maybe you know this … all living things contain deoxyribonucleic acid (dna). dna, in humans, is...
TRANSCRIPT
Maybe you know this …
All living things contain deoxyribonucleic acid (DNA).
DNA, in humans, is located in the nucleus of all of our cells.*
The DNA is arranged in the nucleus as organized packets known as chromosomes.
Packaging of DNAChromatin
Combination of DNA and proteinMass of very long fibres
ChromosomeOne long, condensed DNA moleculeContains hundreds or thousands of genes
DNA is wrapped tightly around proteins called histones
DNA and histone packages form structures resembling beads called nucleosomes
AMAZING DNA FACTS…AMAZING DNA FACTS…DNA from a single DNA from a single
human cell extends in a human cell extends in a single thread for almost single thread for almost 2 metres long!!!2 metres long!!!
we have about 50 trillion we have about 50 trillion cells, so DNA would stretch cells, so DNA would stretch to the sun not once, but …to the sun not once, but …
A HISTORY OF DNAA HISTORY OF DNA
Discovery of the DNA double helixDNA double helix
A. Friedrich Miescher – started investigating a compound he found in the nucleus of cells, called it “nuclein”
(1869)
B. Rosalind Franklin - X-ray photo of DNA.
(1952)
C. Watson and Crick - described the DNA molecule from Franklin’s X-ray.(1953)
DNA StructureDNA consists of two molecules that are
arranged into a ladder-like structure called a Double Helix.
A molecule of DNA is made up of millions of tiny subunits called Nucleotides.
Each nucleotide consists of:1. Phosphate group2. A ring-shaped sugar called
deoxyribose3. Nitrogenous base
Nucleotides
Phosphate
Pentose
Sugar
Nitrogenous
Base
NucleotidesThe phosphate and sugar form the
backbone of the DNA molecule, whereas the bases form the “rungs”.
There are four types of nitrogenous bases.
Nucleotides
A
Adenine
T
Thymine
G
Guanine
C
Cytosine
NucleotidesEach base will only bond with one
other specific base.
Adenine (A)Thymine (T)
Cytosine (C)Guanine (G)
Form a base pair.
Form a base pair.
DNA StructureBecause of this complementary base
pairing, the order of the bases in one strand determines the order of the bases in the other strand.
ACCTTGCCATTGGAACGGTA
Purines and Pyrimidines
G
G
A
T
T
A
A
C
T
G
C
A
T
C
Nucleotide Base pair
DNA StructureA gene is a section of DNA that codes
for a protein.
Each unique gene has a unique sequence of bases.
This unique sequence of bases will code for the production of a unique protein.
It is these proteins and combination of proteins that give us a unique phenotype.
Protein
DNA
Gene
Trait
Preparing and Dividing DNAProcess of copying DNA molecule
called DNA replicationAfter replication and chromatin fibres
have condensed into chromatids, cell enters division
Each chromosome now consists of two identical joined copies called sister chromatids
Joined by a centromere
one chromosome
(unduplicated)
one chromosome(duplicated)
Centromere
Sister Chromatids
Telomere: protective end cap of chromosome