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Flashcards in Test #2 Deck (16):


A nucleotide is a building block of nucleic acids it consists of carbon (pentose) sugar molecule (ribose or deoxyribose) a phosphate group and the bases Adenine (A), Guanine (G), Cytosine, Thymine (T), Uracil (U)


DNA Replication

  1. DNA Helicase (enzyme) unwinds/separates the two strands of DNA by breaking the hydrogen bonds between complementary base pairs, forming a Replication Fork
  2. Single-strand binding proteins attach to each strand and prevent them from reforming a double helix
  3. The leading strand is synthesized continuously in the 5’ → 3’ direction by DNA Polymerase (key enzyme that makes new strands of DNA)
  4. The lagging strand is synthesized discontinuously. Primase synthesizes a short RNA primer (short sequences 10-15 nucleotides long), which is extended by DNA polymerase to form an Okazaki fragment
  5. RNA primer is replaced by DNA by another DNA polymerase DNA ligase joins the Okazaki fragment to the growing strand


Complementary DNA

DNA copy of an mRNA molecule; mRNA can be copied into cDNA by the enzyme reverse transcriptase (for instance, when preparing a cDNA library).


Antiparallel DNA

Refers to the 5′ and 3′ directionality of strands of DNA in which the two strands joined together by hydrogen bonds between complementary base pairs are oriented in opposing directions with respect to their polarity.


Semiconservative Replication

Process by which DNA is copied; one original (parent) DNA molecule gives rise to two molecules, each of which has one original strand and one new strand


Where does the Charge on DNA come from?

phosphate group



  • Single Straded
  • Uracil
  • Deoxyribose Sugar


  • Double stranded
  • Thymine
  • Ribose Sugar



What is agarose gel electrophoresis used for?

is a method for separation and analysis of macromolecules (DNARNA andproteins) and their fragments, based on their size and charge


Why is Agarose used in gel electrophoresis and how does it help the separation of DNA?

Agarose gel is used because it has many different sized bubbles through the gel, the DNA strands slip between these bubbles, the smaller the strand the further it goes. DNA moves toward the positive terminal because DNA has a slight negative charge so it will naturally move away from the negative currents and will move to the positive.


Why do we need to use DNA marker/ladder in agarose gel elctrophoresis?

The DNA marker ladder consists of a set of DNA fragments of know different molecular masses or fragment sizes. This enables you to assign a size to DNA fragments in a test sample by comparing its position after electrophoresis with the fragments in the ladder.


Recombinant DNA


Restriction Enzyme


restriction endonuclease


Where do restriction enzymes come from?

come from bacteria; bacteria use them to cut foreign DNA, such as viruses to protect the cell


restriction site