Nucleotides:
- Biological molecules that participate in nearly all biochemical
processes.
- They are phosphate esters of pentose sugars, where a nitrogenous
base is linked to the carbon 1 atom of the sugar.
- A phosphate group is linked to either carbon 3 or 5 of the sugar.
- Joined by covalent bonds formed by condensation reactions
- Form the monomers of nucleic acids, DNA and RNA. In RNA the nucleotide sugar is
ribose and in DNA it is deoxyribose.
- Nucleotides can become phosphorylated nucleotides when they contain more than one
phosphate group. ADP (adenosine diphosphate) and ATP (adenosine triphosphate). ATP
is an energy rich end product of most energy releasing biochemical pathways, it's used
to drive most energy requiring metabolic processes in cells.
- They can be components of many coenzymes. Adenine nucleotides are components of
the coenzyme NADP - nicotinamide adenine dinucleotide phosphate which is used in
photosynthesis and of NAD - nicotinamide adenine dinucleotide) which is a coenzyme
used in respiration. And of FAD - flavine adenine dinucleotide and coenzyme A (both
involved in respiration.)
Four possible nitrogenous bases:
- URACIL
- GUANINE
- THYMINE
- ADENINE
DNA
- Found in the nuclei of all eukaryotic cells within the cytoplasm of prokaryotic cells and is
also inside some types of viruses
- It is the hereditary material and carries coded instructions used in the development and
functioning of all known living organisms
- DNA is one of the important macromolecules that make the structure of living organisms
the others being proteins, carbohydrates and lipids.
Structure:
- DNA is a polymer made up of many repeating monomers called nucleotides
- A molecule of DNA consists of two polynucleotide strands that coils, wraps around
histone proteins
- Two strands run in opposite directions, so they are described as antiparallel
- Each DNA nucleotide consists of a phosphate group, deoxyribose sugar and one of the
four nitrogenous bases (AGTC)
- The covalent bond between the sugar residue and the phosphate group in a nucleotide
is also called a phosphodiester bond.
, - These bonds are broken when polynucleotides are
synthesised.
- DNA molecules are long are they carry lots of encoded
genetic information.
RNA
- Single stranded polynucleotide
- The pentose sugar is ribose (instead of deoxyribose
like in DNA)
- The nitrogenous base uracil, which is a pyrimidine
replaces the base thymine.
- The chain is much shorter
- There are three forms of RNA, Messenger RNA (mRNA) transfer RNA (tRNA) and
ribosomal RNA (rRNA)
Difference between deoxyribose and ribose:
- Deoxyribose has one less oxygen on the second carbon. Where ribose has a hydroxyl
group, deoxyribose only has a H.
Purines and pyrimidines:
- DNa consists of four types of nucleotide.
- In each nucleotide the phosphate and sugar groups are the same but the nitrogenous
base differs.
- It could be a purine (adenine or guanine) which both have two rings
- or a pyrimidine (thymine or cytosine) which both have just one ring.
Hydrogen bonds:
- Two antiparallel DNA strands are joined to each other by hydrogen bonds between the
nitrogenous bases.
Rules:
- Adenine always pairs with thymine by two hydrogen
bonds
- Guanine always pairs with cytosine by three
hydrogen bonds
- A purine always pairs with a pyrimidine, giving equal
sized rungs on the ladder
- They then twist around into a double helix. This give
the molecule stability.
- Hydrogen bonds allow the molecule to unzip for
transcription.
Backbone:
- Upright part of the DNA molecule that resembles a ladder is formed by the sugar
phosphate backbones of the strands
- Biological molecules that participate in nearly all biochemical
processes.
- They are phosphate esters of pentose sugars, where a nitrogenous
base is linked to the carbon 1 atom of the sugar.
- A phosphate group is linked to either carbon 3 or 5 of the sugar.
- Joined by covalent bonds formed by condensation reactions
- Form the monomers of nucleic acids, DNA and RNA. In RNA the nucleotide sugar is
ribose and in DNA it is deoxyribose.
- Nucleotides can become phosphorylated nucleotides when they contain more than one
phosphate group. ADP (adenosine diphosphate) and ATP (adenosine triphosphate). ATP
is an energy rich end product of most energy releasing biochemical pathways, it's used
to drive most energy requiring metabolic processes in cells.
- They can be components of many coenzymes. Adenine nucleotides are components of
the coenzyme NADP - nicotinamide adenine dinucleotide phosphate which is used in
photosynthesis and of NAD - nicotinamide adenine dinucleotide) which is a coenzyme
used in respiration. And of FAD - flavine adenine dinucleotide and coenzyme A (both
involved in respiration.)
Four possible nitrogenous bases:
- URACIL
- GUANINE
- THYMINE
- ADENINE
DNA
- Found in the nuclei of all eukaryotic cells within the cytoplasm of prokaryotic cells and is
also inside some types of viruses
- It is the hereditary material and carries coded instructions used in the development and
functioning of all known living organisms
- DNA is one of the important macromolecules that make the structure of living organisms
the others being proteins, carbohydrates and lipids.
Structure:
- DNA is a polymer made up of many repeating monomers called nucleotides
- A molecule of DNA consists of two polynucleotide strands that coils, wraps around
histone proteins
- Two strands run in opposite directions, so they are described as antiparallel
- Each DNA nucleotide consists of a phosphate group, deoxyribose sugar and one of the
four nitrogenous bases (AGTC)
- The covalent bond between the sugar residue and the phosphate group in a nucleotide
is also called a phosphodiester bond.
, - These bonds are broken when polynucleotides are
synthesised.
- DNA molecules are long are they carry lots of encoded
genetic information.
RNA
- Single stranded polynucleotide
- The pentose sugar is ribose (instead of deoxyribose
like in DNA)
- The nitrogenous base uracil, which is a pyrimidine
replaces the base thymine.
- The chain is much shorter
- There are three forms of RNA, Messenger RNA (mRNA) transfer RNA (tRNA) and
ribosomal RNA (rRNA)
Difference between deoxyribose and ribose:
- Deoxyribose has one less oxygen on the second carbon. Where ribose has a hydroxyl
group, deoxyribose only has a H.
Purines and pyrimidines:
- DNa consists of four types of nucleotide.
- In each nucleotide the phosphate and sugar groups are the same but the nitrogenous
base differs.
- It could be a purine (adenine or guanine) which both have two rings
- or a pyrimidine (thymine or cytosine) which both have just one ring.
Hydrogen bonds:
- Two antiparallel DNA strands are joined to each other by hydrogen bonds between the
nitrogenous bases.
Rules:
- Adenine always pairs with thymine by two hydrogen
bonds
- Guanine always pairs with cytosine by three
hydrogen bonds
- A purine always pairs with a pyrimidine, giving equal
sized rungs on the ladder
- They then twist around into a double helix. This give
the molecule stability.
- Hydrogen bonds allow the molecule to unzip for
transcription.
Backbone:
- Upright part of the DNA molecule that resembles a ladder is formed by the sugar
phosphate backbones of the strands
