Monday, March 12, 2012 If you were absent Friday, you need to makeup a quiz today or tomorrow in tutorial. Schedule for Tues, Wed, Thursday: 7:30 – 10:00- HSPE Testing for 10th, 11th, 12th (9th graders have an appointment with guidance counselor).
Tuesday Schedule • 1st period 10:15 – 11:20 (65) Lunch 11:20 – 12:10 • 5th period 12:15 – 1:20 (65) • 7th period 1:25 – 2:30 (65) Tutorial 2:35-3:05
Wednesday Schedule • 2nd period 10:15 – 11:20 (65) • 4th period 11:25 – 12:30 (65)
Thursday Schedule • 3rd period 10:15 – 11:20 (65) Lunch 11:20 – 12:10 • 6th period 12:15 – 1:20 (65) • Assembly 1:25 – 2:30 (65) Tutorial 2:35-3:05 Friday is a normal period 1-7 schedule.
Make an entry- Entry 21:DNA structure-3/12/12 In your logbook, tell me what you already know about DNA…
DNA (Deoxyribonucleic Acid)
DNA is universal to life • All living organisms have DNA • Bacteria, fungi, plants, animals…and even many viruses • The function of DNA is to store information for an organism’s characteristics
The nucleus stores DNA in eukaryotic cells Elodea leaf cell human cheek cell mitochondria chloroplasts vacuole nucleus (DNA here) (DNA here)
Prokaryote cells do not have a nucleus but DO have DNA E. coli bacteria cell DNA
In the cell, DNA forms structures called chromosomes • A eukaryotic chromosome is typically a very long, single chain of DNA
In the cell, DNA forms structures called chromosomes • A prokaryotic chromosome is typically a circular chain of DNA • Prokaryotic cells also often have smaller circles of DNA called plasmids E. coli bacteria cell Chromosome DNA Plasmid DNA
DNA structure • Pre-load the following web-based 3-dimensional molecular models and refer to them where noted (the first time loading will take some time) Model 1 Model 2 • Note the buttons below the model window to manipulate and highlight different structural features
DNA is a double helix • The shape of a DNA molecule is like a twisted ladder or spiral staircase See web-based 3-dimensional molecular model
DNA is made of nucleotides • A nucleotide has 3 parts: a phosphate, a sugar, and a base. PHOSPHATE BASE SUGAR See web-based 3-dimensional molecular model
There are 4 DNA nucleotides • They are the same except for their bases Thymine Cytosine Guanine
Making a DNA molecule • One strand of a DNA molecule is formed by linking together the sugars and phosphates of nucleotides.
The two strands (halves) of a DNA molecule are connected by hydrogen bonds between the bases of nucleotides. Hydrogen bonds Hydrogen bonds
Complementary base pairing • In DNA molecules… Adenine only bonds to thymine. Cytosine only bonds to guanine. A—T G—C See web-based 3-dimensional molecular model