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DNA / RNA
Question | Answer |
---|---|
Name the two classes of nucleotides | Purine Pyrimidine |
What three components make up a nucleotide? | Nitrogen base 5 Carbon sugar Phosphate moiety |
Name the two major purines found in DNA and RNA | Guanine and Adenine |
Name the two major pyrimidines found in DNA and RNA | DNA: Thymine and Cytosine RNA: Uracil and Cytosine |
What biochemical component begins the metabolism in the synthesis of IMP? | 5-phospo-A-D-ribosyl-l-pyrophosphate PRPP |
What pathway does the starting material of the synthesis of IMP come from? | Pentose Phosphate pathway |
Name the nucleotides that IMP serves as starting material for. | Adenosine and Guanosine monophosphate |
What is the purpose of the salvage pathway? | It is the principal source of nucleotides for some parasites, etc. |
State the final product of purine catabolism | Uric Acid |
Name the nucleotide that is the precursor of all pyrimidine nucleotides within a cell | Uridine monophosphate (UMP) |
What is the general source of nitrogen atoms needed in pyrimidine metabolism? | Amino Acids (Asparate) |
What is the benefit of combining several enzymes into a single multifunctional polypeptide? | One protein can have multiple sequential enzymatic activities |
How does methotrexate prevent the formation of TTP needed for DNA synthesis? | Methotrexate inhibits the formation of thymidine. Stops cell replication/division. |
What is the main structural difference between ribonucleotides and deoxyribonucleotides? | #2 carbon of the ribose has hydrogen instead of an OH group |
What are the percentages of RNA and DNA found in cells? | RNA: 90% DNA: 10% |
Describe the structure of DNA | Two intertwined complementary strands with hydrogen bonds holding them together. Base pairs are in middle while deoxyribosylophosphate chains are on the outside. |
What are the pairings of nucleotides in DNA? | Guanine-----Cytosine Adenine----Thymine |
How many genes are in the human genome? | 35,000 to 40,000 |
How many chromosomal pairs are in the human genome? | 23 pairs |
State genetic flow information in order to synthesize proteins | DNA ---> RNA ---> protein formation |
name the family of proteins found in chromatin and state the five classes | Histones: H1, H2A, H2B, H3, H4 |
Which class of histones makes up the core? | H2A, H2B, H3, and H4 |
Which class of histones stabilizes the wrapping of DNA around the core? | H1 |
What are the 5 phases of the cell cycle? | G1: growth prior to replication S phase: DNA synthesized G2: second grown phase M phase: cell division G0: growth and replication cease |
What is the Origin of Replication in DNA? | the site at which DNA replication is initiated |
What is DnaB? | The hexameric protein that binds to the separated DNA strands |
What is excision repair? | Cells use excision repair to remove alkylated nucleotides and other unusual base analogs, thereby protecting the DNA sequence from mutations. |
What is deamination? | When uracil bases are found in DNA, specific N-glycosylases remove them. This produces base-pair gaps that are recognized and cleaved at the site of defection |
What is depurination? | Single base-pair alterations, including purine-N-glycosidic bonds are liable so an estimated 3-7 purines are removed from DNA per second per cell. |
What is strand break repair? | Single-strand breaks are introduced by ionizing radiation. The breaks are repaired by direct ligation. |
What is mismatch pair repair? | Mismatch pair system enzymes are used to identify the mismatch and repair the strand by excision repair. |
Define transcription | interaction of enzymes and DNA in specific ways to produce an RNA molecule |
What are the three stages of transcription? | Initiation Elongation Termination |
What are the three general clases of RNA | Ribosomal RNA (rRNA) Transfer RNA (tRNA) Messenger RNA (mRNA) |
Explain the function of rRNA | interacts with proteins to form a ribosome that provides the basic machinery on with protein synthesis takes place |
Explain the function of tRNA | adapter molecule that translates information stored in the mRNA nucleotide sequence to the amino acid sequence of proteins. |
Explain the function of mRNA | carriers of genetic information, defining the sequence of all proteins in the cell |
What is the function of RNA polymerase? | Responsible for the synthesis of RNA, using DNA as a template |
Define translation | Process that involves the interaction of enzymes, tRNAs, ribosomes, translation factors and mRNA in specific ways to produce a protein molecule capable of carrying out a specific cellular function. |
Explain the role of ribosomes | machine on which all proteins are synthesized |
Explain the role of mRNA | contains the information required to direct the synthesis of the primary sequence of the protein, although only a portion of that info is used to encode the protein |
Explain the role of tRNA | carries the amino acids that are to be incorporated into the protein |
What is a codon? | 3 nucleotides together |
How many codons are necessary to make the 20 amino acids? | 61 possible codons |
What is the start codon? | AUG |
What are the stop codons? | UAA, UAG, UGA |
What is the "A" site? | The site where a tRNA molecule sits before the amino acid is incorporated into the protein |
What is the "P" site? | The location in the ribosome that contains a tRNA molecule with the amino-terminal polypeptide of the newly synthesized protein still attached to the acceptor stem |
State the nucleotide that initiates the ribosome complex | GTP |
What provides energy to the large/small ribosome complex as it moves along the mRNA? | ATP |
What three steps in human expression can be controlled? | transcription post transcription translation |
What type of cell tissue is associated with carcinomas | epithelial cells |
What type of cell tissue is associated with sarcomas? | connective tissue or muscle cells |
What types of cells are associated with leukemias? | hematopoietic cells |
How many mutations are needed to turn a healthy cell to cancerous? | 3 - 7 |
What is an oncogene? Is it dominant or recessive? | Genes the infect normal cells and transform them into tumor cells. They are dominant |
What is a tumor suppressor gene? is it dominant or recessive? | Gene that codes against cancerous replication. Recessive |
What is aging? | time-dependent deterioration of an organism |
Name the four changes in muscle over time that aid in the aging process: | Muscle fiber loss Decrease in muscle mass and strength ; skeletal muscles Decrease in blood supply to the muscles Increase in # of cells with mitochondrial deficiencies. |