LS 23L Final Exam
Name everything you know about compound microscope
1) Contains two lenses 2) Focuses on light that passes through the object you are observing 3) Views things in reverse in both the left-right and the up-down orientation. (mirrored) 4) Can magnify to higher powers than discrete increments 5) Greater in magnifying power than dissecting microscope 6) Used to examine cellular structure
Name everything you know about SDS Page
1) Referred to as denaturing electrophoresis 2) SDS refers to anionic detergent sodium dodecyl sulfate 3) The protein of interest is mixed with a loading buffer that contains a reducing agent and SDS 4) Reducing agent breaks sulfide bonds 5) SDS disrupts the non covalent interactions between subunits of proteins 6) SDS associates with the unfolded backbone of the protein, creating an overall negative charge to the protein in proportion to its length 7) The gel is mounted between the two bigger chambers containing separate electrodes so that the only electrical connection between them is the two chambers 8) The proteins are loaded into "well" at the end of the gel with the negative electrode 9) The proteins migrate toward the positive electrode at a rate proportional to their size 10) The run is complete when the smallest, and thus, faster migrating proteins reach the bottom of the gel 11) NuBlue Express is used instead of Coomassie blue to stain the gel blue in order to see the results.
Name everything you know about dissection microscope
1) Works like a zoom lens of a camera with a continuous range of magnification 2) Generally lower in magnifying 3) Used mostly on larger specimens for gross morphological examination 4)Light is reflected off the specimen
Which of the following techniques for handling a pipetter is CORRECT:
A different disposable polyprolene tip should be used when pipetting different solutions so as to ensure no cross contamination between samples. You must be sure to press the pushbutton to the first positive stop before placing the tip of the pipet into the sample liquid. When drawing up the sample liquid into the pipet tip make sure that you slowly release the pushbutton so as to prevent any air bubbles from forming. When releasing the liquid, you must first press the pushbutton to the first stop, then to the second stop so as to expel any remaining liquid.
Proteins treated with SDS carry a similar _______ charge proportional to their length that allows them to be separated based on _______.
Negative, mass
During the SDS-PAGE lab, the TA forgot to add a loading buffer with the protein sample, which usually contains a reducing agent and SDS. What would you expect to happen from this?
Neutral proteins would remain in the well. Negatively charged proteins would migrate slightly into the gel. Positively charged proteins would migrate out of the well.
Does the mitochondrial DNA sequence amplified by the PCR in the DNA Isolation lab code for functional proteins?
No, the amplified sequence is located in the control region, and therefore does not control the coding of functional proteins. The control region is able to accumulate mutations, making it a distinct place to observe changes in the DNA sequence without affecting the function of proteins.
What are differences between mitochondrial and nuclear DNA?
One is linear, one is circular.
Which of the following is false regarding Polymerase Chain Reaction (PCR)?
PCR is performed in a test tube, or in vivo True: PCR requires a heat-resistant DNA polymerase like Taq polymerase. Approximately one billion copies of the target sequence are synthesized. Three primers hybridize to the DNA sequence.
Which one of the following is not true about polyacrylamide gel and/or Agarose DNA gel?
Polyacrylamide is used only for protein but Agarose gel can be used for both DNA and proteins
Which of the following is most affected by a mismatch in the 3' end of a primer with a DNA strand?
Primer Efficiency
Which of the following components is NOT necessary for a typical PCR reaction to initiate/proceed?
Protein kinase
When ejecting a protein sample into a well of the SDS-PAGE gel with a pipetter, why should you only push down on the pushbutton to the first stop and not the second stop?
Pushing down to the second stop will result in ejection of air from the pipet tip, which could blow the content intended for that particular well to the surrounding wells.
The Sanger method does NOT use which of the following:
RNA as the template to be sequenced
In the absence of lactose, what would occur if there was a mutation in the operator of the lac operon that did not allow the lac repressor to bind?
RNA polymerase would bind to the promoter, and would also transcribe B-galactosidase.
Which interval/segment observed via EKG sensor can be used to calculate the heart rate?
RR Interval
When lactose is present which of the following occur together:
Repressor is inactivated; transcription occurs
Using a microscope, you are trying to identify a tissue sample. Using a 40x objective and 10x ocular lens, you see striations within the tissue sample and parallel fibers. The unknown sample you are looking at is most likely:
Skeletal muscle
_______________ cells are striated, tubular, and multi-nucleated. They are classified as voluntary and their structure allows for locomotion and movement.
Skeletal muscle
If you are asked to pipet 590 microliters of colored water, which pipetter would you use and what is the proper setting in each volumeter window? (top, middle, bottom)
p1000 (0,5,9)
In lab, polypeptides were separated on a/an _____________ while DNA fragments were separated on a/an ____________________.
polyacrylamide gel; agarose gel
What is the purpose of having to press the pushbutton of a pipetter to the second stop?
to expel any remaining liquid
Primer Design
• Primers should be 20 - 30 base pairs long (too short = not very specific, too long = difficult to bind to DNA). • Melting temperatures between 55 - 80 C usually produce the best results. • Guanine and cytosine should make up 50 - 60% of the total base pairs (helps determine melting temperature). • • Primers should end (3') in a G, C, CG or GC (G & C bind more tightly than A or T, so this will increase primer specificity). • Long runs (four or more of the same base in a row) should be avoided (can cause the primer to bind in the wrong place).
For a p20 pipetter that is labeled (097), what volume will be pipetted?
9.7 microliters (ul)
All of the following characterize a good PCR primer except:
100-110 base pair length Optimal is 20-30 base pairs. Too many is too specific.
1 milligram (mg) is equal to how many micrograms (μg)?
1000
A student is quickly pipetting 129ul water and observes many bubbles in the tip. You as the second student demonstrate the correct order of steps:1. In order to prevent bubbles, slowly let go off your thumb and Release the pushbutton to aspirate. 2. Choose the correct pipette p200 and the correct tip to aspirate the correct amount of 129ul. 3. Push the pushbutton to the first stop before inserting the tip into the solution, and then put the tip in the solution tube.4. Dial the volume on the adjustment ring by first over dial the volume, and return to the correct amount of 129ul.5. Push the pushbutton to the first stop, raise the tip above the liquid, and press it harder to the second step to discard 129ul.6. Press the ejector to discard the tip.
2, 4, 3, 1, 5, 6
An antibody, with molecular weight 90 kD in its native state, is treated with SDS and a reducing agent before being loaded onto an SDS-PAGE gel. The result shows 2 bands, one is 20 kD and the other band is at 50 kD. How many subunits are in this antibody?
3 1 50 kD subunits and 2 20 kD subunits add up to 90kD
An antibody, with molecular weight 160kD in its native state, is treated with SDS and a reducing agent before being loaded onto an SDS-PAGE gel. The result shows 2 bands, one is 30kD and the other band is at 50kD. How many subunits are in this antibody?
4
In BLAST which of the following signify the best sequence homology?
Low E-value, High Score
A null hypothesis states that the difference between 8 hours of sleep and 3 hours of sleep has no effect on the number of pictures a student will remember during a Picture Memory Interface Test (PMIT). Examining the MIT database, an extremely small t-value of 0.1611 is found. This t-value is much smaller than the smallest t-value on the chart for p-value reference. From this information we can:
Accept the null hypothesis because the p-value obtained shows that the difference between the two groups being tested is not statistically significant
All of the following is true about agarose gels EXCEPT:
Agarose gel electrophoresis has a higher resolution than SDS-PAGE. True is: -Agarose gel electrophoresis can be used for the separation of DNA fragments. -The pores in agarose gels are bigger than those in polyacrylamide gels -Conventionally, agarose gel electrophoresis is set up horizontally. -Agarose is safe to handle, whereas acrylamide is a neurotoxin.
What hypothesis/hypotheses is/are widely accepted as to the origin of humans in the world?
All human life originated from African continent
An ectotherm is:
An animal that obtains its body heat from the environment and therefore its body temperature varies with outside temperature
In a rat, the anatomical position of the heart relative to the position of the kidneys is best described as_______
Anterior
In a histology lab, the pathology slide under examination contains black residue dispersed throughout alveolar walls. What condition is present in this pathology slide?
Anthracosis of the lung
What is the relationship between mass-specific metabolism and body size?
As body size increases, M-S metabolism decreases
Why did we need to measure the absorbance at two wavelengths during the beta-galactosidase lab?
At 600 nm the absorbance is proportional to cell density, which helps standardize our enzyme activity calculations, while at 420 nm the absorbance is proportional to the amount of o-nitrophenol produced
What does the Z gene on the Lac operon code for?
Beta Galactosidase Lac Z - B-Gal Lac Y - Lactose Permease Lac A -Thiogalactoside Transacetylase
What is the normal function of the protein product encoded by the I gene?
Binds to the operator of the lac operon
A life science student uses a compound microscope to look at a slide of human tissue. He is not sure what part of the body the tissue is from, but makes an educated guess based on the cells he sees on the slide. There are hundreds of round disks with no nucleus, as well as a couple of purple-colored disk-like cells. The student would most likely guess that the tissue is of.....?
Blood KEY WORDS: No nucleus
As assay of which of the following solutions will theoretically have the highest amount of b-galactosidase enzyme activity?
Luria Broth and lactose, at 70 mins of incubation
In a series of experiments on the effect of caffeine on goldfish metabolic rates, a p-value of 0.28 is found. The conclusion that should be drawn from these experiments is:
Caffeine did not have a significant effect on metabolic rate and the null hypothesis cannot be rejected
Cows are ruminant animals that have four stomachs. The stomach contains bacteria that break down cellulose. Which organ of the rat serves the same function?
Cecum
In a recent study, scientists proposed the following hypothesis: "Consumption of Omega-3 fatty acid can reduce the size of cancerous tumors." The following hypothesis was tested. A sample of 500 rats with tumors was collected. Within this sample size, 250 rats were feed with omega-3 (Group 1) while the remaining 250 rats were not (Group 2). After one month of periodically feeding Group 1 with Omega-3 fatty acid, rat autopsies were taken for both groups. The average changes of tumor size were measure and recorded. Average Change of Tumor Size Group 1: -0.124 g Group 2: -0.112 g Degrees of Freedom: 498 T-test: 1.75 P-value: 0.08 Based on the results from the experiment, which of the following is the best conclusion?
Consumption of Omega-3 fatty acid has no statistical effect on decreasing the size of previous cancerous tumors. Look at p value. If over 5%, the data is not statistically significant. Retain the null hypothesis.
ONPG, which is a derivative of lactose, is cleaved by beta-galactosidase into which of the following two compounds.
Galactose and o-nitrophenol
Suppose Amy and her friend, Curtis, are orphans. They both are curious about their ancestry and decide to sequence their mitochondrial DNA and create a phylogenetic tree with other classmates. The results show that Curtis and Amy share a relatively recent common ancestor. What can you conclude about the ancestral relationship between Amy and Curtis?
Curtis and Amy share a common maternal ancestor.
In the Sanger method of DNA sequencing, DNA synthesis stops when a ________ is encountered.
Dideoxyribose base
In the Human Physiology lab, you had to complete every experiment at every station in order to earn full credit.
False
In the Human Physiology lab, you were required to wear a lab coat even though you weren't working with chemicals, because you were in a lab room.
False
Which of the following factors would be least significant in affecting the rate of oxygen consumption of goldfish?
Gender of the goldfish
In the human physiology lab, which of the following sensors was used to measure the force with which a hand can grip or pinch?
Hand dynamometer
All individuals with the same haplotype called...
Haplogroup
What is a mitochondrial DNA sequence called?
Haplotype
While using the BLAST search program, you input a eukaryotic nucleotide sequence into blastx (nucleotide to protein sequence. which results in no "hits." Which of the following could be reasons that would explain this? I. The nucleotide sequence was part of a promoter region II. The nucleotide sequence encoded for an intron III. The nucleotide sequence encoded for an exon.
I and II
In the absence of lactose, what gene(s) on the lac operon is/are transcribed?
I gene X, Y, and Z genes are within the lac operon which is currently repressed due to lack of lactose.
What is the formula for calculating the vital capacity of lungs?
IRV plus ERV plus TV
Which of the following regulates the amount of light passing through the slide specimen on the microscope stage?
Iris diaphragm lever
The small intestine of a rat:
Is longer than the large intestine
What is the purpose of the reducing agent, B-mercaptoethanol in SDS- PAGE?
It breaks disulfide linkages
Anterior is equivalent to what part of the rat's body?
It is towards the head in a rat
Why does all the equipment from the epidemiology lab get thrown into the autoclave waste as opposed to the regular waste?
It is unknown which sponge is infected, so they must all be discarded equally.
After performing a gel electrophoresis with sample proteins that have multiple subunits, John noticed that all his protein samples moved down the gel but there was only one band in each of his gel lanes when there was supposed to be more than one. He was confused because he even added denaturing detergent to his samples. What could have been a mistake John made?
John forgot to heat his protein samples to denature them.
In the Human Physiology lab, what physiological activity were we NOT able to measure?
Kidney Filtration
Suppose a woman with haplotype H and a man with haplotype K have a son. The son then marries a woman with haplotype L1. If this couple had one son and one daughter, what would be the respective haplotypes for their son and the daughter?
L1 and L1 Haplotype is only dependent on the maternal lineage. The grandmother is from the father/husband's lineage and does not reflect in the haplotypes of his offspring.
What is spermatogenesis?
Spermatogenesis is the process by which sperm (the male sex cells, or gametes) are formed.
Which of the following can NEVER be a measure of central tendency?
Standard deviation
Beginning with the stomach, which of the following follows the correct path of the digestive system?
Stomach, pyloric valve, duodenum, small intestine, ileocolic, valve, large intestine, rectum
Which of the following is TRUE regarding DNA sequencing and amplification:
Taq polymerase is resistant to denaturation caused by heat.
John wants to measure the activity of B-galactosidase using the same protocol followed by LS3 students. He performs the experiment correctly but instead of ONPG he mistakenly adds galactose to the cells after the chloroform step. How will his spectrophotometry results compare to those obtained with ONPG?
The OD420 be lower because it measures the presence of products from the breakdown of ONPG.
In the Gel Electrophoresis lab, why did we not add SDS and beta mercaptoethanol to the agarose gel before loading our PCR product?
The PCR product is already linear and has a negative charge associated with it.
The traditional Sanger Method, or Dideoxy Method, of DNA sequencing differs from DNA sequencing methods and visualization techniques most often used today in which of the following ways?
The Sanger method uses radiolabeling of DNA for visualization on electrophoresis with reactions using different ddNTPs, while modern methods use fluroescent color tags to visualize the sequence in an electropherogram.
Which of the following is an INCORRECT statement regarding the differences between a dissecting microscope and a compound microscope?
The compound microscope is used for gross morphological examination, while the dissecting microscope is used to examine cellular structure. Correct is: a. Dissecting microscopes do not have as high a magnification as compound microscopes. b. The magnification of a compound microscope is discrete, while the magnification of a dissecting microscope is continuous. c. Light shines on the sample for a dissecting microscope, while light penetrates a sample for a compound microscope. e. A compound microscope displays a mirror image of the object, while a dissecting microscope displays an image in the same orientation of the object.
Which of the following is not true about compound microscopes and the dissecting microscope?
The compound microscope reflects light off the sample, whereas the dissecting microscope shines light through the sample.
A scientist runs an SDS-PAGE experiment two separate times on a protein with a molecular weight of 200 kD. For the first experiment he treats the protein with SDS only and for the second experiment he treats the protein with both SDS and a reducing agent. If the first gel yields one band showing a molecular weight of 200 kD and the second run yields one band showing a molecular weight of 25 kD, the researcher should conclude that
The consists of 8 subunits of equal size connected by a disulfide linkage.
Which of the following is critical in designing a scientific experiment to test memory in chimpanzees?
The experimenter should control for lurking variables by specifying standard conditions (i.e. room temperature).
Tamique tested E. Coli B-Galactosidase activity but the buffer solution she used for the B-Gal assay was 4 pH units higher than the optimal pH. What problem did Tamique observe?
The pH of the solution was too basic for B-Galactosidase to bind to ONPG.
How were the proteins in the SDS-PAGE lab visualized?
The polypeptides were covalently bound to a fluorescent tag that made them visible under UV light.
In the goldfish metabolism lab, there was a probe attached to the chamber.
The probe was measuring the dissolved oxygen concentration in the water.
Which of these primer designs is the most serious for the PCR procedure?
The sequence has mismatched nucleotides at the 3' end because the replication cannot extend from this mismatch.
A student was trying to identify two slides. The first slide consisted of a cluster of cells that contained no nuclei. The second slide consisted of cells that were porous in places, with nuclei that were spread out. What did the three slides depict?
The two slides depicted red blood cells and bone tissue, respectively. KEY WORDS: No nucleus, porous
In the rat dissection lab, the uterus of female rats extended into two horns. This differs from a female human's uterus, which does not have this "horned" structure. Why does this difference exist?
The uterine horns allow rats to support multiple fetuses.
An experimental p-value of 0.06 would mean:
There is a 6% chance your sample groups are not significantly different.
Which of the following is not a parameter of the Lung Function Test?
Tidal Capacity (TC)
In a bimodal distribution of data, you would have:
Two modes, one mean, and one median. In a bimodal distribution, the modes will be different from either the mean or the median. In a unimodal distribution, the mode, median, and mode are the same value.
Which of the following p values would allow for the rejection of the null hypothesis?
Under 0.05
When referring to the back and the front/chest of the rat, which of the following positioning terms are correct?
Ventral (Front/chest), Dorsal (Back)
A scientist got a p-value of 0.039 when testing his data. Assuming there was a small difference between the means in the two groups of his hypothesis, will these results give a significant difference?
Yes, because the p-value is less than 0.05
In the B-galactosidase activity lab, you accidentally forget to add PopCulture to your bacteria samples, both at 20 and 70 minutes of cell incubation. How would your results differ from your those of your classmates who DID add PopCulture?
Your readings would be similar for the 600nm absorbance values but you would have lower readings for the 420nm absorbance.
In mitochondrial DNA isolation lab, if the DNA is susceptible to DNases, what is the best solution to prevent this problem?
add chelex; because it binds to Mg2+ in the extract Chelex binds to Magnesium, a cofactor needed for DNase, an enzyme that degrades DNA. The sample was heated to disrupt the cell membrane.
Goldfish are poikilothermic organisms, which means that they
change their body temperature when the environmental temperature changes
If one wants to measure B-galactosidase activity under different conditions, it is important to take cell density into account primarily because:
if cell density were not measured, one would not know whether more enzyme is being produced because of upregulation, or because of there just being more cells.
A dynamometer ...
is any device that measures power or force
What are the ingredients necessary for the Sanger Method of DNA sequencing?
dNTPs, DNA template, DNA polymerase, ddNTPs, primer
What property allows the dideoxynucleoside triphosphates (ddNTPs) to terminate DNA synthesis when added to a growing chain?
ddNTPs have a -H group instead of a -OH group at the 3' position of the ribose.
SDS, which stands for sodium dodecyl sulfate, is an anionic _______; it may break down _______ bonds.
detergent; dipole-dipole
Female rats differ from humans in that the uterus is split into two ________. The female mouse gives birth through the __________ and urinates through the ________. A rat's liver is split into _____ lobes, and rats also possess a unique structure that houses microorganisms and allows them to digest cellulose found in plant matter; this structure is called the ________.
horns, vaginal canal, urethra, four, cecum.
If one exposes the goldfish to ice cold water, the rate of dissolved oxygen consumption:
slightly decreases over time
Loggerlite detects the amount of dissolved oxygen in the chamber. For each trial, the datapoints are plotted and a curve is generated. The greater the absolute value of the slope:
the greater the rate of oxygen consumption
In the MIT lab, an independent variable is:
the number of hours of sleep Parameters: number of correct responses and average response time
