Inside the Nucleus Interest Grabber Go to Section

Inside the Nucleus Interest Grabber Go to Section:

Genes are made of 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 Pyrimidines Cytosine Thymine Phosphate group Deoxyribose Go to Section:

Structure of 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:

$X-ray diffraction Rosalind Franklin X-rayed DNA from a calf thymus gland but had no$

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 = 0. 001 millimeter So 1 nm = 0. 000001 mm Go to Section:

DNA Replication New strand DNA polymerase Original strand 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 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:

RNA Concept Map RNA can be Messenger RNA also called Ribosomal RNA which functions to m. RNA also called which functions to r. RNA Combine with proteins Carry instructions from to to make up DNA Ribosomes Go to Section: Transfer RNA also called which functions to t. RNA 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 = m. RNA Carries amino acid sequence to the ribosome Transfer RNA = t. RNA Carries amino acid to the codon on m. RNA Codon = 3 nucleotide bases on m. RNA which “code” for an amino acid Anticodon = 3 nucleotide bases on t. RNA 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. m. RNA 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 of the m. RNA 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 = 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 Go to 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:

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 includes Interphase M phase (Mitosis) is divided into G 1 phase Go to Section: S phase G 2 phase Prophase Metaphase Anaphase Telophase

The Cell Cycle G 1 phase M phase S phase G 2 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 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

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 G 2 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 Cell division does not stop and a tumor forms The tumor damages surrounding tissues Go to Section: