Chromosome and Cell Division Final Pdf.pdf

 Learning Objectives: 1. Describe what is a chromosome and examine the DNA structure. 2. Explain how DNA and proteins are organized into chromosome. 3. Differentiate a gene, chromatin from chromatid and chromosome.  Learning Objectives: 4. Explain how a gene is the physica...

 Learning Objectives: 1. Describe what is a chromosome and examine the DNA structure. 2. Explain how DNA and proteins are organized into chromosome. 3. Differentiate a gene, chromatin from chromatid and chromosome.  Learning Objectives: 4. Explain how a gene is the physical basis of heredity. 5. Enumerate and describe major events that occur during cell division. 6. Describe the life history of a cell, including the events of mitosis 7. Explain how the timing of cell division is regulated. Review Time! What is a cell? Can you name or recall part of a cell or its organelle? How about its function? What are the difference between a prokaryotic and eukaryotic cell? What are the biomolecules of life? Today's Discussion  Storage of Genetic Information DNA Hereditary information is encoded in the chemical language of DNA and reproduced in all the cells of your body. The information encoded in the DNA directs the development of many different types of traits.  DNA Structure and Function Image Source: Pearson Education, Inc  DNA Structure and Function Remember: Remember: PuAG PyCUT Purine family Pyrimidine family Adenine Cytosine Guanine Uracil (only in RNA) Thymine Image Source: Pearson Education, Inc  DNA Structure and Function Image Source: Pearson Education, Inc  Purine + Purine: Too wide Pyrimidine + Pyrimidine: Too narrow Purine + Pyrimidine: Width is consistent with x-ray data A-T and C-G are called base pairs. One strand governs the base sequence of the other is called the law of complementary base pairing Image Source: Pearson Education, Inc  Sample Questions 1. What would be the base sequence of the DNA strand across from ATTGACTCG? 2. If a DNA molecule was known to be 20% adenine, predict its percentage of cytosine. Image Source: Pearson Education, Inc  Sample Question #1 1. What would be the base sequence of the DNA strand across from ATTGACTCG? Answer: TAACTGAGC  Sample Question #2 2. If a DNA molecule was known to be 20% adenine, predict its percentage of cytosine and explain your answer. Answer: Based on the law of complementary base pairing, 20% Adenine means there is also 20% Thymine, a total of 40%. To compute for cytosine, simply subtract 40% from 100%, the result is 60% divide it by 2 since the remaining percentage is for both Cytosine and Guanine. There is 30% of cytosine.  The essential function of DNA is to carry instructions for the synthesis of proteins. These instructions were encoded in the Gene. Human Genome Project Humans are estimated to have 20,000 to 25,000 genes, only 2% of the DNA. the 98% is noncoding DNA it plays various roles in chromosome structure and regulation activity  CHROMATIN AND CHROMOSOME STRUCTURE DNA does not exist as a naked double helix It complexed with proteins to form a fine filamentous material called CHROMATIN  Organization of Eukaryotic Chromosomes DNA wraps around histone proteins, forming nucleosomes and the so- called "beads on a string" structure (euchromatin).  Nucleosome is the fundamental unit of chromatin Each nucleosome is consists of a core particle and a short segment of linker DNA leading to the next core particle. http://atlasgeneticsoncology.org/Educ/ChromatinEducEng.html  Nucleosomes are arranged in a zigzag pattern, folding the chromatin like accordion. Chromosome territory  Reminder! The agent of heredity are the genes, and the genes are carried on the chromosomes (sex chromosomes and autosomes) Define the ff.: homologous chromosomes, diploid, haploid, locus, allele, dominant or recessive allele, genotype and phenotype.  RNA Structure and Function RNA is a linear molecule composed of nucleotides and synthesized from DNA by an enzyme known as RNA polymerase during a process called transcription. Sample: mRNA, rRNA, tRNA It interpret the code in DNA and use that instructions to synthesize proteins.  What is a Gene? An information-containing segment of the DNA that codes for the production of a molecule RNA which in most cases goes on to play a role in the synthesis of one or more proteins. The amino acid sequence of a protein is determined by a nucleotide sequence in the DNA.  CELL CYCLE Before a cell divides, it must duplicate its DNA to give complete and identical copies of all its genes to each daughter cell. replication process must be very exact Fundamental Steps of DNA Replication  CELL CYCLE Phases of Cell Cycle Interphase subphases: G1, S, G2 M phase (cell divide) consist of: Mitosis and cytokinesis Image Source: Pearson Education, Inc  Interphase G1 (first gap phase) - the cell synthesizes proteins, grow and accumulation of materials needed for DNA replication. S (synthesis phase) - duplication of DNA and start replicating its centrioles G2 (second gap phase) - cell finishes the replicating its centrioles and synthesizes enzymes that control cell division. it checks the fidelity of DNA replication and usually repairs any errors that are detected.  M (Mitotic) Phase Consist of the following: Mitosis (Karyokinesis or Nuclear Division) Prophase Metaphase Anaphase Telophase Cytokinesis (Division of Cytoplasm) Image Source: Pearson Education, Inc Mitosis in Plants  Mitosis in Animals Image Source: Pearson Education, Inc  Mitosis in Animals Image Source: Pearson Education, Inc  Timing of Cell Division 1. The cell grow large enough. 2. They have replicated their DNA. 3. They receive an adequate supply of nutrients. 4. Stimulated by growth factors, chemical signals 5. The neighboring cells die. The cessation of cell division in response to contact with other cells is called contact inhibition.  References 1. Campbell, Neil and Jane Reece. 2005. Biology 7th Edition. Pearson Education, Inc. 2. Reece, JB., LA Urry, ML Cain, SA Wasserman, PV Minorsky, and RB Jackson. 2011. Campbell Biology 9th Edition. Pearson Education, Inc. 3. Saladin, Kenneth. 2012. Anatomy and Physiology: The Unity of Form and Function 6th Edition. McGraw-Hill Education. 4. https://bio.libretexts.org/Bookshelves/Genetics/Book%3A_Online_Open_Genetics_(Nickle_and_Bar rette-Ng)/02%3A_Chromosomes_Mitosis_and_Meiosis 5. https://www.springer.com/gp/book/9788132236719 Videos as shared/embedded in Moodle LMS website: https://www.youtube.com/watch?v=gbSIBhFwQ4s (chromosome wrapping) https://www.youtube.com/watch?v=4Z4KwuUfh0A (multi-scaling) https://www.youtube.com/watch?v=0JpOJ4F4984 (chromosome and kinetochore) Thank you for joining today's class.