BIO Class 3 Flashcards
What is the monomer of nucleic acids?
Nucleotides
What is nucleotide composed of?
Sugar, base and phosphates
What is the directionality of nucleic acid synthesis?
5’ to 3’
What is the protein synthesis directionality?
N to C
Nucleotides are linked by what bond?
Phosphodiester bond
What are the pyrimidines?
Cytosine and Thymines
What are the purines?
Adenine and Guanines
AG is pure, what does that mean?
AG are purines
How many hydrogen bonds hold AT together?
2
How many hydrogen bonds hold CG together?
3
Where is the prokaryotes genomes?
In the cytosol and subject to damage
What are endonuclease?
Cut in the middle rather than at the end of DNA
What do restriction enzymes do?
Destroy DNA, restrict the growth of viruses whose DNA is not methylated
How do prokaryotes protect their DNA?
Methylation
What supercoils DNA?
DNA gyrase apart of topoisomerase
Where are histones located?
Sugar phosphate backbone wrap around histones
What are nucleosomes?
Histones and DNA together
What is the central dogma?
DNA to RNA to proteins
What is DNA to RNA process?
Transcription
What is the process between RNA to proteins?
Translation
What is the start codon and what does it code for?
AUG - Methionine
What are the three stop codons?
UGA, UAA, UAG
How many chromosomes do humans have?
46 chromosomes
What does human genomes contain?
Large intergenic regions
What type of errors polymerase could make?
- Point mutations
- Small repeats
- Inserts deletion
What are point mutations?
Single base pair changes
What are the three types of point mutations?
- Missense
What is missense point mutation?
Codon for aa becomes new codon for new aa
What is nonsense point mutation?
Codon for aa becomes a stop codon
What is a silent point mutation?
Codon for aa becomes new codon for the same aa
What is a frameshift mutations?
Insertions and deletions changes the reading frame
What are two types of endogenous damage?
- Reaction oxygen species
2. Physical damage
What is the type of endogenous damage that can happen?
- Oxidized DNA
- Crosslinked bases
- Breaks
What are the three types of damage?
- Bad bases
- Broken chromosomes
- DNA rearrangement
What is homology-directed repair?
Use sister chromatic as a template to fix the broken chromosome
What is non-homologous end-joining?
Ligate broken ends together
What are the repair methods of bad bases?
- Mismatch repair pathway
2. Nucleotide excision repair
What are the repair methods of bad bases?
- Mismatch repair pathway
2. Nucleotide excision repair
What does helicase do?
Unwinds DNA
What does topoisomerase?
Cuts DNA, relaxes supercoiling
What does primase do?
Synthesizes the RNA primer
What does DNA poly do?
Replicates DNA, proofreads and removes primer
What does ligase do?
Links Okazaki fragments
What does DNA poly III do?
High processivity, fast 5’ to 3’ polymerase and 3’ to 5’ exonuclease
What type of replication does prokaryotic DNA replication uses?
THETA replication
What are facts about DNA poly I?
- Low processivity
- Slow 5’ to 3’ poly and 3’ to 5’ /5’ to 3’ exonuclease
What is DNA poly II used for?
5’ to 3’ poly and 3’ to 5’ exonuclease
What does telomerase do?
Elongate telomeres on parent strand of DNA
What are the three types of RNA?
rRNA, mRNA, tRNA
What is hnRNA?
Heterogenous nuclear RNA; preprocessed mRNA transcript
What is miRNA and siRNA?
micro RNA and small interfering RNA; complimentary to mRNA
What do miRNA and siRNA do?
Binds to mRNA and prevents translation for regulation
What is needed for a replication but not transcription?
No primer
Why is the error frequency in transcription much more in replication?
No editing
What is the wobble hypothesis?
Anticodon being more flexible
