1 Genetic Material Flashcards
name the two purines
- adenine
- guanine
name the two pyrimidines
- thymine
- cytosine
- uracil
what is the difference between a nucleotide and a nucleoside
nucleosides are composed of a a sugar and a base whereas nucleotides have a sugar, base, and a phosphate group
what time of bond binds the phosphate group to the nucleotide
-ester linkage
what is the backbone of DNA
pentose phosphate
what are the two terms for small strands of DNA?
primers or oligonucleotides
what are the two primary donors/acceptors of H bonds?
oxygen and nitrogen
what base pair has the highest annealing temp and why?
C-G because they have three hydrogen bonds that connect them, vs A and T only having 2
what type of symmetry did francis crick notice in rosalind franklins X ray images of DNA?
monoclonic C2
what do you on find on the inside of the double helix of DNA
purine and pyrimidines base paired
what are the two strands of DNa held together by?
H bonds
what is the diameter of the double helix?
20A
after how many residues, does the structure of DNA repeat?
10
Why does the major and minor groove exist?
because the glycosidic bond of a base pair are not diametrically opposite each other
what does the major groover allow for?
the open nature of the major groove allows for proteins to interact with the DNA - could be in the way of DNA kinases/phosphotases
is relaxed DNA supercoiled?
No
how do you negatively supercoil DNA?
tiwsting the strands in the opposite directions
how do you positively supercoil DNA?
twist the strands in the same direction
do supercoiled or relaxed DNA have more energy?
supercoiled
what is the diference between topo 1 and topo 2?
topo 2 creates a double stranded break whereas topo 1 creates a single strnaded break. these are used to change the topology
what is the clinical relevance of topoisomerases?
they can be targeted by pharmaceuticals to treat cancer
what does camptothecin target
topo1
what does m-AMSA and doxorubicin target?
topo2
what does an adenine repeat create in the DNA structure?
a bend
what happens to the absorption of DNA when you heat it up and why?
absorption goes up because the two strands break away from each other and expose the nitrogenous bases
what is characteristic of a DNA strand with a high melting temp?
is has a large amount of C-G base pairs
how do you hybridize a probe with its complimentary strand
heat up the strand, then cool it back down and the probe with base pair with its compliment
what is a probe?
short strand of DNA that is complimentary to a gene of interest and is usually tagged with a fluorescent marker
what percentage of the human genome codes for protein and how many proteins does this include?
1.5% of the genome, 25,000 proteins
what are pseudo-genes?
look very similar to genes in sequence but do not code for anything functional
what is a processed pseudogene?
mRNA that has be reverse transcribed into cDNA, then synthesized into dsDNA, and integrated back into the genome via integrase
what is a provirus?
a retrovirus that has integrated into our genome
what is a SINE and what are their size?
short interspersed repeat elements. they are abput 280bp long and constitute 10% of the genome
what are lines? how long are they? and what do they code for?
- long interspersed repeat elements
- greater than 500bp long
- 20% of the human genome
- complete LINE sequences code for a reverse transcriptase
what are simple sequence repeats (SSR)? what are their characteristics? how can we use them?
- 2 to 5 bp in length
- present at many locations
- highly polymorpic, therefor we can use them to identify people
- they are present in everybody at the same locations
what are SNPs? how can we use them? where are they found? how are they related to disease
- single nucleotide repeats
- they can serve as biological markers
- may fall within coding, noncoding, or the intergenic parts between genes
- certain diseases are associated with certain SNPs (mutations)
what is the telomere nucleotide sequence?
TTAGGG
what happens to telomeres as we age?
they get shorter and finally reach a point where they can not protect the chromosome anymore and it is destroyed
what synthesizes telomeres and how is this protein important clinically?
- telomerase is what creates telomeres
- in certain cancers, this enzyme is reactivated, allowing the cell continue dividing indefinitely
what type of enzyme is telomerase?
a reverse transcriptase
recite the order of organization of DNA from smallest to largest
DNA, histones, nucleosomes, chromatin, chromosomes
