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29 Cards in this Set

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What is the goal of DNA replication?
To make an exact copy of DNA double helix so both daughter cells will have identical genetic information after the cell divides
_______ transcription --> _______ translation --> _______
DNA
RNA
polypeptide
What are some differences between DNA and RNA?

a. strands
b. sugar
c. bases
a. double single
b. deoxyribose ribose
c. thymine uracil
What is the goal of transcription?
To make a copy of a particular segment (gene sequence) of DNA
What are the players of transcription?
DNA section to be transcrbied
RNA nucleotides
RNA polymerase
What are the three stages of transcription?
Initiation
Elongation
Termination
What is the initiation for transcription?
Segement to be trascribed
Promoter region = "start" located
What is the elongation for transcription?
RNA nucleotides bind to the bases of one of the DNA strands (other DNA can be ignored), RNA polymerase joins up the RNA nucleotides
What is the termination for transcirption?
Termination sequence on DNA strand is reached, mRNA strand is released
What is the goal of translation?
Translate the original DNA segment (via mRNA) and assemble the polypeptide
What are the players of translation?
mRNA, tRNA, ribosomes, release factor protein
What is the initiation for translation?
mRNA attaches to small ribosome unit, "start" codon on mRNA read by a tRNA carring the amino acid "met" methionine
Elongation for translation?
tRNA in middle spot of large ribosome unit holds onto chain
new tRNA enters
reads the mRNA codon
peptide bond formation between new amino acid & rest of the change
transfer of chain to new tRNA
translocation = old tRNA leaves
"new" tRNA moves to middle spot
Termination for translation?
release factor protein binds to "stop" codon on mRNA
tRNA holding amino acid chain releases the chain and leaves the ribosome
mRNA retaches from small unit of ribosome
Templates for transcription (tc) and translation (tl)
tc = DNA
tl = mRNA
Location for tc and tl
tc = nucleus
tl = ribosome (in cytoplasm or on rough ER)
Molecules involved for tc and tl
tc = DNA & RNA nucleotides
tl = mRNA, tRNA, amino acids, ribosomes, release factor protein
Enzymes involved for tc and tl
tc = RNA polymerase
tl = none
Control start & stop for tc and tl
tc = promoter region "start here" & terminator region "stop here"
tl = "start" codon = AUG
1 of 3 "stop" codons: UAA, UAG, UGA
Product for tc and tl
tc = single strand of mRNA
tl = polypeptide chain
Bfore mRNA gets translated, it needs to be processed. How does this happen? What gets added and what gets removed?
Cap: 5' end; sequence of phospahte groups that adds stability and helps to bind ribosome
Tail: 3' end; sequence of A-bases that adds stability and helps mRNA leave nucleus
Introns: intervening sequences that get removed by spliceosomes (make loops, enzyme snips them off, joins exons together)
What are introns?
Introns are DNA segments found between the exons (protein-coding segments of a gene)
Why are introns present?
Evolutionary leftovers - maybe ease of reshuffling into useful new combos
Alternative splicing - different mRNA's produced from same gene, depending on which segments treated as introns/exons
What are point mutations?
Mutations in which as single base-pair gets inserted/deleted/substituted
Original segment of DNA: T-A-C-T-T-C-A-A-A-C-C-G-A-T-T

What is the complimentary mRNA sequence for the original DNA segment?
A-U-G-A-A-G-U-U-U-G-G-C-U-A-A
A-U-G-A-A-G-U-U-U-G-G-U-U-A-A

determine the type of mutation that has occured (base-pair insertion/deletion/substitution), and what the resulting problem is?
base-pair substitution; nothing happens--same as a.a. coded form
A-U-G-A-A-G-U-U-U-A-G-C-U-A-A
base-pair substitution; because substitution at start of codon, different a.a. inserted
A-U-G-U-A-A-G-U-U-U-G-G-C-U-A-A
base insertion; frameshift so now there's a stop codon just after the start codon
A-U-G-A-A-G-U-G-G-C-U-A-A
base deletion; frameshift such that all codons after the deletion are wrong = wrong a.a.'s inserted