Nucleic acids Flashcards
What is a nucleotide
molecule consisting of a five-carbon sugar, a phosphate group and a nitrogenous base
nucleic acids types
DNA (deoxyribonucleic acid) AND RNA (ribonucleic acid)
phosphodiester bonds
sugar molecules join to the phosphate group by a covalent bond
how is a phosphodiester bond broken
hydrolysis
h2o add
forms hydroxides
nitrogenous bases
5 nitrogenous bases: adenine, guanine, cytosine, thymine, uracil
4 in each nucleic acid
name of sub-group of nitrogenous and which bases do they belong to
purine: adenine, guanine
pyrimidine: cytosine, thymine, uracil
DNA: A ,G,C, T
RNA:A,G, U, C
which bases bind to each other and number of hydrogen bonds
DNA- A and T ;2
C and G ;3
RNA- A and U ;2
C and G ; 3
ADP and ATP
both are a ribose sugar
both nitrogenous base is adenine
ADP- 2 inorganic phosphate
ATP- 3 inorganic phosphate
DNA structure
double helix
two polynucleotides strand are complementary, held together by hydrogen bonds between nitrogenous bases in adjacent nucleotides
the strand of anti-parallel
DNA replication
1) DNA uncoils
2) DNA unzips (hydrogen bonds breaks)
3)Complementary base pairs align
4) base pairs are annealed ( hydrogen bonds form)
5) phosphodiester bonds form between sugar and phosphodiester group
unzipping of DNA repication
DNA helicase separates the double-strands allowing each strand to be copied
breaking the hydrogen bond and it moves in one direction (breaking the bonds required ATP)
what is meant by annealing
that hydrogen bonds from A & T and C & G
formation of phosphodiester bond
catalysed by enzymes DNA ligase
DNA polymerase catalyses the formation of new phosphodiester bonds to group to create the sugar-phosphate backbones of the two new DNA strands
3’ to 5’
types of RNA
messenger (mRNA)
ribosomal (rRNA)
transfer(tRNA)
structure of RNA
single strand
has adenine, guanine, cytosine and uracil
sugar ribose (DNA is deoxyribose)
RNA is shorter than DNA - RNA is the length of a gene. DNA the length of many gene
mRNA
nucleus (synthesis)
cytoplasm
ribosomes(where protein synthesis occurs)
roles is to transfer a copy of the genetic information from the DNA in the nucleus to the ribosomes for protein synthesis
tRNA
clover leaf shaped- 3 prominent bulges, parts of strand held in place by hydrogen bonds
nucleus (synthesis)
cytoplasm
ribosomes
Attaches to a specific amino acid. The amino acid attached depends on the anticodon of the t-RNA. The t-RNA moves towards the ribosome and attaches to the codon on the m-RNA, anticodon to codon. The amino acid is thus positioned to enable a peptide bond to form between this new amino acid and the previous one.
rRNA
folds on itself to form a three dimensional structure
nucleus
ribosomes
It is closely associated with protein to form the ribosome. It bonds with protein to form the small and large subunits of ribosomes. Ribosomes are composed of approximately 60% rRNA and 40% ribosomal proteins by mass.
characteristics of genetic code
1) near universal
2) degenerates
3) non-overlapping
4) one triplet code
protein synthesis stages
transcription
translation
transcription
1)DNA uncoils
2)hydrogen bonds between the polynucleotides strands of DNA break
3) DNA unzips
4) complementary RNA and DNA base pairs align - U&A and C&G
5) RNA polymerase- hydrogen bonds form between form between RNA nucleotides and expose DNA nucleotide of template strand
6) phosphodiester bonds form between form between sugar and phosphate group
7) RNA formed is a copy of the coding strand of DNA
translation
1)mRNA enters the cytoplasm and binds to a ribosome.
2) The ribosome moves along the mRNA (translocation) and reads codons (triplets of bases).
3)Each codon corresponds to a specific amino acid.
4)tRNA molecules with complementary anticodons bring the correct amino acids.
5) The ribosome facilitates peptide bond formation between amino acids.
6)A polypeptide chain is formed as the ribosome reads the entire mRNA sequence.
