A1.2 Nucleic acid Flashcards
for nucleic acid what are the monomers and what are the polymers
monomers= nucleotides
polymers= polynucleotides;
- dna= deoxyribose nucleic acid
rna= ribose nucleic acid
what are the monomers of nucleic acids (nucleotides) made of
phosphate group (PO4 3-)
pentose sugar= deoxyribose for DNA and ribose for RNA
nitrogenous base=
ATCG for DNA
AUCG for RNA
describe structure of nucleotide
sugar (pentose sugar= 5 carbons and one oxygen) is the middle part and the C5 connects to the phosphate group, and C1 connects to the nitrogenous base
what is the difference in the structure of a deoxyribose nucleic acid and a ribose nucleic acid
c2 has only a hydrogen in deoxyribose nucleic acid while in ribose nucleic acid is has an OH connected to C2
number of hydrogen bonds between AT compared to CG
AT= 2
CG=3
whats the name of the bases once they are in a nucleoside
adenosine
thymidine
guanosine
cytidine
name of the bases
adenine
guanine
thymine
uracil
cytosine
whats uracil
the base which pairs with adenine in an rna instead of thymine
what are the purines
contains a double ring, adenine (A)
Guanine (G)
what are the pyrimidines
single ring only
Thymine (T)
Uracil (U)
Cytosine (C)
what happens in the condensation reaction between 2 nucleotides
water is removed
bond forms between the C3 of one nucelotide and C5 of another nucleotide bond is called phosphodiester bond this connects nucleotides into one single strand
describe dna structure
5’ end- has a phosphate without connection
3’ end- no phosphodiester bond with C3
DNA is made of 2 polynucleotide strands that run in opposite directions to each other (anti parallel) . They match through complementary base pairing and naturally coil into a twisted double helix.
what are the differences between DNA and RNA
DNA
pentose sugar: deoxyribose (C2-H)
number of strands:
2- double helix
nitrogenous bases:
ATCG
location in cell:
nucleus
function:
Stores genetic info in the form of different lengths and sequence of nucleotides
RNA
pentose sugar:
ribose (C2-OH)
number of strands:
1-single stranded
nitrogenous bases:
AUCG
location in cell:
cytoplasm
function:
has 3
function of mRNA
messenger
carry genetic info in form of codons from the nucleus to the cytoplasm
codons= triplet of bases
each codon codes for 1 amino acid
function rRNA
ribosomal
makes up ribosome and catalyses condensation reaction between amino acids
is seperated in large subunit which has a tRNA attachment and a small subunit which has the mRNA attachment
function tRNA
transfer
brings specific amino acid to the ribosome
has anticodones which is also a triplet of bases
carries the specific amino acid found in codon
deoxyribose
a pentose sugar found in DNA
ribose
a pentose sugar found in RNA
purine
a molecule containing nitrogen and carbon, compromising two ring structures
pyrimidine
a molecule containing nitrogen and carbon comprising one ring structure
complementary
the relationship between adenine and thymine and between cytosine and guanine for example
hydrogen bonds
weak bonds between complementary bases
adenine
a purine base complementary to thymine and uracil
thymine
a pyrimidine base complementary to adenine
cytosine
a pyrimidine base complementary to guanine
guanine
a purine base complementary to cytosine
uracil
a pyrimidine base found only in RNA
double helix
shape of DNA molecules
antiparallel
the arrangement of complementary polynucleotides in the double helix
sugar phosphate bonds
strong bonds between adjacent nucelotides in a polynucleotide
pentose
general name for a five carbon sugar
nucleotide
monomer of nucleic acids
polynucleotide
chain of nucleotides
base pair
two complementary bases held together by hydrogen bonds eg. A-T, C-G
when was the HERSHEY CHASE experiment and summary
1952, the discovery that DNA is heritable factor
what did hershey and chase experiment use
bacteriophage viruses;
contain, dna and proteins
and used radioisotopes of atoms, to track the movement of DNA and protein between generations of viruses
explain bacteriophage virsues
used in hershey and chase experiment
theya re viruses that specifically ingect bacteria in order to reproduce, they inject their genetic mterial into the host cell (bacteria)
what were the two tests done by the hershey and chase experiment
1- test if the protein was the heritable factor
2- test if DNA was the heritable factor
describe the first test, test if protein was the heritable factor
conical flask with culture of bacteria
phages were labelled with 35S (radioactive isotope of sulfur), the protein was coated with this sulfur, and the phages released their genetic material into the bacteria
they then poured this mixture into bacteria and then into a centrifuge
in the centrifuge;
-pellet which is denser is the bacteria
-supernatant which is lighter are the phages
they then tested the centrifuge for radioactivity, and only the supernatent was radioactive showing that the protein isnt the genetic material as when testing the bacteria for radioactivity it was negative meaning protein which was radioactive wasnt transfered to bacteria
describe the 2- test if DNA was the heritable factor
phages labelled with 32p (radioactive isotope of phosphorous), this time DNA was radioactive
blend mixture of phages and bacteria in a mixer, and then centrifuge
pellet contains bacteria
supernatant contains the phages
this time when testing for radioactivity, the bacteria were found to be radioactive, this showed that the radioactive dna passed from the phage into the bacteria, showing that the genetic material is the DNA
what is the impotance of hydrogen bonds for living organisms
promotes surface tension, serves as habitat for animals/insects
what links nucleotides strands making dna
cohesion and adhesion used in xylem, transpiration pull
secondary structure of proteins have hydrogen bonds between beta pleated sheets and alpha helix
water stays liquid for higher temperatures, because of hydrogen bonds
solvent properties of water
in process of transcription, fomation of m RNA through transcription
whats the significance of positvely charged histone protein and the negatively charged dna
creates a force of attraction between both allowing coiling of dna around histones
neg charged dna associates to pos charged amino acids on surface of histones protein
what is the role of histones
packaging of dna in chromosomes
what are chromosomes
chromosomes are most condensed version of nucelosomes and is only present in cells during mitosis or meiosis
when is chromatin present ina cell
during interphase, whenever cell isnt dividing
what is the chromatin fiber
stacking of nucelosomes
nucleosome
octomer of histones (8 histones) with 2 coils of dna around
what is the importance of the central histone
it has a positive charge and is an amino acid
why is dna negatively charged
PO4 3-
importance of H1 histone
linker protein avoids DNA from seperating from histomes
what is a nuclosome molecule composed of
beta pleated sheet
alpha helixes
2 coils of dna
what did chargaffs data suggest
strongly hinted towards complementary base pair makeup of dna
and disproved the tetra nucleotide hypothesis
what was the tetra nucleotide hypothesis
that dna was composed of only 4 nucleotides per molecule with the 4 bases present in euqal amounts and directed to the outside of the structure
this was disproved by chargaffs experiment
