nucleic acids Flashcards
what elements are in nucleic acids
carbon hydrogen oxygen nitrogen phosphorous
name 3 components the makeup nucleotides
pentose monosaccharide (sugar) containing 5 carbon atoms phosphate group- negatively charged nitrogenous base- carbon rig +nitrogen
how are sugar phosphate backbones formed
phosphate group of 5th carbon on pentose sugar forms covalent bond with hydroxyl group 3rd carbon on another pentose sugar adjacent nucleotide
phosphodiester bonds
name the pentose sugar in RNA
ribose
name the pentose sugar in DNA
deoxyribose
name and describe pyrimidines
smaller bases with single carbon ring structure
- cytosine
- thymine- DNA
- uracil- RNA
name and describe purines
larger bases with double carbon ring structure
- adenine
- guanine
what type of bond holds the 2 strands of polynucleotides together in a DNA helix
hydrogen
between bases
define antiparallel
the 2 strands run in opposite directions
(in DNA) which bases pair together
adenine+ thymine
guanine+ cytosine
what happens to DNA helix when cell prepares to divide
strands separate and act as template
how is complementary base pairing useful in DNA replication
ensures 2 new strands will be identical
describe semi-conservative replication
helix unwinds
free nucleotides pair with complementary base
hydrogen bonds form
nucleotides join adjacent ones forming phosphodiester bonds
each of 2 new mols reduced has 1 old and 1 new strand
what enzyme separates the 2 stands of DNA helix
DNA helicase
catalyses reactions that break hydrogen bonds between base pairs
wat enzymes helps form new strand
DNA polymerase
catalyses formation of phosphodiester bonds
what is the genetic code
DNA codes for sequence of amino acids in proteins
universal- same in all organisms
what is a triplet code
sequence of 3 bases (codon) that codes for an amino acid
explain the degenerate code
some amino acids coded for by more than 1 codon
only 1 start codon so code is non-overlapping
3 stop codons that don’t code for any amino acids
64 possible codons
name the stand that codes for protein during transcription
sense strand
other is anti-sense
what are the differences between transcription and replication
in transcription, RNA uracil binds to adenine
RNA polymerase catalyses formation of phosphodiester bonds
what is the product of transcription
messenger RNA
detached from template and leaves through nuclear pore
DNA helix reforms
what is translation
mRNA binds to smaller subunit of ribosome
decoded into sequence of amino acids
what 3 types of activity do cells need ATP for
synthesis
transport
movement
name structures in ATP
nitrogenous base (adenine)
pentose sigar
3 phosphate groups
