THE CELL Structure and Function

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

Objectives Alabama Course of Study 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) Active and passive transport or materials (osmosis, diffusion) Waste disposal Waste disposal

Objectives continued… Alabama High School Graduation Exam 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. Objective 1: Distinguish relationships among cell structures, functions, and organization in living organisms. Eligible content: 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.

Objectives continued… AHSGE Eligible content 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.

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.

The Discovery of Cells Matthias Schleiden concluded that all plants are composed of cells. Anton van Leeuwenhoek was the first person to record looking at water under a microscope.

– Discovered by Schleiden and Theodor Schwann in 1838 All organisms are composed of one or more cells. The cell is the basic unit of organization of organisms. All cells come from preexisting cells. Cell Theory Schleiden Schwann

Two Basic Cell Types Prokaryotes- cells that lack internal membrane- bound structures – Lacks a true nucleus – Ex. Bacteria Eukaryotes- have cells that contain membrane bound organelles. – Ex.-Nucleus The membrane-bound structures within eukaryotic cells – organelles

Microscopes *Electron microscopes use electromagnets to focus and magnify an image. *A major difference between a compound light microscope and a transmission electron microscope is that a light microscope image can be made from living unstained materials. *One advantage of electron microscopes over light microscopes is their higher magnification.

Compound Microscope

The Plasma Membrane Objectives: – Explain how a cell’s plasma membrane functions – Relate the function of the plasma membrane to the fluid mosaic model. Al COS: 4 AHSGE: Standard I-1, II-1, V-1

The Plasma Membrane - structure The plasma membrane is a selectively permeable phospholipid bilayer surrounding the cell. – A plasma membrane allows the movement of materials into and out of a cell. – Does not allow a cell’s contents to be the same as its surroundings.

Contents of the plasma membrane(lipid bilayer)  Phospholipids have a polar (water-loving) head region and a nonpolar (water fearing) tail.  A polar molecule has a partial negative charge on one side and a partial positive charge on the other side. (Ex. Water)  Hydrogen bonds are the bonds that hold water molecules together  A nonpolar molecule has no negative and positive poles.(Ex. Oil)  Because cells have a watery environment both inside and outside, the polar ends of the phospholipids in the plasma membrane form double layers.  The fluid mosaic model describes a structure with polar layers on the outside and nonpolar layer on the inside  Because the phospholipid molecules and some proteins are free to move, the plasma membrane is said to be fluid mosaic. – Important because cell membranes can be structured to fit the needs of different cell types

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.

Folded membranes increase surface area for efficiency. Folded membranes are an advantage to a cell because – Cell processes can be more efficient. – The membranes provide a large surface area. – The membranes form interconnected compartments. Endoplasmic reticulum is made up of folded membranes. Ribosomes are sometimes attached to folded membranes.

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

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”

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

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

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.

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

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

Vacuole 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.

Chloroplast Chloroplasts are the sites for photosynthesis – capture light energy and produce food. Chloroplasts are a type of plastid (organelle that contains pigments) They contain chlorophyll - a green plant pigment that traps energy from sunlight and gives plants their green color. In chloroplasts, the stacks of membranes sacs are called grana.

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.

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

Organelles Cytoplasm Cytoskeleton – Microtubules – Microfilaments Mitochondria Ribosomes Endoplasmic Reticulum – Smooth – Rough Golgi Apparatus Lysosome Nucleus – Nucleolus – Chromatin Special plant structures Vacuole Cell wall Chloroplasts Centrioles Vesicle

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

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.

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

Diffusion

Active Transport

Passive Transport

Hypotonic, Hypertonic, and Isotonic Solutions