Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
MMBIO Quiz 7
| Term | Definition |
|---|---|
| loss of function mutagen | wild-type gene makes a functional protein, but after mutation no functional protein |
| gain of function mutagen | wild-type gene makes a non-functional protein but after mutation/ DNA damage can result in a mutation that restores functionality |
| salmonella bacteria require _____ to grow | histidine |
| the Ames test | use salmonella that has point mutated to have no His add chemical being tested to the DNA if colonies appear, it indicates the His point mutation was mutated back --> high chance the chemical is a mutagen |
| it is easy to spot cells that can grow because they grow and form | colonies |
| mutagen | causes DNA changes |
| carcinogen | causes cancer |
| 3 ways cells detect DNA damage | DNA repair enzymes scan the surface of DNA for kinks/holes DNA replication discover as they use the DNA as a template RNA transcription enzymes discover as they use DNA as a template |
| 3 types of DNA repair | direct repair (no DNA removed or replaced, the damage is reversed) excision repair (bulky additions to nucleotides are removed and replaced with correct nucleotides) mismatch repair |
| direct repair: photolyase | reversal of thymine dimer uses energy in light to catalyze changing of chemical bonds, no nucleotides are removed during this repair process |
| direct repair: methyltransferase | removal of methyl group, reversal of alkylation |
| base excision repair (BER) | can fix single damaged bases only with damage due to depurination, deamination, oxidation, alkylation |
| BER steps | glycosylase recognizes damaged bases and removes it AP endonuclease cleaves bond 5' to AP site fill in missing nucleotide(s) - long path or short path ligase seals nick |
| nucleotide excision repair | another way to fix pyrimidine dimers |
| nucleotide excision repair | UvrA - eyes UvrB - binds UvrC -cuts/nicks 5' and 3' UvrD - carries away 12-13 nucleotides DNA polymerase I fills the gap ligase seals |
| transcription-coupled nucleotide excision repair | sometimes DNA damage is not noticed until RNA polymerase comes along to transcribe the DNA |
| transcription-coupled nucleotide excision repair steps | RNA polymerase moves along path, stalls at lesion reapir enzymes are recruited to the site lesion is repaired resume transcription |
| mismatch repair | assumes that the old strand is the correct one and is methylated switch out the base that is on the strand that is unmethylated |
| hemimethylated | one strand is methylated, the other is not |
| homologous recombination | similar DNA sequences on different molecules swap places |
| DNA recombination | any process where DNA sequences are rearranged, exchanged, swapping or combined new sequences into existing DNA |
| homologous DNA sequences | 2 DNA molecules with very similar DNA sequences and in the same order |
| crossing over | homologous DNA sequences line up next to each other and switch places |
| genetic linkage | method used to determine how close 2 genes are based upon frequency of crossing over together vs separately |
| homolgous recombination is _______ | spontaneous |
| unlinked genes | segregate independently four gamete types formed in equal proportions |
| linked genes | nearly always segregate together most are AB and ab (Ab and aB are minorities) |
| homologous recombination steps | sister chromatids align during prophase in meiosis nicks in the DNA are required for dsDNA recombination DNA strands "breathe" apart (de-hybridize) strands re-anneal with sister strand due to similar sequences |
| Holliday junction/intermediate | two double stranded molecules align and form a four-stranded X-shaped structure |
| ruv A/B/C proteins | promote branch migration and resolution of the Holliday intermediate |
| the 2 strands of the holliday junction become _____ and must be _______ | intertwined, resolved if not, the DNA will break in cell division |
| 2 ways to resolve Holliday junction | branch migrates all the way to the end a double-stranded break occurs before reaching end of molecule (then repaired by ligase) |
| repeat sequences | most commonly involved in recombination because as the strands breathe apart, the likelihood of finding a homologous sequence is much higher for a repeat region |
| double-stranded breaks | line up 2 homologous sequences than you can use them to repair double-stranded breaks by crossing over events |
| DNA polymerase skips past a lesion | you can use the original strand to supply that sequences |
| DNA polymerase stops at a lesion | polymerase let's go and uses the other (good) strand as a template it releases the strand, attaches to the original and can proceed because it skipped the lesion |
| using homolgous recombination to cut a target DNA sequence | clone a fragment with the region you want to manipulate cut at desired location (2 cuts - deletion, 1 cut - insertion) ligate back together (deletion) or insert new fragment (insertion) |
| knockout mouse | a mouse strain that is genetically engineered to be lacking a specific gene |
| knockin mouse | a mouse strain that is genetically engineered to have a new gene (one that it is normally lacking) |
| why use knockout mice? | to study the function of a protein by producing an organism without that protein to test treatments on animals before attempting on humans |
| why use knockin mice? | gene X causes a disease in humans put the gene in mice to see if mice develop same gene |
| example of a knockout mice: SCID mice | lack gene required for T&B lymphocyte development - have no adaptive immune system test out ways to treat human SCID disease |
| another example of a knockout mice: dystrophin knockout mice | lack gene that is mutated in humans with muscular dystrophy study how muscular dystrophy develops and how to cure it |
| you must inbreed animals for multiple generations and select _____ of the knockout | homozygous |
| how to make a knockout mouse | amplify (PCR) and clone DNA for interest gene and additional surrounding DNA into plasmid vector use restriction enzymes and ligase to cut out a specific region of gene + surrounding DNA introduce a selective marker gene (NeoR) |
| NeoR protects mice from toxic | geneticin allows for selection of cells with the NeoR on the gene of interest, so you only get the cells with the change |
| how to make knockout mouse (continued) | introduce the recombinant DNA into mouse cells homologous recombination will swap new sequences implant knockout cells into female mice and pups born should have copies of gene of interest knocked out |
| how to make knockin mouse | similar process but insert gene of interest and Neo selector into mouse genome |
| conditional knockouts | allow us to grow a mouse up to a certain developmental stage and then add the gene of interest into a particular tissue to observe |
| why use conditional knockouts? | some genes are required for development, can't knock it out too soon |
| making a conditional knockout mouse | make knockin mouse with LoxP sites around DNA you want to delete make a seperate knockin mouse with Cre recombinase gene breed together the mouse strains until all are homozygous |
| making a conditional knockout mouse (continued) | the cell-type-specific promoter on the Cre gene will become active and the DNA between the loxP sites will be deleted |
Created by:
anyasalmon