Table of Contents
The Genetic Code
How Cells Make Proteins
Mutations
DNA: The Code of Life
Which picture matches the vocab word?
• Nitrogen bases
• DNA replication
What forms the genetic code?
DNA = sides are made of sugar, “rungs” are made of nitrogen bases, A, T, G, C
What forms the genetic code?DNA STRUCTUREDRAW IN NOTES:
Double Helix shape
nitrogen bases
( (adenine, thymine guanine, cytosine)
Sugar sides
What forms the genetic code?
The order of nitrogen bases along a gene forms a genetic code that specifies what type of protein will be produced
What forms the genetic code?
Chromosome
Gene
Gene
Deoxyribose(a sugar)
Phosphate AdenineCytosine
Guanine
Thymine
A gene is a section of DNAGenes are made of many nitrogen bases (hundreds to millions) they code for one protein*Remember: proteins make up everything!
What forms the genetic code?3 nitrogen bases are the code for 1 amino acid
A chain of amino acids make proteins (like a pearl necklace)
Genes are “on” or “off,” make or don’t make a protein
How does DNA copy itself?
DNA replicates, or makes an exact copy of itself
How does DNA copy itself?
Starts with part of the DNA unwinding, nitrogen bases “unzip” and separate
New nitrogen bases match up with the “unzipped” bases
How does DNA copy itself?
A always pairs with T (adenine with thymine)
G always pairs with C (guanine with cytosine)
This way, the replicated DNA is always the same as the original DNA
Online assignment
3.2
Which picture best matches the vocab word?
Messenger RNA
Transfer RNA
Where does a cell make proteins?
Start – nucleus
The “code” carried to the cytoplasm
Protein is made in the ribosomes (little dots)/cytoplasm
Ribosome
How does a cell make proteins?
During protein synthesis, the cell uses information on a gene to make a specific protein
Proteins are made of little chains of amino acids
There are 20 kinds of amino acids
How Cells Make Proteins
How does a cell make proteins?
Proteins are made in the cytoplasm with RNA
RNA = similar to DNA but contains A G C U
(adenine, guanine, cytosine, uracil)
A to U
G to C
How does a cell make proteins?
1. mRNA copies the DNA in the nucleus, brings to ribosome in cytoplasm
2. tRNA carries amino acids to the ribosome to make a chain of protein
Protein Synthesis Chart
How Cells Make Proteins
Online animation
http://www.youtube.com/watch?v=erOP76_qLWA&feature=related
3.3
How can mutations affect an organism?
Mutation = any change in DNA or base sequence
Mutations cause an incorrect protein to be made
So, traits may be different from normal!
How can mutations affect an organism?
3 types of mutations:Deletion – base pair is removedAddition – base pair is addedSubstitution – one base pair is switched for another
How can mutations affect an organism?
Mutations can be helpful, harmful, or neither
Brainstorm Examples:
Helpful
Harmful
Neither
How is cancer related to mutations and the cell cycle?
Cancer begins in the cell cycle, when DNA mutation causes the cell to divide uncontrollably
Cancer Cell
Mutations
How is cancer related to mutations and the cell cycle?
Cancer = cells divide uncontrollably
tumor = a mass of abnormal cells
Cancer can spread through the blood stream
Cancer Cell
Mutations
Cancer Cell
Mutations
How is cancer related to mutations and the cell cycle?
Doctors use chemotherapy, surgery, or drugs to treat cancer
Chemotherapy – drugs or radiation to destroy cancerous cells
-can destroy healthy cells too
Mutations video
http://www.youtube.com/watch?v=2ZRYp5kRFfI&feature=related
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