Eukaryotes
Analogous Structures
- structures that evolved independently to carry out the same function
- Ex: wing of bee and wing of bird
Homologous Strucutres
- structures that have similar evolutionary history, arising from common anscestor, but have different functions
- Ex: wing of a bee and wing of a bat, forelimbs of mammals (human arm, walrus flipper, bat wing)
- where are post-transcriptional modifications completed?
- what molecules undergo post-transcriptional modification?
- all post-transcriptional modifications occur in the nucleus
- mRNA is modified via post-transcriptional modification (i.e. poly(A) tail, 5’ cap, splicing)
Epimer
- sugars that differ at only 1 stereocenter
- epimers = anomers, diastereomers
Eicosanoids
- family of lipids derived from arachidonic acid
- 20C molecules w/5C ring
- Prostaglandins: signaling molecules w/diverse range of effects including modulation of inflammation
- Thromboxanes: involved in the clotting cascade
• NSAIDS (i.e. aspirin) anti-inflammatory drugs inhibit COX1 & COX2 enzymes involved in early steps of clotting pathway preventing production of prostaglandins
the disruption of which membrane component results in cellular traffic complications similar to that of gap junction disorders?
- cholesterol
- glycoproteins
- glycolipids
- phospholipids
Glycoproteins:
- of all membrane components listed, glycoproteins are the only transmembrane proteins that span the length of the whole PM
- only transmembrane proteins that extrend throughout the entire membrane will play a role in the management of cellular traffic in and out of the cell
What is the average mass of an amino acid residue?
~110 Da
siRNA
- small interfering RNA (siRNA): binds RNA (not DNA or proteins) to interfere w/expression of certain genes (generally dec. expression)
- siRNA interferes w/gene after transcription but before translation ∴ it must prevent the translation of mRNA corresponding to the target protein
Western Blot Test
used to identify protein sequences
Southern Blot Test
used to identify specific DNA sequences
Northern Blot Test
used to identify RNA sequences
ELISA
- Enzyme-linked immunosorbent assay (ELISA): uses a solid-phase imunoassy to detect the presence of an antigen
- intensity of signal following the addition of an enzyme’s substrate is related to the quantity of protein antigen present in the original sample
- Can amino acids cross the BBB?
- can antibodies cross the BBB?
- Yes
- No (too big)
- what types of molecules are more likely to diffuse through the BBB: lipid soluble or hydrophilic molecules?
- lipophilic molecules more readily pass the BBB
EX: by replacing the alcoholic protons with acetyl groups on a molecule is one example of a way to change a drug to make it more soluble within the BBB
Why is folate given as a supplement to pregnant women?
- Folate prevents neural tube defects
- prevents defects b/c it plays a role in ectodermal induction—»folate is important for neurulation (the induction of the ectoderm–from which the CNS is derived–to differentiate into the nervous system)
Uracil is usually found in:
I. tRNA
II. ribosomes
III. ssDNA
I & II —» uracil can be found in any structure that is composed of RNA
Suicide Inhibition
irreversible inhibition where substrate irreversibly binds to the enzyme
Hyperventilation (Physiological Changes)
- dec. of CO2 & inc. of O2 in the blood
- inc. blood pH
- increased Hb O2 affinity
Hypoxia
oxygen deprivation
A) What are the structures of…
- folic acid
- carbonic acid
- ascorbic acid
- citric acid
B) which isnt an organic acid?
(B) Carbonic Acid.
• Organic acids:
- must contain C & H (and must contain 1+ C-H bond),
- weak acids,
- formula R-CO2H (acidic H+ usually bound to O)
What signal is needed to export mRNA from the nucleus to the cytoplasm?
polyadenylation (post-transcriptional modification)
Post-Transcriptional Modifications
• immediate product of transcription in Euk = heterogenous nuclear RNA (hnRNA)—»post-transcriptional modifications convert hnRNA into mRNA
- 3’ poly-A tail: ~250 adenine nucleotides added to 3’ end of hnRNA —» prevent degredation in cytosol of cell
- 5’ cap: 7-methylguanylate triphosphate cap added to 5’ end of hnRNA —» prevent cytosol degredation but also preps RNA for export from nucleus
- splicing: introns are removed and exons are ligated together
Transduction
form of horizontal gene transfer in bacteria —» bacteriophage (bacterial virus) transmits genomic material (viral gene vector)
Transformation
direct uptake of genetic material from environment and is not mediated by viruses
Transfection
transmission of genetic material (usually a human plasmid) via the mechanism of some chemical (NON-VIRAL METHODS) that generates openings in the pores of the cell
What is the difference between intra-subunit and inter-subunit interactions?
- Intra-Subunit: interactions between residues occur on the same chain/subunit
- Inter-Subunit: interactions between residues occur btwn two different chains/subunits
G0 Phase
- the state of the cell cycel a cell enters when it does not need to divide
- Ex: epithilial cells are rarely found in G0 b/c they’re constantly dividing whereas neurons are almost always in G0
Viruses (Characteristics)
- obligate intracellular parasite
- ssDNA/RNA or dsDNA/RNA (viral vector)
- described as “non-living”
Positive-Sense RNA virus
- ssRNA virus
- contains mRNA that’s immidiately translated by the cell
Negative-sense RNA virus
- ssRNA virus
- contain RNA thats complementary to mRNA
• in this case the mRNA is transcribed by the enzyme RNA replicase, which is caried by the viron
Is the ATP generated during B-oxidation of FAs synthesized via glycolysis, ox phos., or both?
all atp is generated by oxidative phosphorylation via the ETC
What nucleic acid substitutions are least likely when they result from methylation or deamination?
a change from purine to pyrimidine or vice versa, would be least likely b/c modifications via deamination and methylation would not alter the # of rings in the structure and ∴ wouldnt make change btwn nucleotide class
- what is the charge on the proteins tested using SDS-PAGE?
- why might the molecular weight of the protein run on the SDS-PAGE appear to be lower than the known MW?
- negative
2a. if there are alot of (+) charges on the protein, then it will have a smaller overall (–) charge and travel less distance—»indicating that its heavier than anticipated
2b. if alot of (-) charge on protien, then overall (-) charge inc. and protein travels farther distance—»indicating that its lighter than anticipated
Passive Immunity
- the transfer of active humoral immunity in the form of ready-made antibodies from one individual to another
•Ex: passage of IgG Ab’s from mom to fetus
Innate (Nonspecific) Immunity
- innate immune system includes:
A) anatomical barriers: Mechanical = skin/internal epithelial layers, movement of the intestines, and oscillation of bronchopulmonary cilia
B) secretory molecules
C) cellular components: WBCs (leukocytes)—»neutrophils, lymphocytes, monocytes (diff. into macrophages/dendritic cells), eosinophils, basophils, and mast cells
- responds generally to threats (doesnt learn to recognize specific pathogens—»adaptive immune system)
Cell-Mediated Immunity
- immune response that does not involve antibodies, but instead the activation of phagocytes, antigen specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen
Natural Immunity
- immunity that is present in the individual at birth, prior to exposure to a pathogen
• includes intact skin, salivary enxymes, neutrophils, natural killer cells, etc.
retrovirus
- have positive-sense RNA genomes (no DNA gemone)
- Require reverse transcriptase to synth mRNA from complementary viral RNA
Why have glucocorticoids been implicated in weight-gain?
- Glucocorticoids: increases blood glucose level (via adipocyte hydrolysis) and decreases protein synthesis -anti-inflammatory
- short-term release of glucocorticoids causes a release of glucose and the hydrolysis of fats from adipocytes—»BUT, glucose not used for metabolism & inc. promotes fat storage—»net result = release of glucose from the liver to be converted into lipids in the adipose tissue under insulin stimulation
What are the chances a child inherits a mutation in a somatic, non-germ line?
0%
How many fused rings are present in a steroid?
4
Where does the filtrate have its highest concentration?
In the medullary portion of the collecting duct, toward the middle of the kidney. The cortical portion of the kidney is the outer cortex.
How does the Na/K ATPase function in an action potential?
It restores the resting potential by moving the ions against their concentration gradients
What are ABC transporters?
They use ATP to actively transport molecules out of the cell
What are lipid rafts?
Cholesterol rich domains of a cell membrane
What is the initial step in glomerular filtration?
A passive flow due to a pressure difference. Blood pressure forces the fluid out of the glomerulus and into the lumen of Bowman’s capsule
How do enzymes affect the rate of chemical reactions?
They lower the activation energy by co-localizing substrates, altering substrate shape, and altering the local pH. Although they may possess proteolytic function, this is not altering the substrate primary structure
If there is increased concentration of a protein, what is also increased in the cell?
The concentration of mRNA for said protein
What happens when a hormone stimulates the release of another hormone which is unable to be produced by the body?
The body will continue to release the stimulatory hormone in an effort to increase the concentration of the other hormone, although the other hormone which is unable to be produced will never enter circulation
How does insulin affect glucose in the liver?
It aids in glucose uptake by decreasing cellular concentration of glucose by stimulating the first step of the glycolytic pathway
How do macrophages trap foreign material?
They trap it within a phagosome which fuses with a lysosome to become a phagolysosome
How does ATP inhibit phosphofructokinase-1?
Allosterically through negative feedback
What is active transport vs. facilitated diffusion?
Active transport pumps molecules against their concentration gradient. Facilitated diffusion uses a protein to guide a molecule with its concentration gradient and therefore is passave and does not require ATP
If a molecule has an isoelectric point of 9, what does this mean?
It has a positive charge at physiological pH
What is the end result of ubiquitination?
It targets a protein for degredation by a proteasome
How are disulfide bonds formed in proteins?
By thiol groups in cysteine residues and the bonds are broken through reduction
What reaction does GAPDH catalyze?
The reversible conversion of G-3-P to 1,3-BPG
What are some ways to influence the reactive oxygen species in yeast?
engineer them to lack antioxidant enzymes, make them overexpress antioxidant enzymes, grow them in the presence or absence of hydrogen peroxide