Unit 2- Intro to Cell Structure and Genetics PDF

Cellular Structure and Processes Prepared by: Jessica R. Francisco, MSc. What is a Cell? The cell is the smallest unit of life. It was first discovered and named by Robert Hooke in 1665. He remarked that it looked strangely similar to “cellula,” or small rooms which monks inh...

Cellular Structure and Processes Prepared by: Jessica R. Francisco, MSc. What is a Cell? The cell is the smallest unit of life. It was first discovered and named by Robert Hooke in 1665. He remarked that it looked strangely similar to “cellula,” or small rooms which monks inhabited, thus deriving the name. retrieved from https://www.biography.com/ Classical Cell Theory All living organisms are composed of cells. They may be unicellular or multicellular. The cell is the basic unit of life. Cells arise from pre-existing cells. (They are not derived from spontaneous generation). retrieved from https://education.national geographic.org/ Modern Cell Theory DNA is passed between cells during cell division. Cells of all organisms within a similar species are mostly the same, both structurally and chemically. Energy flow occurs within cells. retrieved from https://education.national geographic.org/ Types of Cell  Cell Structure A visualization of Animal Cell. Retrieved from https://med.libretexts.org/  Human Cell Somatic Cell Gametes majority of cells are Also called "sex cells" somatic cells. responsible for sexual Also called "body cell' reproduction. not involved in sexual haplod cells reproduction. Diploid cells For eg., sperm and egg cells For eg., cells of the skin, muscle, etc. 1. Plasma Membrane The plasma (cell) membrane separates the inner environment of a cell from the extracellular fluid. It is composed of a fluid phospholipid bilayer (two layers of phospholipids) Retrived from https://med.libretexts.org/  2. Nucleus The nucleus is the largest cellular organelle which contaitains heridetary material (DNA). The control center of cell. the nucleus is surrounded by a nuclear envelope that separates the contents of the nucleus from the contents of the cytoplasm. Retrived from https://med.libretexts.org/ 3. Mitochondria -Important in ATP (cellular energy) production -Site for cellular respiration Retrived from https://med.libretexts.org/ 4. Smooth Endoplasmic Reticulum (SER) -Synthesizes lipids, and stores calcium in muscle cells. Detoxify drugs, certain pesticides, and cancer- causing chemicals Synthesize steroid-based hormones. Retrived from https://med.libretexts.org/ 5. Rough Endoplasmic Reticulum (RER) -Participates in protein synthesis (ribosomes in its membrane synthesize proteins) Retrived from https://med.libretexts.org/ 6. Ribosomes -Found attached to RER and free in the cytosol. -Site for protein sysnthesis. Retrived from https://med.libretexts.org/ 7. Golgi apparatus -also known as the Golgi complex. -Partcipates in protein modification and packagin into small membrane-bound vesicles Retrived from https://med.libretexts.org/ 7. Golgi apparatus Retrived from https://med.libretexts.org/ 8. Lysosomes -Can be referred to the janitorial crew and recycling center; they break down used proteins and other cellular debris. -Contain digestive enzymes For ex. Pinocytosis - cell drinking phagocytosis- cell eating Retrived from https://med.libretexts.org/  9. Peroxisomes Contain enzymes that catabolize (break down) fatty acids and some chemical toxins Retrived from https://med.libretexts.org/ 10. Cytoskeleton Provide and internal cellular scaffolding or framework. (a) microtubule made of tubulin, (b) microfilament made of actin, and (c) intermediate fibers made of keratins Retrived from https://med.libretexts.org/ 11. Centrioles (found in an area in the cell called centrosome). Organize DNA movement during cell division Retrived from https://med.libretexts.org/ Retrived from https://med.libretexts.org/ Thank You References Habbal O. The Science of Anatomy: A historical timeline. Sultan Qaboos Univ Med J. 2017 Feb;17(1):e18-e22. DOI: 10.18295/squmj.2016.17.01.004. Epub 2017 Mar 30. PMID: 28417023; PMCID: PMC5380415.\ The History of Anatomy - from the beginnings to the 20th century. (2018, December 19). Körperwelten. Retrieved August 10, 2022, from https://bodyworlds.com/about/history-of- anatomy/ Norris, M., & Siegfried, D. R. (2011). Anatomy and Physiology For Dummies (2nd ed.). For Dummies. Marieb, E. N., Wilhelm, P. B., & Mallatt, J. B. (2016). Human Anatomy (8th Edition) (8th ed.). Pearson. http://lccn.loc.gov/2015038748 NATSCI4- Human Anatomy and Physiology CELL LIFE CYCLE Prepared by: Jessica R. Francisco MSc. City College of San Jose Del Monte OBJECTIVES: To discuss the cell division To demonstrate understanding of the cell life cycle  HUMAN CELL Somatic Cell Gametes majority of cells are somatic cells. Also called "sex cells" Also called "body cell' responsible for sexual not involved in sexual reproduction. reproduction. haploid cells Diploid cells For eg., cells of the skin, muscle, etc. For eg., sperm and egg cells  TERMINOLOGY: DNA- (deoxyribonucleic acid) is the genetic material of living organisms. In humans, DNA is found in almost all the cells of the body and provides the instructions they need to grow, function, and respond to their environment. retrieved from : https://www.sciencefacts.net/  TERMINOLOGY: Chromosomes A chromosome is a thread-like structure present in the nucleus or nuclear region of the cytoplasm that is made up of a single molecule of DNA. Humans have 46 chromosomes in a typical body cell (somatic cell) retrieved from : https://www.khanacademy.o  TERMINOLOGY: Chromatids A chromatid is an identical half of a duplicated chromosome. After the duplication of a chromosome, two identical halves are formed, each of which is called chromatids. retrieved from : https://www.khanacademy.o  CELL LIFE CYLE All reproduction begins at the cellular level. The process by which a cell divides into two and duplicates its genetic material. This is essential for human growth, reproduction, and cell regeneration. retrieved from : https://www.sciencefacts.net/ CELL LIFE CYCLE INTERPHASE: Recognized by the growth period. chromosome gets duplicated as the cell prepares for division. It is the longest part of the cell cycle involving three sub-phases. The typical duration of this phase is 23 hours. CELL LIFE CYCLE INTERPHASE: G1 PHASE Also known as the first-gap phase. The cells grow in size, synthesize cell organelles and other macromolecules such as proteins that serve as the building block of the cell. The cells also accumulate sufficient energy required for division. CELL LIFE CYCLE INTERPHASE: S PHASE Also known as the synthesis phase. The existing DNA is copied within the nucleus as a process called DNA replication. The entire S-phase requires energy expenditure to proceed. CELL LIFE CYCLE INTERPHASE: G2 PHASE This is the second gap phase and is somewhat similar to the G1-phase. During this period, the cells grow further in size, making more proteins and organelles. All preparations for mitosis get completed before the cells enter the mitotic phase. SAFETY GAP CELL LIFE CYCLE INTERPHASE: GO PHASE 1. G0- The G0 phase is a form of the resting state, or quiescence, in which cells reside until they receive appropriate signals For eg., signals from growth factors - stimulating them to re-enter cell cycle other cells that either never divide or seldom divide, such as nerve cells or cardiac cells, remain in G0-phase permanently. CELL LIFE CYCLE INTERPHASE: CHECKPOINTS 1. G1-checkpoint: Present just before the entry into S-phase. 2. G2-checkpoint: Checks errors in the DNA-synthesis phase and, based on the result, bars the entry into the M-phase. 3. M-checkpoint: Occurs near the end of the metaphase stage. It checks if sister chromatids are correctly attached to the spindle fibers.  CELL LIFE CYCLE MITOSIS- PROPHASE The chromosomes start to condense The mitotic spindle begins to form. The spindle is a structure made of microtubules, strong fibers that are part of the cell’s “skeleton. The nucleolus (or nucleoli, plural), a part of the nucleus where ribosomes are made, disappears. retrived from https://en.wikipedia.org/  CELL LIFE CYCLE MITOSIS- METAPHASE The spindle has captured all the chromosomes and lined them up in the middle of the cell. All the chromosomes align at the metaphase plate At this stage, the two kinetochores of each chromosome should be attached to microtubules from opposite spindle poles. retrived from https://en.wikipedia.org/  CELL LIFE CYCLE MITOSIS- ANAPHASE The sister chromatids separate from each other and are pulled towards opposite ends of the cell. The protein “glue” that holds the sister chromatids together is broken down, allowing them to separate. Microtubules not attached to chromosomes elongate and push apart, separating the poles and making the cell longer. retrived from https://en.wikipedia.org/  CELL LIFE CYCLE MITOSIS- TELOPHASE the cell starts to re-establish its normal structures as cytokinesis. The mitotic spindle is broken down into its building blocks. Two new nuclei form, one for each set of chromosomes. Nuclear membranes and nucleoli reappear. The chromosomes begin to decondense and return to their “stringy” form. Followed by Cytokinesis retrived from https://en.wikipedia.org/  CELL LIFE CYCLE retrived from https://en.wikipedia.org/  CELL LIFE CYCLE MEIOSIS- PROPHASE I The copied chromosomes condense into X- shaped structures. Each chromosome is composed of two sister chromatids containing identical genetic information. The chromosomes pair up so that both copies of chromosome 1 are together, both copies of chromosome 2 are together, and so on. retrived from https://thebiologynotes.com  CELL LIFE CYCLE MEIOSIS 1- PROPHASE I The chromosomes pair up so that both copies of chromosome 1 are together and vice versa. This process, in which homologous chromosomes trade parts, is called crossing over retrived from https://thebiologynotes.com  CELL LIFE CYCLE MEIOSIS 1- METAPHASE I Homologous pairs at metaphase plate for separation. There is an Independent Orientation retrived from https://thebiologynotes.com  CELL LIFE CYCLE MEIOSIS 1- METAPHASE I Homologous pairs metaphase plate for separation. There is an Independent Orientation retrived from https://thebiologynotes.com  CELL LIFE CYCLE MEIOSIS 1- METAPHASE I The homologous chromatids are pulled apart and move apart to opposite ends of the cell. The sister chromatids of each chromosome, however, remain attached to one another and don't come apart. retrived from https://thebiologynotes.com  CELL LIFE CYCLE MEIOSIS 1- TELOPHASE I The chromosomes arrive at opposite poles of the cell. Cytokinesis usually occurs at the same time as telophase I, forming two haploid daughter cells. retrived from https://thebiologynotes.com  CELL LIFE CYCLE MEIOSIS 2 Meiosis II is similar to mitosis, though its genetic results are fundamentally different. The end result is the production of four haploid cells (n chromosomes, 23 in humans) retrived from https://thebiologynotes.com  CELL LIFE CYCLE MEIOSIS retrived from https://thebiologynotes.com  CELL LIFE CYCLE MEIOSIS 4 daughter haploid cell= n=23 retrived from https://thebiologynotes.com THANK YOU FOR LISTENING! Don't hesitate to ask any questions!  REFERENCES: https://www.sciencefacts.net/cell-cycle.html https://www.sciencedirect.com/topics/biochemistry- genetics-and-molecular-biology/g0-phase https://www.sparknotes.com/biology/cellreproducti on/cellcycle/section1/page/2/