Biology - Unit 3

• Recombinant DNA


  Produced when DNA from two sources are recombined together. To make recombinant plasmid, the plasmid DNA and foreign DNA must be cut by the same restriction enzyme to create complementary sticky ends.
• Plasmids


  Small circular pieces of DNA found in prokaryotes
• Template/non-coding strand


  the strand that serves as a template for transcription
• Non-template/coding strand


  The strand which sequence will be the same as the RNA produced.
• Operon


  A cluster of genes in bacteria that are regulated together, containing a promoter, structural genes, regulatory genes, and an operator, and regulates functions by controlling transcription and translation.
• DNA polymerase


  Enzymes that create DNA molecules by assembling nucleotides. These enzymes are essential for DNA replication.
• RNA polymerase


  An enzyme that is responsible for copying a DNA sequence into an RNA sequence during transcription
• Exons


  Coding sections of an RNA transcript or the DNA encoding it that are translated into a protein.
• Introns


  They are non-coding sections of an RNA transcript of the DNA encoding it that are spliced out before the RNA molecule is translated into a protein.
• Genetic code


  Defines how information in nucleic acids is translated into proteins. Its stored as a three-letter code of nucleotides.
• Triplet. | Codon. | Anticodon.


  In DNA. | In mRNA. each codon in mRNA codes for one amino acid in a polypeptide chain. | In tRNA. There is a specific anticodon for every codon. The anticodon can recognise and match up with the codon.
• Trp Operon


  The structural genes in this operon code for enzymes that are involved in the synthesis of tryptophan. It is a repressible operon involved in producing enzymes that produce end-products thats always required by cell.
• Tryptophan.


  An amino acid as it makes protein and has an r group.
• Repressible operon.


  Usually switched on.
• RNA


  RNA function to transfer genetic instructions from the nucleus to the cytoplasm where the information is de-coded.
• mRNA


  messanger RNA is a copy of a gene which codes for a specific polypeptide.
• tRNA


  transfer RNA carries amino acids to ribosome for polypeptide synthesis
• rRNA


  ribosomal RNA forms ribosomal structures together with proteins
• Restriction enzymes


  Cleave foreign DNA that enters via invading viruses. Enable DNA to be cut in a precise way, and work by cutting DNA at a particular recognition sequence which is always different.
• DNA ligase.


  an enzyme that facilitates bonding between two fragments of DNA. It helps sticky ends bond better where it can't. Basically adds extra strong bonds.
• Blunt ends | Sticky ends


  Clean cut by cutting at same location on both strands | Uneven cut by cutting at different locations
• Protein structure


  The conformation a protein takes depends upon the amino acid sequence of the protein. There are 4 levels of protein structure: [Primary / 1] = the sequence of amino acids in a polypeptide chain. [Secondary / 2] = the shape of the polypeptide chain (alpha-helix or beta-pleated sheet). [Tertiary / 3} = the overall three dimensional conformation of the polypeptide caused by folding. [Quaternary / 4] = the association of multiple subunits of polypeptide chains.
• Transcription


  The process by which an mRNA strand is formed using the DNA molecule as a template. Transcription occurs in the nucleus, where the DNA is. The DNA helix is first unwound, and the RNA polymerase will then connect complementary RNA bases to the template DNA strand, which forms a single stranded mRNA. That mRNA strand then leaves the nucleus and heads to a ribosome for translation.
• GMOs


  Genetically modified organisms are organisms that have had their genes altered in a lab to give then specific traits. They are produced through genetic engineering technology. Crops can become resistant to pests, withstand different environmental conditions, have improved nutritional content. Safety risks include allergies, effects on ecosystem and ethical risks.
• TGO's


  Transgenic organisms are a subgroup of GMO's that have had genes of an organism added into an entirely different unrelated organism in hopes of giving it new traits. They are produced through genetic engineering. Some benefits could be increased crop yield, reduced use of pesticides, and positive impacts on sustainability.
• Fibrous proteins


  generally composed of long, narrow strands and have a structural role. (they ARE something)
• Globular proteins


  generally have a more compact, rounded shape and have functional roles. (they DO something)
• Proteome.


  The complete set of proteins expressed by an organism or cell.
• Protein denaturation


  The loss of a proteins three dimensional structure through breakage of bonds. This can cause loss of function.
• Similarities and differences between GMOs and TGOs

  Both GMOs and TGOs refer to organisms that have had their genes modified and all TGOs are GMOs but not all GMOs are TGOs. GMOs genes that are added can come from organisms that are the same species or different with the goal to enhance certain traits. TGOs specifically refer to organisms that have had genes inserted into their DNA from a different species altogether with the aim of adding new traits to the organisms.
• RNA processing


  The process by which the pre-mRNA transcript is modified to produce mRNA. The process of removing introns and rejoining exons of the mRNA, called splicing.
• Translation

  1. Occurs in ribosome

  2. mRNA provides the message to know which tRNA is to come in and which amino acids are going to be transferred

  3. tRNA searches bases on mRNA in sets of three letters, codons, until it finds its three complementary bases, anticodon

  4. tRNA anticodon pairs with complementary mRNA codon

  5. When tRNA leaves, it leaves behind its amino acid

  6. Amino acids are held together by a peptide bond

  7. Chain keeps going until they reach a 'stop' codon typically on the end of mRNA
• DNA


  DNA encodes instructions for synthesis of proteins. DNA is a double helix with two antiparallel strand. One strand runs 3' to 5' beginning with deoxyribose sugar, and the other runs 5' to 3' beginning with phosphate. DNA is composed of nucleotides.
• Palindromic repeat


  Repeated sequences of nucleotides that read the same from the 3' prime end to 5' prime end and 5' to 3' and are separated by a spacer.
• Spacers


  Fragments of foreign DNA and are used to fight off infections.
• PAM site


  A short DNA sequence that follows that DNA region targeted for cutting by the Cas9 enzyme. It is the site of recognition for Cas9. Prevents Cas9 from accessing certain DNA sequences.
• Unwinding | Elongation | Termination | DNA Replication


  The DNA strand is unwound | A new strand is made using the original as a template | Synthesis is completed and the new DNA molecule assumes double helix structure | The process of producing two identical replicas of DNA from one original DNA molecule
• Ribosomes | Endoplasmic reticulum | Golgi apparatus | Exocytosis


  Proteins produced by free ribosomes are for local use in cells. Proteins produced by ribosomes on rough ER are transported together parts of cell or away from cell. | Involved in production, processing, modification, transport and storage of materials within a cell (e.g. proteins). | Final synthesis, modification and packaging of proteins into vesicles for secretion from the cell. | The process by which large substances exit the cell via vesicles.
• CRISPR - Cas9


  A short section of naturally occurring viral DNA that is inserted into a bacterial chromosome and used to prevent infections. The CRISPR consists of the Cas9 protein which can cut DNA and guid RNA that can recognise the sequence of DNA to be edited. A sequence of gRNA is made that is complementary to a target sequence. The guide RNA is added to the cell along with Cas9 enzyme. The gRNA binds to the target sequence then Cas9 excises this DNA sequence. Another piece of DNA is added, which replaces the removed segment.
• Polymerase chain reaction


  A biotechnology that provides a way to make more copies of a portion of DNA, without needing to happen in cell. One cycle of PCR creates 2 double stranded molecules of DNA, and can be repeated as many times with each strand.