CHAPTER 6-DNA AND GENE EXPRESSION Flashcards
(25 cards)
Nucleotide
unit of a DNA molecule has three components: a phosphate group, a nitrogenous base and a sugar
Base Pairs
DNA bases are connected with hydrogen bonds: A-T(U), G-C
DNA and RNA
are nucleic acids consisting of long chains (polymers) of chemical units (monomers) called nucleotides
DNA (deoxyribonucleic acid)
nucleic referring to DNA’s location in the nuclei of eukaryotic cells
RNA (Ribonucleic acid)
uses the sugar ribose and has nitrogenous base Uracil (U) instead of Thymine (T)
Structure of DNA
two polynucleotide strands wrapped around each other in a double helix
Genome
an organism’s complete set of DNA – found in the nucleus of almost every cell
Chromosome
one or more unique pieces of DNA, they vary in length and can consist of hundreds of millions of base pairs
Gene
a specific sequence of DNA on average about 3,000 base pairings long that contains the information necessary for protein synthesis
Allele
different versions of a gene that code for the same trait – version of gene expressed is influenced by the environment and in some cases other genes
Transcription: SLIDE 26-27
the gene’s sequence is copied from DNA to a middleman molecule called mRNA
Translation
the gene’s sequence is now encoded in mRNA which directs the production of a protein
Transcription: Recognize and Bind
once RNA polymerase recognizes a promoter site, it binds to one strand of DNA and begins reading the gene’s message
Transcription: Transcribe
As the DNA strand is processed through the RNA polymerase, the RNA polymerase builds a single stranded RNA copy of the gene, called the mRNA transcript
Transcription: Terminate
when the RNA polymerase encounters a code signaling the end of the gene, it stops transcription and releases the mRNA transcript
Transcription: Cap and Process
In eukaryotes, mRNA receive extra processing before thy can be translated into a protein. a cap and tail are often added for protection and to promote recognition and noncoding sections are removed
Translation: Recognize and initiate protein building
the START sequence of the mRNA signified by the bases, A, U and G is recognized by the corresponding tRNA molecule and the two ribosomal subunits; the attachment site of the tRNA molecule binds to the mRNA as the ribosomal subunit assemble around them
Translation: Elongate
As the ribosome moves along the strand of mRNA, each new amino acid carrying tRNA molecule binds to the next three bases of the mRNA
Translation: Terminate
once the ribosome encounters the three base STOP sequence, protein assembly is complete
Operon
group of several genes along with the elements that control their expression as a unit all within one section of DNA
Promoter
the region of DNA that RNA polymerase recognizes and binds to in order to produce an mRNA transcript of genes
Operator
the region of DNA that a repressor protein can bind to and by doing so, block RNA polymerase from transcribing genes
Dogma
a principle or set of principles laid down by an authority as incontrovertibly true
Point mutations
nucleotide substitution, nucleotide insertion, nucleotide deletion
