DNA and Genetic Material.
Nucleac acids.
- There are 2 types of nucleic acids;
· DNA (deoxyribonucleic acid)
· RNA (ribonucleic acid)
(They are the only macromolecules able to serve as templates to produce precise copies of themselves) this is important so that genetic materials are preserved.
- Nucleic acids are polymers (made up of several repeated units).
- These units are called nucleotides.
Nucleotides
These are made of 3 parts:
· Sugars
· Phosphate (Carbon 5)
· Organic nitrogenous base (Carbon 1)
(The in DNA is called deoxyribase while in RNA this is called Ribose)
Nitrogenous bases
- Nitrogenous bases include:
· Purines = Adenine and Guanine
· Pyrimidines = Thymine, Cytosine and Uracil.
Purines
- Purines are relatively large.
- Because they are double-ringed molecules.
- They are found in both DNA and RNA.
- Examples of Purines are: Adenine (A) and Guanine (G).
- There are 2 types of nucleic acids;
· DNA (deoxyribonucleic acid)
· RNA (ribonucleic acid)
(They are the only macromolecules able to serve as templates to produce precise copies of themselves) this is important so that genetic materials are preserved.
- Nucleic acids are polymers (made up of several repeated units).
- These units are called nucleotides.
Nucleotides
These are made of 3 parts:
· Sugars
· Phosphate (Carbon 5)
· Organic nitrogenous base (Carbon 1)
(The in DNA is called deoxyribase while in RNA this is called Ribose)
Nitrogenous bases
- Nitrogenous bases include:
· Purines = Adenine and Guanine
· Pyrimidines = Thymine, Cytosine and Uracil.
Purines
- Purines are relatively large.
- Because they are double-ringed molecules.
- They are found in both DNA and RNA.
- Examples of Purines are: Adenine (A) and Guanine (G).
Pyrimidines
- Pyrimidines are relatively small.
- Because they are single-ringed molecules.
- Examples of Pyrimidines are: Cytosine (C) which is found in both DNA and RNA.
Thymine (T) which is found in DNA only.
and Uracil (U) which is found only in RNA.
Phosphodiester bonds: bonds that help Nucleic acids attach to each other.
These form by a condensation reaction.
The Phosphodiester bonds always forms between the hydroxyl (OH-) (Carbon 3) and the Phosphate (Carbon 5).
Nucleic Acids
The ends of nucleotides are always:
- A Phosphate from the 5’ end
- And a free OH- (hydroxyl) from the sugar end of the 3’ end.
DNA Structure
· The code of a DNA molecule consists of different combinations of the 4 types of nucleotides in specific sequences.
· Information is
- Used in the everyday metabolism of the organism.
- Passed on from one generation to another.
(The double helix is often compared to a spiral staircase: the strands (The sugar-phosphate backbone) being the “handrails of the staircase” and the base-pairs being the stairs.
· The two strands of nucleotides are anti parallel to each other: one is oriented 5’ to 3’ while the other 3’ to 5’.
· The two DNA strands are held by weak hydrogen bonds between complementary base pairs:
A and T
C and G
A and G are double ringed.
C and T are single ringed.
(This is to make sure that the diameter of the DNA Strand is constant).
Hydrogen Bonds in DNA
A and T have 2 hydrogen bonds.
C and G have 3 hydrogen bonds.
(There is no explanation why this is how it is).
2-ringed Purine pairs with a 1-ringed pyramidine: Keeping the diameter of each base pair equal.
- Pyrimidines are relatively small.
- Because they are single-ringed molecules.
- Examples of Pyrimidines are: Cytosine (C) which is found in both DNA and RNA.
Thymine (T) which is found in DNA only.
and Uracil (U) which is found only in RNA.
Phosphodiester bonds: bonds that help Nucleic acids attach to each other.
These form by a condensation reaction.
The Phosphodiester bonds always forms between the hydroxyl (OH-) (Carbon 3) and the Phosphate (Carbon 5).
Nucleic Acids
The ends of nucleotides are always:
- A Phosphate from the 5’ end
- And a free OH- (hydroxyl) from the sugar end of the 3’ end.
DNA Structure
· The code of a DNA molecule consists of different combinations of the 4 types of nucleotides in specific sequences.
· Information is
- Used in the everyday metabolism of the organism.
- Passed on from one generation to another.
(The double helix is often compared to a spiral staircase: the strands (The sugar-phosphate backbone) being the “handrails of the staircase” and the base-pairs being the stairs.
· The two strands of nucleotides are anti parallel to each other: one is oriented 5’ to 3’ while the other 3’ to 5’.
· The two DNA strands are held by weak hydrogen bonds between complementary base pairs:
A and T
C and G
A and G are double ringed.
C and T are single ringed.
(This is to make sure that the diameter of the DNA Strand is constant).
Hydrogen Bonds in DNA
A and T have 2 hydrogen bonds.
C and G have 3 hydrogen bonds.
(There is no explanation why this is how it is).
2-ringed Purine pairs with a 1-ringed pyramidine: Keeping the diameter of each base pair equal.
DNA
- Sugar is deoxiribose - Bases include A, T, C and G - DNA is double stranded - Function (Stored genetic material) |
RNA
- Sugar is ribose - Bases include A,U,C and G - RNA is single stranded. - Function (Reads the information on DNA) (Protein synthesis) |
Other Nucleic Acids
· ATP: Adenosine triphosphate: Is the primary energy currency in cells.
· NAD and FAD: Electron carriers for many reactions.
Chromosomes
Chromosomes are thread like structures that make up the DNA.
They become visible only during cell division when the DNA becomes tightly packed.
Each chromosome is made up of DNA tightly coiled many times around proteins called histones. These histones help with the tightly packing of DNA.
· ATP: Adenosine triphosphate: Is the primary energy currency in cells.
· NAD and FAD: Electron carriers for many reactions.
Chromosomes
Chromosomes are thread like structures that make up the DNA.
They become visible only during cell division when the DNA becomes tightly packed.
Each chromosome is made up of DNA tightly coiled many times around proteins called histones. These histones help with the tightly packing of DNA.
Human Chromosomes
· In humans: somatic (body) cells contain two complete sets of chromosomes, this is known as a diploid (2n).
· We find 23 pairs of chromosomes in humans.
· Somatic cells are formed by the process of mitosis.
· In humans: somatic (body) cells contain two complete sets of chromosomes, this is known as a diploid (2n).
· We find 23 pairs of chromosomes in humans.
· Somatic cells are formed by the process of mitosis.
· Sex cells (gametes) have only one set of chromosomes
(in humans only 23 chromosomes) and therefore such cells are haploid (n)
· Sex cells are unique and are produced by the process of meiosis.
(in humans only 23 chromosomes) and therefore such cells are haploid (n)
· Sex cells are unique and are produced by the process of meiosis.