interest grabber
DESCRIPTION
Inside the Nucleus. Interest Grabber. 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. DNA Nucleotides. Purines. Pyrimidines. Adenine. Guanine. - PowerPoint PPT PresentationTRANSCRIPT
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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
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Purines Pyrimidines
Adenine Guanine Cytosine Thymine
Phosphate group Deoxyribose
DNA Nucleotides
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Hydrogen bonds
Nucleotide
Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Structure of DNA
DNA Structur
e Link
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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
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Chromosome Structure of Eukaryotes
Chromosome
Supercoils
Coils
Nucleosome
Histones
DNA
double
helix
Chromatin
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Chromosome Structure1 nanometer = 0.001 micrometer1 micrometer = 0.001 millimeter
So
1 nm = 0.000001 mm
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DNA Replication
GrowthGrowth
Replication fork
DNA polymerase
New strand
Original strand
DNA polymerase
Nitrogenous bases
Replication fork
Original strand
New strand
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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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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
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from to to make up
RNA Concept Map
also called which functions to also called also called which functions towhich functions to
can be
RNA
Messenger RNA Ribosomal RNA Transfer RNA
mRNA Carry instructions
rRNACombine
with proteins tRNABring
amino acids toribosome
DNA Ribosome Ribosomes
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How is RNA different than DNA?
RNA•Contains ribose instead of deoxyribose
•Single stranded
•Nucleotide uracil replaces thymine
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Transcription
Messenger RNA = mRNACarries amino acid sequence to the ribosome
Transfer RNA = tRNACarries 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
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RNADNA
RNApolymeras
e
Transcription – Making a Copy of the DNA
Adenine (DNA and RNA)Cystosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)
Transcription Link
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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
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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
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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
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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.
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Substitution
Insertion
Deletion
Gene Mutations: Substitution, Insertion, & Deletion
Frameshift Mutation
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Regulatory sites
Promoter(RNA polymerase binding site)
Start transcription
DNA strand
Stop transcription
Typical Gene Structure
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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
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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.
•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.
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Cell Growth & Reproduction
Why replicate the DNA?•To make new cells•To replace old worn out cells•To replace damaged cells
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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
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Cell Size
Surface Area
(length x width x 6)Volume
(length x width x height)Ratio of Surface Area
to Volume
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Chromosome Structure
Sister chromatids
Centromere – attaches chromatids
46 Chromosomes in humans
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includes
is divided into is divided into
Concept Map – Cell Cycle
Cell Cycle
M phase (Mitosis)
Interphase
G1 phase S phase ProphaseG2 phase Metaphase TelophaseAnaphase
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Figure 10–5 Mitosis and Cytokinesis
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Mitosis and Cytokinesis
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Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Mitosis and Cytokinesis
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Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Mitosis and Cytokinesis
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Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Mitosis and Cytokinesis
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Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Mitosis and Cytokinesis
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Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
CentrioleChromosomes
(paired chromatids)
Prophase
Centromere
Spindle forming
Mitosis and Cytokinesis
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Interphase
Events of Interphase
•Cell grows
•DNA replicates
•Centriole replication
•NOT PART OF MITOSIS
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Prophase
Events of Prophase
•Chromatin condenses into visible chromosomes
•Centrioles separate & spindle fibers form
•Nuclear membrane breaks down
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Metaphase
Events of Metaphase
•Chromosomes line up at the equator
•Spindle fiber attaches to the kineticore of the centromere of each chromosome
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Anaphase
Events of Anaphase
•Kineticore breaks andsister chromatids separate
•Microtubules contract pulling sister chromatids toward the centrioles
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Telophase
Events of Telophase
•Nuclear membrane reforms
•Chromosomes uncoil
•Cleavage furrow forms separating the nuclei
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Cytokinesis
Events of Cytokinesis
•Cytoplasm divided into the two cells
•Cell plate appears in plant cells
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Control of the Cell Cycle
Cells continue to grow in number until they contact other cells
What makes them stop growing?
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A sample of cytoplasm is removed from a cell in mitosis.
The sample is injected into a second cell in G2 of interphase.
As a result, the second cell enters mitosis.
Effect of Cyclins