Chapter 7: Cell Structure and Function

Chapter 4: Cell Structure and Function

Microscopes

History• 1400’s: magnifying glass• 1590: Jansen Bro– Used 1st compound

microscope (2 lenses)

• 1670-80’s: Anton van Leeuwenhoek– Used a simple light

microscope (1 lens)– 1st person to observe living

microorganisms– Father of Microbiology

Terms:

• Magnification: enlarges an object’s image

• Resolution: increases visible detail– Separation of 2 points

Light Microscopes• uses light• Simple (1 lens)• Compound (2 or more lenses)– 1 ocular eyepiece– 1 objective eyepiece

• Stereomicroscope– Gives a 3-D image

• Fluorescent dyes combine with video camera to produce 3-D image of cell processes (ex: cell movement)

Total Magnification• ocular lens x objective lens– Examples: 100 = (10x) x (10x)

430 = (10x) x (43x)• Highest magnification with a light

microscope is 1500x

Electron Microscopes• uses beams of electrons• Transmission electron

microscope (TEM)– Transmits electrons

through a specimen up to 200,000x

– Can study structures within a cell

• Scanning electron microscope (SEM)– Sends electrons across the surface of a

specimen to make a 3-D image up to 100,000x

• Scanning tunneling microscope (STM)–Uses a metal probe to show the arrangement of

atoms (1,000,000x)– Investigates atoms on the surface of a molecule

Advantages/Disadvantages of each microscope:

• Light Microscope:– Advantages: can look at living specimens– Disadvantages: limited in magnification and resolution

• Electron Microscope:– Advantages: greater magnification and resolution– Disadvantages: cannot view living things

Microscope Venn DiagramElectron MicroscopeLight Microscope

Robert Hooke• Studied cork (dead

plant cells from the bark of a tree)

• First identified cells (basic building blocks of all living things)

Matthias Schleiden and Theodor Schwann

• Schleiden plants are made up of cells

• Schwann animals are made up of cells

Cell Theory• 3 parts to the cell theory- applies to all living

organisms–all organisms are composed of 1 or more

cells– the cell is the basic unit of structure and

function (organization) of all living things–all cells come from pre-existing cells

Cells

• Basic units of all living things• Surrounded by a plasma membrane• Have DNA (contains genetic information)• Have cytoplasm (outside the nucleus)• Contain organelles– membrane-bound structures– small, specialized structures– each has a specific function that helps cells survive

• 2 groups of cells

Prokaryotes• Smaller in size• Do not have membrane-bound

organelles• Have genetic material (DNA) but

not surrounded by a membrane– Circular DNA floats in cytoplasm

• Unicellular organisms (bacteria)• ****No nucleus or nuclear

membrane***• have ribosomes, cytoplasm, and

cell membrane

Eukaryotes• Contain membrane-bound organelles• Multicellular organisms and some

unicellular (amoeba, algae, and yeast)• Contain a nucleus

– Control center of the cell– Contains a cell’s genetic material– Responsible for cell division– Manages all cellular functions– Identified by Rudolf Virchow

• Protists, fungi, plants, and animals• Bigger in size than prokaryotes

Cell Types Venn DiagramEukaryotesProkaryotes

Bell Ringer:1. Cell Theory:

a. All __________ are composed of cells.b. Cells are the basic units of _______ and ________ in

all organisms.c. New cells are produced from ____________.2. The cells of eukaryotes have a _________; the cells of

__________ do not.3. Eukaryotic cells also have a variety of specialized

structure called ______________.

Levels of Organization

• Cells in multicellular organisms are specialized (cell specialization)– Perform specific functions (separate roles)– Ex: nerve cells transmit impulses– Ex: red blood cells carry nutrients and gas throughout body– Ex: pancreatic cell produce insulin– Ex: muscle cells contract and relax to move parts of the body

• Cells: basic units– Ex: red blood cells, nerve cells, pancreatic cells, skin cells

• Tissues: group of cells that perform a particular function– Ex: muscle tissue, epithelial tissue

• Organs: group of tissues that work together– Ex: heart, liver, stomach, brain, lungs

• Organ systems: group of organs that work together to perform a specific function– Ex: digestive, respiratory, nervous

organism

organ systems

organs

tissues

cells

organization

Organelle DNA• Chloroplasts and mitochondria have their own DNA• Lynn Margulis

– Came up with the endosymbiotic theory– Suggested that mitochondria and chloroplasts came from

prokaryotic cells• Formed a relationship with early eukaryotic cells

Cell WallFunction:• Provides additional support and protection• Allows H2O, O2, AND CO2 to pass

Type of Cell:• Plant cells, fungal cells, and bacterial cells

Cell WallUnique

Characteristics:• Rigid structure• Inflexible• Made of cellulose (in

plants)• Nickname: “support

center”

Plasma MembraneFunction:• Allows substances to enter and leave a

cell• Provides protection and support

Type of Cell:• Plant and animal cells

Plasma MembraneUnique

Characteristics:• Flexible boundary

• Nickname: “the bouncer”

NucleusFunction:• Controls cell processes• Stores DNA and info to make proteins


NucleusUnique Characteristics:• Has chromatin – Strands of DNA

• Has nuclear envelope

• Nickname: “Control Center” or “The Boss”

VacuoleFunction:• Temporary storage of food, enzymes, wastes,

and other materials


VacuoleUnique

Characteristics:• Sac surrounded by

a membrane• Bigger in plants

• Nickname: “Storage closet”

MitochondriaFunction:• Transforms energy into usable compounds by

breaking down food• Cellular respiration


MitochondriaUnique Characteristics:• Has double membrane• Folded inner

membrane increases surface area• Occurs in varying #’s– Example: more in muscle

cells

• Nickname: “Powerhouse” or “Mighty-chondria”

ChloroplastFunction:• Captures light energy and makes food• Photosynthesis

Type of Cell:• Plant cells only

ChloroplastUnique Characteristics:• Double membrane• Plastids used for

storage• Contain chlorophyll–Green pigment

• Nickname: “Green sugar shack”

RibosomesFunction:• Where proteins are made


RibosomesUnique

Characteristics:• Not bound by a

membrane• Can be found in

cytoplasm or ER

• Nickname” “Protein factory”

NucleolusFunction:• Makes ribosomes


NucleolusUnique

Characteristics:• Within the nucleus• Small and dense

• Nickname: “Ribosome factory”

CytoplasmFunction:• Clear gelatinous fluid inside a cell• Holds organelles in place


CytoplasmUnique

Characteristics:• Mostly made of

water

• Nickname: “Celly jelly”

Endoplasmic ReticulumFunction:• Rough: protein synthesis• Smooth: make and store lipids


Endoplasmic ReticulumUnique

Characteristics:• Highly folded

membranes• Internal

membrane system• Nickname: “Transport

system”

LysosomesFunction:• Digests excess or worn out organelles, food,

and bacteria

Type of Cell:• Animal cells

LysosomesUnique Characteristics:• Contains digestive

enzymes

• Nickname: “Suicide sac”

CytoskeletonFunction:• Support structure within cytoplasm• Forms framework for the cell


CytoskeletonUnique

Characteristics:• Composed of tiny

rods and filaments

• Nickname: “Body shaper”

Golgi Apparatus or Golgi Body

Function:• Modifies, sorts, and packages proteins


Golgi Apparatus or Golgi Body

Unique Characteristics:• Flattened system

of tubular membranes

• Nickname: “Gift wrap” or “UPS”

CiliaFunction:• Aids in locomotion and feeding


CiliaUnique Characteristics:• Pairs of microtubules• Short, numerous

hairlike projections

• Nickname: “Hair”

FlagellaFunction:• Aids in locomotion and feeding


FlagellaUnique

Characteristics:• Pairs of

microtubules• Longer projections• Whiplike motion

• Nickname: “Tail”

CentriolesFunction:• Function during cell division


CentriolesUnique

Characteristics:• None

Nickname: none

Nuclear EnvelopeFunction:• Surrounds nucleus


Nuclear EnvelopeUnique Characteristics:• Has pores that allow

materials to move in and out of the nucleus

No nickname

Animal vs. Plant Cells Venn Diagram

Animal Cells Plant Cells

Bell Ringer:1. Place the following terms in order from smallest to largest level of

organization:tissues, organ systems, organs, individual cells

2. The small dense region in the nucleus where the assembly of ribosomes begins is called the ____.a. nucleolus b. nuclear envelopec. chloroplast d. vacuole

3. Which organelles can use energy from sunlight to create energy-rich food molecules?

a. lysosomes b. golgi apparatusc. vacuoles d. chloroplasts

Chapter 7: Cell Structure and Function

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