Go to Section: Interest Grabber Inside the Nucleus

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

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PurinesPyrimidines AdenineGuanine CytosineThymine Phosphate group Deoxyribose DNA Nucleotides

Go to Section: Hydrogen bonds Nucleotide Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Structure of DNA DNA Structure Link

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 Supercoils Coils Nucleosome Histones DNA double helix Chromatin

Go to Section: Chromosome Structure 1 nanometer = micrometer 1 micrometer = millimeter So 1 nm = mm

Go to Section: DNA Replication Growth Replication fork DNA polymerase New strand Original strand DNA polymerase Nitrogenous bases Replication fork Original strand New strand

Go to Section: 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

Go to 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: fromtoto make up RNA Concept Map also calledwhich functions toalso called which functions to can be RNA Messenger RNA Ribosomal RNA Transfer RNA mRNACarry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome DNARibosomeRibosomes

Go to Section: 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: RNA DNA RNA polymerase 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

Go to Section: 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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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: Substitution Insertion Deletion Gene Mutations: Substitution, Insertion, & Deletion Frameshift Mutation

Go to Section: Deletion Duplication Inversion Translocation Chromosomal Mutations

Go to Section: Regulatory sites Promoter (RNA polymerase binding site) Start transcription DNA strand Stop transcription Typical Gene Structure

Go to Section: 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. 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

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: includes is divided into Concept Map – Cell Cycle Cell Cycle M phase (Mitosis) Interphase G 1 phaseS phaseProphaseG 2 phaseMetaphaseTelophaseAnaphase

Go to Section: M phase G 2 phase S phase G 1 phase The Cell Cycle

Go to Section: Figure 10–5 Mitosis and Cytokinesis Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Mitosis and Cytokinesis

Go to Section: Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Mitosis and Cytokinesis

Go to Section: Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Mitosis and Cytokinesis

Go to Section: Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Mitosis and Cytokinesis

Go to Section: Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Mitosis and Cytokinesis

Go to Section: Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Mitosis and Cytokinesis

Go to Section: 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

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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?

Go to Section: A sample of cytoplasm is removed from a cell in mitosis. The sample is injected into a second cell in G 2 of interphase. As a result, the second cell enters mitosis. Effect of Cyclins

Go to Section: Uncontrolled Cell Growth = Cancer Cancer Cell division does not stop and a tumor forms The tumor damages surrounding tissues