What is DNA

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Transcript What is DNA

DNA stands for:
D: Deoxyribose
N: Nucleic
A: Acid
DNA is too
small to see,
but under a
microscope it
looks like a
twisted up
ladder!
Every living thing has DNA. That means
that you have something in common with a
zebra, a tree, a mushroom and a beetle!!!!
DEOXYRIBONUCLEIC ACID
STORES AND PASSES ON
GENETIC INFORMATION
FROM ONE GENERATION TO
ANOTHER .
Nucleotides
• Consist of a five-carbon sugar
• Phosphate Group
• Nitrogenous base
Polynucleotides
• Nucleotide monomers
are linked into long
chains
– These chains are
called
polynucleotides, or
DNA strands
– A sugar-phosphate
backbone joins them
together
Backbone
Nucleotide
Bases
(a) DNA strand
Figure 3.26a
Two strands of DNA join
together to form a
double helix
Base
pair
Figure 3.26b
(b) Double helix
REPLICATION
MAKING ANEW COPY OF DNA
Why cells need to copy DNA?
TYPES OF REPLICATION
How big is the Human Genome?
• Contains over 3 billion base pairs
• One meter long when fully streched
• Size of 6 billion genomes, one from each person on
earth = 1 meter long human hair
•
150000 times under
•
electron micrograph
What is a Gene?
One Gene
One Protein
Over 100,000 genes reside in the human genome
• Each gene (DNA sequence) contains the genetic
code of a protein (amino acid sequence)
• Gene to protein
transcription
translation
From DNA to Protein
• Transcription
– Copies and splices a gene (single strand of DNA
sequence) into an mRNA sequence
• Translation
– Converts mRNA into a protein (string of amino acids)
• Promoter
– tells the cell when to turn on the gene and how much transcription
will occur