Inside the Nucleus
Interest Grabber
Go to
Section:
Genes are made of DNA
DNA is composed of individual units
called nucleotides
Three of these units form a code
(codon).
The order, or sequence, of the code
determine the meaning of the
message
Go to
Section:
Go to
Section:
DNA Nucleotides
Purines
Adenine
Guanine
Phosphate
group
Go to
Section:
Pyrimidines
Cytosine
Thymine
Deoxyribose
Structure of DNA
DNA
Structure
Link
Nucleotide
Hydrogen
bonds
Sugar-phosphate
backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Go to
Section:
Chargaff’s Rules
Go to
Section:
X-ray diffraction
Rosalind Franklin
X-rayed DNA from a calf
thymus gland but had no
idea what it was
James Watson saw this
x-ray & interpreted DNA
as a double helix
Go to
Section:
James Watson & Francis Crick
Go to
Section:
Chromosome Structure
of Eukaryotes
Chromosome
Nucleosome
DNA
double
Coils
Supercoils
Chromatin
Go to
Section:
Histones
helix
Chromosome Structure
1 nanometer = 0.001
micrometer
1 micrometer = 0.001
millimeter
So
1 nm = 0.000001 mm
Go to
Section:
DNA Replication
New
strand
DNA
polymerase
Original
strand
Growth
Growth
Replication
fork
Nitrogenous
bases
Replication
fork
New
strand
Go to
Section:
DNA
polymerase
Original
strand
Replication
Link
Go to
Section:
Replication – Making New DNA
1. Helicase separates two strands of DNA by
breaking hydrogen bonds
2. Primase starts replication
3. DNA polymerase “polymerizes” the individual
nucleotides & proof-reads the new DNA
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Section:
Now that new cells have been made, new proteins will
be needed.
HOW ARE PROTEINS MADE
?
We first need to look at something called RNA
Go to
Section:
RNA Concept Map
RNA
can be
Messenger RNA
also called
Ribosomal
RNA
which functions to
mRNA
also called
which functions to
rRNA
Combine
with proteins
Carry
instructions
from
to
to make up
DNA
Ribosome
Ribosomes
Go to
Section:
Transfer
RNA
also called
which functions to
tRNA
Bring
amino acids to
ribosome
How is RNA different than DNA?
RNA
•Contains ribose instead
of deoxyribose
•Single stranded
•Nucleotide uracil
replaces thymine
Go to
Section:
Transcription
Messenger RNA = mRNA
Carries amino acid sequence to the ribosome
Transfer RNA = tRNA
Carries amino acid to the codon on mRNA
Codon = 3 nucleotide bases on mRNA which
“code” for an amino acid
Anticodon = 3 nucleotide bases on tRNA which
match up with the codon
Go to
Section:
Codon
Go to
Section:
Transcription – Making a Copy of the DNA
Transcription
Link
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
RNA
polymerase
RNA
Go to
Section:
DNA
Transcription – Making a Copy of the DNA
1. RNA polymerase separates the DNA strands at a
promoter region on the DNA
2. mRNA adds nucleotides in sequence
3. RNA polymerase falls off the DNA at a terminator
sequence on the DNA
Go to
Section:
RNA Editing
Introns - Intervening
sequence = Junk DNA
Exons – Expressed sequence
1. Introns are cut out of the
mRNA
2. Exons are held together by
a cap and a poly A tail
Go to
Section:
The Genetic Code - Amino Acid Sequence
4 x 4 x 4 = 64
Possible Codons
for 20 amino
acids
AUG = Start Codon
Begins transcription
AAU, GAU, AGU
Stop Codons which
end transcription
Go to
Section:
Translation – On the Ribosome
Go to
Section:
Translation (continued)
Translation
Link
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Section:
Go to
Section:
Determining the Sequence of a Gene
DNA contains the code of instructions for cells.
Sometimes, an error occurs when the code is
copied. Such errors are called mutations.
Go to
Section:
Gene Mutations:
Substitution, Insertion, & Deletion
Substitution
Insertion
Deletion
Frameshift Mutation
Go to
Section:
Chromosomal Mutations
Deletion
Duplication
Inversion
Translocation
Go to
Section:
Typical Gene Structure
Regulatory
sites
Promoter
(RNA polymerase
binding site)
Start transcription
Go to
Section:
DNA strand
Stop transcription
Gene Regulation
Operon – A group of genes that operate together
Lac Operon = operon expressed in E. coli to use the
sugar lactose
Operator – region where repressor protein binds
Promoter – region that signals beginning of operon
Go to
Section:
lac Operon
Go to
Section:
lac Operon
Go to
Section:
lac Operon
Go to
Section:
lac Operon
Go to
Section:
Gene Regulation
Tying it altogether - the lac
Operon Gene
E. Coli bacteria can synthesize
lactase, which is an enzyme that
breaks down lactose. Lactase is
only synthesized in the presence
of lactose. If there is no lactose
in the environment, the gene is
repressed.
Go to
Section:
•E. Coli has three genes that code for
lactase.
•It also has an operator and a
promotor.
•Without lactose, the lac repressor
binds to the operator site.
•With lactose, the repressor is removed
•Once repressor is removed, RNA
polymerase binds to the promoter
•RNA is transcribed, which is then
translated, and becomes the lactase
enzyme.
Go to
Section:
Cell Growth & Reproduction
Why replicate the DNA?
•To make new cells
•To replace old worn out cells
•To replace damaged cells
Go to
Section:
Cell Size Limitations
Why are cells so small?
• Cell size Limitations
- Diffusion (The bigger the cell the slower the
diffusion
- DNA (Large cells need more DNA to make more
proteins)
- Surface area to volume ratio
Go to
Section:
Cell Size Limitations
Surface Area-to-volume Ratio
Go to
Section:
Cell Size
Surface Area
(length x width x 6)
Volume
(length x width x height)
Ratio of Surface Area
to Volume
Go to
Section:
Chromosome Structure
Sister chromatids
Centromere – attaches
chromatids
46 Chromosomes in
humans
Go to
Section:
Concept Map – Cell Cycle
Cell Cycle
includes
Interphase
M phase
(Mitosis)
is divided into
is divided into
G1 phase
Go to
Section:
S phase
G2 phase
Prophase
Metaphase
Anaphase
Telophase
The Cell Cycle
G1 phase
M phase
S phase
G2 phase
Go to
Section:
Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Centriole
Prophase
Spindle
Figure 10–5 Mitosis and Cytokinesis
Cytokinesis
Centriole
Telophase
Nuclear
envelope
reforming
Go to
Section:
Individual
chromosomes
Anaphase
Metaphase
Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Interphase
Events of Interphase
•Cell grows
•DNA replicates
•Centriole replication
•NOT PART OF MITOSIS
Go to
Section:
Prophase
Events of Prophase
•Chromatin condenses into
visible chromosomes
•Centrioles separate & spindle
fibers form
•Nuclear membrane breaks
down
Go to
Section:
Metaphase
Events of Metaphase
•Chromosomes line up at the
equator
•Spindle fiber attaches to the
kineticore of the centromere
of each chromosome
Go to
Section:
Anaphase
Events of Anaphase
•Kineticore breaks and
sister chromatids separate
•Microtubules contract
pulling sister chromatids
toward the centrioles
Go to
Section:
Telophase
Events of Telophase
•Nuclear membrane reforms
•Chromosomes uncoil
•Cleavage furrow forms
separating the nuclei
Go to
Section:
Cytokinesis
Events of Cytokinesis
•Cytoplasm divided into
the two cells
•Cell plate appears in
plant cells
Go to
Section:
Go to
Section:
Control of the Cell Cycle
Cells continue to grow in number
until they contact other cells
What makes them stop growing?
Go to
Section:
Effect of Cyclins
The sample is
injected into a
second cell in G2
of interphase.
A sample of
cytoplasm is
removed
from a cell
in mitosis.
As a result, the
second cell
enters mitosis.
Go to
Section:
Uncontrolled Cell Growth = Cancer
Cancer
Cell division does not
stop and a tumor forms
The tumor damages
surrounding tissues
Go to
Section: