Lab exam - cell biology Flashcards
(31 cards)
Diffusion:
When substances move from an area of high concentration to an area of low concentration.
Do not require energy.
Osmosis:
Movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a cells partially permeable membrane.
If a plant cell is surrounded by a solution that contains a:
Higher concentration of water molecules than the solution inside the cell
Water will enter the cell by osmosis and the plant cell will become turgid (firm).
If a plant cell is surrounded by a solution that contains a:
Higher concentration of water molecules than the solution inside the cell
Water will enter the cell by osmosis and the plant cell will become turgid (firm).
If a plant cell is surrounded by a solution that contains a: Lower concentration of water molecules than the solution inside the plant cell
Water will leave the cell by osmosis and the plant cell will become flaccid (soft).
Erythrocytes:
Red Blood Cells
If the solution is hypertonic
Water will move out of the RBC and cause it to crenate (shrivel or shrink).
If the solution is hypotonic
The RBC will swell and lyse (rupture or explode) as water moves into the RBC.
RNA Extraction is:
The purification of RNA from biological samples
RNA isolation requires:
Cautious handling of samples, good aseptic technique, and RNase free solutions during the extraction.
Extracting high quality and quantity of RNA from cells in monolayer is essential for:
Many gene expression experiments.
In physical methods:
Cell membranes are physically broken down by using shear or external forces.
In regent-based methods:
Specialty formulated lysis buffers are used to disrupt the cell membrane.
TRIzol Reagent:
It is a mono-phasic solution of phenol and guanidine isothiocyanate RNA integrity during tissue homogenization, while at the same time disrupts and breaks down the cells and cell components.
It is used for adherent cell detachment, and it is commercially available.
RNA concetration calculation (impurties considered):
RNA concentration (μg/ml) = [A260 – A320)/0.025] x DF
Total RNA amount (μg) = RNA concentration (μg/ml) x final sample volume (ml).
Quality assessment of the RNA sample:
(A260/A280) = (A260 – A230) / (A280 – A320)
(A260/A230) = (A260 – A320) / (A230 – A320)
Beer-Lambert Law: (Principle-Instrumentation-applications) A = εLC
The relationship between I and lo (i.e. the Absorbance) depends on the path length (L) and the concentration of the molecules in the solution (C).
A=
absorbance (calculated by the A=log)I/lo)
ε=
absorptivity or extinction coefficient (a constant, ability of specific molecules to absorb light)
L=
length of path (the light pathlength through the cuvette is 1cm)
C=
concentration
DNA and RNA absorb at:
260 nm
Proteins absorb at
280 nm of wavelength.
By applying Beer’s- Lambert’s equation, with set length (10mm):
The concentration is evaluated
