DNA Structure, replication, Transcription and translation – Flashcards
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DNA Replication
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the process of making identical copies of DNA before cell division
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central dogma
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DNA -> RNA -> Protein
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DNA helicase
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An enzyme that unwinds the double helix of DNA and separates the DNA strands in preparation for DNA replication.
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DNA Polymerase
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"Proof reads", to fix mistakes in DNA, Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule
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double helix
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The form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape.
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stages of replication
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Initiation (RNA primer, then DNA polymerase attaches) + Elongation (DNA polymerase adds bases)
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Primase
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An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.
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RNA primer
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short segment of RNA used to initiate synthesis of a new strand of DNA during replication
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DNA helicase
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An enzyme that unwinds the DNA double helix during DNA replication
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Leading strand
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the new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' --> 3' direction
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Lagging strand
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A discontinuously synthesized DNA strand that elongates in a direction away from the replication fork.
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semi conservative
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Each half of an original DNA molecule serves as a template for a new strand, and the two new DNA molecules each have one old and one new strand.
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deoxyribonucleic acid
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A nucleic acid molecule, usually a double stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases A T C G; capable of being replicated and determining the inherited structure of cell's proteins.
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nucleotide
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long chain of polymers; A subunit of nucleic acids formed from a simple sugar, a phosphate group, and a nitrogenous base.
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adenine
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A nitrogenous base found in DNA and RNA. It pairs with thymine in DNA and with uracil in RNA
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guanine
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A nitrogenous base found in both DNA and RNA; pairs only with cytosine.
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thymine
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A nitrogenous base that pairs with adenine. Found only in DNA.
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cytosine
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A nitrogenous base found in DNA and RNA; pairs with guanine
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purine
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A class of nucleotides that includes adenine and guanine. - double ring
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replication
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The process whereby DNA makes a copy of itself before cell division
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complementary
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Capable of precisely base-pairing with one another by matching G with C and A with T.
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base pairs
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Any of the pairs formed between complimentary bases in the two nucleotide chains of DNA, such as A-T and C-G (DNA); A-U and C-G (RNA)
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replication fork
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A Y-shaped region on a replicating DNA molecule where new strands are growing. - Point where DNA is separated and replication begins
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Mutation
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- An error during replication - any change in the nucleotide sequence of DNA - wrong nucleotide is added, changes the gene sequence, one error per billion nucleotides
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Nitrogenous Base
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Flags, two different groups (Pyrimidines and Purines)
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Double Helix
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Two twisted strands of DNA
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Polyneucleotides
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long chain of nucleotides - assembled in the 5 prime to 3 prime direction (covalent bonds)
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Transcription
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(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA DNA to mRNA Construction of mRNA from a DNA molecule
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RNA polymerase
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Enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription An enzyme that links together the growing chain of RNA nucleotides during transcription, using a DNA strand as a template.
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mRNA
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A type of RNA, synthesized from DNA, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein; also called messenger RNA.
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Stages in Transcription
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initiation, elongation, termination
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Initiation in transcription
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Attachment of RNA polymerase to the promoter RNA polymerase binds to a promoter start (start!)
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elongation In transcription
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RNA nucleotides are added to the chain
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promoter
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A specific nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing RNA.
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Termination in transcription
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RNA polymerase reaches a terminator sequence (Stop codon) and detaches from the template
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tRNA
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An RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing the appropriate codons in the mRNA
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rRNA
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-gives physical support for mRNA and tRNA Ribosomal RNA
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Ribosomes
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Cytoplasmic organelles at which proteins are synthesized. A cell organelle constructed in the nucleolus and functioning as the site of protein synthesis in the cytoplasm; consists of rRNA and protein molecules, which make up two subunits.
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Translation
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(genetics) the process whereby genetic information coded in messenger RNA directs the formation of a specific protein at a ribosomes in the cytoplasm Decoding of a mRNA message into a polypeptide chain
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Codon
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A specific sequence of three adjacent bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid
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Anticodon
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A sequence of three bases of a tRNA molecule that pairs with the complementary three-nucleotide codon of an mRNA molecule during protein synthesis.
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Start codon
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AUG; the codon that begins all RNA. AUG (methionine) specific codon (AUG) that signals to the ribosome that the translation commences at that point
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Stop codon
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UAG, UAA, or UGA; the codon that ends all RNA. Codon that signals to ribosomes to stop translation
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degenerate codon
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A codon that specifies the same amino acid as another codon. more than one codon codes for amino acid
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Codon table
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shows all 64 codons with the amino acids they code for.
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Nucleus
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Contains DNA
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epigenetics
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HERITABLE changes in expression of a gene that changes phenotype but not the DNA itself... just changes in chromatin structurer
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ribosomes
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A cell organelle constructed in the nucleolus and functioning as the site of protein synthesis in the cytoplasm; consists of rRNA and protein molecules, which make up two subunits.
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origin of replication
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Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides. short stretches of DNA having a specific sequence of nucleotides
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eukaryote origin of replication
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many (maybe in the thousands) origins of replication
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prokaryote orgin of replication
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one orgin of replication
