Week 2

Question 1

chromosomes

Answer 1

carriers of genetic information

contain both proteins and nucleic acids

Question 2

Griffith and Avery experiments

Answer 2

S bacteria: fatal to mouse, infectivity killed by heat
R bacteria: not fatal

smooth (S) bacteria contain something not destroyed by heat, can be passed on to R bacteria so that they kill and pass on

conclusion: molecule that carries heritable information is dna

Question 3

Hershey and Chase

Answer 3

virus: consists of both dna and proteins

labeled dna with 32P, proteins with 35S

infected bacteria contain 32P but not 35S

Question 4

Chargaff’s rules

Answer 4

dna, not proteins, is heritable material

A:T and G:C ratio always 1

A/T:G/C ratio variable from species to species

Question 5

Franklin and Wilkens, Watson and Crick

Answer 5

showed dna is double helix (X-ray crystallography)

built model of structure of dna

Question 6

nucleus of cell

Answer 6

the design and management center of the cell

stores dna

Question 7

cytoplasm

Answer 7

production site of the cell, makes proteins

Question 8

mRNA

Answer 8

messenger rna, used to transmit information from the nucleus to the cytoplasm

Question 9

tRNA

Answer 9

transfer dna, adaptors from 4 base dna code to 20 amino acid protein code

Question 10

ribosomes

Answer 10

make proteins using mRNA as template, amino acids as building blocks

large, complex molecules consisting of both proteins and rRNA

Question 11

central dogma

Answer 11

Francis Crick, 1958

dna, rna, and proteins are linear, sequential polymers

each position in sequence is drawn from fixed alphabet (nucleotides for dna, rna—4, and amino acids for proteins—20)

flow of primary sequence information: conversion between alphabets (translation)

no way to convert protein alphabet back to nucleic acid

transcription from dna to rna, then translation from rna to protein

Question 12

gene expression

Answer 12

regulation of this determines if cell is liver, muscle, nerve

levels vary from cell to cell in same organism, at times in development, and with outside signals

Question 13

RNA polymerases

Answer 13

enzymes that carry out transcription

synthesis of rna from 5’ to 3’

signals on dna that tell rna polymerases where to start/stop (subject to regulation)

Question 14

promoter

Answer 14

defines where transcription should begin

rna poly. binding site

then coding region

Question 15

prokaryotes

Answer 15

have no nucleus

single cellular (but may join together)

can live in diverse temps

can grow and evolve quickly

Question 16

eukaryotes

Answer 16

have nucleus

are multicellular

have other intracellular organelles (some of which are thought to have evolved from invading bacteria—mitochondria, chloroplasts)

Question 17

prokaryotic genes

Answer 17

minimal gene

promoter—binding site for rna polymerase

ribosome binding site (initiate protein synthesis in mRNA)

coding sequence—encodes protein synthesis

transcriptional terminator—stop mRNA synthesis

often multiple protein coding regions controlled by single promoter (operon)
-polycistronic: more than one protein encoded in single mRNA molecule

Question 18

polycistronic mRNA

Answer 18

more than one protein encoded on single mRNA molecule

common in prokaryotes

Question 19

eukaryotic genes

Answer 19

5’ caps and 3’ poly-A- tails

require general transcription factors

most have introns (noncoding regions) that are spliced

can be simple of very large

Question 20

introns and exons

Answer 20

noncoding and coding regions in the dna

Question 21

splicing

Answer 21

requires intronic signal sequences

lariat formed from introns

Question 22

alternative splicing

Answer 22

can be differentially regulated

enables a mRNA to direct synthesis of different protein variants

Question 23

translation

Answer 23

once mRNA is out of nucleus, it is translated into proteins—different alphabet

genetic code

Question 24

genetic code

Answer 24

directional: 5’ to 3’ mRNA

no doves to indicate start or stop of words

6 different reading frames from dna to proteins

Question 25

Kozak sequence

Answer 25

all proteins start with amino acid methionine A/GccAUGG/A

Question 26

stop signal

Answer 26

TGA, TAA, TAC (UGA, UAA, UAC)

Question 27

tRNA synthetases

Answer 27

charge tRNA with amino acids

Question 28

tRNA anticodons

Answer 28

base pair with the correct codon on mRNA (after tRNA synthetases charge)

Question 29

rRNA

Answer 29

ribosomal rna, most abundant rna in most cells form the core of the ribosome and catalyze protein synthesis

Question 30

ribosome sites for tRNA

Answer 30

A—admission of codon if mRNA, checking and decoding P—peptide synthesis, consolidation, elongation, transfer of peptide chain to site A E—preparation of now uncharged tRNA for exit

Question 31

electrophoresis

Answer 31

separation of charged biomolecules in a gel matrix in which an electric field has been established separates proteins, rna, dna

Question 32

phosphate moieties of dna/rna

Answer 32

provide nucleic acid molecules with constant, negative charge to mass ratio charge of protein depends on primary structure and ph of the solution

Question 33

equipment for gel electrophoresis

Answer 33

power source, electrophoresis tank, anode (+) and cathode cable, support, comb

Question 34

bands on electrophoresis gel

Answer 34

population of identical molecules that are not exactly identical in migration behavior -> distribution variables affecting: molecular, thermal, gel heterogeneity, observation error

Question 35

the southern blot

Answer 35

dna separated on gel and dna as the probe

Question 36

the northern blot

Answer 36

rna separated on gel and dna as the probe

Question 37

charge/mass ratio

Answer 37

constant for dna and rna (so just separate by size) unique for every protein

Question 38

two solutions for unique charge:mass ratio in proteins

Answer 38

treat proteins to give them uniform charge take advantage of this property to separate proteins

Question 39

SDS (sodium dodecyl sulfate)

Answer 39

strongly denaturing detergent (disrupts 2o-4o structures) binds and confers negative charge to proteins (charge ~ mass)

Question 40

denaturing protein gel electrophoresis

Answer 40

proteins unfolded by loss of disulfide and hydrogen bonds SDS coating -> uniform charge/mass ratio mobility is inverse of mass proteins of known mass used as standards to calibrate gel

Question 41

isoelectric focusing

Answer 41

not denatured, ph gradient within gel protein migrated from well to ph where is has no net charge (isoelectric pt, pi)

Question 42

2d gel

Answer 42

electrophoresis in 1st rim by isoelectric point (native) electrophoresis in 2nd din by size (reduced/SDS)

Question 43

antibodies

Answer 43

proteins that bind strongly with specific 3D structure (specific protein) produced naturally by immune system to help in detection of foreign antigens used to identify proteins in bio samples

Question 44

Western blot

Answer 44

detection of specific protein structure using antibody