dna review objective: to review the structure and function of dna
TRANSCRIPT
DNA REVIEW
Objective: To review the structure and function of DNA.
IntroductionIntroduction• You are made up of billions of cells and each cell has its own unique set of 46 chromosomes.• A chromosome is just one big long chain of DNA! • DNA (Deoxyribonucleic Acid) contains all the information that determines who you are!
DNADNA• DNA DNA is often called the
blueprint of life..
• DNADNA contains the instructions for making proteins within the cell.
Chromosomes and DNAChromosomes and DNA
• Our genes are on our chromosomes.
• Chromosomes are made up of DNA.
The Shape of the MoleculeThe Shape of the Molecule
• DNA is a very long polymer. (chain of nucleic acids)
• Its basic shape is like a twisted ladder or zipper.
• It is called a double helix.
The Double Helix MoleculeThe Double Helix Molecule
• The DNA double helix has two strands twisted together.
One Strand of DNAOne Strand of DNA• The backbone of
the molecule is alternating phosphates and deoxyribose sugar.
• Nitrogenous bases are attached to the backbone.
phosphate
deoxyribose
nitrogenous bases
Four nitrogenous basesFour nitrogenous bases
• Cytosine C• Thymine T
• Adenine A
• Guanine G
DNA has four different bases:
TThymine and hymine and CCytosine are ytosine are pyrimidinespyrimidines..
• Thymine and cytosine each have Thymine and cytosine each have one one ringring of carbon and nitrogen atoms. of carbon and nitrogen atoms.
C
C
C
C
N
N
OO
N
cytosinecytosine
C
C
C
C
N
N
OO
OO
thyminethymine
C
AAdenine and denine and GGuanine are uanine are purinespurines..
• Adenine and guanine each have Adenine and guanine each have two two ringsrings of carbon and nitrogen atoms. of carbon and nitrogen atoms.
C
C
C
C
N
N
N
AdenineAdenine N
N
C
C
C
C
C
N
NOO
N
GuanineGuanine N
N
C
Two Stranded DNATwo Stranded DNA• Remember, DNA
has two strands that fit together something like a zipper.
• The teeth are the nitrogenous bases but why do they stick together?
C
C
C
C
N
N
OO
N
C
C
C
C
N NOO
N
N
N C
Hydrogen BondsHydrogen Bonds• The bases attract each
other because of hydrogen bonds.
• Hydrogen bonds are weak but there are millions and millions of them in a single molecule of DNA.
To the right: Cytosine and Guanine hydrogen bonded
Hydrogen Bonds, Hydrogen Bonds, cont.
• When making hydrogen bonds:– Cytosine always
pairs up with Guanine.
– Adenine always pairs up with Thymine.
To the right: Adenine and Thymine hydrogen
bonded
C
C
CC
N
N
N
N
N
C
C
C
C
C
N
N
OO
OO
C
Important:Important:
• Adenine and Thymine always join together
A T
• Cytosine and Guanine always join together
C G
BRAINPOP DNA
www.brainpop.com