DNA and RNA Flashcards
name the parts of a DNA nucleotide
3
phosphate
deoxyribose
nitrogenous base
what bond is formed between phosphate and deoxyribose
phosphodiester bond
what bonds are formed between the nitrogenous bases in a DNA double helix
hydrogen bonds
describe the formation of DNA strands in a double helix
antiparallel strands
name the monomers of DNA
polynucleotides (joined together using hydrogen bonds)
define genome
all of the DNA in an organism
name 3 things DNA is that RNA isnt
has deoxyribonucleic acid
G-C A-T
double stranded
what percentage of each base is found in humans
cytosine and guanine have 23%
adenine and thymine have 27%
describe DNA in eukaryotes
linear
double stranded
found in nucleus
bound to proteins
contains non-coding parts
what protein is DNA bound to in eukaryotes
histones
describe DNA in prokaryotes
naked
circular
pure function (has no non-coding parts
difference in function between DNA and RNA
DNA holds genetic information
RNA transfers genetic information to ribosomes
what are ribosomes formed from
rRNA and proteins
why did scientists doubt DNA carried the genetic code
because of it’d relative simplicity
define semi-conservative replication
making 2 molecules of DNA that are identical using one original strand of DNA as the termplate
what are the 4 sections of the cellcycle
growth
DNA synthesis
growth + preparation for mitosis
mitosis
what enzyme unzips DNA for semi-conservative replication and how does it work
DNA helicase
it breaks hydrogen bonds between nitrogenous bases
what are the split strands of DNA called
parental strands
how do bases join the parental strands during complimentary based pairing
free floating nucleotides in the nucleus are attracted to these parental strands of DNA
what does DNA polymerase do in semi conservative replication
reads nucleotides and enables them to join new strand as condensation reactions occur to form phosphodiester bonds
what direction does DNA polymerase work in and what does that mean
works in 5’ - 3’ direction
DNA polymerase can only bind to 3’ end so will only go in one direction
the anti-parallel strands mean the enzyme goes in opposite directions for each strand
who made the proof for semi-conservative replication
Meselson and Stahl
what was Meselson and Stahl’s proof
labelled the DNA of bacteria across generations using isotopes of nitrogen. From the patterns of DNA labelling they saw,
they confirmed that DNA is replicated semi-conservatively.
how many hydrogen bonds are there between
adenine and thymine
cytosine and guanine
A-T =3
C-G=2
what happens before mRNA is sent out of the nucleus
pre-mRNA is spliced
in translation, what energy is used to form peptide bonds
ATP
name the bases
adenine
thymine (only DNA)
Guanine
Cytosine
Uracil (only RNA)
how is a phosphodiester bond formed
a condensation reaction between two adjacent nucleotides
describe a DNA molecule
double helix
two polynucleotide chains
held together by hydrogen bonds
between complimentary base pairs
describe an RNA molecule
relatively short polynucleotide chain
in prokaryotic cells, what form is dna
short, circular, not associated with proteins
what is the name of the protein associated with DNA
histones
in eukaryotic cells, what is the form of dna
long linear
associated with proteins
DNA molecule and proteins form a chromosome
what are the 2 things a base sequence of dna codes for
amino acid sequence of a polypeptide
a functional RNA
in eukaryotic cells, what else contains DNA
how does this dna differ from the dna in the nucleus
mitochondria
chloroplasts
it is short, circular and not associated with proteins
what is teh fixed position a gene occupies on a particular DNA molecule
a locus
give 3 words to describe the genetic code
degenerate
non-overlapping
universal
what does degenerate mean
multiple codons can code for the same amino acid
what does universal mean
in all organisms on earth, the same codons code for the same amino acids
what does non-overlapping mean
each base can only be in one codon/tripet
