chapter 8 objectives Flashcards
what is the griffith experiment; role in discovering DNA
s. pne could either be smooth with capsule (more virulent) or rough without capsule
contribution of oswald with streptococcus pneumoniae
found that animals survived when they targeted DNA and that DNA was key to transformation of rough to smooth
overview of hershey chase experiment
proved that dna was hereditary material becayse when bacteriophages infect host only their DNA enters cell
contributions of watson and crick
they founded the structure of DNA shape (double helix)
4 nitrogenous bases in rna
purines: adenine and guanine
pyrimidines: uracil, cytosine
sugar in rna
ribose
dna vs rna
function: molecule of inheritance (d) protein synthesis (r)
location: nucleiod (d) proteins (r)
bases: a,g,c,t (d) a,g,c,u (r)
sugar: deoxyribose, ribose
structure: double stranded vs single stranded
central dogma
DNA–> RNA–> proteins
why is dna semi conservative
one strand is used as a template, while the other remains as an original strand
2 types of bacterial dna replication
bidirectional replication:
rolling circle replication
steps of bacterial dna replication
topoismerases unwinds dna, helicases breaks down bonds, binding proteins keep strands apart, dna poly III adds nucleotides, rna primase adds primers, ligase brings together okazaki fragments
what direction does dna polymerase II read
it reads in a 3’ to 5’ direction
synthesis of leading/lagging strands during dna replication
leading strand is sythesized 5’ to 3’ while lagging strand is synthesized 3’ to 5’
enzymes and the role they play in dna replication
Helicase: unzipping the DNA helix
Gyrase: helping to untangle the DNA supercoils
Primase: synthesizing an RNA primer
DNA polymerase III: adding bases to new DNA chain; proofreading the chain for mistakes
DNA polymerase I: removing primer, closing gaps, repairing mismatches
Ligase: final binding of nicks in DNA during synthesis and repair
Topoisomerases I and II: supercoiling and untangling
structural/functional differences between rna and dna
transcription
dna–> rna
initiation: sigma determines transcription starting pt
elongation: sigma released, rna polymerase moves along strand
termination: termination sequence tells rna polymerase to stop adding
three types of rna involved in traslation
mRNA, tRNA, rRNA
wobble
multiple codons can code for the same amino acid because only the first two nucleotides are required to encode the correct amino acid, the third will not change its sense
codon
3 bases that code for one amino acid
anticodon
carried by tRNA and contains complementary nucleotides to the codon in mRNA
three start and stop codons
start: AUG
stop: UAA, UAG, and UGA
locations of promoter, start codon, and a/p sites during translation
promoter: DNA
start: on mRNA
A site: holds the next amino acid
P site: holds growing polypeptide chain
transcription/translation bacteria vs. eukaryotic
eukaryotic: transcription happens in nucleus, separate process, translation on 80s ribosomes
bacteria: happens simultaneously in cytoplasm using 70s ribosomes
