Genes and Proteins (Transcription & Translation)

• As the new RNA strand is built, what rules must if follow?

  the template DNA strand is "read in its 3' to 5' direction, the RNA strand is built anti-parallel to the template DNA strand, the RNA is built in its 5' to 3' direction
• The process of copying the information in a DNA sequence into a complementary RNA molecule

  transcription
• The process of using the information in and RNA sequence to construct the amino acid sequence of a polypeptide or protein

  translation
• How does the RNA polymerase know where the end of the gene is, and therefore where to stop transcribing?

  there is a particular base sequence which specified/signals termination
• Order of direction and process of genetic information flow in organisms

  DNA, transcription, RNA, translation, and polypeptide
• Only one strand of DNA will be "read" by the RNA polymerase and used to create a complementary RNA strand. What is this strand called?

  the template strand
• Which subunit is critical to proper initiation in prokaryotic RNA polymerase?

  the sigma subunit
• the promoter is a small part of a larger DNA sequence called the transcription initiation site

  false
• one method of prokaryotic termination of transcription involves a protein called rho

  true
• 
  

  We can "translate" an RNA sequence into an amino sequence using a chart of the genetic code. To do this, we examine the RNA sequence in groups of three nucleotide "letters" called a codon. The fact that a given amino acid can be coded for by more than one of these groups makes the code degenerate, or redundant
• The sequence that begins when the enzyme RNA polymerase binds to a specific DNA sequence located at the beginning of a gene is called

  promoter
• The genetic code is highly variable between species - each different species uses its own unique version

  false
• As the RNA polymerase moves down the DNA, it must separate the 2 strands so it can read and create a complementary RNA. What happens to the DNA as the RNA polymerase moves forward down the gene?

  it rewinds into a helix
• Which parts are the "good parts" - the coding regions used for translation, and which parts are removed?

  exons are kept, and introns are removed
• Pre-mRNAs have a 5' cap and a 3' polyA tail added to them during mRNA processing. Why?

  they prevent degradation of the mRNA (making it last longer before degradation)
• What are the proteins that help recruit (or attract) RNA polymerase to come and bind to the promoter in eukaryotic initiation of transcription?

  basal transcription factors
• What does it mean to "splice" an mRNA?

  splicing refers to the removal of introns prior to translation
• tRNAs don't encode proteins. Instead, pre-tRNAs are transcribed, processed, and sent to the smooth endoplasmic reticulum where they aid in lipid synthesis

  false
• Transcription of a eukaryotic gene produces a pre-mRNA which will need further processing. The pre-mRNA contains


  introns and exons
• rRNAs do not encode proteins. Instead pre-rRNAs are transcribes, processed, and then assembled into ribosomes in the nucleolus of the cell

  true
• Do nucleosomes need to be disassembled (and histone proteins removed) in order for a stretch of DNA to be transcribed?

  Yes: a protein complex called FACT removes histones and then replaces them after transcription occurs
• What transcribes most protein-coding genes, creating mRNAs?

  RNA polymerase II
• The genetic code is "read" by grouping the nucleotides into 3 letter units called

  codons
• Translation is initiated by the large subunit of the ribosome and the tRNA for phenylalanine. These assemble at the 3' end of the mRNA. The small subunit the joins, and translation begins

  false
• What special method for targeting proteins involves pausing translation until the ribosome can bind to a receptor on what organelle's surface?

  endoplasmic reticulum (ER) -rough
• About how many different tRNA species does a cell need to properly match each codon with its corresponding amino acid?

  about 40-60
• What interaction ensured that the proper amino acid is added next in the chain?

  the match between the codon on the mRNA and the anticodon on the tRNA
• The ribosome links amino acids together in a chain using what type of chemical bond?

  peptide bond
• termination happens when the ribosome encounters a stop codon. What binds to stop codons?

  a protein release factor
• The presence of a signal sequence can be used to target a newly-made protein to what sorts of locations?

  chloroplasts & the mitochondria
• As the ribosome moves along the mRNA molecule, a codon (and its matching tRNA molecule) will move through the ribosome sites in what order?

  First A, then P, then E
• How does a tRNA get matched and linked to its proper amino acid?

  a set of enzymes called aminoacyl tRNA synthetases matches each tRNA with its amino acid