Lab Final Flashcards
a. If a diploid parent cell with 8 chromosomes undergoes one round of mitosis, what is the result on a cellular level?
i. Two identical daughter cells with 2n=8
b. What is the purpose of mitotic cell division?
i. Replace somatic cells with identical copies
c. What is the purpose of meiotic cell division?
Allow production of games from germ cells to create 4 non-identical daughter cells to increase genetic diversity
d. During which phase of mitosis do the chromosomes condense and the nuclear envelope breakdown?
i. Prophase
e. What do we call the physical division of the cell following the division of DNA?
i. cytokinesis
f. At what stage of the eukaryotic cell cycle DNA replication occur?
i. S Phase
g. How many DNA molecules in Anaphase of mitosis 2n=24?
i. 48
h. How many chromosomes in methaphase of mitosis? Cell is 2n=62
i. 62
i. Homologous pairs of duplicated chromosomes line up as _______ during metaphase I of meiosis
i. Tetrads
j. The event know as crossing over that leads to reassortments occurs in which phase of meiosis?
i. Prophase I
a. Assume that the 100x objective lens is in place and a magnification of ocular lens is 10X as shown in the picture above, what is the total magnification of the object you are viewing?
i. Total magnification= ocular lens x objective lens
ii. 10x * 100x = 1000x magnification
b. Which wavelength of light has more energy, light at 340 nm or 600 nm?
i. 340 nm; energy is inversely proportional to wavelength
c. What components of a choloroplast contain light-capturing pigments and proteins?
i. Thylakoids
d. What organic solvent is mostly used to extract the plant pigments?
i. Ethanol
e. What is the purpose of cytoplasmic streaming in elodea plant?
i. To better expose chloroplast to sunlight
f. Which plant pigments absorb green light?
i. Carotenoids
Photosynthesis occurs in this organelle of the plant cell?
Cholorplast
The products of photosynthesis are?
Glucose and O2
The region of an enzyme which interacts with other molecules involved in a reaction is:
Active site
In our enzyme lab, did we measure the disappearance of substrate or appearance of product? What equipment and/or reagents did we use to quantify this?
We measured the disappearance of substrate (starch) by using a spectrophotometer (wavelength =540 nm) measuring the absorbance values of a starch + amylase + Lugol’s iodine solution at set time intervals. Absorbance values were then interpolated into % amylose using the standard curve.
For most enzymes, there is little enzyme activity at the two temperature extremes: 4°C and 95°C. What are the reasons for the low activity at these temperatures?
At low temperatures there is not enough activation energy for the reaction to proceed and therefore enzyme activity decreases. At high temperatures the structure of the enzyme can denature (or even permanently degrade) into its secondary or primary structures. The minimal level of function in an enzyme is tertiary structure and therefore enzyme activity would be reduced significantly to minimal (or even zero function).
Starch is composed of this molecule:
Amylose and amylopectin
Starch is broken down into__________ by amylase
Maltose
Lugol’s iodine turns __________ (color) in the presence of ______(substrate). This is ________________ (quantitative/qualitative test)
1)Blue-black
2)Starch
3)Qualitative
You will prepare ____ blank(s) for the concentration portion, ____ blank(s) for pH portion, and ____ blank(s) for the temperature portion of the enzyme activity experiment.
3 blanks for concentration (undiluted, 1:3, 1:9)
1 blank for pH
1 blank for temperature
Which of these is correct concerning isozymes?
a)They can form different products
b)They can form the same products
c) They can have different active sites
d) they act on the same substrates
e)All of the above
e)All of the above
What was the source of amylase in our experiment?
Porcine amylase
Which of these conditions may denature an enzyme outside of its optimal range?
a)high temperature
b)low pH
c) high pH
d) All of the above
d) All of the above
What are the functional units of DNA molecules called?
Genes
These regions_______________(coding/non-coding) are used as the basis for DNA fingerprinting
variable length non-coding regions
What type of enzymes are capable of cutting DNA into known segments and are at the heart of DNA fingerprinting technology? What are the resulting DNA segments called?
1) restriction endonucleases
2)restriction fragment length polymorphisms (RFLPS)
What are the three steps of polymerase chain reaction?
1) Melting (heating)
2)Annealing (formation of hydrogen bonds between primers and single strands of DNA at the complementary base pairs) - DNA ligase
3)Polymerization: Taq DNA polymerase extends bases fromt he primer in the 5’ to 3’ direction
Gel electrophoresis will allow for the separation of RFLPs on the basis of _____________________
Size
All DNA molecules are negatively charged and will migrate towards the more positive terminal. Smaller segments will migrate faster and farther towards the cathode.
DNA molecules are compared and identified using which control?
Standardized DNA Ladder
You extracted DNA and recorded the absorbance at two wavelengths:
1) A260 = 0.7
2) A280 = 0.39.
a) is your DNA pure?
b)What is the concentration if absorbance is 1 at 260 nm for 50 ug/mL?
a) Yes; A260/A280 ratio is 1.79~ 1.80 is pure. >1.80 is contamination with solvent and <1.80 is a greater amount of proteins
b) 35 ug/mL
.7*50 ug/mL = 35 ug/mL
You are asked to make 200 mls of a 20mM working (diluted) solution of NaCl using a 2M stock solution. Record the volume of 2M stock solution and the volume of water you would use the make the working (diluted) solution.
V1= 2mL + 198 mL DI Water
C1V1=C2V2
(2000 mM)V1= (20 mM)(200 mL)
V1= (20mM)(200 mL)/(2000 mL)
V1= 2 mL. Total volume = 200 ml = 2mL + 198 mL
How many micrograms (µg) are in 55 mg? Make sure to use correct scientific notation.
5.5 x10^4 ug
55 mg * (1000 ug/1mg)
You are asked to record the absorbance of an unknown compound on a spectrophotometer at 540 nm.
a. What wavelength do you set the machine to?
b. What do you do to “zero” your spec before analyzing your sample?
c. Your spec gives you a reading of 0.8, but after 15 seconds moves to a reading of 0.9. Which number do you record?
a) 540 nm
b)Place blank cuvette in a 540 nm, hit 0.00, and zero machine
c)First stable reading = 0.8
Nucleotides are always added in the ______________(5’ to 3’ or 3’ to 5’ direction)
5’ to 3’
What substance is used to break down the phospholipid cell and nuclear membranes in order to release the DNA in the strawberry lab?
Soap/sodium lauryl sulfate (surfactant) and mashing. Ethanol can also be used
Why was the homogenized solution placed in a hot water bath? Why was it then cooled quickly?
To inactivate DNAse enzymes which would digest the DNA once it is released
To prevent denaturation of the DNA
What is the relationship between the storage of starch location in the Coleus leaf?
Edges of the leaf turned dark blue after treatment with Lugol’s iodine indicating that there is more starch stored at the distal tips
What are three cellular components observed in the wet mount of an Elodea leaf?
1) Chloroplasts
2) Cell wall
3) Central vacuole
What happened to the Coleus leaf after placing in hot ethanol?
Solution turned green indicating the extraction of photosynthetic pigments
What are four methods for separating macromolecules?
1) Dialysis
2) Salting out
3) Centrifugation
4) Electrophoresis
Which term is used to describe the strength of a solution? (Hint: for example isotonic, hypotonic, hypertonic etc)
Tonicity
For the extraction of proteins lab, how were the milk proteins precipitated? Was this done at low or high temperatures?
Salting out by dissolving in a hypertonic solution of Ammonium sulfate which causes the proteins to precipitate. These are collected via vacuum filtration and/or centrifugation.
Low temperatures to prevent denaturation of proteins.
Dialysis tubing has pores large enough to allow (1)________, _________, and ________, but too small for the passage of (2) _________. This is why the solution in the bag turned (3)_______
1) glucose, water, and iodine
2)starch
3) Blue
Thinking of the dialysis bag in Part A as an artificial cell, would you label the surrounding environment in the beaker isotonic, hypertonic, or hypotonic?
Hypotonic
There is less solute in the surrounding environment compared to the environment in the dialysis bag. This causes a net movement of water molecules into the dialysis bag and was supported by the increase in mass of the dialysis bag.
What would happen if red blood cells were placed in a beaker of distilled water. Why?
The RBCs would swell and potentially lyse due to an influx of water. Because the solution is hypotonic relative to the red blood cells, water will move towards the higher concentration of solutes inside the red blood cell via osmosis causing the red blood cell to swell.
Which indicator was used to test for the presence of glucose in the protein extraction lab? What color did it turn?
Clinistix Strip
Dark brown
After completion of the dialysis procedure, where is the majority of the ammonium sulfate going to be found?
The majority of the ammonium sulfate salts should be found in the solution outside of the dialysis bag as they diffuse from a solution of high concentration inside the bag to an area of low concentration in the beaker solution.
After vacuum filtration where should most of your protein be found, in the flask or on the filter paper?
In the flask.
Will be dissolved in the solution due to the protein’s inherent hydrophilicity
Which reagent is used to test for reducing sugars?
a)Benedict’s
b)Barfoed’s
c)Ninhydrin
Is this a qualitative or quantitative test?
a)Benedict (Possesses a free aldehyde or ketone group)
2)Quantitative as it changes into a colored precipitate depending on the amount of the amount sugars present
What reagent is used to test for the presence of monosaccharides?
a)Benedict’s
b)Barfoed’s
c)Ninhydrin
b)Barfoed’s Reagent
Example: glucose and fructose
Which reagent is used to detect the presence of proteins? Is it qualitative, quantitative, or both?
a)Benedict’s, quantitative
b)Ninhydrin, quantitative
c)Ninhydrin, qualitative
d) Ninhydrin, qualitative AND quantitative
d)Ninhydrin, qualitative AND quantitative
Turns a deep purple as concentration of protein increases (Purple Rain)
Which minimum level of protein structure would you expect to see a-helices and B-pleated sheets?
a)Primary
b)Secondary
c)Tertiary
d)Quaternary
b)Secondary
Which level of protein organization represents the minimal functional form for many proteins?
a)Primary
b)Secondary
c)Tertiary
d)Quaternary
c)Tertiary
Which level of protein organization is comprised of multiple proteins or domains to form a mega functional unit?
a)Primary
b)Secondary
c)Tertiary
d)Quaternary
d)Quaternary
Which reagent is used to detect the presence of lipids in a sample?
a)Benedict’s
b) Oil Red O
c) Barfoed’s
d) Ninhydrin
b) Oil Red O; qualitative
Examination of your negative control in the Benedict’s test reveals the presence of a colored precipitate. What would this indicate?
Presence of a colored precipitate in the negative control (water) would indicate contamination with a reducing sugar.
Imagine that the protein sample was boiled and denatured (but still soluble) prior to testing. What result would you expect from the ninhydrin test; would it still show a color change? Why or why not?
Yes; ninhydrin reacts with the amine group on amino acids (primary structure) and therefore even if the protein sample was denatured from quaternary -> tertiary -> secondary -> primary structure it would still show a color change.
A test for water solubility indicates that butanol is insoluble in water but ethanol is soluble. Which is more hydrophobic?
Butanol is more hydrophobic due to increased length of hydrocarbon chain
Propose a solution that could potentially be used as a positive control for the Barfoed’s test?
A positive control for Barfoed’s test should be a known monosaccharide such as glucose or fructose.
A well-written hypothesis is which of the following?
a) testable
b) falsifiable
c) reproducible
d) All of the above
d)All of the above
In the bean experiment, which condition was the independent variable? Dependent?
Independent: color (white vs red)
Dependent: number of each bean
What is the difference between a positive and negative control?
Positive control: testing solution which contains a known positive (example testing for the presence of glucose in unknown compounds should also include a positive control of a solution known to contain glucose).
Negative control: solution which is a known negative (example a solution of just DI water).
Error introduced into the experiment by a flaw in a measuring device would be best classified as:
a) Human error
b) Systematic Error
c) Random Error
d) None of the above
b) Systematic error
You weigh an unknown compound 10 times and get the same result 10 times (69 grams). The actual weight of the compound is 42.0 grams. These results could be best considered:
a)Accurate but not precise
b)Precise but not accurate
c)Accurate and precise
d)Neither accurate nor precise
b)Precise but not accurate
True or false: random error is inherently present in all experiments and is unavoidable
True
For example, slight differences in reagent concentrations and volumes in repeated trials.
Which of the following sample sizes on a study of cats would have the greatest validity?
1) 5 cats
2) 10 cats
3) 20 cats
4) 1000 cats
4) 1000 cats
Validity increases with larger sample sizes
A cell culture has 4.5x10^5 cells/mL, and the flask holds 10mLs of culture and you have 15 flasks, how many cells are there in total?
6.75 x10^7 cells
This biomolecule is identical in 4 ways: central carbon, hydrogen, carboxyl group, amino group but the R group differs. What is this biomolecule?
a) Carbohydrate
b) Amino acid
c) Lipid
d) Nucleotide
b) Amino acid
Diffusion depends on which of the following:
a) Temperature
b) diameter of molecules
c) concentration gradient
d) all of the above
d) All of the above
How many DNA molecules will I have after running 10 polymerase chain reaction (PCR) cycles?
1024
2^n = 2^10
