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Genetics-Final
cumulative
| Question | Answer |
|---|---|
| Structural genes | encode polypeptides, transcribed into mRNA |
| Functional RNAs | genes do not encode polypeptides, snRNA in nucleus, tRNA, rRNA |
| The main function of genetic material | to encode the production of cellular proteins (in the correct cell, proper time, and suitable amounts) |
| Translation | interpretation of one language into another |
| translation relies on the | genetic code |
| The genetic information is coded within | mRNA in groups of 3 nucleotides (codons) |
| AUG | start codon |
| UAA, UAG and UGA | termination/stop codons |
| in most instances, the third base is the | degenerate base |
| the code is | degenerate and nearly universal |
| Start codon determines the | reading frame |
| Start codon AUG on mRNA determines | when the triplets of bases begin |
| Mutation | remove one base close to the start codon |
| Removal of one base does what | shifts the reading frame and completely changes the sequence of amino acids |
| Degenarate code | amino acids are specified by more than one codon |
| mRNA is complementary to template strand therefore they have to be | antiparallel: template 3'-5' and mRNA 5'-3' |
| polypeptide synthesis has a directionality that | parallels the 5'-3' orientation of mRNA |
| polypeptide directionality | n terminal to c terminal |
| within cells, protein will not be found in | linear state |
| A proteins primary structure is its | amino acid sequence |
| tRNA has what 2 functions | recognizing a 3 base codon in mRNA and carrying an amino acid that is specific for that codon |
| Adaptor hypothesis of tRNA | tRNAs play a direct role in the recognition of codons in the mRNA |
| tRNA anticodon binds to | mRNA complementary codon |
| the secondary structure of tRNA | cloverleaf pattern, 3 stem loop structures, an acceptor stem and a 3' single strand region |
| Aminoacyl-tRNA synthetases | catalyze a 2 step reaction involving 3 different molecules (amino acid, tRNA, and ATP) |
| The amino acid is attached to the 3' end by an | ester bond |
| Wobble hypothesis | codon-anticodon recognition, the first 2 positions pair strictly according to the a-u g-c rule, the 3rd position can wobble or move |
| bacterial cells have | one type of ribosome |
| eukaryotic cells have | two types of ribosomes (cytoplasm, organelle) |
| Ribosomes are composed of | structures called the large and small subunits (each formed from proteins and rRNA) |
| When ribosomes are not involved in translation, ribosomes are | dissociated into their large and small subunits |
| Synthesis and assembly of all ribosome components occurs in the | cytoplasm |
| to begin the process of forming a charged tRNA a specific aminoacyl tRNA synthetase binds what to its active site | a particular amino acid and a molecule of ATP |
| the specific tRNA that then binds to the synthetase has | a specific anticodon that corresponds to the specific amino acids |
| the charged tRNA molecule is then released from the aminoacyl tRNA synthetase and is used in the process of | translation |
| Charged tRNA goes to | ribosomes |
| Initiation step 1 | small ribosomal unit and initiation factors bind to mRNA (shine dalgarno sequence) |
| initiation step 2 | charged tRNA binds to small subunit- initiation complex, initiator rRNA recognizes the start codon |
| initiation step 3 | initiation complex binds to large ribosomal unit (initiation factors are released) |
| 70s initiation complex marks the | end of the first stage |
| elongation stage | amino acids are added to the polypeptide chain |
| elongation step 1 | 2nd mRNA codon dictates which charged tRNA will bind the A site |
| elongation step 2 | peptide bond formed between 2 aa's peptide attached tRNA in A site |
| elongation step 3 | uncharged tRNA moves to E site, 3rd mRNA codon available in A site for next charged tRNA |
| stop codons are not recognized by tRNAs but by | proteins called release factors |
| As soon as mRNA strand is long enough a ribosome will | attach to its 5' end |
| gene regulation in prokaryotes | rapid growth and division, utilizing transient resources, immediate changing environment |
| gene regulation in multicellular eukaryotes | protected from transient changes in the environment, most cells experience constant conditions, directing growth |
| prokaryotic gene expression | mostly lack introns, one mRNA= several genes, translation begins before transcription completed |
| eukaryotic gene expression | mostly have introns, alternative splicing, one transcript rarely contains more than one gene, mRNA must be completed before translation, 5' cap, poly-a-tail |
| gene regulation | level of gene expression vary under different conditions |
| constitutive genes | unregulated, constant levels of expression, encode proteins that are continuously necessary |
| Repressors | bind to DNA and inhibit transcription |
| Activators | bind to DNA and increase transcription |
| negative control refers to | transcriptional regulation by repressor proteins |
| positive control to regulation by | activator proteins |
| Allosteric proteins have | active site, allosteric site |
| Inducers | increase transcription, bind activators and cause them to bind to DNA OR bind repressors and prevent them from binding to DNA |
| Co-repressors bind to | repressors, cause them to bind to DNA |
| Inhibitors bind to | activators, prevent them from binding to DNA |
| synthesis of proteins is induced by | presence of lactose |
| induction | presence of lactose prevents regulatory proteins from binding to regulatory DNA sequence |
| Operons | multiple genes that are part of single expression unit all part of the same mRNA, controlled by the same promoter |
| the lac control system has 2 parts | the actual lac operon and the lacI gene |
| The lac operon contains | DNA elements and structural genes |
| LacZ converts lactose to | allolactose |
| If repressor is bound to operator then | RNA polymerase can not proceed to transcribe structural genes |
| presence of lactose | prevents from binding the operator |
| repressor protein binds to | a specific DNA sequence or binds to allolactose |
| if no lactose present | lac operon is repressed |
| if glucose and lactose are present | shuts off the lactose metabolism in favor of glucose metabolism, lac operon repression is maintained until glucose is gone |
| cAMP binds an activator protein known as | CAP |
| in the presence of glucose | the enzyme that produces cAMP is inhibited which decreases the levels of cAMP in the cell |
| lactose present and glucose present transcription is | not present |
| lactose and glucose not present transcription is | not present |
| lactose present, glucose not present transcription is | present |
| lactose not present, glucose present transcription is | not present |
| Enzymes do what | cut, replicate, ligate DNA |
| Nucleases do what | cut, shorten or degrade nucleic acid molecules by breaking the phosphodiester bonds |
| Ligases do what | join nucleic acid molecules together DNA ligase catalyzes phosphodiester bonds |
| 4 types of enzymes | nucleases, ligases, polymerases, modifying enzymes |
| Polymerases do what | synthesize complementary DNA/RNA strands, DNA polymerase reverse transcriptase |
| endonucleases cleave DNA at specific nucleotide sequences called what | restriction sites |
| restriciton enzymes allow creation of | recombinant molecules |
| type II restriction enzymes | cut at a particular base within a sequence of 4-12 bases, palindromic, sticky ends |
| Host- controlled restriction | enzymes degrade phage DNA before it replicates itself and directs synthesis of new phage particles |
| Vectors are molecules which have the ability to | transfer DNA |
| What is gene cloning? | core process of genetic engineering |
| Vector DNA serves as | the carrier of the DNA segment that is to be cloned |
| Chromosomal DNA serves as | the source of the DNA segment of interest |
| When a vector is replicated inside a host cell, the DNA that it carries | is also replicated |
| Vectors used in gene cloning are derived from | plasmids and viruses |
| Requirements to function as a vector | capable of entering a host cell, once inside capable of replicating to produce multiple copies of itself |
| Plasmids must have | origin of replication, selectable marker |
| when lactose present | transcription on |
| when lactose absent | no transcription |
| Why is lac operon important in gene technology? | blue/white screening (fake lactose is blue) |
| Screening | all bacteria would grow, some would be blue and some would be white |
| Selection | bacteria without plasmid do not survive |
| Fusion protein is composed of | one chain of insulin and e.coli native sequence, this prevents degradation by bacteria |
| 2 fusion proteins are used to make | insulin |
| Cross 2 palominos what is the ratio you get | 3 phenotypes; 2 palomino (50%) 1:2:1 |
| When does cross over occur | in prophase 1 |
| When is the reduction from diploid to haploid | meiosis 1 |
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