2.  What is a genome?  A genome is an organism’s full collection of genes.  Why do cells need to control gene expression?  Cells need to control gene expression because they only need to express genes when necessary. This is to conserve energy and nucleotides.  Define an operon.  An operon is a group of genes that code for functionally related protein in a prokaryotic cell.  Explain the function of the following parts to the lac operon.  Promoter: Area on an operon where RNA polymerase attaches  Repressor: Attaches to operator and blocks movement of RNA polymerase to structural genes  Operator: Area where repressor attaches. On/off switch  RNA polymerase: Attaches to promoter and transcribes structural genes to make a lactase enzyme  Structural genes: DNA that codes for lactase enzyme

3.  When lactose is present what happens to the lac operon? Absent?  When lactose is present, the operon is on and the repressor protein is not attached to the operator therefore RNA polymerase can attach to the promoter and transcribe the RNA to make a lactase enzyme.  When lactose is absent, the operon is off and the repressor protein is attached to the operator which blocks RNA polymerase from transcribing RNA.  What are the differences between introns and exons?  Introns are the noncoding portions of DNA and do not leave the nucleus. Exons are coding regions of DNA and are transcribed and translated.

4.  Explain the roles of the following enzymes  Restriction enzymes: ­­­Enzymes that cut specific regions of DNA (“restricted” because can only cut in specific region) Biological scissors.  DNA ligase: Joins pieces of DNA together (glue)  What are sticky ends and what is their importance?  Sticky ends are the overhang of nucleotides that result when a restriction enzyme cuts DNA. Their importance is that this allows for DNA from other organisms to join this genome in order to make recombinant DNA.  How is recombinant DNA formed?  Recombinant DNA is formed when a restriction enzyme cuts the DNA from one organism and DNA from another organism is added to the sticky ends of the cut DNA. Once DNA ligase binds the two species DNA then the DNA is recombinant.

5.  What are the steps in gel electrophoresis?  DNA is cut by restriction enzymes to VNTRs.  DNA samples are added to chamber wells  Electrical current is added to move DNA through gel (DNA is negative, end of gel is positive)  DNA is transferred to a membrane with probes  Gel is exposed to X-rays  List the steps of PCR.  The ingredients to make new DNA are added to PCR machine (DNA strands, DNA polymerase, DNA ligase, primers, and free nucleotides) DNA is heated in order to separate the strands.  Sample is cooled down and primers are added to segments in order for DNA polymerase to attach to strands.  DNA polymerase attaches to primers and adds free nucleotides to DNA strands.  DNA ligase binds strands together and process repeats.  How does gel electrophoresis organize DNA segments?  Gel electrophoresis organizes DNA segments by their size.

6.  What determines how far a DNA segment can travel in electrophoresis?  Size and weight determine how far a DNA segments can travel in electrophoresis. The smaller fragments move farther and faster through the gel.  Why are VNTR sequences important for identification?  VNTR sequences are non-coding regions of DNA that are different to each person. These are helping in identifying an individual because VNTR sequences can create a bio fingerprint that is specific to only them.  List the steps in cloning an organism.  The nucleus of an egg cell is extracted.  The cell containing the DNA desired to be cloned gets fused to egg cell by electric shock.  The fused cell begins to grow and divide to an embryo and is implanted into a female vector to carry the clone.

7.  Why does the nucleus of the egg cell need to be extracted in cloning?  The egg cell does not contain the DNA desired to clone.  What results from a vaccination?  A vaccination will result in a patient building immunity for the pathogen that has been introduced to their body. The vaccine does not cause the disease, but will create antibodies against it.  Explain how genetically modified foods are produced.  Genetically modified foods are produced by making recombinant DNA using restriction enzymes. The enzyme will cut the DNA from one organism and add the desired gene to the DNA segment. This is used in farming to help farmers make their crops stronger or to incorporate vitamins/minerals into a crop. An example would be a tomato plant with arctic flounder genes to withstand cold temperatures or rice with Vitamin A genes.