DNA and RNA Flashcards
what is the roles of DNA and RNA
DNA: hold genetic information
RNA: transfers genetic information from the DNA to the ribosome
what are ribosomes formed from
RNA and proteins
what are nucleotides composed of
-pentose sugar
-a nitrogen containing organic base
-a phosphate group
how are polynucleotides formed
-many nucleotides joined together to form polynucleotide strand via a condensation reaction between the phosphate group of one nucleotide and the sugar of another
-forms a phosphodiester bond
what is the chain of phosphate and sugar known as
sugar- phosphate backbone
describe the structure of DNA
-polymer of nucleotides
-each nucleotides formed from a deoxyribose sugar, a phosphate group and a nitrogen containing organic base
- double helix formed by joing two polynucleotide strands via condensation reaction
-forms a phosphodiester bond between the nucleotides
- hydrogen bonds form between complementary base paring - Adenine with Thymine and Cytosine with Guanine
what are the four possible bases in DNA nucleotide
-Adenine (A)
-Thymine (T)
-Cytosine (C)
-Guanine (G)
how many hydrogen bonds form between
a) A and T
b) C and G
a) 2 hhydrogen bonds
b) 3 hydrogen bonds
describe the structure of RNA nucleotides
-ribose sugar, phosphate group and a nitrogen containing organic base
what are the possible bases for RNA nucleotide
-adenine
-cytosine
-guanine
-uracil
compare the DNA and RNA
-SIMILARITIES
-both are polymers of nucleotide
-both made up of a sugar, phosphate group and an organic base
-both have the same organic bases of adenine, cytosine and guanine
DIFFERENCES
-DNA is double stranded whilst RNA is single stranded
-DNA is long polynucleotide strand whilst RNA is short polynucleotide strand
-sugar in RNA is ribose whilst for DNA its deoxyribose
DNA contains Thymine whilst RNA contains Uracil
who discovered the structure of DNA and its model
-James Watson and Francis Crick
what does semi conservative replication mean
-each of the DNA molecule contains one strand from the original DNA molecule and one strand that is brand new
why does DNA replicate itself
- parental DNA copies itself before cell division so that each new cell has the full amount of DNA
what does semi- conservative replication ensure
- ensures that there is genetic continuity between generation of cells ( I.e : cells produced by cell division inherit the genes from their parent cells
what is the first step of DNA replication
1) the enzyme DNA helicase breaks the hydrogen bonds between the complementary base pairs between the two polynucleotide strands
- causes the the DNA double helix to unwind and form two single strands
2nd step of DNA replication
-each of the separated parental DNA strands acts as a template
- the free floating DNA nucleotides are attracted to their complementary base pairs on the template strands of the parental DNA
3rd step of DNA replication
- the adjacent nucleotides of the new strand join together by condensation reaction - catalysed the by the enzyme DNA polymerase
-hydrogen form between the original and new strands
4th step of DNA replication
-two sets of the DNA daughter (new DNA molecule) now contains one strand of the parental DNA and the newly synthesised strand
decribe how a phosphodiester bond is formed between two nucleotides within a DNA molecule
-via condensation reaction
-between deoxyribose sugar and phosphate group
-catalysed by the enzyme DNA polymerase
