DNA Flashcards
(21 cards)
nucleoside
sugar + base
deoxyribose + thymine
=> deoxy-thymidine
deoxyribose + adenine
deoxy-adenosine
deoxyribose + guanine
deoxy-guanosine
deoxyribose + cytosine
deoxy-cytidine
telomeres
- highly repetitive DNA…
- that allow chromosomes ends to be replicated
- also protect ends of chromosomes being mistaken as broken
origin of replication
- special seq where duplication of DNA begins
- each chromosome has many origins
how is dsDNA molecule packaged in eukaryotic cells?
- packaged into chromosomes…
- through interactions with specialised proteins
nucleoli
regions where…
- chromosomes carrying RNA cluster
- rRNAs are synthesised
- ribosomes are assembled
2 types of chromatin
euchromatin:
- less compact DNA form (“open”)
- contains genes that are frequently expressed
heterochromatin:
- more compact
- contains DNA that is not transcribed
genome
complete set of genes of organism
(all DNA in cell)
genomics
- genome-wide analysis of…
- gene structure & expression
gene
section of DNA that codes for a protein
what does notation Tt mean to geneticists?
- 1 dom allele
- 1 recessive allele
- would see phenotype of T
explain why RNA is less stable than DNA
- RNA chemically more reactive than DNA -> due to ribose sugar having 2’ OH group (attracts ox.)
- RNA more prone to mutation -> Cytosine deanimation to Uracil cannot be detected & repaired by RNA
suggest why transcription may not take place
- RNA polymerase doesn’t bind to DNA without transcription factors present
- transcription factors must bind to control region
^if these things don’t happen => no transcription
what types of RNA are transcribed from DNA?
- mRNA -> encodes proteins
- tRNA -> act in protein synthesis as adaptors between specific codon seqs on mRNA & a.a
- rRNA (ribosomal) -> forms part of ribosome & catalyses protein synthesis
-
small RNAs (eg. small nuclear RNA snRNA) -> used in…
-> pre-mRNA processing
-> transport of proteins to ER
-> other cellular processes - miRNAs (micro) -> act in regulation of gene expression, inc. inhibiting translation & cleaving mRNAs
the central dogma
DNA ——–> RNA ——-> a.a chain ——-> protein
transcription - translation - folding
what do you need to replicate DNA in a test tube?
- DNA polymerase enzyme & Mg²⁺
- dNTPs (dATP, dCTP, dGTP, dTTP)
- single stranded template DNA
- primer 3’-OH
-> DNA synthesis will proceed in 5’ -> 3’ direction
lagging strand synthesis in bacteria
- primase synthesises short RNA oligonucleotides (primer) copied from DNA
- DNA pol. 3 elongates RNA primers with new DNA
- DNA pol. 1 removes RNA at 5’ end of neighbouring fragment & fills gap
- DNA ligase connects adjacent fragments
explain why E.coli (bacteria) has a faster bp/s than eukaryotes
E.coli has high processivity because DNA pol. attaches to sliding clamp
