MATER DEI ACADEMY GENERAL BIOLOGY 1 Lesson 2 CELL BIOLOGY Cell Modification and Cell Cycle INCLUSIVE DATES: WEEK 3 Prepared by: Earl Justine S. PalleraQUARTER: First Quarter LEARNING COMPETENCIE S 1. Describe some cell modifications that lead to adaptation to carry out specialized functions (e.g., microvilli, root hair), STEM_BIO11/12 -Ia-c-5 2. Characterize the phases of the cell cycle and their control points STEM_BIO11/12 -Id-f-6 VALUES INTEGRATED Commitment to stewardship of creation Awe and Wonder Zeal for creativity and Innovation Responsible Cyber citizenship Scientific Inquiry TERMS TO REMEMBER Animal Cells - eukaryotic cells that contain various membrane-bound organelles. Cell Cycle - the life cycle of a dividing cell, including Interphase and the M phase or Mitotic phase (mitosis and cytokinesis). Cytokinesis - the division of the cytoplasm that produces distinct daughter cells. Cytosol - semi-fluid component of a cell's cytoplasm. Daughter Cell - a cell resulting from the replication and division of a single parent cell. Daughter Chromosome - a chromosome that results from the separation of sister chromatids during cell division. Diploid Cell - a cell that contains two sets of chromosomes—one set of chromosomes Plant Cells - eukaryotic cells that contain various membrane-bound organelles. They are distinct from animal cells, containing various structures not found in animal cells. Polar Fibers - spindle fibers that extend from the two poles of a dividing cell. Prokaryotes - single-celled organisms that are the earliest and most primitive forms of life on earth. Genes - segments of DNA located on chromosomes that exist in alternative forms called alleles. GETTING STARTED 1. Somatic cells are cells that fill the body, and must reproduce to repair damage. Gametic cells are cells that produce gametes. Which type of cell division do each type of cell undergo? A. Somatic= mitosis; Gametic= meiosis B. Somatic= mitosis; Gametic= meiosis and mitosis C. Somatic= mitosis and meiosis; Gametic= meiosis and mitosis 2. Mitochondria are organelles in cells that create ATP, a molecule used for energy. Mitochondria must replicate inside the cell, separate from mitosis or meiosis, to regulate the amount of energy being delivered. In mitochondria, there is a ring of DNA that controls the mitochondrial metabolism. A. Binary Fission B. Mitosis C. Meiosis LET’S EXPLORE CELL MODIFICATIONS As organisms felt the pressure of natural selection and attempted to colonize new territories, the need for advancements in both structure and function were necessary. They evolved with modified structures (evolution) or were created with the appropriate structures (creationism) to fit the environment. Advancements in structure and function created complex life-supporting systems that are more versatile and allow the organisms’ greater freedom for colonization in fringe territories. Photosynthesis, respiration, and protein synthesis are typical examples of complex chemical phenomena that occur around and within us constantly. The following cells are some types of modifications. Cheek Cells (Animal Cells) • Lysosomes – Digests food vacuoles and recycles unwanted materials. • Centrioles – Development and produces spindle fibers for cell division. • Flagella – For locomotion. Onion Cells (Plant Cells) • Cell Wall – Rigid outer covering that contains cellulose. Central Vacuole – Water, food and waste storage. • Plastids – Responsible for photosynthesis via chloroplast (a plastid that contains chlorophyll). • Plasmodesmata – Channels that connects plant cells. Blood Cells • Disc-like or Biconcave shape – For oxygen diffusion. • Nucleus is absent – For greater surface area. Liver Cells • Smooth and Rough ER is abundant. • Contains many ribosomes. Stomach Cells • Chief Cells – Secretes pepsinogen and gastric lipase. Digests Protein • Parietal Cells – Produces Gastric acid and secretes intrinsic factor for digestion of vitamin B12. • Mucous Cells – For protective covering of stomach. It is the counterpart of Parietal cells. • Microvilli – For increasing the surface are for nutrient absorption. Tracheal Cells • Ciliated Cells – to propel mucus. • Goblet Cells – responsible for producing mucus to trap particles. Muscle Cells • Characteristics 1. Multi-nucleated – to produce proteins because muscles are 2. Long and Cylindrical 3. Striated • Contains contractile filaments: Actin and Myosin 1. Light Band/I band – Actin 2. Dark Band/A band – Actin and Myosin Bone Cells • Osteocytes – They do not contain nuclei because they need to be stable. Toughest part of the bone which bounded by calcium and phosphate. • Osteoblast – Builds bone. • Osteoclast – Bone restoration. Nerve Cells • Soma – It is where the metabolic activities of the cell happens. • Dendrites – It is the receiver of electrical impulses and sends it toward the cell or soma. • Axon – It is the sender of the impulses away from the cell or soma. • Myelin Sheath – Protects the long axon. It insulates the cell to make the impulses travel faster. • Nodes of Ranvier – The gap between two myelin sheaths. It speeds up the transmission of impulses. • Saltatory conduction – The jumping of impulses from two myelin sheaths. • Schwann Cells – Produces myelin sheath. Skin Cells • Epidermis 1. Stratum Corneum – Has the most keratin. 2. Stratum Lucidum – Flattened and clear layer. 3. Stratum Granulosum – Waxy material. 4. Stratum Spinosum – Intercellular bridge. 5. Stratum Basale – Deepest part where mitotic division happens. a. Keratinocyte – Produces keratin; a protein that protects epithelial cells from damage or stress. b. Melanocyte – Produces melanin; a pigment that responsible for black and reddish color of skin. c. Langerham Cells – For immunity against foreign bodies. • Dermis • Hypodermis (Subcutis) Mammary Cells • Inner Epithelial Cells – For lactation. • Outer Epithelial or Myoepithelial Cells – Contractile cells which ejects milk from the nipple. THE CELL CYCLE The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and subsequently the partitioning of its cytoplasm and other components into two daughter cells in a process called cell division. In eukaryotic cells (i.e., animal, plant, fungal, and protists cells), the cell cycle is divided into two main stages: interphase and the mitotic (M) phase which includies mitosis and cytokinesis. During interphase, the cell grows, accumulating nutrients needed for mitosis, and replicates its DNA and some of its organelles. During the mitotic phase, the replicated chromosomes, organelles, and cytoplasm separate into two new daughter cells. To ensure the proper replication of cellular components and division, there are control mechanisms known as cell cycle checkpoints after each of the key steps of the cycle that determine if the cell can progress to the next phase. PHASES IN THE CELL CYCLE The eukaryotic cell cycle consists of four distinct phases: G1 phase, S phase (synthesis) G2 phase (collectively known as interphase) M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm divides forming two daughter cells. STATE PHASE ABBREVIATION Resting Gap 0 Gap 1 G0 G1 DESCRIPTION A phase where the cell has left the cycle and has stopped dividing. Cells increase in size in Gap 1. The G1 checkpoint control mechanism ensures that everything is ready for DNA synthesis. Interphase Synthesis Gap 2 DNA replication occurs during this phase. During the gap between DNA synthesis and mitosis, the cell S will continue to grow. G2 The G2 checkpoint control mechanism ensures that everything is ready to enter the M (mitosis) phase and divide. Cell division Cell growth stops at this stage and cellular energy is focused on the orderly division into two daughter cells. Mitosis M A checkpoint in the middle of mitosis (Metaphase Checkpoint) ensures that the cell is ready to complete cell division. After cell division, each of the daughter cells begin the interphase of a new cycle. Although the various stages of interphase are not usually morphologically distinguishable, each phase of the cell cycle has a distinct set of specialized biochemical processes that prepare the cell for initiation of cell division. FIRM UP ACTIVITY # 1 – ON CELL MODIFICATIONS ACTIVITY # 2 – CELL CYCLE & MODIFICATIONS Attached to this module are the worksheets on cell modification and cell cycle. Download the worksheet and answer the questions briefly and submit it on the scheduled date. GENERALIZATION All organisms consist of cells and arise from pre - existing cells. • Mitosis is the process by which new cells are generated. • Meiosis is the process by which gametes are generated for reproduction. • The Cell Cycle represents all phases in the life of a cell. • DNA replication (S phase) must precede mitosis so that all daughter cells receive the same complement of chromosomes as the parent cell. • The gap phases separate mitosis from S phase. This is the time when molecular signals mediate the switch in cellular activity. • Mitosis involves the separation of copied chromosomes into separate cells. • Unregulated cell division can lead to cancer. • Cell cycle checkpoints normally ensure that DNA replication and mitosis occur only when conditions are favourable and the process is working correctly. • Mutations in genes that encode cell cycle proteins can lead to unregulated growth, resulting in tumor formation and ultimately invasion of cancerous cells to other organs. LESSON TAKE AWAY As a student of biology, what is the importance of cell cycle in your daily life? The cell cycle teaches us to value the concept of time and patience. Time is very important in the cell cycle because it will allow a cell to produce another. In life, we need time; time to heal all wounds, time to study how things work, time to be successful, and time for everything. This lesson taught us that time is a valuable thing that we cannot take back what was done already. We can’t reverse time. TAKE HOME TASK Research on the different stages of Cell Division and its distinct activities. Write your answer on the table below. MITOSIS STAGES IMPORTANT ACTIVITY MEIOSIS STAGES IMPORTANT ACTIVITY NAME: _____________________________________________________ CELL MODIFICATIONS LESSON 2: ACTIVITY # 1 Critical Thinking: Answer the following items. 1. There are anti-cancer drugs that are used to prevent the formation of spindle fibers. Why do you think this is effective in treating cancer? __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ 2. What might happen if certain phases of the cell cycle do not function well? __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ 3. What happens to the body when there is uncontrolled cell growth? __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ NAME: _____________________________________________________ CELL CYCLE AND MODIFICATIONS LESSON 2: ACTIVITY # 2 1. What is the importance of having a tissue level in the hierarchy of biological organization (cell modification)? ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ 2. Why are there voluntary and involuntary muscle tissue functions? ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ 3. What is the importance of glial cells in nervous tissues? ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ 4. Identify two cell modifications and describe their respective functions. ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________
