DNA Ms. Garcia LN #21 California Content Standards Genetics 5a. Students know the general structures...
-
Upload
bonnie-dorthy-young -
Category
Documents
-
view
217 -
download
0
Transcript of DNA Ms. Garcia LN #21 California Content Standards Genetics 5a. Students know the general structures...
DNA
Ms. Garcia
LN #21
California Content Standards
Genetics5a. Students know the general structures and functions of DNA, RNA, and protein.5b. Students know how to apply base-pairing rules to explain precise copying of DNA during semiconservative replication and transcription of information from DNA into mRNA.
Chromosomes & DNA………..• Chromosomes are made of DNA and
protein.– deoxyribonucleic acid (DNA)
• The total DNA in our 46 chromosomes would stretch for 3 meters.
• The reason all this DNA fits in our cells is because of the way DNA is coiled in our chromosomes.
• Our chromosomes contain 20,000 to100,000 genes, this makes up 10% of our DNA.– 90% of our DNA does not code for traits.
Double Helix
• DNA’s shape was first described in 1953 by Watson and Crick.– Rosalind Franklin was the
first to take an X-ray photograph of DNA.
• Watson and Crick described DNA as a double helix.
Double Helix
What is a Nucleotide?
• DNA is made of nucleotides.
• Nucleotides are repeating subunits that make up DNA.
• Nucleotides contain 3 parts.1. phosphate group2. sugar (deoxyribose)3. nitrogen base
1
2
3
Base Pairing Rules
• DNA contains 4 types of nitrogen bases.
• The nitrogen bases are categorized in 2 groups.– Purines
• Adenine (A)
• Guanine (G)
– Pyrimidines• Thymine (T)
• Cytosine (C)
• A always bonds with T • G always bonds with C
PyrimidinesPurines
Too big
Too small
Just right
Genetic Code
• Deoxyribose and the phosphate group make up the backbone of the DNA strands.
• The nitrogen bases form a code that contains the instructions for making proteins.
• Our bodies read DNA’s code to express our traits.
• DNA is located in the nucleus of cells.
DNA Replication
• Every cell in our body, with the exception of red blood cells, contain DNA.
• DNA replication ensures that every cell will have the correct amount of DNA after meiosis and mitosis have been completed.
• DNA replication takes place during interphase.
Summary
• What are chromosomes made of?
• What is a nucleotide?
• What are the three parts of a nucleotide?
• What is the general structure of DNA?
• What are the base pairing rules of DNA?
• Why is DNA replication important?
• Do Pre Reading 11.1 on page 287.