Nucleic acids
One of the characteristics of living organisms is to reproduce. Reproduction means to produce healthy offspring to keep the species. Living things use nucleic acids to replicate themselves. Our chromosomes are made of Deoxyribonucleic Acid (DNA) tightly wound, attached to a structural protein called histone.
DNA Replication..
During cell division, DNA replicates itself to make cells with the same traits (genetic characteristics) as the first one. DNA encodes to produce amino acids that bind together to build proteins. To produce proteins, DNA must be copied with the help or Ribonucleic Acid (RNA).
Nucleotides are substances made of sugar, phosphate and nitrogenous bases or heterocyclic bases that can be classified as Pyrimidines (Molecules with a single ring) and purines (molecules with two rings)
Those nitrogenous bases are attached to a strand of a 5 carbon sugar called ribose for RNA and deoxyribose for DNA. Each molecule has a phosphate attached to it.
The nucleic acids that ROCK!!
RNA structure
DNA structure
As you may see in the drawing, adenine binds to thymine and cytosine binds to guanine.
In the RNA molecule, thymine is replaced by uracil.
Protein synthesis: DNA carries the instructions to build up aminoacids, that bind to make peptides that are the base of proteins. The arrangement of the nucleotides along the DNA chain gives a specific code to build a determined protein. To make this process DNA is assisted by RNA. Each strand of DNA is used as a template for RNA to make a copy of it and to send it to the ribosomes, the protein factory of a cell.
introductory questions
1. How can a cell make copies of itself?
2. Why DNA and RNA are called "nucleic acids"?
3. How are DNA and RNA alike and different?
4. Why is it important to have proteins in our diet?
5. Why do cells synthesize proteins?
6. when is it necesary for DNA to copy itself?
Activity
- Use cardboard and clay of different colors to build up a model of the molecules of DNA and RNA, and the structure of a chromosome.
LAB AT THE KITCHEN: DNA EXTRACTION FROM TOMATO CELLS
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