3.1.5.1 Structure of DNA and RNA Flashcards
DNA function
holds genetic information in all living cells
RNA function
transfers genetic information
from DNA to the ribosomes
in all living cells
What are Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)?
Important information-carrying molecules
What are ribosomes formed from
RNA and proteins
Nucleotide components
Phosphate group
Pentose sugar
Nitrogen containing organic base
Nucleotides
Complex chemicals
made up of an organic base, a sugar and a phosphate
They are the basic units of which the nucleic acids DNA and RNA are made.
The components of a DNA nucleotide
Phosphate group
Deoxyribose sugar
Nitrogen containing organic base
└adenine, cytosine, guanine, thymine
The components of a RNA nucleotide
Phosphate group
Ribose sugar
Organic base
└adenine, cytosine, guanine, uracil
RNA
Bases
4 bases Specific and complimentary base pairs └purine to pyrimidine └purine= A,G └prymidine= C, U └A + U, C + G └purine= larger molecules └double ring structure └prymidine= smaller base └single ring structure
A condensation reaction between two nucleotides forms..
…a phosphodiester bond
DNA molecule structure
Double helix 2 poly nucleotide chains └sugar phosphate backbones └antiparralel └strands run in opposite rirections parallel to each other └5’-3’ └phosphodiester bonds └hydrogen bonds between specific complementary base pairs
DNA molecule
Bonds
Held together by hydrogen bonds
└2 bonds between A + T
└3 bonds between C + G
└specific and complimentary base pairs
Phosphodiester bond
└in sugar phosphate backbone
DNA
Complimentary base pairing
4 bases Specific and complimentary base pairs └purine to pyrimidine └purine= A,G └prymidine= C, T └A + T, C + G └purine= larger molecules └double ring structure └prymidine= smaller base └single ring structure
Purine
Definition + examples
E.g. Adenine and guanine
nitrogenous bases consisting of a double ring structure
Prymidine
Definition + examples
E.g. Thymine, cytosine and uracil
nitrogenous bases consisting of a single ring structure.
DNA
Location
Prokaryotic- cytoplasm
Eukaryotic- nucleus
Mitochondria, chloroplasts
DNA
Structure to function
Very stable - can pass through generations without change
- weak hydrogen bonds: so double strand separates more easily for replication
- Extremely large molecule and therefore carries and immense amount of genetic information.
- By having base pairs within helical cylinder of deoxyribose-phosphate backbone the genetic information is protectted from chemical and physical forces.
- double standed: so replication can occur semi-conservatively / strands can act as template / complementary base pairings mean accurate replication/identical copies can be made
- sugar-phosphate backbone: provides stability/strength / protects the bases
- large: store a lot of information
- helix: so compact
RNA molecule
structure
Relatively short polynucleotide chain
RNA
location
Eukaryotes- nucleus +cytoplasm
RNA
Types
mRNA (messenger ribonucleic acid)
└codes for chemical blueprint of protein in protein synthesis
└carries the complementary DNA/genetic information out of the nucleus to the ribosome for protein synthesis
tRNA ( transfer ribonucleic acid)
└protein synthesis- transports specific amino acid to the ribosome to be added onto the growing polypeptide chain
└carries amino acids
rRNA (ribosomal ribonucleic acid)
└ribonucleic acid component of the ribosome
the relative simplicity of DNA led…
many scientists to doubt that it carried the genetic code
DNA vs RNA
DNA= double stranded (double helix held together by H bonds) RNA= single stranded
DNA= deoxyribose sugar RNA= ribose sugar
DNA= bases- ATCG RNA= bases- AUCG
DNA= long RNA= relatively short
