CHAPTER 7 CELL STRUCTURE & FUNCTION PGS CELL STRUCTURE & FUNCTION

ANTON VAN LEEUWNENHOEK One of the first person’s to use a microscope. Looked at pond water and saw small organisms.

ROBERT HOOKE Looked at plant tissues in He specifically looked at cork. Looked like tiny chambers he called “cells”

THE CELL THEORY 1. All living things are composed of cells. 1. All living things are composed of cells. 2. Cells are the basic unit of structure & function in living things. 2. Cells are the basic unit of structure & function in living things. 3. New cells are produced by existing cells. 3. New cells are produced by existing cells.

Cells are the basic unit of life. Cells come in all different shapes & sizes. All living things are made up of cells!

Structures common to most cells 1. cell membrane/cell wall 1. cell membrane/cell wall 2. nucleus 2. nucleus 3. cytoplasm 3. cytoplasm

Biologist divide cells into one of two types: 1. PROKARYOTE: do not contain a membrane bound nucleus (all bacteria are prokaryotes) 2. EUKARYOTE: DO contain a membrane bound nucleus, and most have other specialized organelles.

Cell Size 1. Cells are small because materials need to get into and out of the cell at a rate that will meet into and out of the cell at a rate that will meet the cell’s needs. the cell’s needs. 2. Surface area – to – volume ratio (Fig pg. 243) 243) a. Larger surface area/volume ratio, the more materials a cell can exchange more materials a cell can exchange b. As cell size increases, surface area to volume ration decreases volume ration decreases

Cell Size

CELL STRUCTURES We are going to focus on eukaryotic cells and all their specialized organelles. We are going to focus on eukaryotic cells and all their specialized organelles. ORGANELLES: literally means “little organs” ORGANELLES: literally means “little organs” The cell is broken up into 2 regions: The cell is broken up into 2 regions: 1. nucleus – contains DNA 2. cytoplasm – portion of cell outside the nucleus; contains a variety of the nucleus; contains a variety of organelles; many substances are organelles; many substances are dissolved here dissolved here

NUCLEUS FUNCTION: controls most of the cell’s processed & contains the DNA. FUNCTION: controls most of the cell’s processed & contains the DNA. Nuclear envelope – selectively permeable; dotted with pores Nuclear envelope – selectively permeable; dotted with pores Nucleolus – site of ribosome production Nucleolus – site of ribosome production Contain CHROMATIN Contain CHROMATIN This is the granular material visible in the nucleus. They thicken & become CHROMOSOMES during cell division. This is the granular material visible in the nucleus. They thicken & become CHROMOSOMES during cell division.

NUCLEOLUS Dense structure INSIDE nucleus that make ribosomes! Dense structure INSIDE nucleus that make ribosomes!

NUCLEAR PORES “Holes” in the nuclear envelope that allow materials to pass between the nucleus and the cytoplasm. “Holes” in the nuclear envelope that allow materials to pass between the nucleus and the cytoplasm.

RIBOSOMES Small particles of RNA & protein found throughout the cytoplasm or attached to the endoplasmic reticulum Small particles of RNA & protein found throughout the cytoplasm or attached to the endoplasmic reticulum MAIN FUNCTION: make proteins! MAIN FUNCTION: make proteins!

ENDOPLASMIC RETICULUM Continuous network of fluid filled canals Continuous network of fluid filled canals ER is where proteins, lipid components of the cell membrane and other materials are synthesized ER is where proteins, lipid components of the cell membrane and other materials are synthesized

MORE ABOUT ER ER can be one of 2 types: SMOOTH ER: no ribosomes/make lipids ROUGH ER: have ribosomes on the surface so it looks “rough”. Involved in the making of proteins

GOLGI APPARATUS MAIN FUNCTION: MAIN FUNCTION: Modify, sort & package proteins from the ER for storage or export Modify, sort & package proteins from the ER for storage or export

LYSOSOMES Filled with digestive enzymes Filled with digestive enzymes MAIN FUNCTIONS: Digestion or breakdown of lipids, carbs, proteins, and worn out organelles so that they can be used by the rest of the cell. Found in white blood cells – kill bacteria bacteria Function in developmental processes ( ex. digestion & processes ( ex. digestion & absorption of tadpole tail) absorption of tadpole tail)

VACUOLES MAIN FUNCTION: MAIN FUNCTION: Storage! Storage! Much more obvious in plants. They are usually filled with water. This pressure makes it possible for a plant to support heavy structures like flowers.

MITOCHONDRIA MAIN FUNCTION: POWERHOUSE of the cell! Site of cellular respitation respitation Some cells may have up to 800 Contain own DNA & can reproduce themselves May have evolved from a prokaryotic ancestor that formed a symbiotic relationship with another prokaryotic cell

CHLOROPLASTS ONLY in plant cells. ONLY in plant cells. MAIN FUNCTION: Capture energy from sunlight and convert it to chemical energy that the cell can use. (Like solar power plants.) Contain the green pigment CHLOROPHYLL

CYTOSKELETON MAIN FUNCTION: Protein filaments that have structural and locomotive functions Includes MICROTUBULES. They are long, hollow, cylindrical tubes Examples of microtubules include centrioles, cilia, and flagella

CYTOSKELETON Includes MICROFILAMENTS. Long, solid, threadlike structures that give structures that give a structural frame- a structural frame- work to the cell. work to the cell.

CENTRIOLES Centrioles are specialized parts of the cytoskeleton that are involved in cell division. Centrioles are specialized parts of the cytoskeleton that are involved in cell division. Plant cells DO NOT have centrioles. Plant cells DO NOT have centrioles.

Cilia & Flagella Cilia are short structures used to move substances along cell surfaces or to move cells Cilia are short structures used to move substances along cell surfaces or to move cells Flagella are long structures used to move cells Flagella are long structures used to move cells

Cilia & Flagella

ANIMAL CELL VS. PLANT CELL

What are the parts?

Cell Boundries Cell membrane is selectively permeable & provides protection & support Small particles move more easily than large particles Neutral molecules more easily than charged ions Non polar more easily than polar Substances that move across the cell membrane can vary from cell to cell, or the same cell from moment to moment Major component of the cell membrane is a lipid bilayer Proteins & carbohydrates are also found in the cell membrane

Cell membrane

Cell Wall Found in plants, algae, fungi, and nearly all prokaryotes. Found in plants, algae, fungi, and nearly all prokaryotes. MAIN FUNCTION: provide support & protection for the cell MAIN FUNCTION: provide support & protection for the cell Animal cells DO NOT have cell walls! Animal cells DO NOT have cell walls!

Maintaining Homeostasis All cells must regulate what materials enter & leave; sometimes no energy is required to do this, other times energy is required All cells must regulate what materials enter & leave; sometimes no energy is required to do this, other times energy is required Passive transport – no Passive transport – no energy is required to energy is required to move substances from move substances from an area of high an area of high concentration to an concentration to an area of low concentration area of low concentration

Types of Passive Transport Diffusion – the movement of a solute from an area of high conc. To an area of low conc. Equilibrium is reached when an equal number of molecules move in both directions Diffusion – the movement of a solute from an area of high conc. To an area of low conc. Equilibrium is reached when an equal number of molecules move in both directions

Types of Passive Transport Osmosis – the diffusion of water across a membrane from a region of high water concentration to a region of low water concentration Osmosis – the diffusion of water across a membrane from a region of high water concentration to a region of low water concentration hill.com/sites/ /student_view0/chapter2/animation__how_diffusion _works.html

Types of Passive Transport Facilitated diffusion – process by which transport proteins carry certain molecules across a membrane from high concentration to low concentration Facilitated diffusion – process by which transport proteins carry certain molecules across a membrane from high concentration to low concentration

Types of Osmotic Solutions Isotonic solution – solution has the same solute concentration as that of the living cell, there is no net movement of H 2 O Isotonic solution – solution has the same solute concentration as that of the living cell, there is no net movement of H 2 O

Types of Osmotic Solutions Hypertonic solution– solution has a higher solute concentration than the inside of the cell; H 2 O moves out of the cell; animal cell will shrink (crenate); vacuole collapses in plant cells Hypertonic solution– solution has a higher solute concentration than the inside of the cell; H 2 O moves out of the cell; animal cell will shrink (crenate); vacuole collapses in plant cells

Types of Osmotic Solutions Hypotonic solution – solution has a lower solute concentration than the inside of the cell; H 2 O moves into the cell; animal cell will burst (lyse); plant cell will not (why?) Hypotonic solution – solution has a lower solute concentration than the inside of the cell; H 2 O moves into the cell; animal cell will burst (lyse); plant cell will not (why?)

Types of Osmotic Solutions hill.com/sites/ /student_view0/chapter21/animation__hemolysis_and _crenation.htmlhttp://highered.mcgraw- hill.com/sites/ /student_view0/chapter21/animation__hemolysis_and _crenation.html (animation of isotonic, hypertonic, hypotonic solutions)

Types of Osmotic Solutions

Active Transport Energy is required to move substances from an area of low concentration to an area of high concentration; allows cells to have internal environments that are different chemically from the external environment Energy is required to move substances from an area of low concentration to an area of high concentration; allows cells to have internal environments that are different chemically from the external environment

Types of Active Transport Molecular transport - proteins in the cell membrane work as “pumps” to move substances against the concentration gradient Molecular transport - proteins in the cell membrane work as “pumps” to move substances against the concentration gradient

Types of Active Transport Endocytosis - process by which a cell takes material into the cell by infolding of the cell membrane Endocytosis - process by which a cell takes material into the cell by infolding of the cell membrane Phagocytosis – large particles taken in Phagocytosis – large particles taken in Pinocytosis – H 2 O or small particles are taken in Pinocytosis – H 2 O or small particles are taken in Exocytosis – process by which cell releases large amounts of material; vacuole membrane fuses with the cell membrane Exocytosis – process by which cell releases large amounts of material; vacuole membrane fuses with the cell membrane

Types of Active Transport e8e/content/cat_040/ html e8e/content/cat_040/ html

Diversity of Cellular Life Unicellular- one celled organisms Unicellular- one celled organisms Bacterial, some protists Bacterial, some protists Colony – a group of unicellular organisms living together Colony – a group of unicellular organisms living together Multicellular - more than one cell; cells are specialized to perform a specific function Multicellular - more than one cell; cells are specialized to perform a specific function

Diversity of Cellular Life Unicellular Multicellular

Levels of Organization