dna chapter 8 section 3 p. 224- 229. a. dna a chemical that contains the information that an...
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DNADNA
Chapter 8 Section 3Chapter 8 Section 3
p. 224- 229p. 224- 229
A. DNAA. DNA
• A A ChemicalChemical that contains the that contains the information that an organism information that an organism needs to grow and functionneeds to grow and function
• 1. Watson and 1. Watson and CrickCrick made the first made the first accurate model of DNA in 1953.accurate model of DNA in 1953.
A. DNAA. DNA
• 2. The Structure of DNA is similar 2. The Structure of DNA is similar to a to a Twisted LadderTwisted Ladder (a double (a double helix)helix)
A. DNAA. DNA
A. A. DNADNA 2.The Structure of DNA is similar to a 2.The Structure of DNA is similar to a
Twisted LadderTwisted Ladder (a double helix) (a double helix)
• a. The sides of the a. The sides of the ladder are made ladder are made up of up of sugar-sugar-phosphate phosphate moleculesmolecules
a. The sides of the a. The sides of the ladder are made ladder are made up of up of sugar-sugar-phosphate phosphate moleculesmolecules
• b. The rungs of b. The rungs of the ladder are the ladder are made up of made up of nitrogen basesnitrogen bases
A. A. DNADNA 2.The Structure of DNA is similar to a 2.The Structure of DNA is similar to a
Twisted LadderTwisted Ladder (a double helix) (a double helix)
• There are 4 There are 4 Nitrogen Bases that Nitrogen Bases that make the Rungs make the Rungs (steps) of the ladder (steps) of the ladder – – – IN DNA, IN DNA, – AdenineAdenine always always
bonds to bonds to ThymineThymine– Guanine Guanine always always
bonds to bonds to CytosineCytosine
A. A. DNADNA 2.The Structure of DNA is similar to a 2.The Structure of DNA is similar to a
Twisted LadderTwisted Ladder (a double helix) (a double helix)
• 3. Before a Cell 3. Before a Cell divides, its DNA divides, its DNA duplicates itself by duplicates itself by unwinding and unwinding and separating its sides, separating its sides, then forming then forming new new sides.sides.
A. A. DNADNA 2.The Structure of DNA is similar to a 2.The Structure of DNA is similar to a
Twisted LadderTwisted Ladder (a double helix) (a double helix)
B. GenesB. Genes
• Sections of Sections of DNADNA on a chromosome on a chromosome
B. GenesB. Genes
• 1. Contain instructions for making 1. Contain instructions for making specific specific proteinsproteins
BB22. RNA. RNA
• Carries the Carries the codescodes for making for making proteins from the nucleus to proteins from the nucleus to the ribosomes in the the ribosomes in the cytoplasmcytoplasm
Three types:Three types:– Messenger RNA Messenger RNA
(mRNA)(mRNA)– Transfer RNA (tRNA)Transfer RNA (tRNA)– Ribosomal RNA (rRNA)Ribosomal RNA (rRNA)
BB22. RNA. RNA
•There are 4 Nitrogen There are 4 Nitrogen Bases that make the Bases that make the Rungs (steps) of the Rungs (steps) of the ladder – ladder –
–IN RNA, IN RNA,
–AdenineAdenine always bonds to always bonds to UracilUracil
–Guanine Guanine always bonds to always bonds to CytosineCytosine
BB22. RNA. RNA
• 2a. Messenger 2a. Messenger RNA (mRNA) RNA (mRNA) copies the code copies the code that directs the that directs the order in which the order in which the Amino acidsAmino acids bond bond
• 2b. Ribosomal RNA makes up the 2b. Ribosomal RNA makes up the ribosomesribosomes where the proteins are where the proteins are builtbuilt
BB22. RNA. RNA
• 2c. 2c. TransferTransfer RNA brings amino RNA brings amino acids to the ribosomes to build the acids to the ribosomes to build the proteinsproteins
BB22. RNA. RNA
• 3. Cells use only the 3. Cells use only the genesgenes that that direct the making of proteins direct the making of proteins needed by that cellneeded by that cell
B. GenesB. Genes
A theatrical example:A theatrical example:
• DNADNA is like is like lettersletters that make up that make up• GenesGenes which are like which are like words or sentenceswords or sentences
which make upwhich make up• Chromosomes Chromosomes like like paragraphs or paragraphs or
chapterschapters which work together with which work together with • All the ChromosomesAll the Chromosomes which makes the which makes the
script of the playscript of the play that is YOU! that is YOU!
C. MutationsC. Mutations
• Any Any permanent changepermanent change in the DNA in the DNA sequence of a cell’s genes or sequence of a cell’s genes or chromosomeschromosomes
• 1. Can be caused by outside factors 1. Can be caused by outside factors like x-rays, like x-rays, SunlightSunlight, and some , and some chemicals.chemicals.
C. MutationsC. Mutations
• 2. A change in a gene or 2. A change in a gene or chromosome can change the chromosome can change the traitstraits of an organism.of an organism.
C. MutationsC. Mutations