Chapter 3- Sec 1 What is DNA? Life Science. DNA What does DNA stand for? Deoxyribonucleic Acid !!! De/oxy/ribo/nucleic Acid Deoxyribonucleic Acid,
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Chapter 3- Sec 1What is DNA?
Life Science
DNA
What does DNA stand for? Deoxyribonucleic Acid !!! De/oxy/ribo/nucleic Acid
Deoxyribonucleic Acid, or DNA, is a code that contains information that an organism needs to grow and function.
Discovering DNA In 1952, Rosalind Franklin discovered
that DNA is two chains of molecules in a spiral form.– Used X-Rays
In 1953, James Watson and Francis Crick created an accurate model of DNA.– Model was similar to a ladder
The structure of DNA is similar to a twisted ladder.
Thieves?
Watson
Crick
The structure of DNA is a similar to a twisted ladder
(double helix)…
DNA Structure The structure of the “Ladder”…
The sides of the ladder are made up of Deoxyribose (sugar) and Phosphate.
The rungs (or steps) of the ladder are made up of nitrogen bases (ATCG).
The steps of the ladder are made of pairs of smaller molecules called Nitrogen Bases.
These bases “fit together” in the combination:– Adenine fits with Thymine
– Cytosine fits with Guanine Connected by a Hydrogen bond
A molecule of DNA is formed by millions of nucleotides joined together in a long chain
PO4
PO4
PO4
PO4
sugar-phosphate backbone
+ bases
Joined nucleotides 7
What does ATCG stand for???
DNA Replication When a cell divides, the DNA
“code” is copied (or duplicated) and passed to the new cells.
The DNA duplicates itself by unwinding and separating the bases forming 2 strands.
http://www.hhmi.org/biointeractive/media/DNAi_replication_vo1-lg.mov
DNA makes up chromosomes–Each chromosome is composed
of a long strand of DNA wrapped around.
Human Body cells have 46 chromosomes or 23 pairs.
<stop here>
How many chromosomes are in other living things?
Toucan – 104
Goldfish – 94
Dogs – 78 chromosomes
Horse- 64
Banana- 22 chromosomes
Jack Jumper Ant- only 2 chromosomes!
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