Lab exam - cell biology

Question 1

Diffusion:

Answer 1

When substances move from an area of high concentration to an area of low concentration.
Do not require energy.

Question 2

Osmosis:

Answer 2

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.

Question 3

If a plant cell is surrounded by a solution that contains a:
Higher concentration of water molecules than the solution inside the cell

Answer 3

Water will enter the cell by osmosis and the plant cell will become turgid (firm).

Question 3

If a plant cell is surrounded by a solution that contains a:
Higher concentration of water molecules than the solution inside the cell

Answer 3

Water will enter the cell by osmosis and the plant cell will become turgid (firm).

Question 4

If a plant cell is surrounded by a solution that contains a: Lower concentration of water molecules than the solution inside the plant cell

Answer 4

Water will leave the cell by osmosis and the plant cell will become flaccid (soft).

Question 5

Erythrocytes:

Answer 5

Red Blood Cells

Question 6

If the solution is hypertonic

Answer 6

Water will move out of the RBC and cause it to crenate (shrivel or shrink).

Question 7

If the solution is hypotonic

Answer 7

The RBC will swell and lyse (rupture or explode) as water moves into the RBC.

Question 8

RNA Extraction is:

Answer 8

The purification of RNA from biological samples

Question 9

RNA isolation requires:

Answer 9

Cautious handling of samples, good aseptic technique, and RNase free solutions during the extraction.

Question 10

Extracting high quality and quantity of RNA from cells in monolayer is essential for:

Answer 10

Many gene expression experiments.

Question 11

In physical methods:

Answer 11

Cell membranes are physically broken down by using shear or external forces.

Question 12

In regent-based methods:

Answer 12

Specialty formulated lysis buffers are used to disrupt the cell membrane.

Question 13

TRIzol Reagent:

Answer 13

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.

Question 14

RNA concetration calculation (impurties considered):

Answer 14

RNA concentration (μg/ml) = [A260 – A320)/0.025] x DF
Total RNA amount (μg) = RNA concentration (μg/ml) x final sample volume (ml).

Question 15

Quality assessment of the RNA sample:

Answer 15

(A260/A280) = (A260 – A230) / (A280 – A320)
(A260/A230) = (A260 – A320) / (A230 – A320)

Question 16

Beer-Lambert Law: (Principle-Instrumentation-applications) A = εLC

Answer 16

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).

Question 17

A=

Answer 17

absorbance (calculated by the A=log)I/lo)

Question 18

ε=

Answer 18

absorptivity or extinction coefficient (a constant, ability of specific molecules to absorb light)

Question 19

L=

Answer 19

length of path (the light pathlength through the cuvette is 1cm)

Question 20

C=

Answer 20

concentration

Question 21

DNA and RNA absorb at:

Answer 21

260 nm

Question 22

Proteins absorb at

Answer 22

280 nm of wavelength.

Question 23

By applying Beer’s- Lambert’s equation, with set length (10mm):

Answer 23

The concentration is evaluated

Question 24

260/280 should be:

Answer 24

~1.8 for DNA and ~2 for RNA

Question 25

260/230 are commonly around:

Answer 25

2.0 – 2.2

Question 26

Absorbance at 320 is an indication of:

Answer 26

Cuvette or random debris introduced during the extraction and thus it is subtracted as the background from other wavelength readings

Question 27

Sample 260/230, RNA=

Answer 27

2.00 (2.00-2.20)

Question 28

Sample 260/280, RNA =

Answer 28

2.00 (1.80-2.00)

Question 29

Restriction Fragment Lenght Polymorphism (RFLP):

Answer 29

A type of polymorphism that results from variation in the DNA sequence recognized by restriction enzymes.

Question 30

The resulting fragments are separated according to their:

Answer 30

Lengths and the pattern of fragment sizes will differ for each individual tested.