DNA to Proteins, DNA Structure and Replication

DNA to Proteins

• A codon is a sequence of three nucleotides on mRNA that codes for a specific amino acid.
• Ribosomes, a non-membranous organelle, are where polypeptides and proteins are assembled.
• RNA polymerase II continues to slide along the DNA strand assembling mRNA until it reaches a termination signal.
• The process of assembling a specific sequence of amino acids from the code on mRNA is called translation.
• RNA polymerase II copies RNA from DNA.
• mRNA (messenger RNA) carries the genetic code from DNA in the nucleus to ribosomes in the cytoplasm.
• The introns are non-coding sequences of mRNA that are removed prior to translation.
• A specific sequence of three nucleotides on tRNA that is a complement of a codon is called an anticodon.
• All proteins are made up of amino acids.
• The start codon is the same in all proteins. It is AUG which codes for methionine.
• Ribosomes are made up of a large and small subunit.
• Aminoacyl-tRNA synthetase's function is to charge tRNA molecules with their corresponding amino acids.
• Anticodon is found on tRNA and is the complement of a mRNA codon.
• Transcription is the process of copying RNA from DNA, while translation is the process of producing a protein from the code on mRNA.
• Transcription factors must bind to the promoter before RNA polymerase II can bind.
• Ribosomes continue to slide along the mRNA strand until it reaches a stop codon which are UGA, UAG, or, UAA.
• A mutation is a physical change in the DNA sequence.
• Three types of point mutations are:
  • Substitutions
  • Insertions
  • Deletions
• Copy the following template strand of DNA sequence into RNA and translate it into a protein. (use your textbook for codons to amino acid codes) T T A C G T A G G G C T A T A G A A C G A T A T C C G A T T T. This section requires external knowledge (codon table) to complete the transcription and translation.
• Matching:
  • GGC - D. Glycine
  • UGA - B. STOP
  • CUA - A. Leucine
  • AUG - C. Methionine
  • GCC - E. Alanine

DNA Structure and Replication

• DNA replicates to facilitate cell division, growth, and repair, ensuring each new cell receives a complete and accurate copy of the genetic information.
• Adenine and guanine are double-ringed nitrogenous bases and are classified as purines.
• The main difference between DNA and RNA nucleotides is that DNA contains deoxyribose sugar, while RNA contains ribose sugar. Also, DNA uses thymine as a base, whereas RNA uses uracil.
• DNA is the heredity substance of life and codes for proteins.
• DNA stands for deoxyribonucleic acid.
• The four nitrogenous bases in DNA are adenine, guanine, cytosine, and thymine.
• Purines are double-ringed nitrogenous bases, while pyrimidines are single-ringed nitrogenous bases.
• Guanine always pairs with cytosine.
• Adenine pairs with thymine in DNA and uracil in RNA.
• Nucleotides are the building blocks for DNA.
• Helicase is the enzyme that binds and unzips the DNA, separating it into two strands.
• Hershey and Chase used radioactive sulfur and radioactive phosphorus to prove that DNA was the genetic material.
• Watson and Crick discovered the double helical structure of DNA.
• DNA polymerase reads DNA from the 3' end and assembles the new DNA from the 5' end.
• The two strands of DNA are held together by hydrogen bonds.
• The complement of Thymine is always Adenine.
• Electrophoresis separates compounds based on size and charge.
• Anti-parallel means that the two strands of DNA run in opposite directions. One strand runs from 5' to 3', and the other runs from 3' to 5'.
• The daughter strand or the complement strand from this parental strand of DNA A A G T A C T A G G T A C T would be T T C A T G A T C C A T G A.
• DNA replication is half old and half new. This is called semiconservative replication and is important in proofreading.
• Polymerase chain reaction (PCR) amplifies a specific region of DNA, creating many copies of it.
• The RNA primer is important because DNA polymerase can only add nucleotides to an existing strand of DNA or RNA. The primer provides a starting point for DNA synthesis.
• The five reagents needed for PCR are:
  • DNA template
  • DNA polymerase
  • Primers
  • Deoxynucleotides (dNTPs)
  • Buffer
• The primers determine the location within the genome that will be amplified by PCR.
• Matching:
  • B. Helicase - The enzyme that unwinds the double helix of DNA and breaks the hydrogen bonds.
  • E. DNA Polymerase III - The enzymes that assemble the majority of the new DNA strand.
  • C. RNA Primase - The enzyme that adds an RNA Primer to DNA.
  • A. DNA Ligase - The enzyme that joins the Okazaki fragments together.