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what are the three components of a nucleotide? which parts make up the backbone of a DNA strand? |
1) five carbon sugar aka deoxyribose 2) phosphate group 3) nitrogen base (adenine, thymine, cytosine, guanine) |
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what are the four nitrogen bases? which bases are complementary? |
1) adenine and guanine 2) thymine and cytosine |
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what is the purpose of DNA replication and when during the cell cycle does it occur? why is it considered "semi-conservative"? |
the purpose of DNA replication is to pass the genetic material of one cell to grow new cells and continue hereditary information. it occurs in the S phase. it is called semi-conservative because each new double helix has one old strand and one new strand, each mother strand serves as a template for a new strand form the nucleotide. they are complimentary but not identical. |
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explain the roles of helicase and DNA polymerase in DNA replication. |
helicase unzips the DNA molecule by breaking the weak H-bonds and DNA polymerase binds the phosphate of one nucleotide to the sugar of the adjacent nucleotide. |
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what complimentary DNA sequence would be made from the following DNA template sequence :: TAGCCTGACCCG? |
TAGCCTGACCCG::ATCGGACTAAAC |
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what does the "one gene-one polypeptide" hypothesis state? |
the hypothesis states that the function of an individual gene is to dictate the production of a specific enzyme. this meant that the "mutant" strain lacked a single enzyme that is needed to produce the molecule mold needed. it is only defective in a single gene. |
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what is transcription and translation? |
transcription is DNA -> RNA. translation is RNA -> protein. |
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what role does DNA play in protein synthesis? |
the DNA shows the order the amino acids have to be in to make a protein. |
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list three ways RNA is different from DNA. |
RNA has a single strand, has oxygen, and has uracil instead of thymine. |
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describe the process of transcription and explain the role RNA polymerase. |
1) RNA helicase separates DNA strand 2) RNA nucleotides pair with DNA nucleotides on one side of the DNA chain 3) a promoter (all 3 types of RNA are produced from transcription) 4) RNA polymerase begins bonding the ribose sugars to the phosphates of adjacent nucleotides 5) RNA polymerase hits a sequence of DNA bases that signal it to stop, the termination signal, & the new strand of mRNA is released from the template. |
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how do introns and exons relate to RNA splicing? |
introns are noncoding regions that are found in most plant and animal genes. exons are the parts of a gene that remain in the mRNA and will be translated or expressed. RNA splicing is when the introns are removed and the exons are joined together, producing an mRNA molecule with continuous coding sequence. |
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What mRNA sequence would be transcribed from the following DNA sequence :: TAGCCTGACCCG? |
TAGCCTGACCCG::AUCGGACUGGGC |
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what amino acid sequence would be coded for DNA sequence :: TAGCCTGACCCG? |
TAGCCTGACCCG::lle, gly, leu, gly |
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briefly describe the steps of translation and explain the roles of mRNA, tRNA, and rRNA in the process? |
1) mRNA moves out of nucleus to a group of ribosomes 2) tRNA picks up free floating amino acids in the cytoplasm 3) rRNA moves along the mRNA 4) tRNA moves into the ribosome and pairs its anticodon to the mRNA’s codon 5) AMino acid that is attached to the tRNA bonds to the previous amino acid forming a chain of amino acids (proteins) 6) ribosomes releases the mRNA and the protein is complete when a stop codon is reached. mRNA transcribes from a DNA template – tRNA is translates 3 letter codons of mRNA to the amino acids that make up proteins – rRNA binding site for mRNA on its small subunit and two binding sites for tRNA on its large subunit. |
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Explain why a base substitution is often less harmful than an insertion? |
if the base is substituted the reading frame is altered by only that one base which may or may not change the amino acid encoded on the codon. if it is deleted there is a reading change shift. |
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