Micro Test 3

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Micro Test 3
2013-04-24 19:55:52

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  1. Which bases are found in DNA, which in RNA?
    DNA: adenine, thymine, cytosine and guanine. In RNA thymine is replaced by uracil
  2. What is the general structure of a nucleotide (RNA and DNA)?
    DNA is a double helix made up of chains of nucleotides which are made up of a base (A, T, C, G) a 5-carbon sugar and a phosphate held together by hydrogen bonds. RNA has a ribose sugar instead of a deoxyribose. They are single stranded rather than double and has U in place of T.
  3. What are complementary base pairs and why are they important to DNA replication?
    Each separate chain serves as a template for nucleotides to match up. Each identical to the other and containing half of the orginal strand exact copies are made. A T(U) & G C.
  4. What is the difference between genotype and phenotype?
    Genotype is how DNA affects appearance, Phenotype is how those genes are actually expressed.
  5. What is a chromosome?
    where the genes are located. Consist of DNA and protein
  6. What is a gene?
    segments of DNA which code for protein
  7. What is semi-conservative replication?
    Each identical chain is identical to the other and contains half of the original strand
  8. What is the function of helicase (unwinding enzyme)?
    it separates DNA
  9. What is the function of DNA polymerase?
    Enzyme that produces DNA.
  10. What is the function of RNA polymerase?
    Enzyme that produces RNA
  11. What is the function of ligase?
    Joins the DNA fragments
  12. What strand is DNA polymerase active on the leading strand, lagging strand, or both strands?
    Both, continually on leading and discontinuously on the lagging.
  13. What is the function of a ribosome?
    To synthesize protein
  14. What is a polyribosome?
    a cluster of ribosomes bound to a mRNA molecule all synthesizing proteins
  15. How does a bacteria overcome the problem of DNA replication being too slow for rapid growth requirements?
    replication begins at the origin of replication (a specific site) and moves bi-directionally around the chromosome with two replication forks moving in opposite directions away from the origin. Results in two identical circular daughter chromosomes.
  16. When DNA and RNA are copied and transcribed, what is meant by the 5' to 3' direction?
    The two DNA strands are oriented in opposite directions to each other (leading and lagging). The parent strands can only be read in the 5'to 3' direction
  17. As protein is translated from mRNA, why do they all begin with the amino acid methionine?
    Its the start codon
  18. What are the three types of RNA?
    Messenger, Transfer and ribosomal
  19. What happens when mRNA is processed?
    It is an exact copy of DNA made in the nucleous
  20. What is a codon and an anti-codon?
    Codon: a sequence of three nucleotides that together form a unit of genetic code. An anticodon is a sequence of three base pairs of the tRNA that is complementary to the mRNA pairs
  21. What is a triplet and how many amino acids can one code for?
    A triplet is is a combo of three nucleotides. One triplet can code for only one amino acid but one amino acid can be coded by a couple of triplets
  22. What are the steps of translation?
    a. Initiation: mRNA binds to smaller subunit of ribosome followed by the larger subunit b. Elongation: tRNA carrying amino acid attaches to mRNA at P site matching codons. Second one attaches to A site, mRNA shifts along c. Termination: stop codon is reached, ribosome breaks apart, mRNA and protein are released.
  23. What are sense and nonsense codons?
    Sense codons code for amino acids and nonsense (stop) codons signal the end of RNA synthesis
  24. What does a regulatory gene code for?
    A gene that causes the production of a protein that regulates or suppresses the activity of one or more structural genes.
  25. What is an operon and what are its parts?
    a stretch of DNA found in bacteria that controls gene regulation. 3 parts are promoter, operator and structural gene.
  26. What is the difference between a repressible and inducible model?
    Iducible operons are always off and can be turned on. Repressible operons are always on and can be turned off.