NUCLEIC ACIDS Flashcards
what does DNA and RNA do?
DNA holds the genetic information and RNA transfers the genetic information from the DNA to ribosomes.
ribosomes is made of
Proteins and rna.
monomers of dna
nucleotides
each nucleotide contains
pentose sugar, phosphate group and a nitrogenous base.
bond between formed two nucleotides
phospho diester bonds.
discovery of dna
James watson and Francis Crick
what is dna made of
dna is made up of double stranded polynucleotide chains held together by hydrogen bonds in which the two chain runs antiparallel to each other and twists around each other to form a double helix.
bases in dna and rna
adenine, thymine cytosine and guanine and uracil
omplementray bases
adenine and thymine
cytosine and guanine
purines
having a double ring structure. adenine and guanine
pyrimidines
having a single ring structure. thymine , cytosine and uracil.
dna as a twisted ladder
dna can be thought as a twisted ladder where the uprights of the ladder are composed of deoxyribose sugar and phos[hate groups whereas the rungs are composed of organic bases.
what does 5’ and 3’ means?
5’ means that the phosphate group is attatched to carbon number 5 and 3’ means that the hyfroxyl group is attatched to carbon number 3.
direction of prime ends
5’ to 3’ on lhs and 3’ to 5’ on rhs
what bonds is present between the bases
hydrogen bonds
what is a gene
a series of codons is a gene.
why dna molecule is suited to carry out its role?
- dna has one less oxygen than rna which makes it more stable and able to withstand the presuured during cell division.
- the two strands of dna allows the information to be copied during protein synthesis and s phase.
- since the dna has a coiled structure, a lots of information can be stored even in a small space.
- dna contains phosphate groups. the phosphate group has a negative charge which attract the histones. histones regulate the genes.
- the sugar phosphate backbone present in dna provides stability by protecting the internal bases.
- dna is a large molecule so it can store alot of genetic infomation.
hydrogen bonding
The two antiparallel DNA polynucleotide strands that make up the DNA molecule are held together by hydrogen bonds between the nitrogenous bases
These hydrogen bonds always occur between the same pairs of bases:
The purine adenine (A) always pairs with the pyrimidine thymine (T) – two hydrogen bonds are formed between these bases
function of dna and rna
DNA
The function of DNA is to hold or store genetic information
DNA is the molecule that contains the instructions for the growth and development of all organisms
RNA
The function of RNA is to transfer the genetic code found in DNA out of the nucleus and carry it to the ribosomes in the cytoplasm
Ribosomes are where proteins are produced - they ‘read’ the RNA to make polypeptides (proteins) in a process known as translation
codon
the sequence of three bases that codes for a single amino acid is called a codon.
