Transcript Chromosomes - Down the Rabbit Hole

DNA the Molecule
 DNA
is a very
long polymer.
 The basic shape
is like a twisted
ladder or spiral
staircase.
 This is called a
double helix.
DNA the Molecule
5’
1’
4’
3’
2’
Genome
A genome is an
organism's complete
set of DNA, including
all of its genes.
Each genome
contains all of the
information needed to
build and maintain
that organism.
Cell Replication - Duplicating DNA

Two cell types
 Prokaryote
 Eukaryote

Prokaryotes are simple
and much less
complicated than
Eukaryotes therefore
they contain much less
genetic information
(DNA).
Prokaryote cell division
Binary Fission
Prokaryotic cells
have a circular
DNA molecule
attached to the
inner cell
membrane
 They divide through
a simple form of
division called
Binary Fission

E. coli dividing by binary fission
Prokaryotic cell division
• 3 step process
• DNA strand splits and
forms a duplicate of
itself.
• The two copies move
to opposite sides of the
cell
• Cell membrane forms
between two new and
identical cells.
Eukaryotic Cells
• 1,000 times more DNA then
an average prokaryotic
cell.
• All eukaryotic cells store
genetic information in
chromosomes.
• Most eukaryotes have
between 10 and 50
chromosomes in their body
cells.
• Human cells have 46
chromosomes.
• 23 pairs
Figure 12.3
50 µm
Chromosomes
Chromosomes
• Organization is much
more complex than the
single, circular DNA
molecule in a prokaryotic
cell
• Linear
• organized into coils
• wrapped around
proteins called
histones.
• Condenses during cell
division
Chromosome
Jumping Jacks = Sister Chromatids
Center of the jumping jack is the CENTROmere
Chromatin


Complexes of DNA and
protein are called
chromatin.
In humans, a copy of the
entire genome—more than
3 billion DNA base pairs—is
contained in all cells that
have a nucleus.
Gene

A gene is an
address – a
location on the
chromosome and
in the DNA
sequence where
info for a specific
trait is located.