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41 Cards in this Set
- Front
- Back
what is the point of DNA
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it's a code that gives us the order for a sequence of amino acids
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what is the reaction that combines amino acids
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condensation
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what do amino acids joined together form
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A polypeptide chain
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where is DNA found
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the nucleus
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where are proteins synthesized
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cytoplasm
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what is 'central dogma'
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the production of mRNA which is read by ribosomes to position tRNA into a particular sequence forming a particular protein.
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what is the role of mRNA
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A messenger molecule, it transfers the DNA code from the nucleus to the cytoplasm because it is small enough to leave through the nuclear pores.
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what are the structural differences between DNA and RNA
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RNA remains single stranded
RNA contains uracil RNA has ribose sugar back bone DNA contains thymine DNA has deoxyribose back bone |
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when is mRNA produced
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the first step of protein synthesis
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where is mRNA produced
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in the nucleus when DNA is unraveled exposing a template stand for free RNA nucleotides to assemble
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what enzyme is responsible for the unraveling of DNA
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DNA helicase
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How many nucleotides are exposed at any one moment
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No more than 20
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is mRNA identical or complementary to the DNA template from which it has been formed
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complementary
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after pre-mRNA is formed what happens
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pre-mRNA leaves the nucleus through a nuclear pore where it attaches to ribosome which acts as a scaffold to form proteins on.
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what do the bases of mRNA indicate
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the order of amino acids in the polypeptide chain (protein) that is being made
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what is a codon
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3 nucleotide bases that code for an amino acid
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what is a degenerate code?
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when an amino acid has more than one cousin
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what mark the end of a polypeptide chain
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A stop codon, for which there are three.
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the triplet code prevents
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overlapping of amino acids
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the triplet code is universal, what does this mean
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the same codon codes for the same amino acid in all organisms.
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structural features of tRNA
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single stranded and folded into a cover leaf shape, contains uracil, very small
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what is the role of tRNA
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to bring amino acids to a ribosome during protein synthesis.
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the process of producing a protein from DNA
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what is transcription
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the production of mRNA by using DNA as a template
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what is translation
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translating the base sequence of mRNA into an amino acid sequence.
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what is the function of RNA polymerase
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to form phosphodiester bonds (sugar phosphate backbone) to produce a single stand of pre-mRNA complementary to the DNA base sequence
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when does RNA polymerase detach from the DNA and pre mRNA
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when it reaches a stop codon, pre-mRNA is complete
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what bonds does DNA helicase break
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hydrogen bonds between bases
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what happens when ends polymerase detaches?
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the DNA rewinds forming hydrogen bonds between it's bases
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does all DNA code for proteins?
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No, only 2% is coding DNA the other 98% is non-coding
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exons are...
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coding sections of DNA and pre-mRNA
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introns are...
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non coding sections of DNA and RNA
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what happens to separate introns and exons
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useful exons are removed from pre-mRNA and spliced together to form a final strand of mRNA.
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what is translation
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the synthesis if the polypeptide
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tRNA contains a complementary _ _ _ _ _ _ _ _ _ to the mRNA
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anticodon
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what is attached to the tRNA
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the amino acid that is specific to the anticodon.
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what is the job of the ribosome in translation
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to bring complementary tRNA molecules to the mRNA, it brings two tRNA molecules at a time.
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what bond is formed between amino acids in a condensation reaction
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A peptide bond
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what is used to join amino acids?
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an enzyme and ATP
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once the amino acids are bonded what happens to the tRNA
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it is released so it can collect another amino acid.
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what is the process called when many ribosomes travel laying the mRNA at the same time
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polysome
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