Zoology 101 - DNA
Terms
undefined, object
copy deck
- 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 --> _______
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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?
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DNA section to be transcrbied
RNA nucleotides
RNA polymerase - What are the three stages of transcription?
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Initiation
Elongation
Termination - What is the initiation for transcription?
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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?
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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?
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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)
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tc = DNA
tl = mRNA - Location for tc and tl
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tc = nucleus
tl = ribosome (in cytoplasm or on rough ER) - Molecules involved for tc and tl
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tc = DNA & RNA nucleotides
tl = mRNA, tRNA, amino acids, ribosomes, release factor protein - Enzymes involved for tc and tl
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tc = RNA polymerase
tl = none - Control start & stop for tc and tl
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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
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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?
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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?
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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
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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
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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