DNA and replication Flashcards
What is DNA ?
DNA is a polymer it is made of nucleotide molecules joined together by phosphodiester bonds
What does a nucleotide consist of?
It has a phosphate group a pinto sugar and a nitrogen containing base. The pinto sugar is deoxyribose.
What are the four bases?
Adenine joins to thymine and cytosine joins to guanine, adenine with thymine forms 2 hydrogen bonds and cytosine with guanine forms 3 hydrogen bonds
Explain condensation
Condensation reactions join the phosphate of one nucleotide to the pinto sugar of another nucleotide. This bond is called a phosphodiester bond.
Describe the structure of DNA
I said double helix structure and it has two polynucleotide change joined together by hydrogen bonding between the bases the chain twists into a helical shape. The bonds between bases are known as complementary base pairing the sugar and phosphate are on the outside of the structure and is known as a sugar phosphate backbone and the strands are anti-parallel.
How does the DNA structure suit its function?
DNA2 jobs are DNA replication and carrying instructions for protein synthesis
What are the adaptations of the structural features of DNA?
DNA is long so it can store lots of information
It is helical which means it’s compact
It is double stranded so each strand acts as a template for DNA replication
Sugar phosphate backbone provides strength and stability and protect the bases within the helix
It has weak hydrogen bonds between bases which means it can be equally broken for DNA replication or protein synthesis
It has lots of hydrogen bonds which makes the molecules stable and strong
What is RNA
RNA is a polymer and it is made of nucleotides joined together by phosphodiester bonds
What is the structure of RNA?
In RNA, the penal sugar is called ribose and there are four possible bases which are your cell which replaces thymine adenine Guanine or cytosine
What are the three types of RNA?
Messenger RNA transfer RNA and ribosome RNA
What is the role of mRNA and what is it structure?
It is a single stranded straight chained molecule made of basis which read in triplets called codons. It’s a role is to carry the genetic code out of the nucleus to the ribosome for the formation of one polypeptide.
What is the role of tRNA and what is it structure?
tRNA is a single strand of RNA folded in many places forming complementary beast pairs. Its shape is described as a clover leaf and it has an amino acid binding site and a triplet of bases is called an anticodon which is complementary to the mRNA codon its role is to carry specific amino acid to the mRNA at ribosomes for the formation of a polypeptide.
What is the role of rRNA?
It is found in the cytoplasm and its role is to form ribosomes
Compare The structure of DNA and RNA
DNA has two strands, whereas RNA has one strand
DNA is very long whereas RNA is short
DNA has adenine thymine guanine and cytosine whereas RNA has uracil adenine cytosine and guanine
DNA store genetic information whereas RNA transfers genetic information in the formation of proteins and helps form ribosomes
When does DNA replication occur?
It happens during interphase and it ensures accurate replication of DNA before a cell divides
What are the stages of DNA replication?
DNA has a case separates the DNA strands by breaking the hydrogen bonds
Each strand acts as a template
Three nucleotides attached to the exposed basis by complementary base pairing
DNA polymer is joint nucleotides forming phosphodiester bonds
How is DNA replicated?
It is replicated uni directionally. This means that new DNA strands are replicated in the 5 to 3 direction polymers enzymes have an active site which is complementary and specific to the three end of the DNA chain. This means that new nucleotides are added in the 5 to 3 direction.
What is the role of DNA polymerase?
It joins adjacent DNA nucleotides it catalyses condensation reactions and a catalyses formation of phosphodiester bonds
