dna dna is often called the blueprint of life. in simple terms, dna contains the instructions for...
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DNADNA DNA is often
called the blueprint of life.
In simple terms, DNA contains the instructions for making proteins within the cell.
Why do we study Why do we study DNADNA??We study DNA for We study DNA for
many reasons:many reasons: its central its central
importance to importance to all life on Earthall life on Earth
medical benefits medical benefits such as cures such as cures for diseasesfor diseases
better food better food crops.crops.
Chromosomes and Chromosomes and DNADNA
Chromosomes Chromosomes are made up of are made up of genes.genes.
Genes are Genes are made up of a made up of a chemical called chemical called DNA.DNA.
The Shape of the The Shape of the MoleculeMolecule
DNA is a very DNA is a very long molecule.long molecule.
The basic shape The basic shape is like a twisted is like a twisted ladder or zipper.ladder or zipper.
This is called a This is called a double helix.double helix.
OneOne Strand of DNAStrand of DNA
The backbone of The backbone of the molecule is the molecule is alternating alternating phosphatephosphate and and deoxyribosedeoxyribose, a , a sugar, parts.sugar, parts.
The teeth are The teeth are nitrogenousnitrogenous basesbases..
phosphate
deoxyribose
bases
The Double Helix The Double Helix MoleculeMolecule
The DNA double The DNA double helix has two helix has two strands twisted strands twisted together.together.
(In the rest of (In the rest of this unit we will this unit we will look at the look at the structure of one structure of one strand.)strand.)
The Nucleus
DNA is located in the nucleus
DNAdeoxyribonucleic acid
The code of life
One deoxyribose together with its phosphate and base make
a nucleotide.
C C
C
OPhosphate
O
CC
O -P OO
O
O -P OO
O
O -P OO
O
Nitrogenous base
Deoxyribose
The Basics
Each side of the ladder is made up of nucleic acids.
The backbone is a phosphate and a sugar
The rung of the ladder is the nitrogen base.
Hydrogen BondsHydrogen Bonds When making When making
hydrogen bonds, hydrogen bonds, cytosine always cytosine always pairs up with pairs up with guanine, guanine,
And adenine And adenine always pairs up always pairs up with thymine.with thymine.
C
C
CC
N
N
N
N
N
C
C
C
C
C
N
N
OO
OO
C
FourFour nitrogenous nitrogenous basesbases
Cytosine Cytosine C C Thymine Thymine TT
Adenine Adenine AA Guanine Guanine GG
DNA has four different bases:DNA has four different bases:
Two Stranded DNATwo Stranded DNA Remember, DNA Remember, DNA
has two strands has two strands that fit together that fit together something like a something like a zipper.zipper.
The teeth are The teeth are the nitrogenous the nitrogenous bases but why bases but why do they stick do they stick together?together?
• Adenine and Adenine and Thymine always join Thymine always join
togethertogether
A -- TA -- T• Cytosine and Cytosine and
Guanine always join Guanine always join togethertogether
C -- GC -- G
Copying DNA Step 1- DNA unwinds and
unzips Step 2- Once the molecule
is separated it copies itself. The new strand of DNA has
bases identical to the original
DNA by the DNA by the numbersnumbers Each cell has about Each cell has about
2 m of DNA.2 m of DNA. The average human The average human
has 75 trillion cells.has 75 trillion cells. The average human The average human
has enough DNA to has enough DNA to go from the earth go from the earth to the sun more to the sun more than 400 times.than 400 times.
DNA has a DNA has a diameter of only diameter of only 0.000000002 m.0.000000002 m.
The earth is 150 billion mThe earth is 150 billion mor 93 million miles from or 93 million miles from the sun.the sun.
What’s the main difference between DNA and RNA
RNA In RNA Thymine is
replaced by Uracil A-U (RNA) not A-T (DNA)
Quiz Time
IF the DNA strand is GTACCAGATTAGC
What would the RNA strand be?