the secret code. genes genes, which are sections of dna, are known to: carry information from one...
DESCRIPTION
How do we know that all of our genetic information comes from DNA? Thanks to many scientists and many experiments over the last ≈ 80 years. Griffith Hershey and Chase Franklin Watson and CrickTRANSCRIPT
The Secret Code
Genes• Genes, which are sections of DNA, are
known to:– Carry information from one generation to
the next.– Put that information to work by determining
the heritable characteristics of organisms.– Be easily copied, because all of a cell’s
genetic information is replicated (copied) every time a cell divides.
How do we know that all of our genetic information
comes from DNA?
Thanks to many scientists and many experiments over the last ≈ 80 years.
• Griffith• Hershey and Chase• Franklin• Watson and Crick
DNA• Nucleic Acid:
Deoxyribonucleic Acid (polymer)
• Made up of units (monomers) called nucleotides.– Three components:
•5-carbon sugar: Deoxyribose
•A phosphate group•A nitrogenous base
NucleotideNucleotide
DNA Structure• Called a double
helix– Twisted Ladder– Backbone (sides) :
5-carbon sugar and phosphate groups
– Rungs: nitrogenous bases
Nitrogenous bases• Our alphabet has 26 letters
– Can create many different words many different sentences billions of different books of information.
• DNA’s alphabet has 4 letters– A, T, C, and G– Create 3 letter words Amino acids
proteins billions of different organisms
Nitrogenous bases• Purines:
– Adenine
– Guanine
• Pyrimidines:– Thymine
– Cytosine
DNA Replication
Replication: The process of making a copy of DNAReplication: The process of making a copy of DNAThe “parent” molecule has two complementary The “parent” molecule has two complementary strands of DNA.strands of DNA.Each is base paired by hydrogen bonding with its Each is base paired by hydrogen bonding with its specific partner:specific partner:
A with T and G with CA with T and G with C
DNA Unzips
The first step in replication is the separation of the The first step in replication is the separation of the two strands. two strands.
An enzyme called DNA helicase unzips DNAAn enzyme called DNA helicase unzips DNA
New nucleotides added
Each parental strand now serves as a template Each parental strand now serves as a template that determines the order of the bases along a new that determines the order of the bases along a new complementary strand.complementary strand.
an enzyme called DNA polymerase adds the an enzyme called DNA polymerase adds the basesbases
Gaps are closed (zipped closed)
The nucleotides are connected to form the sugar-The nucleotides are connected to form the sugar-phosphate backbones of the new strands. DNA phosphate backbones of the new strands. DNA ligaseligaseEach “daughter” DNA molecule consists of one Each “daughter” DNA molecule consists of one parental strand and one new strand….semi-parental strand and one new strand….semi-conservativeconservative
• Reviewing DNA Replication• Replication #2• Replication #3 and more
Here are some interesting Facts!
• A single strand of DNA (one chromosome) is about 2 inches long when uncoiled.
• Each human cell contains 46 chromosomes (6 to 9 feet of DNA)
• Your body contains 75-100 trillion of cells.• All of your DNA (when uncoiled and tied
together) could make about 6000 trips from the Earth to the Moon.
A few more cool things about DNA
• It takes about 8 hours for one of your cells to copy all of its DNA.
• Our entire DNA sequence is called a Genome…and there is an estimated 3,000,000,000 DNA bases
• This would take up about 3GB of storage• If you could type 60 wpm, 8 hours/day…it would
take you 50 years to type this.• 99.9% of our DNA is the same…it is the 0.01% that
makes you who you are!