Topic 5- Nucleic Acids Flashcards
What is a nucleotide
The basic unit from which nucleic acids are formed. They are a combination of a phosphate a pentose sugar and an organic nitrogenous base
What are the three components that make up a nucleotide
A phosphate group
A pentose sugar
And an organic nitrogenous base
How do the components of a nucleotide come together
Via two condensation reactions with the removal of a water molecule
Condensation to join the phosphate group to the pentode sugar and a condensation joining the pentode sugar and the organic nitrogenous base - forming a Single nucleotide
Where do the condensation reactions occur in the formation of a nucleotide
A condensation reaction between the phosphate group r and the pentose sugar and a condensation reaction between the pentose sugar and the nitrogenous base
What are nucleic acids
Polymers made up of many units of monomers called nucleotides
What does ATP stand for
Adenosine-tri-phosphate
What is ATP known as
The universe energy of currency
Describe the three advantages of ATP for its function as the universal source of energy
It’s soluble so diffuses easily across the cell membrane and hence can be transported around the cell easily
It is an immediate source of energy as only one type of enzyme is needed to hydrolyse it
And it realises energy in a useable amount that are matched closely to the energy required in a couple reaction
Name cellular activities requiring ATP
Active transport
Protein synthesis
Nerve transmission
Muscle contraction
What is the structure of ATP
Phosphorylated RNA nucleotide composed of a nitrogenous base adenine joined to a ribose sugar and three phosphate groups
What are the two types of nucleic acid
Deoxyribosenucleic acid
And ribonucleic acid
What are the pyramidine bases
Cytosine uracil thymine
What are the purine bases
Adenine and guanine
What are the pyrimidine bases in DNA
Thymine and cytosine
What are the pyrimidine bases in RNA
Uracil and thymine
What structure is pyrimidine bases
Single ring structure
What is the structure of a purine base
Double ring structure
Describe the structure of DNA
Millions of nucleotides linked together to form a long chain called a polynucleotide. These two polynucleotide chains wind together to form a double helix
How is a polynucleotide formed
When the nucleotide join together via condensation reactions between the deoxyribose sugar and the phosphate group the deoxyribose of one sugar forms a bond via a condensation reaction with the phosphate group of another nucleotide to forms a sugar phosphate backbone
In a polynucleotide strand where do the bases attach
The bases attach to the sugar phosphate backbone
How is the double helix of DNA formed
The two polynucleotides are wound together and held by hydrogen bonds between the nitrogenous bases
How are the two polynucleotides held together
Hydrogen bonds between pairs of nitrogenous bases
Why is complimentary base pairing important
It ensures the DNA replicates correctly
It ensures the same proportion of A and T is in a DNA molecule and the same proportion of G and C
It ensures the polynucleotide strands are anti parallel to each other
How many hydrogen bonds are there between G and C
3 hydrogen bonds
How many bonds are there between A and T
2 bonds
How many polynucleotide strands make up DNA
2
What are the main functions of DNA
Replication and proving the code for protein synthesis
What forms the backbone of a DNA strand
Deoxyribose sugar and phosphate group
What is the term used to describe how the bases pair up
Complimentary base pairing
Write out the process of DNA replication
Check book for answer
Why is it called semi conservative DNA replication
Because each new DNA molecule contains one original strand and one newly formed strand
What is the section of DNA that codes for one polypeptide called
Gene
How many amino acids are there in total
20
Describe the structure of RNA
A single stranded polynucleotide
What is the pentose sugar used in RNA
Ribose
What is the pentose sugar used in DNA
Deoxyribose
How many types of RNA are there
Three
What are the three types of RNA
Transfer RNA
Ribosomal RNA
Messenger RNA
Where is messenger RNA formed
In the nucleus
How is mRNA formed
In the nucleus by transcription of a strand of DNA
What is the function of mRNA
Carried the code for the polypeptide chain that will be formed in translation of protein synthesis
How does mRNA exit the nucleus
Through the nuclear pore
Where is rRNA found
In the cytoplasm
What is rRNA
Component of ribosome, combined with protein to form the ribosome
What is the function of tRNA
Transports amino acids to the ribosome for translation
What are the 2 features of tRNA
It has anti codon and an amino acid binding site
What is the word used to describe the shape of tRNA molecules
Clover leaf shape
Who proposed the semi conservative hypothesis
Meselson and stahl
In DNA replication what enzyme is used to break the hydrogen bonds
DNA helicase
What enzyme catalyses the addition of free DNA nucleotides to the exposed bases
DNA polymerase
What is the end product of DNA replication
Two identical DNA molecules each made up of one newly synthesised chain and one chain from the original molecule
How does one amino acid differ from another
The allkyl group
