Midterm Flashcards
What are the five steps of the scientific method? (OHPEC)
Observation, hypothesis, prediction, experiment, conclusion
What is a hypothesis?
A proposed explanation for a phenomena
Why must a hypothesis be falsifiable?
You must be able to prove that it is false because if you can’t prove it false, you can’t prove it right.
Meaning that it can be tested in a way that can lead to evidence that does not support the hypothesis.
What is a beaker?
A beaker is used to hold large amount of liquid, but does not accurately measure volume
What is a graduated cylinder?
A graduated cylinder is used to measure smaller amounts of liquid, more accurate than beakers
Pipettes accurately measure small volumes of liquid, usually between __-__ml
0-10ml
Micropipettes measure volume in ____________
microliters
Mohr pipettes have…
graduation marks that stop before the end of the tip
Serological pipettes have…
graduation marks that continue to the tip
Volumetric pipettes…
Precisely and accurately measures one volume.
Wide at the middle of the pipette; dispenses a single volume
Always hold the pipette upright and view the meniscus at ____ ______
Eye level
How do you calculate % error?
(Measured vol -theoretical vol)/
(theoretical vol)x100
What is a spectrophotometer?
The spectrophotometer is an instrument used to measure the amount of light that is absorbed by (scale of 0-2) or transmitted through (percentile scale 0-100%) a sample at a particular wavelength of light.
Absorbance of a solution is directly proportional to the concentration of molecules in the solution according to _____-_________ law.
Beer-Lambert Law
You will use the spectrophotometer to obtain an __________ __________ and a ___________ _______ for a blue dye called ___________ ______
Absorption spectrum and a standard curve, bromophenol blue
What is an absorption spectrum?
A pattern of light absorption over a range of wavelengths for a particular substance
What can one determine from an absorption spectrum?
One can determine the wavelength of max (peak) absorbance by the substance
What is a standard curve?
A plot of known concentrations of a series of samples against absorbance.
How can the standard curve be used to find the concentration of an unknown substance?
Find the absorbance of the unknown sample, and then plug it into your standard curve, and you can 1) estimate the concentration by eye, or 2) plug in the absorbance of the unknown sample to the equation of the line
What is the control?
The single variable of interest that is being tested. The control is used as a standard of comparison when assessing the results of an experiment
What is the independent variable?
The variable that is being changed or controlled
What is the dependent variable?
The variable that is being tested or measured
Why are graduated cylinders more accurate than beakers?
They have smaller graduated increments
The _______ is the portion of the fluid’s surface that has a concave appearance; this concavity is caused by surface tension
meniscus
What is the difference between an absorbance curve and a standard curve?
An absorbance curve measures the absorbance of a sample over a series of wavelengths.
A standard curve is used to determine the unknown concentration of a sample.
What is the optimum range for bromophenol blue?
580-600nm
Know the names and functions of parts of a microscope
Know the names and functions of parts of a microscope
What is resolution?
The effectiveness by which two points can
be perceived as distinct
What is magnification?
Enlargement of something’s physical appearance
What is contrast?
The difference between the light and dark areas of an image; higher contrast means more difference
What is depth of field?
The range of distance in front of and behind an object focused by the microscope, within which other objects will also appear clear and sharply defined in the resulting image.
What is the index of refraction?
At higher magnifications, light is refracted, or bent, into the objective lens because the refractive index of air between the slide and the objective is lower than the refractive index of glass.
How does the addition of immersion oil solve this problem?
Immersion oil has a refractive index similar to glass and allows higher resolution at high magnification
How do calculate the total magnification?
Multiply the objective lens x 10
How do you calculate diameter of field of view?
If 4x has a f.o.v. of 4mm, then what would would the unknown f.o.v. be for 40x?
Take the total magnification of 4x (which is 40x). Divide the known magnification (40x) by the unknown magnification (400x) and then multiply it by 4mm = .4mm
How would you estimate the size of a cell depending upon the magnification and diameter of the field of view?
Take the diameter of FOV (micrometers) and divide it by the number of cells that would fit across the diameter.
What is one advantage and disadvantage of an electron microscope?
Advantage: use electrons to view details
Disadvantage: specimen is killed
When is it appropriate to use the coarse adjust? Fine adjust?
Course adjust: 4x and 10x
Fine adjust: 40x and 100x
What happens to the depth of field as you increase the magnification?
Increase magnification, decrease field of view
A drop of ___________ is used when viewing a specimen under the 100x objectives?
immersion oil
By staining the cells, you have improved the ______, the difference between light and dark parts of the image.
contrast
What is a prokaryote?
No nucleus, no membrane-bound organelles,
1-10micrometers in size
What is a eukaryote?
Have a nucleus, membrane-bound organelles, 10-100 micrometers in size
The DNA of prokaryotes is suspended within the cell’s aqueous interior, or _______.
cytosol
What are the most common prokaryotes?
Bacteria
Prokaryotes divide by _______ _______
binary fission
______, the microscopic inhabitants of pond water, are single celled eukaryotes.
Protists
Cell wall gives shape and prevents cells from bursting due to ________ _______.
osmotic pressure
As size ________, the SA to volume ratio ________, so larger cells have more trouble obtaining enough nutrients and ridding themselves of waste.
increase, decreases
Which bacterium makes yogurt?
Lactobacillus
What are the two prokaryotic organisms observed?
Lactobacillus and Cyanobacteria
Which other six are eukaryotic?
Elodea, potato, onion, amoebae, paramecium, and hypermastigotes
Which are photosynthetic?
Cyanobacteria, elodea, and (euglena)
Which three organisms are heterotrophs?
Amoebae, paramecium, and hypermastigotes
Do onion and potato cells have chloroplasts? If not, explain.
No, onion and potato cells do NOT have chloroplasts because they are underground and there is no light
Which organism was previously know as ‘blue-green algae’?
Cyanobacteria
Endosymbiont theory is a theory that offers an explanation for how plant cells acquired ________, the organelle where photosynthesis occurs. Evidence includes:
chloroplasts.
Evidence includes: chloroplasts similarity to cyanobacteria (1-10 micrometers size) double membranes around mitochondria and chloroplasts, and these organelles have possession of their own circular DNA
Endosymbiont theory is the concept that…
mitochondria and chloroplasts evolved from an endosymbiotic relationship between two prokaryotes
Cyanobacteria form enlarged cells called _________
heterocysts
Heterocyst’s are capable of…
nitrogen fixation
Do cyanobacteria have chloroplasts?
No
Plant cells have ____ _____ and _______
cell walls and chloroplasts
Animal cells have neither ____ ______ nor ________
chloroplast
In______, the nuclei are almost transparent and hard to see unless stained.
Elodea
The chloroplasts circulate around the cytoplasm, dragged along cytoskeletal filaments by tiny molecular motors known as _______
kinesins
The SA to volume ratio of plant cells puts a limit on their size. What two mechanisms offset this problem?
Cytoplasmic streaming and large central vacuoles
In potatoes, starch is stored in organelles known as _________.
amyloplasts
Amoebae are a diverse group of ______.
protists
Do amoebae have cell walls?
No
An amoebae uses __________ (false feet) to slowly creep along a surface.
pseudopodia
This ________ ________ occurs through cytoplasmic streaming, which is also used for capturing food.
amoeboid movement
The protist Paramecium is covered with tiny, hair like ____ that the cell uses for propulsion.
cilia
Paramecium use ________ _______ for nutrient uptake.
cytoplasmic streaming
Hypermastigotes have a symbiotic relationship with ________.
termites
Hypermastigotes are responsible for digesting ______
wood
Where do we throw away toothpicks with cheek cells?
BioHazard Bin
What is diffusion?
Diffusion is the movement of particles from an area of high concentration to an area of low concentration, until it reaches a state of dynamic equilibrium
What is meant by diffusion down a concentration gradient?
Down a Concentration Gradient refers to going from regions of high concentration of some entity to regions of low concentration, and such movement generally occurs spontaneously, that is, if allowed to happen it happens.
What is dynamic equilibrium?
When the particles are equally dispersed in both areas
What is osmosis?
The movement of water across a semi-permeable membrane where water can cross but other solutes cannot.
Water molecules moving from an area of high concentration to an area of low concentration
Explain hypertonic.
Solutions that have a relatively greater concentration of solute, so the water moves out of the cell
Explain hypotonic.
Solutions that have lower concentration of solute, so the water moves into the cell
Explain Isotonic.
Solutions that have the same concentration
Why is osmosis important to cells?
Osmosis is important to cells because the cell membrane is permeable to water
Why are cells in a hypotonic solution in danger?
They are in danger of swelling to the point of bursting
How do animals cells and protists deal with osmosis?
Contractile vacuoles
How do plant and bacteria cells deal with osmosis?
They have rigid cell walls
What is pH?
The measure of hydrogen ions in a solution. It’s another factor that affects the livelihood of cells.
Describe how paramecia and hypermastigotes differed in their sensitivity to environmental pH
The paramecium was moving freely in the pH 6, slowed in the pH 7, and was found dead in pH 8.
The hypermatigotes were not able to handle the changes in pH and died.
Hypermatigotes are found in termites stomachs and cannot tolerate changes in pH because of this. Paramecium are found in ponds, therefore they’re used to an unregulated pH.
What’s the difference between quantitative and quantitative data?
There are two general types of data. Quantitative data is information about quantities; that is, information that can be measured and written down with numbers. Some examples of quantitative data are your height, your shoe size, and the length of your fingernails. Speaking of which, it might be time to call Guinness. You’ve got to be close to breaking the record.
Qualitative data is information about qualities; information that can’t actually be measured. Some examples of qualitative data are the softness of your skin, the grace with which you run, and the color of your eyes. However, try telling Photoshop you can’t measure color with numbers.
These cells provide a favorable environment for cyanobacteria under extreme conditions…
Akinete
Why are strawberries a good choice in terms of DNA extraction?
They are octaploid
In DNA, what is the polymer? Monomer?
Polymer: polynucleotide
Monomer: nucleotide
What is a nucleotide made up of?
Deoxyribose sugar, nitrogenous base, phosphate group
What makes up the polynucleotide backbone?
Phosphate-sugar backbone (nitrogen base on the inside)
Since DNA is charged and polar, it is __________
hydrophilic, and SOLUBLE in water
Purine… __ fused rings. Consists of ________ and _______
2 fused rings.
Consists of adenine and guanine
Pyrimidine… __ fused ring. Consists of _______ and _______
1 fused ring.
Consists of thymine and cytosine
You can only pair a purine with a pyrimidine by
________ bonding
hydrogen
Purines have __ H bonds
Pyrimidines have __ H bonds
Purines have 2 H bonds
Pyrimidines have 3 H bonds
How is it possible to separate nucleic acids from the cells that contain them??
Break the cells open
Why were DNA containing solutions kept on ice throughout the lab exercise?
To slow down the production of enzymes
What was the purpose of shampoo?
To break open the cells and dissolve the membranes
What was the purpose of baking soda?
To maintain pH
What was the purpose of Isopropyl?
To precipitate the DNA
What was the purpose of alcohol and salt?
To neutralize the negative charges on DNA, allowing the DNA to precipitate.
At which ‘optimum’ wavelengths do DNA and protein absorb the most light?
DNA absorbs at 260 nm
Protein absorbs at 280 nm
What does the absorbance ration 260 nm/280 nm tell us about a DNA sample?
used to assess the purity of DNA and RNA
What happens on prolonged exposure to UV?
Extra energy absorbed by DNA can result in mutations and could give rise to cancer
Why are GC bonds more stable than AT bonds?
GC bonds have 3 hydrogen bonds
AT bonds have only 2 hydrogen bonds
What does OD stand for?
Optical density
If given a DNA strand and asked to write the complimentary strand…
write the 3’ to 5’, then FLIP IT to make it 5’ to 3’
