2.3 DNA/nucleotides Flashcards
what is a nucleotide made of
nitrogenous base
phosphate group
5 carbon sugar (deoxyribose)
name the functions of a nucleotide
monomer of nucleic acids
become phosphorylated when contain more then one phosphate group
regulate metabloic pathways
components of coenzymes
explain the difference between AMP, ADP, ATP
AMP= one phosphate group adenosine monophosphate
ADP= two phosphate groups
adenosine diphosphate
ATP= three phosphate groups
adenosine triphosphate
what is a phosphoryolated nucleotide and name two examples
a nucleotide thats had phosphates added to it
ADP , ATP
what is DNA
macromolecule that makes up the structure of living organisms
describe the structure of DNA
polymer made of nucleotides in two strands that run in opposite direction (antiparalell)
phosphodiester bond between sugar and phosphate group
double helix
name the two types of nucleotides based off bases
purines
pyrimidines
desribe the difference between a purine and pyrimidine
purine= two rings
pyrimidine= one ring
what bases are a purine
adenine
guanine
what bases are a pyrimidine
thymine
uracil
cytosine
how many hydrogen bonds form between adenine and thymine
2
how many hydrogen bonds form between cytosine and guanine
3
how are polynucleotides made and broken
forming and breaking phosphodiester bonds
what is the role of hydrogen bonds in DNA
form between the bases on two anitparallel DNA strands
what is the importance between purines and pyrimidines
purine always joins a pyrimidine so there is equal sized rungs on the DNA ladder
twists into double helix
how does DNA replicate
enzyme gryase unwinds/ helicase unzips DNA double helix by breaking hydrogen bonds on antiparallel strands
dna polymerase - free phosphorylated nucleotides and bonds with the exposed bases
energy released and used in next reaction to form bonds
what is the product of DNA replication
two DNA molecules identical to another
each containing one strand of original DNA and newly replicated DNA
why is DNA replication semi conservative
semi=half
contains one strand from original and one replicated
define universal for the nature of genetic code
in all organisms the same triplet of DNA bases codes for same amino acid
define degenerate
for all amino acids there is more then one base triplet so amino acids can be coded for by multiple codons
define non overlapping
genetic code/bases are only read from a fixed point in groups of 3
what does the order of bases result in
the codon = the amino acid = order of amino acids = shape of protein
what is RNA made of
nucleotides
ribose sugar
nitrogenous base (AUCG)
phosphate group
what are the three forms of RNA
mRNA
tRNA
rRNA
what is mRNA
messanger RNA
what is tRNA
transfer rna
what is rRNA
ribosomal RNA
what happens in transcription
DNA is transcribed and an mRNA molecule is produced
what happens in translation
mRNA (messenger RNA) is translated and an amino acid sequence is produced
steps of transcription
gryase and helicase unwinds and unzips DNA
RNA polymerase catalyses the formation of temp. hydrogen bonds between free RNA nucleotides and DNA bases
copy of strand produced
mRNA leaves the nucleus
steps of translation
tRNA binds to complementary triplet
has amino acid
peptide bond forms
what direction does RNA polymerase move in
3’ to 5’ direction
what direction does mRNA move/grow in
opposite to RNA polymerase
5’ to 3’ direction
what is the template strand
strand of DNA used to produce the mRNA molecule
what is the coding strand
length of RNA bases that are complementary to the template strand
where does transcription and translation occur
-scription = nucleus
-slation= cytoplasm
describe the structure of tRNA
hairpin shape
anticodon at one end = triplet of unpaired bases complementary to mRNA
triplet of bases at other end where amino acid attaches
what is the role of tRNA
bind with their specific amino acids and bring them to the mRNA molecule on the ribosome
what bond forms between amino acids as tRNA binds to the mRNA strand
peptide bonds
how does translation stop
process continues until stop codon on mRNA is reached and final polypeptide chain forms
name the steps in DNA purification
grind with pester and mortar
add salt
add detergent
add protease
place in water bath
filter into beaker/tt
tilt and poor in ice cold ethanol
when purifying DNA why do you crush sample with pestle and mortar
to break open cell wall
in DNA purification what enzyme do you need to use and why
protease
to break down histone proteins associated with DNA
why do you add detergent (DNA purification)
to break down phospholipid bilayer
why is ethanol added
to precipitate DNA (white layer forms)
why is salt added
helps DNA precipitate/ shed water
explain what the experiment with isotopes of nitrogen show and support semi conservative replication
tube 1
shows DNA / band contains light nitrogen and heavy nitrogen
tube 2
DNA / band, made from
only, light nitrogen so strand of DNA must be a template
tube 10
highest band more of the DNA is made from only, light nitrogen
