4.1-5.17

Question 1

kind of independent variables

Answer 1

MANIPULATED

• age
• sex
• race
• SES
• standardized measures and scores

Question 2

4 sampling biases

Answer 2

a NOT random sample. types of bias include

1. special real area - people are selected in a physical space (the quad - this is not representative of all the students)
2. self-selection bias - participant choose to participate
3. advertising - only the advertised people
4. healthy user bias - picking only healthy subjects (say, people who use the gym)

Question 3

standard error

Answer 3

standard deviation / (sample size)^(1/2)

Question 4

test-retest reliability

Answer 4

taking the MCAT multiple times should result in equivalent scores

Question 5

inter-rater reliability

Answer 5

the degree to which two researchers or raters agree in; two doctors come up with the same diagnosis

Question 6

validity

Answer 6

how well an experiment measures what it is trying to measure

Question 7

internal validity

Answer 7

demonstrate a causal relationship between two variables (highly controlled), avoid confounding factors

Question 8

external validity

Answer 8

results of study can be generalized to other situations and other people

Question 9

construct validity

Answer 9

does the survey ask the question clearly?

Question 10

liquid-liquid extraction

Answer 10

like dissolves like

organic compound is extracted with water; inorganic salts, acids/bases, and polar low-molecular weight compounds (alcohols, amines, carboxylic acids)

Question 11

acid extraction

Answer 11

basic (amines) can be extracted from mixtures of organic compounds upon treatment by an acid

formation of a positively charged ion (cation), soluble in AQUEOUS solution and removed from organic compounds that remain dissolved in the organic phase

Question 12

base extraction

Answer 12

converts carboxylic acids into anionic salt -> found in aqueous layer

NaHCO3 cannot extract phenols, but NaCl can

convert the acid into a SALT, which can be extracted away

Question 13

chromatography

Answer 13

SEPARATE MIXTURES

“Chromatography involves the SEPARATION of colors”

Question 14

thin layer chromatography (TLC)

Answer 14

“The polar ice caps are dangerously thin layered”

POLARITIES

more polar -> travels SLOWER (POLAR STATIONARY PHASE)

less polar -> travels FASTER

Rf = ratio (1/1 is extremely not polar)

good for small amounts

thin layer of absorbant (silica, SiO2) = POLAR STATIONARY PHASE

Question 15

column (flash) chromatography

Answer 15

POLARITY - good for BULK

pour down a column, SiO2 slows down the polar, so you capture the non-polar first

Question 16

Ion exchange chromatography

Answer 16

VARIOUS CHARGES

MIXTURES OF PROTEINS

a resin (anionic sulfate groups) captures positive charges, the negative and neutral charged particles are eluted first. Later, the positive charged species can be eluted afterward with sodium-containing solution

CATION exchange resin -> positively charged proteins with pI greater than pH elute elute SLOWLY (CATION exchange KEEPS positively charged) -> proteins with pI below pH pass through

anion exchange -> hold on to low pI, while high pI (positive charged) elute first

Question 17

High performance liquid chromatography

Answer 17

reverse phase HPLC:

opposite of TLC; more polar compounds elute first (stationary phase is silica gel bonded to a non-polar group = NONPOLAR STATIONARY PHASE)

Mobile phase = POLAR

Question 18

size exclusion chromatography

Answer 18

MOLECULAR SIZE

POROUS BEADS

BIG = FAST

Question 19

affinity chromatography

Answer 19

PURIFY PROTEINS/macromolecules

Target is TRAPPED in the STATIONARY PHASE

ANTIGEN/ANTIBODY

Enzyme/Subtrate

Receptor/Ligand

Protein/Nucleic acid

trapping in a stationary phase, washing to remove unwanted components; target protein is released off the solid phase

affinity tags = His tags

Question 20

Gas chromatography

Answer 20

DIFFERENT VOLATILITIES

MORE VOLATILE = carried away FASTER

Question 21

distillation

Answer 21

raise temperature, overcome intermolecular forces, vapor is collected and condensed

SIMPLE -> salt water is boiled, removing the salt

Question 22

Fractional distillation

Answer 22

when difference in boiling points is not large

remove something of a lower boiling point

Question 23

spectroscopy (light)

Answer 23

SEEING structural features based on absorption patterns; light excites the molecules, energy is released

Question 24

Mass spectroscopy

Answer 24

determines the MASS of compounds in a sample

ionized in a high vacuum, bombarded by high energy ELECTRONS, magnetic field, flight path of charged species alters

Question 25

UV/VISIBLE light spectroscopy

Answer 25

conjugated systems = wavelength of maximum absorption increases if a compound absorbs UV, all visible wavelengths will be reflected (white) if a compound absorbs BLUE light, it is will appear ORANGE MEMORIZE THIS: RED - GREEN (725 nm - 525 nm) Orange - blue (625 nm - 460 nm) Yellow - violet (580 nm - 415 nm) MORE CONJUGATED = ABSORBS LOWER FREQUENCY = more likely blue/violet

Question 26

infrared spectroscopy (identify functional groups)

Answer 26

IR == STRETCH ("I REALLY need to STRETCH") IR (2.5 - 20 micrometers) can excite organic molecules Wavenumber = 1/wavelength = 1/c * v (measured in reciprocal centimeters) MEMORIZE THE STRETCH FREQUENCIES (p. 64) carbonyl = 1700 cm-1 Alkene = 1650 triple bond = 2260-2100 hydroxyl -> 3600-3200 C-H for sp3 = 3000-2850 C-H for sp2 = 3150-3000 C-H for sp = 3300

Question 27

NMR Spectroscopy (proton NMR)

Answer 27

look at unique hydrogens (group them) peaks is number of neighboring hydrogens + 1 area is the number of protons (the integration) if EN atom is in close proximity, decreases electron density and DESHIELD it, DOWNfield shift (goes LEFT) AROMATIC proton = 6.5-8 ppm shift ALKENE = 5-6 ppm shift attached to O, N are DESHIELDED (2-5 ppm) carboxylic acid = 10-13 ppm alcohol = 2-5 ppm ALKYL = 0-2 ppm

Question 28

ELISA*

Answer 28

enzyme-linked antibodies determines PRESENCE of ANTIGENS/PROTEINS/CYTOKINES/ANTIBODIES LOOK AT PICTURE "Enzyme-linked ANTIBODY" is the DETECTION enzyme, which leads to COLOR CHANGE

Question 29

radioimmunoassay (RIA)*

Answer 29

measures RADIOACTIVITY in immune complexes via RADIOLABELED ANTIBODIES measure radioactivity determine amount of HORMONES or drugs

Question 30

electrophoresis*

Answer 30

SEPARATION based on SIZE or CHARGE acrylamide and agarose (GEL) form "nets" as they solidify DNA is negatively charged SMALL moves FASTER NEGATIVE move FASTER

Question 31

Southern blotting

Answer 31

blotting = transfer of DNA/proteins from electrophoresis to nitrocellulose SPECIFIC SEQUENCES within a heterogenous sample of DNA -> isolate and purify target DNA sequences filter is PROBED with radiolabeled NUCLEOTIDES that are complementary to portion of target DNA -> allows visualization 1. Cleave DNA (endonuclease) 2. Run on gel electrophoresis 3. Add filter

Question 32

Northern blotting

Answer 32

RNA is separated via gel electrophoresis, rather than DNA determines if GENE PRODUCTS are being expressed

Question 33

Western blotting

Answer 33

presence of certain PROTEINS, DIAGNOSTIC TOOL an enzyme FLOURESCES when detecting a substrate, brightness is proportional to abundance Use of PRIMARY/SECONDARY ANTIBODIES instead of nucleotides

Question 34

restriction endonuclease

Answer 34

bacterial enzyme RESTRICT the reproduction of hostile viruses CUTS in the MIDDLE of DNA chain (exo cuts on the ends) STICKY END is GOOD

Question 35

plasmid

Answer 35

can have a gene for antibiotic resistance, and incorporate a gene of interest, and can survive while the other bacteria die

Question 36

heating DNA can separate the strands

Answer 36

primers bond, then DNA pol adds nucleotides to the 3' end

Question 37

DNA fingerprinting depends on ...

Answer 37

POLYMORPHISMS = 2-100 base pair stretches of repetitive DNA 1. Restriction Fragment Length Polymorphism (10-100 base pairs) - RESTRICTION ENDONUCLEASE followed by GEL ELECTROPHORESIS 2. Short tandem repeats - DNA obtained, PCR'd, and repetitive DNA in introns is analyzed via SOUTHERN BLOTTING

Question 38

knocking down gene expression with ...

Answer 38

RNA interference - microRNA - small interfering RNA degrade mRNA

Question 39

ddNTPs

Answer 39

dideoxynucleotide triphosphate lack the 3' hydroxyl group, cannot elogate important for DNA sequencing (Sanger)

Question 40

immunohistochemistry

Answer 40

specific for protein expression

Question 41

Bradford Quantification

Answer 41

protein quantification proteins bind to blue pigment

Question 42

dna sequencing

Answer 42

ddNTPs