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27 Cards in this Set
- Front
- Back
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genetics
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The science of heredity, what genes are, how genes carry information, how genes are expressed, how genes are replicated
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genome
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genetic information in a cell
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chromosome
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genetic information in a cell
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gene
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genetic information in a cell
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what is the structure of DNA? of what 3 parts does a nucleotide consist?
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DNA is a macromolecule composed of repeating units called nucleotides
Nucleotides consist of Nucleobase (adenine, thymine, cytosine or guanine), deoxyribose (pentose sugar), phosphate group |
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How are its strands held together?
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held together by hydrogen bonds
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s a typical bacterial chromosome circular or linear? How does the chromosome fit inside a bacterial cell?
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Circular . the chromosome is supercoiled
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What is DNA replication?
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Parental dsDNA molecule converted to 2 identical daughter molecules
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What is the function of the following enzymes: topoisomerase, helicase, DNA polymerase
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Supercoiling relaxed by topoisomerase, two strands unwound by helicase, separated form each other. Newly added nucleotide is joined to growing DNA strand by DNA polymerase
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DNA replication requires energy. How is this energy supplied?
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Supplied from nucleotides. Two phosphate groups removed to add nucleotide to growing strand of DNA
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DNA replication is an amazingly accurate process. Why? How are base pairing mistakes avoided?
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Due to proofreading capability of DNA polymerase. – As each new base is added, enzyme evaluates whether it forms proper complementary base-pairing structure. – If not, enzyme excises improper base and replaces it with correct
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What is transcription?
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Synthesis of a complementary strand of RNA from a DNA template
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What is the name of the major enzyme required for transcription?
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Requires RNA polymerase and a supply of nucleotides
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What is a promoter?
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RNA polymerase binds to DNA at promoter
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What is a terminator?
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Transcription ceases when RNA polymerase reaches terminator
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What is translation?
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In prokaryotes, mRNA is synthesized in cytoplasm → transcription and translation may be coupled
. IN eukaryotes, mRNA is synthesized in nucleus. Must be completely synthesized, processes, and transported to cytoplasm before translation can begin (therefore, transcription and translation are not coupled in eukaryotic cells) |
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What does it mean if transcription and translation are coupled
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They occur at the same time in the cytoplasm. mRNA is synthesized in cytoplasm → transcription and translation may be coupled
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Does this occur in prokaryotes, eukaryotes, both, or neither? Why?
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Happens in prokaryotes. NOT in eukaryotes, in eukaryotes, mRNA is synthesized in nucleus.
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What are exons? What are introns?
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Exons: regions of DNA that are expressed, Introns: intervening regions that do not encode protein
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What is a codon?
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mRNA language
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What does the codon sequence determine?
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Sequence of codons determines sequence of amino acids that will be in protein to be synthesized. Each codon codes for a particulat amino acid (genetic code)
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The genetic code is degenerate. What does this mean? Why is this important for proper protein production?
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Most aa’s are signaled by several alternative codons. Degeneracy makes it so a minor mutation in DNA will not affect protein produced
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What is the sequence of a start codon? For which amino acid does it encode?
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Start codon AUG, methionine
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What is a stop codon?
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3 nonsesne codons- signal the end of protein synthesis
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Where does translation occur?
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ribosome
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What role do tRNA molecules play in translation?
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tRNA molecules “read” codons and add the appropriate amino aci to a growing polypeptide chain
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What is an anticodon?
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Sequence of 3 bases that is complementary to a codon, so that it can base-pair with associated codon
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