Download DNA Structure and Function Notes

BELL RINGER 9-16-15
1.
In an experiment involving an enzyme, the pH is raised from 2 to 11.
What will be the MOST LIKELY effect of this on the reaction?
a.
b.
c.
d.
2.
Which organelle is responsible for making proteins?
a.
b.
c.
d.
3.
The enzyme will denature, stopping the reaction
The activation energy of the reaction would be reduced
The rate of reaction will reduce due to a decrease in the kinetic energy of the
molecules
The rate of reaction will increase due to the increased number of collisions of the
enzyme and substrate
Ribosomes
Chromosomes
Chloroplasts
Golgi apparatus
Substances that enter the cell without the expense of cellular ATP, but
are too large to directly pass through the membrane use
_____________________ in order to gain access to the inside of the cell.
a.
b.
c.
d.
Osmosis
Vesicles
Pseudopodia
Membrane proteins
AGENDA
Standard
 Key Ideas
 Notes on DNA
 DNA Modeling
 DNA coloring

STANDARD
SB2. Students will analyze how biological traits are passed
on to successive generations.
b. Explain the role of DNA in storing and transmitting
cellular information
KEY IDEAS
What is genetic material composed of?
 What is the shape of the DNA molecule?
 How is information organized and stored in a DNA
molecule?

WHAT DOES THIS HAVE TO DO WITH MENDEL?

Mendel did his work
with pea plants in the
1800s - well before
scientists knew what
was responsible for
the passing down of
traits Mendel studied.
WHAT DOES THIS HAVE TO DO WITH MENDEL?

Since then, scientists have discovered that genes are the
instructions for inherited traits.


A gene is a segment of DNA located on a chromosome and it
codes for a specific hereditary trait.
By the way, it wasn’t until the 1950s that scientists
discovered that genes are made up of DNA.

DNA is the primary material that causes recognizable,
inheritable characteristics in related groups of organisms
THE SHAPE OF DNA
James Watson and
Francis Crick were the
first to put together a
model of DNA’s
structure.
 So, what does it look
like?


We call this a double
helix (or a spiral
staircase)
THE SHAPE OF DNA
DNA is composed of two parallel strands of linked
subunits (called nucleotides)
 Nucleotides are made up of three parts: a phosphate
group, a five-carbon sugar molecule, and a nitrogencontaining base.

DNA STRUCTURE
If we were to unwind all
of the DNA in just one of
our cells it would be over
6 feet long!
 How does that fit in a
microscopic cell?


It’s all in the twist!
DNA STRUCTURE

Why doesn’t DNA get tangled up if there’s so much of it
in a cell?
Parallel strands!
 Do parallel lines ever cross?

HOW DOES THAT HOLD INFO?

The Nitrogen Bases
4 different nitrogen
bases: adenine (A),
guanine (G), thymine (T),
cytosine (C)
 A and G are purines.
Purine – a nitrogen base
that has a double-ring
structure
 T and C are pyrimidines.
Pyrimidine – a nitrogen
base that has a singlering structure

HOW DOES THAT HOLD INFO?

Base-Pairing
Purine with Pyrimidine ….. So,
A with T and G with C.
 Pairing happens across the
parallel strands
 Bases are held together by
weak hydrogen bonds, this
keeps the DNA strand together
 Paired bases are said to be
complementary because they fit
together like puzzle pieces.

HOW DOES THAT HOLD INFO?


If the sequence on one
strand is TATGAGAGT, the
sequence on the other strand
must be ATACTCTCA.
Pairing ensures that each
strand of the DNA molecule
contains the same
information (the information
on one is just the reverse of
the information on the
other).
BASE PAIRING PRACTICE

Given the following strands, write the complementary
strand








AGGCCTAT
TCCGGATA
TTCCGGAA
AAGGCCTT
GACGACTA
CTGCTGAT
ATGCGCAT
TACGCGTA
DNA MODELING

To help you get a better idea of what DNA looks
like we’re going to model it.