THE CELL

1. THE CELL Structure and Function

2. THE CELL: Structure and Function • Objectives • Alabama Course of Study • Alabama High School Graduation Exam • Teacher/Text objectives • Cellular basics • The cell membrane • Structure and function • transport • Organelle structure and function • Animal cells vs. Plant cells • Quiz

3. Objectives • Alabama Course of Study • 17. Identify the basis of the cell theory • 18. Analyze relationships among cell structure, function, and organization in prokaryotes and eukaryotes. • 20. Relate cellular functions to specialized structures within cells. • Active and passive transport or materials (osmosis, diffusion) • Waste disposal

4. Objectives continued… • Alabama High School Graduation Exam • Standard V: The student will understand concepts of cells • Objective 1: Distinguish relationships among cell structures, functions, and organization in living organisms. • Eligible content: • Define and identify representations of diffusion and osmotic systems. • Recognize differences between active and passive transport of substances and the energy requirements associated with each.

5. Objectives continued… • AHSGE Eligible content continued: • Identify and define similarities and differences between plant and animal cells. • Classify organisms and prokaryotic or eukaryotic. • Describe cell locomotion by means of cilia and flagella. • Identify cell organelles and define functions of cell organelles. • Distinguish and identify examples of cellular organization at the cell, tissue, organ, system, and organism level.

6. Teacher / Text Objectives • Differentiate between active and passive transport. • Describe the structure and functions of the cell membrane. • Relate each organelle to a task essential to the life of the cell. • Explain the structural differences between plant and animal cells.

7. Cellular basics review • Cell – basic unit of living organisms • Prokaryote – cell without membrane-bound structures. Example: bacteria • Eukaryote – cell with membrane-bound structures. • Examples: multicellular organisms such as plants and animals; and some unicelllular organisms. • Cilia – short, numerous, hair-like structures that aid in locomotion or feeding. • Flagella – long, whip-like structure used for locomotion. • Organelle – membrane-bound structures within a cell that carry out a specific function.

8. The Plasma Membrane - structure • The plasma membrane is a selectivelypermeable phospholipid bilayer surrounding the cell. • Contents of the plasma membrane: • Phospholipids have a polar (water-loving) head region and a nonpolar (water fearing) tail. • The fluid mosaic model of phospholipids allow fexibility • Proteins are scattered throughout the membrane and allow for transport of materials, identification, and transfer of information. • Cholesterol provides stability and prevents the fatty acids of phospholipids from sticking together.

9. Cell membrane – function • Through transportation, the cell membrane regulates the raw materials (glucose, amino acids, and lipids) that enter the cell and waste products that leave the cell. • This process of maintaining a cell’s internal environment is called homeostasis. • The cell membrane also protects the cell from its external environment.

10. Cytoplasm Cytoskeleton Microtubules Microfilaments Mitochondria Ribosomes Endoplasmic Reticulum Smooth Rough Golgi Apparatus Lysosome Nucleus Nucleolus Chromatin Special plant structures Large Central Vacuole Cell wall Chloroplasts Organelles

11. Cytoplasm and Cytoskeleton • Cytoplasm is a clear gelatinous fluid inside the cell that surrounds the organelles. • The cytoskeleton is a framework of microtubules and microfilaments that help shape and support cells, and to assist organelles in moving from place to place.

12. Mitochondria • The mitochondria is the site of energy production through respiration. • It consists of two membranes; The inner membrane is folded into structures called cristae. • Nicknamed “the powerhouse”

13. Endoplasmic Reticulum • The endoplasmic reticulum (ER) resembles a folded membrane that forms a network of interconnected compartments in the cytoplasm • Smooth ER does not containribosomes • Rough ER is covered with ribosomes • Function: transportation of materials between the nucleus and the cytoplasm.

14. Ribosomes • Ribosomes are the site for protein synthesis in the cell. • Produced in the nucleolus • Found floating free in the cytoplasm • Also exist on the rough endoplasmic reticulum

15. Golgi Apparatus • The Golgi apparatus resembles closely stacked flattened membranous sacs • Function: processing, packaging, and secreting proteins, lipids, etc. • Vesicles are membranous pouches that may bud from the ER or golgi apparatus filled with protein.

16. Nucleus • The nucleus is the control center of the cell that manages cellular functions. • Nucleolus – structure inside the nucleus that produces ribosomes. • Chromatin – thin strands of DNA • Nuclear pore – holes in the nuclear envelope through which ribosomes leave the nucleus.

17. Lysosome • Lysosomes are small, spherical organelles surrounded by a single membrane and contain digestive enzymes. • Function: to digest excess or worn out cell parts, food particles, and invading viruses or bacteria

18. Vacuole • Vacuoles are found only in plant cells. • Stores food, water, enzymes, and waste products. • Vacuoles fill with water through osmosis and can fill up to 90% of the cell. The pressure that results inside the cell as a result of this is called turgor pressure.

19. Chloroplast • Chloroplasts are the sites for photosynthesis – where light is converted into chemical energy. • Chloroplasts are a type ofplastid (organelle that contains pigments) • They contain chlorophyll - a green plant pigment that traps energy from sunlight and gives plants their green color.

20. Cell wall • The cell wall is found outside the cell membrane. • made of cellulose. • They are found in plants, bacteria and fungi that give cells their shape.

21. Centrioles • Centrioles are small, rod-shaped structures that appear during mitosis. • Only found in animal cells. CENTRIOLES

22. Plant vs. Animal Cells • Only animal cells contain centrioles and lysosomes. • Only plant cells contain a cell wall, chloroplasts, and large central vacuole.

23. Two Major Types of Transport • Passive transport – materials enter and exit the cell through diffusion without the use of energy. • Diffusion – mixing of two substances through random motion of molecules. • Osmosis – diffusion of water molecules through the plasma membrane (Types of solutions) • Facilitated Diffusion – transports with the aid of a protein molecules • Active transport – Cells use energy to bring raw materials into the cell and export waste products. • sodium-potassium pump, proton pump

24. Examples of Cellular Transport • Water moves into a cell placed in ?? Solution • Ans: hypotonic • Water moves out of a cell if the cell is placed in a ?? Solution • Ans: hypertonic solution • Cells placed in a strong sugar solution, water will ?? • Ans: Pass from the cells to the sugar solution

25. Review : Cellular Transport • Passive: region of higher concentration to lower concentration • Passive: facilitated diffusion, diffusion, osmosis • Active: region of lower concentration to higher concentration. • Active: endocytosis, exocytosis • Plants wilt due to a loss of turgor pressure • Water enters or leaves due to Osmosis

26. Review: Cellular Transport • Plasma Membrane: structure most responsible for maintaining cell homeostasis. • Exocytosis: release of wastes or cell products from inside to outside a cell • Osmosis: diffusion of water molecules through a selectively permeable membrane • Plasmolysis: loss of water from a cell resulting in a drop in turgor pressure.

27. Review: Cellular Transport • Contractile Vacuole: Structure inside protists that collects excess water and squeezes it outside through the membrane. • Dynamic equilibrium: continuous movement of particles but no overall change in concentration • Diffusion: Movement of particles from an area of higher concentration to one of lower concentration. • Active transport: This is a process by which the cell maintains differences on concentration of certain ions inside and outside the cell. In order to move ions into or out of a cell, against a gradient, cells use the process of active transport. This will provide the chemical energy needed to go against the gradient .

28. Cell Size and Reproduction • DNA limits cell size • Surface area to volume ration limits size • As a cell grows, its volume increases more than its surface area. Therefore the cell will divide before it becomes too large to function properly. • Ex. If the sides of a cell double in length, its Volume increases by 8 times and the surface area becomes 4 times as large.. • Homeostasis is disrupted by a cell that is too large and therefore limits cell size • Chromosomes: Dark – staining structures that carry the genetic material. • Chromatin: Long strands of DNA wrapped around proteins. pre – chromosome. • Gene: is a segment of DNA that controls for the production of proteins.

29. The Cell Cycle • Cell Cycle:Sequence of growth and division of a cell. • A series of Enzymes monitors a cell’s progress from phase to phase • Two Stages: • Interphase (growth stage) (G1, S, G2) • Mitosis (nuclear division)

30. Interphase • Interphase: • Longest phase of the cell cycle • Busiest phase fo the cell cycle • Cell grows in size • Chromosomes are duplicated • Cell carries out metabolism • Cell produces organelles that are needed

31. Mitosis • Nuclear Division / occurs in 4 stages • The process by which nuclear material is divides equally between two new cells. • Process by which two identical daughter cells are formed • Prophase • Metaphase • Anaphase • Telophase

32. Prophase (1st stage) • Longest phase of mitosis • Chromatin becomes visible chromosomes due to the tighter coiling of the chromosomes • Nuclear Envelope breaks down releasing the chromatids • Nucleolus disappears • There are two distinct parts an early and a late stage of prophase marked by the disappearance of the nuclear membrane..

33. Prophase cont. • Centromeres – structures that hold togethersister chromatids. • Centromere – this is also the point of attachment for the chromatids to the spindle fiber • Centrioles and spindles form. • Spindles – The football-shaped structure consisting of thin fibers seen in a dividing cell. • Centrioles – cylindrical rod structures that function in anaphase

34. Metaphase (2nd stage) • Meta ( middle) • Chromatids align along the middle or the equator of the cell • Chromosomes attach to spindle fibers • This is where crossing over occurs

35. Anaphase ( 3rd stage) • Ana (separate) • The phase in which the sister chromatids separate from each other. • The Centromeres split apart and the chromosomes move to opposite poles pulled by the centrioles

36. Telophase (4th and Final stage) • Begins as the chromosomes reach opposite poles • New cells prepare for independent existence • Chromosomes unwind • Spindle breaks down • Nucleolus reappears • A new double membrane begins to form between to the two new nuclei

37. Cytokinesis • Division of the cell’s cytoplasm • Part of the cell cycle occurs during Telophase • Differs in animals and plants • Animals: Plasma membrane pinches inwardalong the equator and the two new cells are separated • Plants: A Cell Plate forms (cell wall) across the equator and both plasma membranes and cell walls are formed between the two new cells.

38. Cell Organization • Unicellular organisms – when mitosis is complete they remain as one cells • Multicellular organisms – made of many cells that result in organization (5 levels of cell organization) • Cell – basic unit • Tissue – similar cells with the same function • Organ – dissimilar tissues with the same function • Organ system – different organs with the same function • Organism - Different systems with the same function

39. Control of the Cell Cycle • Normal Control is by a series of enzymes controlling the cell cycle • Loss of Control: • Cancer: uncontrolled division of cells • Caused by environmental factors or by changes inenzyme production. • Causes are difficult to pinpoint; When people move from one country to another, their cancer rates follow the pattern of the county where they live not their county of origin. • 2nd leading cause of death in US

40. How well do you know your cells? match game a virtual cell quiz membrane worksheet Another virtual cell organelle worksheet