CHAPTER 7CHAPTER 7CELL STRUCTURE & CELL STRUCTURE &

FUNCTIONFUNCTIONPGS. 168 - 199PGS. 168 - 199

CELL STRUCTURE & FUNCTION

ANTON VAN ANTON VAN LEEUWNENHOEKLEEUWNENHOEK

One of the first One of the first person’s to use person’s to use a microscope.a microscope.

Looked at Looked at pond water pond water and saw small and saw small organisms.organisms.

ROBERT HOOKEROBERT HOOKE

Looked at plant Looked at plant tissues in 1665.tissues in 1665.

He specifically He specifically looked at cork.looked at cork.

Looked like tiny Looked like tiny chambers he chambers he called “cells”called “cells”

THE CELL THEORYTHE CELL THEORY

1. 1. All living things are composed All living things are composed of cells.of cells.

2. Cells are the basic unit of 2. Cells are the basic unit of structure & function in living structure & function in living things.things.

3. New cells are produced by 3. New cells are produced by existing cells.existing cells.

Cells are the basic unit of Cells are the basic unit of life.life.

Cells come in Cells come in all different all different shapes & sizes.shapes & sizes.

All living things All living things are made up of are made up of cells!cells!

Structures common to Structures common to mostmost cellscells

1. cell membrane/cell 1. cell membrane/cell wallwall

2. nucleus2. nucleus3. cytoplasm3. cytoplasm

Biologist divide cells Biologist divide cells into one of two types:into one of two types:

1. 1. PROKARYOTEPROKARYOTE: do not contain a membrane bound : do not contain a membrane bound nucleusnucleus

(all bacteria are prokaryotes)(all bacteria are prokaryotes)

2. 2. EUKARYOTEEUKARYOTE: DO contain a membrane bound : DO contain a membrane bound nucleus, and most have other specialized organelles. nucleus, and most have other specialized organelles.

Cell SizeCell Size

1. Cells are small because materials need to get1. Cells are small because materials need to get

into and out of the cell at a rate that will meetinto 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. 10-2 pg.2. Surface area – to – volume ratio (Fig. 10-2 pg.

243)243)

a. Larger surface area/volume ratio, the a. Larger surface area/volume ratio, the

more materials a cell can exchangemore materials a cell can exchange

b. As cell size increases, surface area tob. As cell size increases, surface area to

volume ratio decreasesvolume ratio decreases

Cell SizeCell Size

CELL STRUCTURESCELL STRUCTURES We are going to focus on eukaryotic cells and We are going to focus on eukaryotic cells and

all their specialized organelles.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 DNA1. nucleus – contains DNA

2. cytoplasm – portion of cell outside 2. cytoplasm – portion of cell outside

the nucleus; contains a variety of the nucleus; contains a variety of

organelles; many substances areorganelles; many substances are

dissolved heredissolved here

NUCLEUSNUCLEUS FUNCTIONFUNCTION: controls most : controls most

of the cell’s processed & of the cell’s processed & contains the DNA.contains the DNA.

Nuclear envelope – Nuclear envelope – selectively permeable; selectively permeable; dotted with poresdotted with pores

Nucleolus – site of Nucleolus – site of ribosome productionribosome production

Contain Contain CHROMATINCHROMATIN This is the granular This is the granular

material visible in the material visible in the nucleus. They thicken & nucleus. They thicken & become become CHROMOSOMESCHROMOSOMES during cell division.during cell division.

NUCLEOLUSNUCLEOLUS Dense Dense

structure structure INSIDE INSIDE nucleus that nucleus that make make ribosomes!ribosomes!

NUCLEAR PORESNUCLEAR PORES ““Holes” in the Holes” in the

nuclear nuclear envelopeenvelope that that allow materials allow materials to pass to pass between the between the nucleus and the nucleus and the cytoplasm.cytoplasm.

RIBOSOMESRIBOSOMES Small particles of Small particles of

RNA & protein RNA & protein found throughout found throughout the cytoplasm or the cytoplasm or attached to the attached to the endoplasmic endoplasmic reticulumreticulum

MAIN FUNCTIONMAIN FUNCTION: : make proteins!make proteins!

ENDOPLASMIC ENDOPLASMIC RETICULUMRETICULUM

Continuous network Continuous network of fluid filled canalsof fluid filled canals

ER is where proteins, ER is where proteins, lipid components of lipid components of the cell membrane the cell membrane and other materials and other materials are synthesizedare synthesized

MORE ABOUT ERMORE ABOUT ER ER can be one of 2 ER can be one of 2

types:types:SMOOTH ERSMOOTH ER: no : no

ribosomes/make ribosomes/make lipidslipids

ROUGH ERROUGH ER: have : have ribosomes on the ribosomes on the surface so it looks surface so it looks “rough”. Involved “rough”. Involved in the modification in the modification of proteinsof proteins

GOLGI APPARATUSGOLGI APPARATUS MAIN MAIN

FUNCTIONFUNCTION::

Modify, sort & Modify, sort & package package proteins from proteins from the ER for the ER for storage or storage or exportexport

LYSOSOMESLYSOSOMES Filled with digestive enzymesFilled with digestive enzymes

MAIN FUNCTIONSMAIN FUNCTIONS::Digestion or breakdown of Digestion or breakdown of

lipids, carbs, proteins, and lipids, carbs, proteins, and worn out organelles so that worn out organelles so that they can be used by the rest they can be used by the rest of the cell.of the cell.

Found in white blood cells – killFound in white blood cells – kill

bacteriabacteria

Function in developmentalFunction in developmental

processes ( ex. digestion &processes ( ex. digestion &

absorption of tadpole tail)absorption of tadpole tail)

VACUOLESVACUOLES MAIN FUNCTIONMAIN FUNCTION::

Storage!Storage!

Much more obvious in Much more obvious in plantsplants. They are . They are usually filled with usually filled with water. This pressure water. This pressure makes it possible for makes it possible for a plant to support a plant to support heavy structures like heavy structures like flowers.flowers.

MITOCHONDRIAMITOCHONDRIAMAIN FUNCTIONMAIN FUNCTION::

POWERHOUSE of the cell! Site POWERHOUSE of the cell! Site of cellularof cellular

respirationrespiration

Some cells may have up to 800Some cells may have up to 800

Contain own DNA & can Contain own DNA & can reproduce themselvesreproduce themselves

May have evolved from a May have evolved from a prokaryotic ancestor that prokaryotic ancestor that formed a symbiotic formed a symbiotic relationship with another relationship with another prokaryotic cellprokaryotic cell

CHLOROPLASTSCHLOROPLASTS found in plant cells found in plant cells

and protists.and protists.MAIN FUNCTIONMAIN FUNCTION::Capture energy from Capture energy from

sunlight and convert sunlight and convert it to chemical energy it to chemical energy that the cell can use.that the cell can use.

(Like solar power (Like solar power plants.)plants.)

Contain the green Contain the green pigment pigment CHLOROPHYLLCHLOROPHYLL

CYTOSKELETONCYTOSKELETONMAIN FUNCTIONMAIN FUNCTION::Protein filaments that Protein filaments that

have structural and have structural and locomotive functionslocomotive functions

Includes Includes MICROTUBULESMICROTUBULES. . They are long, They are long, hollow, cylindrical hollow, cylindrical tubestubes

Examples of microtubules include centrioles, Examples of microtubules include centrioles, cilia, and flagellacilia, and flagella

CYTOSKELETONCYTOSKELETONIncludes Includes

MICROFILAMENTMICROFILAMENTSS. Long, solid, . Long, solid, threadlikethreadlike

structures that structures that givegive

a structural a structural frame-frame-

work to the cell.work to the cell.

CENTRIOLESCENTRIOLES Centrioles are Centrioles are

specialized parts specialized parts of the of the cytoskeleton that cytoskeleton that are involved in are involved in cell division.cell division.

Plant cells DO Plant cells DO NOT have NOT have centrioles.centrioles.

Cilia & FlagellaCilia & Flagella Cilia are short Cilia are short

structures used to structures used to move substances move substances along cell surfaces along cell surfaces or to move cellsor to move cells

Flagella are long Flagella are long structures used to structures used to move cellsmove cells

Cilia & FlagellaCilia & Flagella

ANIMAL CELL VS. PLANT ANIMAL CELL VS. PLANT CELLCELL

What are the parts?What are the parts?

Cell BoundriesCell BoundriesCell membrane is selectively permeable & Cell membrane is selectively permeable &

provides protection & supportprovides protection & supportSmall particles move more easily than large particlesSmall particles move more easily than large particles

Neutral molecules more easily than charged ionsNeutral molecules more easily than charged ions

Non polar more easily than polarNon polar more easily than polar

Substances that move across the cell membrane can Substances that move across the cell membrane can vary from cell to cell, or the same cell from moment vary from cell to cell, or the same cell from moment to momentto moment

Major component of the cell membrane is a lipid Major component of the cell membrane is a lipid bilayerbilayer

Proteins & carbohydrates are also found in the Proteins & carbohydrates are also found in the cell membranecell membrane

Cell membraneCell membrane

Cell WallCell Wall Found in plants, algae, Found in plants, algae,

fungi, and nearly all fungi, and nearly all prokaryotes.prokaryotes.

MAIN FUNCTIONMAIN FUNCTION: provide : provide support & protection for support & protection for the cellthe cell

Animal cells DO NOT have Animal cells DO NOT have cell walls!cell walls!

Maintaining HomeostasisMaintaining Homeostasis All cells must regulate what materials All cells must regulate what materials

enter & leave; sometimes no energy is enter & leave; sometimes no energy is required to do this, other times energy is required to do this, other times energy is requiredrequired 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 anconcentration to an

area of low concentrationarea of low concentration

Types of Passive TransportTypes of Passive Transport Diffusion – the movement of a solute from an area of Diffusion – the movement of a solute from an area of

high conc. To an area of low conc. Equilibrium is reached high conc. To an area of low conc. Equilibrium is reached when an equal number of molecules move in both when an equal number of molecules move in both directionsdirections

Types of Passive TransportTypes of Passive Transport Osmosis – the diffusion of water across a membrane from Osmosis – the diffusion of water across a membrane from

a region of high water concentration to a region of low a region of high water concentration to a region of low water concentrationwater concentration

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

Types of Passive TransportTypes of Passive Transport Facilitated diffusion – process by which transport proteins Facilitated diffusion – process by which transport proteins

carry certain molecules across a membrane from high carry certain molecules across a membrane from high concentration to low concentrationconcentration to low concentration

Types of Osmotic SolutionsTypes of Osmotic Solutions Isotonic solution Isotonic solution

– solution has the – solution has the same solute same solute concentration as concentration as that of the living that of the living cell, there is no net cell, there is no net movement of Hmovement of H22OO

Types of Osmotic SolutionsTypes of Osmotic Solutions Hypertonic Hypertonic

solutionsolution– solution – solution has a higher solute has a higher solute concentration than concentration than the inside of the cell; the inside of the cell; HH22O moves out of the O moves out of the cell; animal cell will cell; animal cell will shrink (crenate); shrink (crenate); vacuole collapses in vacuole collapses in plant cellsplant cells

Types of Osmotic SolutionsTypes of Osmotic Solutions Hypotonic solution Hypotonic solution

– solution has a – solution has a lower solute lower solute concentration than concentration than the inside of the cell; the inside of the cell; HH22O moves into the O moves into the cell; animal cell will cell; animal cell will burst (lyse); plant burst (lyse); plant cell will not (why?)cell will not (why?)

Types of Osmotic SolutionsTypes of Osmotic Solutions

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter21/animation__hemolysis_and_crenation.html (animation of isotonic, hypertonic, hypotonic solutions)

Types of Osmotic SolutionsTypes of Osmotic Solutions

Active TransportActive Transport

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

Types of Active TransportTypes of Active Transport

Molecular transport Molecular transport - proteins in - proteins in the cell membrane work as “pumps” the cell membrane work as “pumps” to move substances against the to move substances against the concentration gradientconcentration gradient

Types of Active TransportTypes of Active Transport

Endocytosis Endocytosis - process by which a cell - process by which a cell takes material into the cell by takes material into the cell by infolding of the cell membraneinfolding of the cell membrane Phagocytosis Phagocytosis – large particles taken in– large particles taken in Pinocytosis Pinocytosis – H– H22O or small particles are O or small particles are

taken intaken in Exocytosis Exocytosis – process by which cell – process by which cell

releases large amounts of material; releases large amounts of material; vacuole membrane fuses with the cell vacuole membrane fuses with the cell membranemembrane

Types of Active TransportTypes of Active Transport

http://bcs.whfreeman.com/http://bcs.whfreeman.com/thelifewire8e/content/thelifewire8e/content/cat_040/0504003.htmlcat_040/0504003.html

Diversity of Cellular LifeDiversity of Cellular Life

UnicellularUnicellular- one celled organisms- one celled organisms Bacterial, some protistsBacterial, some protists Colony – a group of unicellular organisms Colony – a group of unicellular organisms

living togetherliving together Multicellular Multicellular - more than one cell; cells - more than one cell; cells

are specialized to perform a specific are specialized to perform a specific functionfunction

Diversity of Cellular LifeDiversity of Cellular Life

UnicellularUnicellular

MulticellularMulticellular

Levels of OrganizationLevels of Organization