Cell Biology: Cell Structure and Function

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Cell Biology: Cell Structure and Function. Lesson 1 – Eukaryotic Cells and Organelles ( Inquiry into Life pg. 49-62 ). Today’s Objectives. Analyze the functional inter-relationships of cell structures, including: Describe the major cell structures and their functions - PowerPoint PPT Presentation

Transcript of Cell Biology: Cell Structure and Function

Inquiry into Life Twelfth Edition

Cell Biology:Cell Structure and FunctionLesson 1 Eukaryotic Cells and Organelles (Inquiry into Life pg. 49-62)

Todays ObjectivesAnalyze the functional inter-relationships of cell structures, including:Describe the major cell structures and their functionsState the balanced chemical equation for cellular respirationDescribe how the Endomembrane System functions to compartmentalize the cell and move materials through itIdentify cell structures depicted in diagrams and electron micrographsThe CellThe cell is the structural and functional unit of an organism. It is the smallest structure capable of performing all the functions necessary for life.

The study of cellsThe study of cells had its birth with the invention of the microscope, but it became a product of the 19th century. As biologists became increasingly familiar with the detailed microscopic features of organism they were able to make certain generalizations about cells.

In the late 1830s two German biologists, Schleiden ( a botanist) and Schwann, (a zoologists) made similar claims. They realized that all organisms they were studying were composed of cells. Their discoveries are now generalized as The cell is the building block of all organisms.

A few years later, Rudolph Virchow added the observation that cells come from pre-existing cells.

These two statements comprise what is now known as the Cell Theory.

Cell TheoryCell theory states: All organisms are composed of one or more cells. Cells are the basic unit of structure and function in an organism.All cells come from other cells. Cell SizeCells are very small. Most cells are between 1 micrometer (1 thousandth of a millimeter) and 100 micrometers.

Cell SizeSmall cells are advantageous to multicellular organisms.Nutrients and wastes are passed through the cell at its surface, therefore the amount of surface area affects the ability to material in and out of the cell. As cells increase in volume, the proportionate amount of surface area decreases.

Surface Area: 96 cm2192 cm2384 cm2Types of CellsThere are two overall classifications of cells:Prokaryotic cells (simple cells)Do not contain nucleus or membrane enclosed organellesFound in Bacteria, ArchaeaUsually exist as single celled organisms (unicellular)Eukaryotic cells (complex cells)possess nucleus and organellesContains internal membranesMulticellular organismsProkaryotic Cells

Eukaryotic Cells

Examples of Eukaryotic cells include Plants, Animals, Protists, Fungi.

Prokaryotic cells are considered to be less efficient than Eukaryotic cells because the chemical reactions occur all over the cytoplasm rather than in areas of specialization.

Cell Organelles Plant Cell

Cell Organelles Animal CellNucleusLargest Organelle.

Surrounded by a double-layered membrane (the nuclear envelope).

Membrane has pores through which larger molecules pass. (Nuclear Pores)

Control center for the cells functions. (The brain).

Contains a fluid called the nucleoplasm.

Contains chromatin (DNA strands which forms chromosomes during cell division.)

Nucleus and Nuclear Envelope

NucleolusDark region in the Nucleoplasm.One or more found in the nucleus.Site where ribosomal RNA (rRNA) is produced or stored.Involved in interactions between the nucleus and the cytoplasm.

ChromatinThe hereditary material of the cell.Condenses to form chromosomes during cell division. Composed of Protein and DNA

ChromosomesCondensed chromatinContains the hereditary information. (genes)Rod-shaped bodies in the nucleus, particularly during cell division

Each eukaryotic species has a characteristic number of chromosomes

A typical human cell has 46 chromosomes, but sex cells (eggs and sperm) have only 23 chromosomes.

CytoplasmA semifluid (like a gel) medium composed of water, salts and dissolved organic moleculesContains and supports all the cells organelles.

Plasma MembraneAll cells are surrounded by a plasma membrane.The material inside of a cell is the cytoplasm.The plasma membrane regulates what enters and exits a cell.

Plasma Membrane (cell membrane)Composed of proteins and phospholipids (fats with Phosphorus).

Acts as skin around the cells contents.

Acts as a selectively permeable membrane to allow movement of materials in and out of the cell.

Located around the outside of the cell.

Single membrane around the vacuoles/vesicles, lysosomes, E.R., Golgi Apparatus.

Double membrane around the nucleus and mitochondria

End of Part 1Cell Organelle JigsawHalf of groups research organelles on front sideHalf of groups research organelles on back sideHalf way through, 2 groups join to teach other group about their organellesLocation in cellStructureFunctionThe Endomembrane SystemConsists of:Nuclear EnvelopeEndoplasmic reticulumGolgi apparatusVesiclesThis system compartmentalizes the cell so that particular enzymatic reactions are restricted to specific regionsOrganelles of the endomembrane system are connected directly or by transport vesiclesSystem of interconnected flattened tubes, sacs, or canals.Begins at the nuclear envelope and branches throughout the cytoplasm to the cell membrane.Moves molecules from one area to another.

Smooth Endoplasmic Reticulum (Smooth ER)-Location of lipid manufacture. Cells that produce steroid hormones, have an abundant smooth ER.

-Section of both types of ER can break free blebbing to produce small membrane bound sacs of either proteins or lipids called vesicles.

-Contains enzymes that synthesize lipids and related products such as steroids.Like Smooth E.R., but with attached ribosomes.Folds and processes proteins and packages them in transport vesiclesAbundant in cells that produce large amounts of protein for export from the cell.

Rough Endoplasmic Reticulum (Rough ER)

Golgi Apparatus (Golgi Body)Stack, of a half dozen or more flattened sacs.On one side receives protein-filled vesicles from the E.R.Sorts the proteins and packages them in vesicles at the other side. From here the vesicles move to different locations in the cell.Like the post office of the cell.

Many transport vesicles from the ER travel to the Golgi apparatus for modification of their contents.The Golgi is a center of manufacturing, warehousing, sorting, and shipping.The Golgi apparatus is especially extensive in cells specialized for secretion.

Vesicles and VacuolesVesicles and vacuoles (larger versions) are membrane bound sacs with varied functions.VacuolesStorage areas for water, nutrients, and salts. VesiclesA small vacuoleStorage sites in various kinds of molecules.Transport and secretory vesicles move their contents within the cell and in and out of the cell. Can be made by the Golgi Apparatus or from an infolding of the cell membrane

LysosomesSpecial vacuoles formed by the golgi body. Contain powerful digestive enzymes that break down unwanted, foreign substances or worn-out parts of cells

The Endomembrane System

Fig. 7.14

RibosomesContain rRNA and protein subunits.Function as sites for protein synthesis.Found on ER (proteins for export) or in the cytoplasm (proteins for use in the cell).

- Several ribosomes together in a line, all producing the same protein is called a polyribosome.Mitochondria (singular Mitochondrion)Burn glucose to produce adenosine triphosphate (ATP).Use up oxygen and give off carbon dioxide (this process is called cellular respiration).C6H12O6 + 6O2 6CO2 + 6H2O + EnergyComposed of two membranes.

-Considered the powerhouse of the cell.

Their inner membranes loop back and fourth through the inner fluid, matrix, of the mitochondria increasing its surface area and producing shelf-like structures called cristae.

This inner membrane is the site of cellular respiration

CytoskeletonProtein components of cytoskeleton provide internal structure to maintain the cells shape, anchor the organelles, and allows them to move when appropriate.Composed of microfilaments (actin filaments) and microtubules.Like the bones and muscles of the cell

Cytoskeleton Microfilaments (Actin Filaments)Primarily functions to maintain cell structure and cell movementsExtremely thin protein fibers usually occurring in bundles.Similar in composition to the protein in the muscle (allows for muscle contraction).

Cytoskeleton - Microtubules Maintain the shape of the cell and act as tracks that organelles can move on.

Thin cylinders several times larger than microfilaments.Found in both cytoplasm and certain organelles.Used to construct material to make up Cilia, Flagella and Centrioles.


Other OrganellesCentrioles: short cylinders with a 9+0 pattern of microtubule tripletsTwo centrioles lying at right angles form the centrosome which is the microtubule organizing center (MTOC)Cilia and Flagella:Hair like projections that can move in undulating fashion (like a whip) or stiffly (like an oar)Cells with cilia and/or flagella are capable of movementCilia also line the respiratory system and help remove foreign material from the lungs

A cell is a living unit greater than the sum of its partsWhile the cell has many structures that have specific functions, they must work together.The enzymes of the lysosomes and proteins of the cytoskeleton are synthesized at the ribosomes.The information for these proteins comes from genetic messages sent by DNA in the nucleus.All of these processes require energy in the form of ATP, most of which is supplied by the mitochondria.A cell is a living unit greater than the sum of its parts.

ABCD Quiz!I believe you all know how to play this game:Groups of 41 scorekeeper4 contestantsI will show a clue about an organelle, each team member will guess one of the 4 choices providedTeam with highest score winsNo notes or books allowedQuestion 1I am the largest organelle in a cell, and I contain hereditary material. I am a:A) RibosomeB) MitochondrionC) NucleusD) Golgi ApparatusAnswer is CQuestion 2I am composed of phospholipids and proteins and I control what enters and exits the cell. I am a:A) Plasma MembraneB) LysosomeC) VesicleD) Smooth ERAnswer is AQuestion 3I am kind of like the subway system of the cell because I transport molecules from one place to another. I am a:A) Rough ERB) VesicleC) LysosomeD) MitochondrionAnswer is BQuestion 4I receive protein filled transport vesicles from the ER which I then sort and repackage for use inside the cell. I am the:A) RibosomeB) VacuoleC) CytoplasmD) Golgi ApparatusAnswer is DQuestion 5I synthesize protein and I can be found in the cytoplasm or attached to another organelle. I can also be found in groups. I am a:A) MitochondrionB) RibosomeC) LysosomeD) MicrofilamentAnswer is BQuestion 6I have attached ribosomes that synthesize proteins which I then process and package. Cells that export a lot of protein have a lot of me! I am the:A) LysosomeB) Nuclear EnvelopeC) Rough ERD) Smooth ERAnswer is CQuestion 7I have a double membrane and I am the site of cellular respiration and production of ATP. I am a:A) MitochondrionB) Golgi ApparatusC) Smooth ERD) Rough ERAnswer is AQuestion 8My job is to digest nutrients for use in the cell or to get rid of unwanted molecules and waste. I am a:A) VesicleB) NucleusC) LysosomeD) RibosomeAnswer is CQuestion 9I maintain the shape of the cell and allow different organelles to move around the cytoplasm. I am the:A) CytoplasmB) VesicleC) CytoskeletonD) Plasma MembraneAnswer is CQuestion 10I am capable of forming transport vesicles and lipids and steroids are synthesized inside of me. I am:A) Rough ERB) Smooth ERC) Golgi ApparatusD) MitochondrionAnswer is B