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Replication
DNA → DNA
Transcription
DNA → RNA
Translation
RNA → Protein
Fats
comprised of lipids, which form membranes around cells and organelles
Carbohydrates
made of small sugars and have a wide variety of roles, such as energy storage
Nucleic Acids
made up of nucleotides (phosphate group, pentose sugar, and nitrogenous base). Nucleic acids such as DNA and RNA store information.
Proteins
made from amino acids, carry out most of a cell’s functions.
To act as the genetic material, DNA must:
have the information to make an entire organism, must be transmittable from parent to offspring, must be copied (replicated), and must be capable of changes (variation).
Griffith’s Experiment
used smooth (secretes polysaccharide capsule) and rough (no capsule) streptococcus pneumoniae in experiments with mice. Through one of his experiments, he discovered that injecting living type R bacteria and dead type S bacteria killed a mouse, when previously, only injecting living with R bacteria would leave the mouse alive.
Griffith then believed that something called transformation was turning the type R bacteria into type S bacteria.
Hershey and Chase’s experiments
Studied bacteriophage T2. They believed that if the bacteriophage was injecting its genetic material, then radioisotopes would reveal if the genetic material was DNA or proteins.
Chargaff’s Experiment
Analyzed the base composition of DNA. Revealed that the % of Adenine = % of Thymine, and % of Cytosine = % of Guanine.
DNA is extensively compacted with the help of
DNA binding histone proteins
Purmines
Adenine (A) and Guanine (G)
Pyrimidines
Cytosine (C), Thymine (T), and Uracil (U)
The A-T pairing shares how many hydrogen bonds?
2
The G-C pairing shares how many hydrogen bonds?
3
Nucleotides are joined by a
Phosphodiester bond
Nucleoside
Base + sugar
Nucleotide
Base + sugar + phosphate(s)
What does the histone H1 do?
It is a linker histone that helps with compaction.
10 nm fiber gets compacted into the
30 nm fiber
The 30 nm fiber brings
Nucleosomes together using histone H1
Base stacking
Strengthens hydrogen bonding by having flat regions face each other
DNA helix is
Anti parallel. One strand runs 5’ to 3’ while the other runs 3’ to 5’.
Some examples of model systems:
Viruses, bacteria, yeast, roundworm, fruit fly, zebrafish (cancer), mice, and plants.
What is the central dogma of molecular biology?
That genetic information transfer happens in one direction, from DNA to RNA to protein. (Replication, transcription, translation.)
Acetylation
Associated with active transcription.
Methylation
associated with transcription activation or repression, depending on the residue that is methylated, so the position as well as the modification are significant for regulation
Phosphorylation
provides additional regulatory signals. Added by kinases and removed by phosphates.
Ubiquitination
Of lysine side chains is another histone modification. Can be attached by enzymes, regulates transcription and DNA repair.
