DNA, RNA, and Gene Regulation
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Created by:
gohmezzz on May 30, 2009
Subjects:
dna and rna, dna replication, DNA Structure, protein synthesis, gene regulation
Description:
AP Biology, DNA, RNA, and Gene Regulation Chapters.
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73 terms
Terms | Definitions |
|---|---|
 Structure of DNA | Double helix made of units called nucleotides |
| Nucleotide | individual building blocks of protein |
| Parts of A DNA Nucleotide (3) | Deoxyribose sugar, one or more phosphate groups (make the molecule acidic), and nitrogenous bases, Adenine, Thymine, Guanine, Cytosine (ring compound that contains nitrogen) |
| Purine | Double- ringed nitrogenous base (Adenine and Guanine) |
| Pyrimidine | Single-ringed nitrogenous base (Cytosine and Thymine) |
| Parts of an RNA Nucleotide (3) | Ribose sugar, one or more phosphate groups (make the molecule acidic), and nitrogenous bases; Adenine, Guanine, Cytosine, Uracil |
| Phosphodeister Linkages | join linear chains of nucleotides. Consist of a phosphate group and the covalent bonds that attach it to the sugar of adjacent nucleotide (hold sides together). Stronger than hydrogen bonds. |
| Hydrogen Bonds | weak and allow DNA to zip and unzip. Hold nitrogen bases together. |
| Messenger RNA (mRNA) | A long, single strand that varies in length depending on the protein it's coding for. |
| Function of mRNA | copies code from DNA and moves the info to the ribosome |
| Structure of Transfer RNA (tRNA) | 1) clover leaf shape; 70-80 nucleotides 2) must have an anticodon 2) must be recognized by a specific aminoacyl-tRNA synthetase that adds the correct amino acid 3) it must have a region that serves as the attachment site for the specific amino acid specified by the anticodon 4) must be recognized by ribosomes |
| Function of tRNA (2) | Provide a connection between amino acids nd nucleic acids. Each tRNA can 1) link with a specific amino acid 2) recognize the appropo mRNA codon for that particular amino acid. A particular tRNA can recognize a specific codon because it has a sequence of 3 bases called the anticodon. |
| Clover Shape of tRNA | 1) 3D shape of a tRNA molecule is determined by hydrogen bonds that form between complementary bases. 2) One loop contains the triplet anticodon . amino acid is attached to the terminal nucleotide at the OH 3' end. 3) amino acid attached to its tRNA by its carboxyl group |
| General Function of tRNA | Picks up amino acids and carries them to the ribosome and organizes the protein |
| Codon | sequence of three consecutive bases in mRNA that specifies one amino acid. |
| Anticodon | allows tRNA to recognize a specific codon. Sequence of 3 bases that hydrogen bonds witht he mRNA codon by complementary base-pairing. |
| Transposons (jumping genes) | sections of DNA which will move from location to location and will act as gene switches to turn on/off DNA. Disovered by Barbara McClintock. |
| DNA Replication Step 1 | Begins at a specific base sequence- origin of replication. Helicase breaks the H bonds between pairs and unwinds the strands |
| DNA Replication Step 2 | Helix destabilizing protein binds to open DNA which prevents repaining |
| DNA Replication Step 3 | Topoisomerase prevents and corrects tangling of the strands |
| DNA Replication Step 4 | New Nucleotides are matched to the template mediated by DNA polymerase @ 3' |
| DNA Replication Step 5 | RNA primes are synthesized first to allow polymerase to add nucleotides in 5' to 3' direction |
| DNA Replication Step 6 | One side is copied first and is continuous (not copied and assembled in parts)- leading strand |
| DNA Replication Step 7 | The other side is copied last and is discontinuous- lagging stand |
| DNA Replication Step 8 | Fragments of lagging strand are called Okasaki fragments- joined together using ligase |
| DNA Replication Step 9 | H bonds reform to complete the process producing 2 new semiconservative copies of the original DNA |
| DNA Replication Step 10 | The ends of the DNA molecule are not compies and therefore lost telomere become shorter with each replication |
| Operon | collection of genes that controls the production of a protein |
| Regulator Gene | DNA that will produce repressor protein |
| Operator Gene | switch that controls mRNA synthesis. |
| Structural Gene | section of DNA that codes for the product |
| Inducer | substance OUTSIDE that will cause a gene to be switched on:. Example; lactose switches lactase on |
| Repressor | blocks promoter site. gene is off. |
| Transcription | First major step of gene expression. It is the synthesis of RNA molecules complementary to the DNA. (basically it copies the info from DNA onto a strand of RNA) |
| Transcription Step 1 | Begins when DNA dependent RNA polymerase recognizes and binds to the promotor at the beginning of a gene |
| Transcription Step 2 | DNA helix unwinds as new RNA nucleotides are brought into the nucleus- matching DNA template |
| Transcription Step 3 | mRNA strand lengthening in the 3' direction since enzyme adds at this carbon (downstream) |
| Transcription Step 4 | Ceases when RNA polymerase recognizes and codes a STOP signal |
| Result of Transcription | A strand of mRNA that codes for a protein |
| Post Transcriptional Modification | Cleans mRNA and chops out useless stuff (snRNPs) and processing of mRNA |
| Post Transcriptional Modification Step 1 | As mRNA strand is assembled an enzyme adds a cap to the 5'1' end end (5' to 5' linkage) to prevent the strand from degrading |
| Post Transcriptional Modification Step 2 | at the 3' end of mRNA a string of adenine (nucleoties_ is add- poly A tail to stabilize the end |
| Post Transcriptional Modification Step 3 | mRNA stand coded everything, even DNA codes that don't build the protein (introns) |
| Post Transcriptional Modification Step 4 | snRNPs remove the introns and join the exons |
| Post Transcriptional Modification Step 5 | Finished, the mRNA strand movies out to the ribosome which recofnizes and binds the 5' cap end. |
| DNA Dependent RNA polymerase | enzyme that uses DNA as a model to build the mRNA chain |
| Upstream | towardstowards 5' end of mRNA sequence or the 3' end of the transcribed DNA end |
| Downstream | towards 3' end of the RNA or the 5' end of the transcribed DNA strand. |
| Promoter | specific nitrogen base sequence on DNA that indicates beginning of a gene |
| Stop signal | sequence of nucleotides on the DNA that indicates the end of a gene (end of code) |
| Cap | sequence of nucleotides at the beginning of mRNA strand, attached with 5' to 5' bond |
| poly A tail | sequence of adenine nucleotides; keep mRNA strands safe |
| intron | codes that do not build a part of the protein (useless) |
| exons | coded info that will code protein |
| snRNPs | (small nuclear ribonucleoproteins) molecules that will identify introns and remove them and splice together remaining exons to produce finished mRNA product. |
| Translation | RNA is used as a coded template to direct protein synthesis. (assembling protein) |
| Translation Part A | Initiation |
| Translation Step 1 | tRNA molecule links to its specific amino acid (aminoacyl tRNA) |
| Translation Step 2 | Two sites on the ribosome: A-site: joins the aminoacyl tRNA; P-site: joins the forming peptide chain |
| Translation Step 3 | First a special tRNA amino acid joins the P-site- initiation and lock two parts of the ribosome toegher |
| Translation Step 4 | Next the A-site is filled by another aminoacyl tRNA matching codon (mRNA) to anticodon (tRNA) |
| Translation Step 5 | A peptide bond joins the two amino acids to bein formation of the protein chain |
| Translation Step 6 | Then the tRNA is release from the P-Site and the chain in the A-Site moves over to fill the P-site |
| Translation Part B | Elongation |
| Translation Step 7 | the next aminoacyl tRNA comes in to fill the A-site, repeating steps 4-6 |
| Translation Part C | Termination |
| Translation Step 8 | the end of the mRNA has a special sequence that doesn't code for an amino acid, so when this is reached the ribosome opens up and frees the protein. |
| Griffith | • late 1920s • used mice and pneumococcus (a bacteria) there are 2 kinds of pneumococcus: 1) rough; no capsule, harmless 2)smooth; capsule, dangerous • 4 step process: 1. Infect mice with rough strain: lived 2. Infect mice with smooth strain, died 3. Attenuated smooth strain (heat treated, mad them non-infectious); gave it to mice, mice lived (accidentally vaccinated mice) 4. Took another group of mice and infected them w/ a combo of rough and attenuated smooth strains; mice died; smooth still had DNA for capsule, and rough picked it up (transformation) |
| Avery, Macleod, and McCarty | • early fifties, did extension of Griffith's experiments, tried to take transformation further • 1-3 same as Griffith • 4, took some attenuated bacteria and separated into 2 portions; 1 portion has DNA, the other has protein • Gave DNA and rough bacteria to mice and gave protein and rough bacteria to mice • the portion w/ the DNA died • the portion w/ the protein lived |
| Hershey and Chase | • using E. coli bacteria and bacteriophages 1) Radioactively labeled bacteriophage; protein coat w/ sulfur, nucleic acid w/ phosphorous (the elements were present in one but not the other) 2) Radio-labeled bacteriophage allowed to attack E. Coli 3) Analyze E. Coli for presence of radioactive tags 4) Finds phosphorous inside E. Coli: means DNA, not protein, is attacking the E. Coli; DNA is infectious, protein is not |
| Chargaff | By 1950, the base composition from a number of organisms and tissues had been determined by Erwin Chargaff. "the ratios of purines to pyrimidines adn also of adenine to thymine and of guanine to cytocine were not far from 1." In double-stranded DNA molecules, the number of purines = to the number of pyrimidines. A= T and G= C |
| Wilkins and Franklin | • did x-ray crystallography imaging of DNA molecules, helical • controversy as to whether they or Watson&Crick got there first |
| Watson and Crick | • got Nobel prize for building a model of and describing the structure of DNA as a double helix• got Nobel prize for building a model of and describing the structure of DNA as a double helix |
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