class lecture mod 3 Flashcards
genetic information is stored in
DNA, which is stable
RNA is ___ stable
not
different genes code for
different proteins that give each cell type its unique characteristics
core promoter
-marks the beginning of a gene where transcription should start
-tells the RNA polymerase where to bind through transcription factor, binding to the promoter sequences
How is DNA transcribed into RNA
-by the RNA polymerase
regulatory region
-enhancers and silencers control when and how much RNA is transcribed
-these binding sites can be far away from the promoter
what is required of the molecule that encodes the genetic information?
1) must be stable, so the info can’t break down
2) must be consistently replicated, so genetic information must be transferred reliably from one generation to the next
3) must be mutable- genetic info can be able to change for evolution to occur
Adenine and Guanine are
purines
Cytosine, Uracil, and Thymine are
pyrimidines
what is DNA made of?
-deoxyribonucleotides which includes a 5-Carbon sugar, phosphate group, and a nitrogenous base
Nitrogenous base
-nitrogen-containing ring structures that is responsible for complementary base pairing btw nucleic acid strands
carbon atoms of a DNA 5-carbon deoxyribose are
-numbered 1’,2’,3’,4’,5’
the 2’ has a Hydrogen!
makes it more stable
DNA 5’ and 3’
5’: phosphate group
3’:hydroxyl group
Rosalind Franklin found with X-ray diffraction
DNA has a double helix structure
Erwin Chargaff examined DNA and found that
A,T,G and C not found in = quantities and varied in species
-lead to A=T and G=C rule
Watson and Crick proposed DNA is made of
-antiparallel strands
-the sugar and phosphate form the backbone of the structure
In DNA, A and T and then G and C are
complementary base pairs
-stabilized by H-bonds
A and T have ___ H-bonds
2
C and G have ___ H-bonds
3
H-bonds are weak so you can
‘melt’ the DNA strands y applying high heat which is the basis for PCR (lab technique amplifying DNA segments)
Phosphodiester bonds are ____ bonds. Base paring relies on ____ bonds
-covalent
-hydrogen
DNA is packaged into chromatin with 3 roles:
1) protection
2) compaction
3) utilization and distribution of info stored in DNA (including transcription)
chromatin structure is
dynamic
the epigenome consists of
chemical “tags” that mark genome and provide additional instructions
-they can be passed from cell to cell as they divide
transcriptionally active gene
-acetylated histones
-De-methylated DNA
transcriptionally inactive genes
-De-acetylated histones
-Methylated DNA
when histone tails bound to the DNA around a gene are acetylated…
-the chromatin structure is loose and the enzymes in transcription can bind to gene
-gene will be expressed
when acetylation is removed from histone tails bound to the DNA around a gene…
-the chromatin structure is tight and the enzymes in transcription are not able to bind to gene
- gene will NOT be expressed
histone deacetylases (HDACs)
remove acetyl groups from histone tails and convert active chromatin into inactive chromatin
inhibitors of HDACs
can increase overall histone acetylation, leading to and increase in expression of genes that favor cell cycle arrest and cell death (apoptosis)
