Senior Health Sciences Unit 2: Cell Theory and Cell Structure PDF

***SENIOR HEALTH SCIENCES -- Semester 1*** ***[UNIT 2: Cardiorespiratory Health]*** *2.1 Cell Theory and Cell Structure* **[Cell Theory and Cell Structure]** - *Cell theory is a fundamental concept that explains the structure and function of living organisms* - *Cells are the smallest s...

***SENIOR HEALTH SCIENCES -- Semester 1*** ***[UNIT 2: Cardiorespiratory Health]*** *2.1 Cell Theory and Cell Structure* **[Cell Theory and Cell Structure]** - *Cell theory is a fundamental concept that explains the structure and function of living organisms* - *Cells are the smallest structures capable of performing all necessary life processes and the basic unit of life* **[Cell Theory]** Cell theory is a fundamental concept that explains the structure and function of living organisms It has three main parts: 1. **all living things are made of cells** - Cells are the basic building blocks of life 2. **Cells are the smallest unit of life** - They carry out all the processes needed to keep an organism alive 3. **All cells come from pre-existing cells** - New cells are made when existing cells divide **[Cell Division]** - Organisms grow and reproduce through **cell division.** - In eukaryotic cells, the production of new cells occurs as a result of **mitosis** and **meiosis** - These two nuclear division processes are similar but distinct. - Both processes involve the division of a diploid cell, or a cell containing two sets of chromosomes (one chromosome donated from each parent). - **Meiosis is for sperm and ovum cells** - **Mitosis is important for cardiorespiratory (repairing of the body system)** - **Humans are eukaryotic** **[What is Mitosis?]** **PURPOSE OF MITOSIS** - In a **unicellular** organism **(not humans)** the purpose of mitosis is to **multiply** as a species. - In a **multicellular** organism **(humans)** the purpose can be to **grow** during development, or to **repair** or **regenerate** damaged tissue, for example. **OUTCOME OF MITOSIS** - **Two diploid cells** with **identical** genetic information. **PROCESS OF MITOSIS** - Every day, our skin cells and other somatic (**body)** cells undergo division to replenish the dying cells. - When this happens, the new cell will have the **same number of chromosomes and organelles** - Occurs in all diploid (2n) cells, **except for sex cells** - There are 4 phases - Followed by **cytokinesis splitting into 2 new cells** **[Prophase]** - doubling of chromosomes - organelles and centrioles visible **[Metaphase]** - chromosomes line-up in the middle - spindles from centrioles connect to each chromatid (half of chromosome) **[Anaphase]** - chromatids pulled apart to separate ends - the membrane begins to pinch off in the middle **[Telephase]** - complete division of cytoplasm - two cells are formed  **[What is Meiosis?]** **PURPOSE OF MEIOSIS** - To **create gametes** with only one copy of the organism's genetic information, in preparation for **sexual reproduction** - Various steps in meiosis create opportunity for **genetic diversity** in the daughter cells. - **This is seen as diversity among looks (except for twins)** - This is the **raw substrate for evolution** **OUTCOME OF MEIOSIS** - **Four haploid** cells with **different **genetic information. **PROCESS OF MEIOSIS** - **Meiosis is process of gametes generated in sexually reproducing organisms** - New gene combinations are introduced in a population through the genetic recombination that occurs during meiosis. - Thus, unlike the two genetically identical cells produced in mitosis, the meiotic cell cycle produces **four cells that are genetically different**. Stock Photo and Image Portfolio by Ody\_Stocker \| Shutterstock **[SIMILARITIES AND DIFFERENCES BETWEEN MITOSIS AND MEIOSIS]**  **[Structure of an Animal Cell]** A diagram of a cell Description automatically generated **1.** nucleolus ---------- ---------------------------------------------------------- **2.** nucleus **3.** cytosol **4.** ribosomes **5.** cytoskeleton **6.** Mitochondrion (aerobic respiration takes place -- power) **7.** peroxisome **8.** Golgi body **9.** lyosome **10.** Plasma membrane **11a.** Endoplasmic reticulum -- smooth **11b.** Endoplasmic reticulum -- rough **[Organelles of an Animal Cell]** +-----------------------------------+-----------------------------------+ | ***ribosomes*** |  | | | | | **Structure**: Two subunits made | | | of RNA and protein | | | | | | **Function**: Site of polypeptide | | | synthesis (this process is called | | | translation) | | +===================================+===================================+ | ***cytoskeleton*** | cytoskeleton | | | | | **Structure**: A filamentous | | | ***(thin, made of filaments)*** | | | scaffolding within the cytoplasm | | | | | | **Function**: Provides internal | | | structure and mediates | | | intracellular transport | | +-----------------------------------+-----------------------------------+ | ***Plasma membrane*** |  | | **Structure**: Phospholipid | | | (**phosphorous fat lipid)** | | | bilayer embedded with proteins | | | | | | **Function**: Semi-permeable and | | | selective barrier surrounding the | | | cell | | +-----------------------------------+-----------------------------------+ | ***nucleus*** | nucleus | | | | | **Structure**: Double membrane | | | structure with pores; contains | | | inner region (nucleolus) | | | | | | **Function**: Stores genetic | | | material (DNA); site of ribosome | | | assembly | | +-----------------------------------+-----------------------------------+ | ***Endoplasmic reticulum*** |  | | **Structure**: Membrane that may | | | be bare (smooth ER) or with | | | ribosomes (rough ER) | | | | | | **Function**: Transports | | | materials between organelles (SER | | | = lipids; RER = proteins) | | +-----------------------------------+-----------------------------------+ | ***Golgi apparatus*** | golgi body | | | | | **Structure**: Assembly of | | | vesicles **(liquid/cytoplasm | | | layer held between lipid | | | bilayer)** and folded membranes | | | located near cell membrane | | | | | | **Function**: Involved in the | | | sorting, storing, modification | | | and export of secretory products | | +-----------------------------------+-----------------------------------+ | ***mitochondrion*** |  | | **Structure**: Double membrane | | | structure, inner membrane highly | | | folded into cristae | | | | | | **Function**: Site of aerobic | | | respiration (ATP production) | | +-----------------------------------+-----------------------------------+ | ***peroxisome*** | peroxisome | | | | | **Structure**: Membranous sac | | | containing a variety of catabolic | | | enzymes | | | | | | **Function**: Catalyses breakdown | | | of toxic substances (e.g. | | | H~2~O~2~) and other metabolites | | +-----------------------------------+-----------------------------------+ | ***centrosome*** |  | | | | | **Structure**: Microtubule | | | organising centre (paired | | | centrioles in animal cells) | | | | | | **Function**: Radiating | | | microtubules form spindle fibres | | | and contribute to cell division | | | (mitosis / meiosis) | | +-----------------------------------+-----------------------------------+ | ***lyosome*** | lysosome | | | | | **Structure**: Membranous sacs | | | filled with hydrolytic enzymes | | | | | | **Function**: Breakdown / | | | hydrolysis of macromolecules | | | (presence in plant cells is | | | subject to debate) | | +-----------------------------------+-----------------------------------+