Gene to Protein & Cell Division PDF

Anatomy & Physiology I BIOL 2001 C Ibanez Gene to Protein & Cell Division pp. 83-90 & 102-109 1. Importance of Cell Division: a. Reproduction in prokaryotes b. Growth...

Anatomy & Physiology I BIOL 2001 C Ibanez Gene to Protein & Cell Division pp. 83-90 & 102-109 1. Importance of Cell Division: a. Reproduction in prokaryotes b. Growth and Development c. Wound Healing d. Cancer 2. Chromosomes: condensed packages of DNA a. Two identical chromatids joined by a centromere b. Diploid (2n): having two copies of the same chromosome; one from each parent c. Haploid (n): having only one copy of each chromosome d. Humans have 23 pairs = 46 chromosomes (Usually) i. 22 autosomal chromosome pairs ii. 1 sex chromosome pair i. X and Y ii. X chromosome is larger and contains more genes iii. The presence of the Y chromosome produces males (Usually) e. Composition: i. DNA → genes ii. Histones i. Proteins to provide structure ii. Turn off/on genes iii. Cohesin: proteins that hold the two chromatids together iv. Kinetochores i. Two per centromere ii. Used for attachment of microtubules during mitosis and meiosis Anatomy & Physiology I BIOL 2001 C Ibanez 3. “Mitosis”: cell division for somatic cells a. Produce two identical daughter cells b. Mitosis: replication and division of chromosomes c. Cytokinesis: division of cytoplasm with organelles 4. Somatic Cell Cycle a. Interphase i. “Resting Phase” ii. G0 (Gap Zero) Phase i. Non-dividing state iii. G1 (Gap One) Phase i. Cellular components, except chromosomes, are duplicated iv. S (Synthesis) Phase i. DNA duplication ii. 2 copies → 4 copies iii. 1 chromatid per chromosome → 2 chromatids per chromosome iv. Diploid → Diploid v. G2 (Gap Two) Phase i. Cell checks over duplicated DNA and makes repairs if necessary Anatomy & Physiology I BIOL 2001 C Ibanez b. Mitosis i. Prophase i. Chromatin coil up → chromosomes ii. Nuclear envelope disintegrates iii. Centrosomes migrate to opposite ends iv. Mitotic spindles form from centrosomes ii. Metaphase i. Mitotic spindle fibers line chromosomes (chromatid pairs) individually along the equatorial plane iii. Anaphase i. Begins as soon as the enzyme separase breaks cohesin ii. Sister chromatids separate and move toward opposite ends because of spindle fibers shortening iv. Telophase i. Opposite of prophase ii. Nuclear envelopes form around each set of chromosomes iii. Chromosomes loosen up → chromatin iv. Mitotic spindles disappear c. Cytokinesis: cytoplasm and organelles divide Anatomy & Physiology I BIOL 2001 C Ibanez 5. Mitosis Summary http://www.youtube.com/watch?v=VlN7K1- 9QB0&eurl=http://video.google.com/videosearch?q=meiosis&ie=UTF8&um=1&sa=N&tab= wv 6. “Meiosis”: cell division for the production of gametes a. Produces four unique haploid daughter cells b. Used for production of the egg and sperm → sexual reproduction c. Gamete: sex cell (egg or sperm) i. 22 autosomal (individual) chromosomes ii. Either X or Y d. Syngamy: restoration of 2n → zygote → embryo → new adult 7. Steps in Meiosis: a. Interphase i. “Resting Phase” ii. G0 (Gap Zero) Phase i. Non-dividing state iii. G1 (Gap One) Phase i. Cellular components, except chromosomes, are duplicated iv. S (Synthesis) Phase i. DNA duplication ii. 2 copies → 4 copies iii. 1 chromatid per chromosome → 2 chromatids per chromosome iv. Diploid →Diploid v. G2 (Gap Two) Phase i. Cell checks over duplicated DNA and makes repairs if necessary Anatomy & Physiology I BIOL 2001 C Ibanez b. Prophase I i. Synapsis = chromosomes come together in pairs (tetrads) ii. Nuclear envelope disintegrates iii. Centrosomes migrate to opposite ends iv. Mitotic spindles form from centrosomes v. At birth, human eggs are in prophase I and will stay in prophase I until puberty (girls are born with all the eggs she is going to have in her lifetime) c. Metaphase I i. Tetrads line up in pairs along equatorial plane d. Anaphase I i. Homologous chromosomes separate ii. Identical sister chromatids stay together e. Telophase I i. Nuclear envelopes form around each set of chromosomes ii. Mitotic spindles disappear f. Cytokinesis i. Two daughter cells i. In females, daughter cells are of uneven size (large one will become egg) g. Prophase II i. Nuclear envelope disintegrates ii. Centrosomes migrate to opposite ends iii. Mitotic spindles form from centrosomes h. Metaphase II i. Chromosomes (identical sister chromatids) line up along equatorial plain i. Anaphase II i. Sister chromatids separate and move toward opposite ends because of spindle fibers shortening j. Telophase II i. Nuclear envelopes form around each set of chromosomes ii. Chromosomes loosen up → chromatin iii. Mitotic spindles disappear k. Cytokinesis i. Four daughter cells are produced ii. In human females, one big one = egg and three small ones = polar bodies Anatomy & Physiology I BIOL 2001 C Ibanez 8. Diversity a. Egg → 223 = 8,388,604 b. Sperm → 223 = 8,388,604 c. After syngamy = fertilized egg → 223 x 223 = 70,368,744,177,644 d. Crossing Over: exchange of genetic material between homologous chromosomes during synapsis 9. Summary of Meiosis http://www.youtube.com/watch?v=D1_- mQS_FZ0&eurl=http://video.google.com/videosearch?q=meiosis&ie=UTF8&um=1&sa=N &tab=wv Anatomy & Physiology I BIOL 2001 C Ibanez 10. Regulation of Cell Division: a. Cyclins: proteins only made at certain points in the cell cycle to bind Cdks b. Cdk: cyclin dependent kinase i. Always present in the cell, but the active site is not exposed c. Regulator proteins for cell division d. Cyclin-Cdk combinations i. Cyclin D-Cdk4: i. Acts during mid G1 ii. Moves cell past restriction point (R) = commitment for cell division ii. Cyclin E-Cdk2: i. Acts during mid G1 in concert with cyclin D-Cdk4 ii. Process inactivates (via phosphorylation) retinoblastoma protein iii. Cyclin A-Cdk2: i. Acts during S phase ii. Stimulates DNA duplication iv. Cyclin B-Cdk1: i. G2-M boundary ii. Moves cell into prophase Anatomy & Physiology I BIOL 2001 C Ibanez 11. Cancer: uncontrolled cell division a. Short or no interphase b. Cancer can be caused by genetic changes that can be inherited from our parents or they can also arise during a person’s lifetime as a result of errors that occur as cells divide or because of damage to DNA caused by certain environmental exposures c. HeLa cells i. Henrietta Lacks (August 1, 1920 to October 4, 1951) ii. Cervical carcinoma cells iii. Collected in 1951 iv. Used for testing/research 12. Protein Synthesis: a. Transcription: DNA → RNA i. DNA template ii. Enzymes i. RNA polymerase adds nucleotide bases at 3’ end b. Translation: RNA → Protein https://youtu.be/bKIpDtJdK8Q Anatomy & Physiology I BIOL 2001 C Ibanez