BIOCHEM Ch21 Cheat Sheet by sunshine23
Ch116 final reviewer
Ch116 final reviewer
BASES OF NUCLEIC ACIDS
- PHOSPHODIESTER BOND: the bond between the 3' OH of a sugar (nucleotide) and a phosphate group attached to the 5' C of another sugar.
- HYDROGEN BOND: Weak, noncovalent linkages with favorable electrostatic interactions.
- N-GLYCOSIDIC BOND: In DNA, refers to the N-C linkage between the 9' N of purine bases or 1' N of pyrimidine bases and the 1' C of the sugar group.
TYPES OF RNA
There are 3 major types of RNA:
- messenger RNA (mRNA - 5%): carries genetic info copied from DNA to the ribosomes --> TRANSCRIPTION phase.
- transfer RNA (tRNA - 15%): translates the genetic info in mRNA into the AA sequence for the protein --> TRANSLATION phase.
-ribosomal RNA (rRNA - 80%): most abundant type of RNA; combined with proteins to form ribosomes.
RNA & TRANSCRIPTION
Genetic Code & Protein Synthesis
PYRAMIDINE & PURINE BASES
-Template Strand (ANTI-SENSE): info that codes for genes; contains anti-codons.
-Coding Strand (SENSE): complementary to anti-sense; contains codons (decoded by tRNA, which interacts with ribosome-bound mRNA).
-mRNA: made from template strand; has the same info as coding strand except T is replaced by U.
TYPES OF MUTATIONS
- POINT MUTATION: the replacement of one base in the template strand of DNA with another, causing a change in AA.
- SILENT MUTATION: when a point mutation does not change the amino acid.
- DELETION MUTATION: a base is deleted from codon, changing all that follow and producing a different sequence of AA.
- INSERTION MUTATION: a base is inserted into the normal order of bases, changing all the codons that follow and producing a different sequence of AA.
In reverse transcription:
- a retrovirus, which contains viral RNA but no viral DNA, enters a cell.
- the viral RNA uses reverse transcriptase to produce a viral DNA strand.
- the viral DNA strand forms a complementary DNA strand.
- the new DNA uses the nucleotides and enzymes in the host cell to synthesize new virus particles.
NUCLEOSIDES VS NUCLEOTIDES
-helicase unwinds the parent DNA at several sections.
-DNA polymerase catalyzes the replication process at each of the open DNA sections called replication forks.
-polymerase moves in the 3′–5′direction, catalyzing the formation of new phosphodiester linkages.
-lagging strand (growing in the 5′–3′ direction) is synthesized in short sections called Okazaki fragments.
-DNA ligase joins the Okazaki fragments.
After a retrovirus injects its viral RNA into a cell, it forms a DNA strand by reverse transcription. The single-stranded DNA forms a double-stranded DNA called a provirus, which is incorporated into the host cell DNA. When the cell replicates, the provirus produces the viral RNA needed to produce more virus