A1.2 Nucleic Acids Flashcards
What is a nucleotide?
What are the three components of a nucleotide?
What elements can they contain?
What are the types of nucleic acids?
The monomer of a nucleic acid:
1. Nitrogenous base
2. Sugar (ribose or deoxyribose)
3. Phosphate
CHONP
- DNA
- RNA
What is DNA? Why is it important?
DNA is deoxyribose nucleic acid and it carries the genetic code.
DNA is universal
What is the purpose of DNA? How does it do this?
It’s purpose is to use those genes to make proteins.
It also passes information between generations.
DNA is a sequence of bases that form a code which stores all the information needed to make proteins and is then translated by RNA.
What are the nitrogenous bases?
Which are double and single rings? What are the names for this?
How are they attached to nucleotides?
How are they attached to each other?
Adenine (Purine - Double)
Thymine (Pyrimidine - Single)
Guanine (Purine - Double)
Cytosine (Pyrimidine - Single)
Uracil (Pyrimidine - Single)
Through covalent bonds at carbon 1
Through complementary base pairing and hydrogen bonds (double or single)
How do nucleotides join together?
What carbons do they attach at?
Nucleotides join by condensation reactions, which also makes water.
The phosphate group attaches to the 5th carbon of the same nucleotide and join the 3rd carbon of the nucleotide it is joining.
Explain the structure of DNA
- Antiparallel (5’ and 3’)
- Sugar and phosphate form the backbone of DNA
- Double stranded helix joined by H bonds
- Can vary in length and sequences of bases
- The sugar and phosphates are bonded by covalent (phosphodiester) bonds
What are the differences between RNA and DNA?
Bases:
RNA - AUCG
DNA - ATGC
Sugar:
RNA - Ribose
DNA - Deoxyribose
Strands:
RNA - 1
DNA - 2
What is complimentary base pairing? What is it based on?
- When bases pair up with each other in a consistent way. A base will only pair with one other base.
(AT Glorias Crib)
Complimentary base pairing between bases of the old and the new DNA ensures in two identical molecules being formed
It is based on hydrogen bonding.
How is DNA so useful? What is its capacity for stroing information and why?
- Huge diversity of possible DNA base sequences
- varying lengths of DNA - arranged in any order means there is are endless different sequences and combinations
- DNA can archive a staggering amount of information in an almost inconceivably small volume.
- Has a practically limitless capacity
How is DNA evidence of common ancestry?
All organisms use DNA and RNA as genetic material and the genetic code by which proteins are synthesised is universal.
The base sequence of DNA or different organisms can be compared to show common ancestry
BUT
Over the course of millions of years, mutations accumulate and the differences between base sequences shows the degree of evolutionary divergence.
More changes/differences suggests more time has passed since two species diverged.
What is a nucleosome?
The structural unit of a chromosome.
It is made of 8 histone proteins with a DNA wrapped around it (bonded to the proteins)
An extra histone is on the outside and acts as a linker protein as well as the linker DNA to join the nucleosomes together.
Outline how it is possible for these universal DNA molecules to store varied genetic information both within species and between species.
- There are a huge number of different base sequences possibe (in a DNA molecule or a genome) which provides variety in the genetic information / genomes.
- Different lengths of DNA, or different sequences of the bases causes variation in the genetic information stored in a genome
- Base sequence is a code/can determine protein structure/amino acid sequence and the characteristics of an organism.
- Within species there each organism has many genes with a lot of similarity in the DNA sequence and this gives the species it’s recognisable characteristics.
- There is some variation in the sequence of DNA in some genes even within species giving elements of variation in characteristics.
- Between species there are more differences in the DNA sequence, which gives more variation in characteristics.
- Differences in the DNA sequence between two species can prevent reproduction between members of two different species.
What is the charge of DNA?
DNA is slightly negative
