Download Lesson1_DNA structure

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 entryEntry 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
human cheek
cell
Elodea leaf 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
Adenine
Cytosine
Thymine
Guanine
Making a DNA molecule
1. One strand of
a DNA
molecule is
formed by
linking
together the
sugars and
phosphates of
nucleotides.
Hydrogen bonds
2. The two strands
(halves) of a DNA
molecule are
connected by
hydrogen bonds
between the
bases of
nucleotides.
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