nucleotides and nucleic acids Flashcards
describe DNA
double stranded
genetic code makes proteins
deoxyribose sugar
describe RNA
single stranded
3 types of RNA all make proteins
ribose sugar
what are the 3 types of RNA
mRNA
tRNA
ribosomal
what is the monomer of RNA and DNA called
nucleotides
describe the structure of a nucleotide
pentose sugar
organic nitrogenous base
phosphate group
what are the bases of DNA
A, T, C, G
what is the base ‘A’ called
adenine
what is the base ‘t’ called
thymine
what is the base ‘C’ called
cytosine
what is the base ‘G’ called
guanine
what are the bases of RNA
A, U, G, C
what are the 2 purines
A and G
what is a purine
larger, double ring bases
what are the 3 pyrimidines
C, T, U
what is a pyrimidine
smaller, single ring bases
how do nucleotides join
condensation reaction
what is the polymer of nucleotides called
polynucleotide
what are the bonds between the phosphate group and the sugar of a nucleotide called
phosphodiester bond
why is the bond between nucleotides referred to as a 3’ 5’ bond
the carbon 3 bonds with carbon 5
what bond bonds the helix structure of DNA
hydrogen bonds
how many bonds are between A and T
2 hydrogen bonds
how many bonds are between C and G
3 hydrogen bonds
what does anti-parallel mean
one strand is flipped upside down so the bases can pair in the middle
give 4 reasons why the structure of DNA is good
coiled makes it compact
specific sequence gives a genetic code
double stranded makes it more stable
double stranded structure makes it easy for replication
DNA extraction practical: why do you grind the sample with a mortar and pestle
to break down the cellulose cell wall
DNA extraction practical: why do we mic the sample with detergent
to break down the cell membrane and the nuclear membrane
DNA extraction practical: why do you add salt
takes water away from DNA
DNA extraction practical: why do you add protease enzyme
break down histone proteins that DNA is wrapped around
DNA extraction practical: why do you add a layer of alcohol on top of the sample
causes the DNA to precipitate out of solution
give 3 reasons why need ATP
synthesis
transport
movement
draw the structure of ATP
adenine
ribose sugar
3 phosphate
what is the product after ATP is hydrolysed
ADP, phosphate and energy
how and where is ATP made in cells
mitochondria
aerobic respiration
give 4 ways that make ATP a good energy source
fairly small
water soluble (can move across membrane)
releases a small amount of energy (just enough for cellular reactions)
easily re-made
when does DNA need to replicate itself
mitosis or meiosis
why does DNA need to replicate itself
this is to make enough DNA to be shared amount the new daughter cells
describe the method of DNA replication
1) double helix had to unwind and separate exposing the bases by hydrogen bonds breaking using the enzyme DNA helicase
2) free nucleotides line up next to the exposed bases by complimentary base pairing
3)new hydrogen bonds form
4) new sugar phosphate back bones are formed (phosphodiester bonds form), using the enzyme DNA polymerase
why is DNA replication called semi-conservative
each new daughter molecule has an original strand and a new strand
what makes DNA replication so accurate
complementary base pairing
why does one of the strands had to be copied continuously and the other has to be copied in sections
DNA polymerase enzyme can only move along the DNA in one direction (3’ 5’)
what is it called when the strand is copied in sections
okazaki fragments
what is the name for an error in a genetic code?
mutations
what is a gene
a specific sequence of DNA nucleotides that code for a particular sequence of amino acids
why is mRNA called messenger RNA
it carries a version of the genetic code as a message to the ribosome
why is tRNA called transfer RNA
transfers amino acids to the ribosome to make proteins
why is rRNA called ribosomal RNA
it makes up the ribosome
where are proteins made
ribosome/ RER
what are the 2 stages of protein synthesis
transcription and translation
describe the first stage of protein synthesis (transcription)
1) enzyme DNA helicase attaches to gene causing it to unwind, breaking hydrogen bonds and making it unwind
2) one strand is the coding and the other is the template strand
3) free nucleotides line up for complementary base pairing (U replaces T)
4) temporary hydrogen bonds form
5) RNA polymerase makes the phosphate sugar backbone
6) once the enzyme leaves the DNA molecule reform, hydrogen bonds reform
what are introns
non coding gene
what are three bases on mRNA called
codon
describe what happens in translation
1) mRNA attaches to a ribosome
2) tRNA molecules contain 3 bases called anticodons which line up next to the codons on the mRNA by complementary base pairing
3) amino acids join by peptide bonds
4) a new tRNA molecule now leaves the ribosome leaving it’s amino acid behind
5) this happens until a ‘stop’ codon on the mRNA is reached
6) polypeptide is then released into the polypeptide
where will the polypeptides pass to in order to be modified
Golgi apparatus
what does it mean when the code is degenerate
there are more possible triplet codes than there are amino acids
what is the ‘start’ codon called
AUG
what does AUG code for
methionine
