Structure of DNA & RNA Flashcards
What does DNA code for?
The sequence of amino acids in the primary structure of a protein
What is the monomer that makes up DNA?
Nucleotide
What is the structure of a nucleotide in DNA?
a pentose sugar (deoxyribose in DNA), a nitrogenous base and a phosphate group
What are the examples of the nitrogenous bases in DNA?
Adenine, Thymine, Guanine, Cytosine
How are nucleotide’s joined to each other
A phosphodiester bond is formed between the deoxyribose and the phosphate group via a condensation reaction
What are phosphodiester bonds and what do they do?
They are strong covalent bonds and they ensure that the genetic code is not broken down. They also form the sugar-phosphate backbone of DNA.
What does the structure of DNA look like and how is it formed?
Two polymer chains of DNA are held together by hydrogen bonds and they twist around each other to form the double helix structure.
The hydrogen bonds only form between complementary base pairings ( CG and AT)
How many hydrogen bonds can the complementary bases form?
CG = 3 hydrogen bonds
AT = 2 hydrogen bonds
How does the structure of DNA relate to its function?
- It has a sugar-phosphate backbone which is strong due to the covalent bonds which allows it to have a stable structure.
- It is double stranded which means both strands can act as templates
- The hydrogen bonds are weak which means it is easy to unzip the two strands in the double helix during replication
- It is a large molecule which means it can carry lots of information
- The complementary base pairings allow identical copies to be made
What is the monomer that makes up RNA?
Nucleotide
What is the nucleotide in RNA made up of?
a pentose sugar (ribose in RNA), a phosphate group and a nitrogenous base
What are the nitrogenous bases in RNA?
Adenine, Guanine, Cytosine, Uracil
What is the function of RNA?
To copy and transfer the genetic code from DNA in the nucleus to the ribosomes. Some RNA combines with proteins to create ribosomes.
Describe and explain the shape, features and function of mRNA.
mRNA = messenger RNA
- It is a copy of a gene from DNA
- Inside the nucleus, the DNA unravels at the start of protein synthesis and a copy of the unravelled DNA is made in mRNA.
- This is because DNA is too large to leave the nucleus since it could risk being damaged by other enzymes so instead, the copy of a gene is made into mRNA
-It is short because it is only the length of one gene so it can leave the nucleus. It is short-lived because it is only needed temporarily to help create a protein. It is single stranded and every 3 bases in the sequence code for a specific amino acid. The three bases are called codons.
Describe and explain the shape, features and function of tRNA.
tRNA = transfer RNA
- It is only found in the cytoplasm
- It is single stranded but it is folded to create a cloverleaf shape that contain nucleotide’s held in place by hydrogen bonds
- The function of tRNA is to transfer amino acids. There are three exposed bases at the top which is where the amino acid attach.
- Each tRNA molecule can attach and bring a specific amino acid to the mRNA which is attached to the ribosome. This is controlled by complementary base pairing between the codon on mRNA and the anticodon on tRNA
