Cell Division Reviewer PDF

Lesson ​ 15.1 Cells Beget Cells Rudolf Virchow (1821-1902) A.)Proposed the third tenet of the cell theory B.)German Physician C.)Cells come from preexisting cells” Cell Division A.)A parent cell normally gives rise to two daughter cells. B.)A daughter cell rece...

Lesson ​ 15.1 Cells Beget Cells Rudolf Virchow (1821-1902) A.)Proposed the third tenet of the cell theory B.)German Physician C.)Cells come from preexisting cells” Cell Division A.)A parent cell normally gives rise to two daughter cells. B.)A daughter cell receives a complete set of identical hereditary material from each parent cell and half of its cytoplasm. C.)All cells (bacteria, plants, animals, or humans) undergo cell division Unicellular Organisms A.)made up of a single-cell Examples: bacteria, amoeba, paramecium, and yeast A.)Binary Fission is a method of asexual reproduction commonly seen in B.)prokaryotic organisms. Multicellular Organisms A.)It is composed of multiple cells that work together B.)Cells are specialized and organized into tissues organs and systems Cellular reproduction A.)It is a way of production of new tissues or body parts during growth and development. B.)Replace worn-out and damaged cells C.)To produce new plants or animals in asexually reproducing organisms. Cell Differentiation A.)The daughter cells may grow and divide again B.Specialized for specific functions such as fighting infection (white blood cells), contraction (muscle cells), impulse conduction (nerve cells), and digestive enzyme secretion (stomach or intestine cells) Cell Categories A.)Permanently differentiated cells- differentiated cells that never divide again such as cells in the heart and brain B.)Stem cells- that have the ability to perform self-renewal and differentiate into a variety of cell types.  Lesson 15. 2 Organelles Involved in Cell Division Nucleus A.)Contains the cell’s genetic material (DNA) DNA- Deoxyribonucleic Acid B.)Cell division starts C.)Chromatin fibers are the genetic material of the cell that is found inside the nucleus. D.)Responsible for regulating cell division by controlling the processes of mitosis or meiosis Chromosomes A.)Condensed structure of DNA and proteins that carry genetic information. B.)Humans have estimated roughly 25,000 genes contain mostly in the nucleus of 46 chromosomes. C.)Essential for accurate distribution of genetic material to daughter cells D.)Has centromere, a region containing kinetochore Centrioles A.)Paired organelles found in the cytoplasm near the nucleus and become visible only to take part in cell division B.)Found in animal cells and play a critical role in the formation of the C.)mitotic spindle during cell division D.)During cell division it duplicates itself E.)Help in organizing the movement of chromosomes. Spindle Apparatus A.) Composed of microtubules and other proteins that help separate B.)chromosomes during cell division. -​ Are formed from microtubules -​ Facilitates chromosome movement to opposite poles of the cell. Nuclear membrane -​ Disintegrates during cell division Cytoplasm -​ The fluid-filled region where organelles are suspended. -​ Provides the necessary environment for cell division to occur. Plasma membrane  Plays a role in cytokinesis (the physical separation of the cytoplasm) During cell division. Summary of the Process: 1.​ Chromosomes get copied and get ready to split. 2.​ Centrosomes organize the spindle fibers to pull the chromosomes apart. 3.​ The nucleus disappears to allow chromosome separation. 4.​ Cytoskeleton helps in physically separating the cell into two. 5.​ A cleavage furrow or cell plate forms to divide the cell’s contents. Lesson 15.3 Stages of Cellular Reproduction Cellular Reproduction -​ The process by which cells divide to create new cells. This is essential for growth, repair, and reproduction in living organisms. 2 stages: A.) Cellular growth and maturation ​ The cell undergoes processes to prepare for division. ​ Key process: ○​ Growth to normal size ○​ Assembly of organelles and cellular components ○​ Energy accumulation ○​ Replication of genetic material (DNA) B.) Cell division ​ The genetic material (chromosomes) is divided equally into two daughter cells ​ Organelles and cytoplasmic components are also distributed Cell Growth and Division in the Human Body ​ Cells increase in number, not size as the body grows ​ Adult human cells are similar in size to young human cells, but adults have more cells Limits of Cell Growth ​ Cells do not grow indefinitely due to two main factors: 1.​ The larger the cell becomes, the more difficult for its DNA to handle the cell’s demands. ​ DNA stores critical genetic information needed for growth ​ DNA stands for Deoxyribonucleic Acid ​ A larger cell would demand more from the fixed amount of DNA ​ If cells grows too large, DNA cannot keep up with the needs of the cell ​ If cells grows, it does not make extra copies of DNA 2.​ The larger the cell becomes, the harder to move nutrients and waste across its membrane ​ The size of a cell affects how efficiently it can transport nutrients and remove waste. ​ Smaller cells have a higher surface area-to-volume ratio, allowing for faster exchange of materials. ​ Larger cells struggle to move substances efficiently, leading to slower cell functions. ​ Before the cell becomes too large, a growing cell divides, forming two identical daughter cells. Factors that Limit Cell Size 1.​ Surface Area-to-Volume Ratio ​ Surface area determines how much material can enter or leave the cell. ​ Volume determines how much material the cell needs. ​ As a cell grows, its volume increases faster than its surface area, making nutrient and waste exchange inefficient. 2.​ Diffusion efficiency ​ Essential nutrients (oxygen, water, food) and waste move through the cell membrane. ​ In larger cells, diffusion takes longer, making it difficult to transport materials effectively. 3.​ DNA Limitations  ​ DNA controls all cell activities, but the amount of DNA remains the same even if the cell grows. ​ A larger cell places higher demands on its DNA, which can slow down cell functions. Why do cells divide? ​ Instead of growing too large, cells divide to maintain an efficient surface area-to-volume ratio. ​ This ensures they can transport nutrients, eliminate waste, and function properly. MOLECULAR BIOLOGIST- study the molecules present in the cells of living things and how these molecules interact with one another. They often examine the genetic information in the form of DNA and how it affects the structure and functions of the body. LESSON 15. 4 The Cell Cycle The major events and important characteristics of each stage during interphase are summarized as follows: Stage 1: G1 (Gap 1) Phase ​ This is the longest phase in most cells. ​ The cell at this stage is still young and undergoes rapid growth until it attains its normal size. ​ Organelles are formed. ​ Proteins are produced such as the enzymes needed in S phase. ​ Cells that do not divide 9 muscle and nerve cells) remains at this stage throughout their life cycle. Stage 2: S (Synthesis) Phase ​ The DNA, the main composition of the chromosomes inside the nucleus of the cell, doubles at this stage through a process called replication. ​ At the end of this stage, each chromosome is made up of sister chromatids attached to the centromere. Stage 3: G2 (Gap 2) Phase ​ Preparation for cell division ​ Assembly of proteins such as microtubules that cause the chromosomes to move during cell division Stage 4: M (Mitosis/Meiosis) Phase ​ The cell undergoes division. ​ Division of the nucleus is called karyokinesis, while division of the cytoplasm is called cytokinesis. Lesson 15.5 Stages of Mitosis Mitosis ​ type of cell division in which the nucleus divides into two nuclei with identical genetic material. ​ The resulting two daughter cells have the same number of chromosomes similar to the parent cell. ​ Only occurs in eukaryotes. ​ Used by multicellular organisms for growth and development, for repair of tissues, and in asexual reproduction. Diploid parent cell containing two sets of chromosomes (maternal and paternal chromosome sets) A normal human body cell containing 46 chromosomes undergoes mitosis, it produces 2 genetically identical daughter cells each with 46 chromosomes ​ ​ ​ ​ ​ Mitosis consists of 4 stages ​ 1. Prophase – Chromosomes condense, nuclear membrane breaks down, and spindle fibers begin to form. ​ 2.​ Metaphase – Chromosomes align at the center (metaphase plate). Spindle fibers attach to centromeres. ​ 3.​ Anaphase – Sister chromatids are pulled apart toward opposite poles of the cell. ​ 4.​ Telophase – Nuclear membranes start to reform, and chromosomes begin to decondense.  Cytokinesis The cytoplasm divides, fully splitting the cell into 2 identical daughter cells. Cleavage furrow formation forms during cytokinesis (the final step of cell division) in animal cells. Cell plate formation occurs during cytokinesis in plant cells and other cells with cell walls, cytokinesis starts at the middle of the cell and moves outward.