chapter 4 Flashcards
nucleotides
monomers made up of 3 things
join together/polymerize via condensation/dehydration reaction
3 components of nucleotides
nitrogenous base, 5 carbon (pentose) sugar, phosphate group
linked tg by covalent bonding
nucleic acids
Polymers… DNA or RNA
what do nucleic acids do?
store genetic info that’s needed for cells to function, replicate, and grow
ribonucleotides
sugar moiety is ribose
in rna
uses uracil
HAS a hydroxyl group on secondary carbon
deoxyribonucleotides
sugar moiety is deoxyribose
in dna
uses thymine
absent hydroxyl group
nitrogenous bases
adenine, thymine, cytosine, guanine, uracil
pyrimidines
uracil, cytosine, thymine
purines
adenine and guanine
where does the polymerization/ condensation/dehydration reaction of nucleotides take place in?
between 3’ hydroxyl group on sugar molecule and the 5’ phosphate group of another nucleotide
what does the linking of nucleotides form
strand of DNA or rna (have directionality)
which has free 5’ phosphate group and other end free 3’ hydroxyl group
how is the sequence of bases in RNA/DNA written
5’ to 3’ direction bc rna and DNA is always synthesized in that direction
is the polymerization of nucleotides to form rna/dna spontaneous?
NOOO, it requires consistent input of energy
but inside cells, nucleic acid polymerization is made spontaneous by chemically modifying nucleotides
chemically modifying nucleotides inside cells to make nucleic acid polymerization spontaneous involves…
adding 2 phosphate groups to 5’ phosphate of nucleotides to generate (deoxy)nucleoside triphosphates orrr activated nucelotides
increases potential energy
atp (adenosine triphosphate) is an example of what
activated nucleotides
what drives the polymerization of a nucleic acid?
energy release when two phosphates are hydrolyzed from nucleoside triphosphate
similar to proteins DNA has what?
Primary and secondary structures with sugar-phosphate backbone created by phosphodiester bonds (w. any 4 nitrogenous bases extending from that backbone)
2 rules of dna based on observations are
- # of purines = # of pyrimidines
- equal # of T’s and A’s…. equal #’s of G’s and C’s
this hints at base pair makeup of dna
what did watson crick model predict and propose?
complementary base pairing
proposed DNA is a biological reservoir of info.
realizing that pairing A with t… C with G occur from
hydrogen bonding
purine- pyrumidine pairing allows
2 hydrogen bonds to form between Adenine and thymine
3 hydrogen bonds between Guanine and Cytosine
when could hydrogen bonding between base pair form?
if the bases on opposite strands are flipped 180 relative to one another….
one strand runs 5’ to 3’ and the other 3’ to 5’ (strands run antiparallel to one another)
carbon nitrogen runs of nucleotides are hydrophobic in DNA so in aq. solution this makes the DNA what?
helical / twist into a helix so that the hydrophobic bases don’t come in contact w. water (minimally)
is dna hydrophobic or hydrophilic?
hydrophilic and soluble in aq. solutions bc of the sugar phosphate backbone (negatively charged phosphate groups)
phosphate groups interact with water due to their polarity
how is DNA further stabilized?
by van der waals interactions
van der Waals interactions between nucleotides allow…
adjacent bases to stack on top of each other, stabilizing the double helical structure of DNA
the sequence of nucleotides along a segment of DNA acts as what
a code for the production of RNA and protein… central dogma
- DNA has blueprint needed for the products of both ^ (has biological function)
does DNA have info to copy itself to be produced by cells?
yes it does
dna can copy itself
whats the process of DNA replication?
- 2 strands of dna are seperated by breaking hydrogen bonds that hold it tg
- free deoxyribonucleotides form hydrogen bonds w. original strand of DNA (template strand) thru complementary base pairing, forming new complementary strand of DNA
- complementary base pairing + phosphodiester bond formation allows production of 2 daughter DNA molecules (same)
DNA IS ____ meaning each strand of original DNA acts as template for new strand of DNA
semiconservative
instead of thymine (dna), RNA uses what
Uracil
instead of deoxyribose (dna), RNA uses what sugar
ribose
what does ribose have
has 2’ carbon with hydroxy group (OH) making rna less stable than dna
is dna or rna less stable and why?
RNA due to the presence of hydroxyl group on secondary carbon
RNA is single stranded but could be found double stranded in what structure?
secondary
since rna is single stranded it can …
twist and fold upon itself
when 1 part of strand folds over n aligns with another part of strand, 2 strands run antiparallel of each other
(WITH complementarity hydrogen bind to one another)
where do most purine and pyrimidine bases in RNA undergo hydrogen bonding with complementary bases?
Same strand of RNA due to the alignment of strands running antiparallel
unpaired regoins of NO complementarity form…
loops (unbounded regoins of RNA)
when does a RNA Tertiary structure arise?
When secondary structure forms more complex shapes
How does RNA have more versatility than dna?
It is able to form more complex shapes and sometimes perform enzymatic functions like ribozymes
whats a ribozyme
rna enzymes performing many functions
since rna stores info and provides a template for replication and catalyzes reactions whats theory comes up
that life could have originated from rna-based world
