biology chap7.1-7.2 last updated 9/10/2010

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Cell structure and function*Show 2 video clips Honors book.

Chapters 7.1- 7.2

Voc Terms 7.1-7.2

• Cell• Cell theory• Cell membrane• Nucleus• Eukaryote• Prokaryote• Cytoplasm• Organelle• Vacuole• Lysosome

• Cytoskeleton• Centriole• Ribosome• Endoplasmic reticulum (smooth and

Rough)• Golgi apparatus• Chloroplast• Mitochondrion• Cell wall• Lipid bilayer• Selectively permeable

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What to know:• Name the scientist who first observed living and

non living cells.• State the three principles of the cell theory.• Explain why the cell is considered to be the basic

unit of life.• Know all cell organelles and functions• Why are cells so small• Explain a fluid mosaic model• Know diff/sim between plant and animal and pro

vs euk

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Discovery of cells• Cell- is the smallest unit that can carry on

all of the processes of life. • 1665, English scientist Robert Hooke

used a light microscope to look at cork • Leeuwenhoek- Dutch trader (1632-1723)-

first person to look at living cells (protists)

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Discovery of cells

150 years after Leeuwenhoek1838- Matthias Schleiden – plants were

composed of cellsTheodore Schwann- animal were also made

of cellsRudolf Virchow (1821-1902) said all cells

come from other cells

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Developments in Cell Biology

• 1665- Hooke discovers cork cells• 1827- Baer discovers mammalian egg• 1855- Virchow adds to cell theory• 1857- Golgi discovers the Golgi apparatus

in the cell• 1996- Scotland researchers clone a sheep

from an adult sheep cell• 2004- Tissue engineering used to grow

new skin an bone for transplant.

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Cell Theory3 parts:1. All living organisms are composed of one

or more cells.

2. Cells are the basic units of structure and function in an organism.

3. Cells come only from the reproduction of existing cells.

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The Cellular Basis of LifeAll living things share several basic characteristics:1. Organized parts- Made of cells2. Obtain energy from their surroundings/ Perform chemical reactions (metabolism)3. Change with time (Evolution)4. Respond to their environments (Stimuli)5. Reproduce (asexual and sexual)6. Made of DNA7. Regulate internal conditions (Homeostasis)8. Grow and develop

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Cell Diversity• Cells function influences its physical features!!Cell shape:- Cells shape can be simple or complex

depending on the function of the cell- Each cell has a shape that has evolved to

allow the cell to perform its function effectively

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Cell DiversityCell size:- Size of the cell is limited by the

relationship of the cell’s outer surface area to its volume

- As the cell grows its volume increases - Smaller the cell the more efficient it is in

allowing nutrients and oxygen to pass in and out of the cells

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Basic Parts of the Cell4 common features in all cells1. Plasma membrane: or cell membrane, covers a cell’s

surface and acts as a barrier between the inside and outside of a cell (in and out)

2. Cytoplasm: fluid, cytoskeleton, and organelles except cytoplasm- cytosol: cytoplasm that has no membrane bound organelles (20% protein)

3. Coded information in the form of DNA-some float freely inside the cell or-Nucleus: membrane bound organelle that contains a cell’s DNA

4. Ribosomes- makes proteins

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2 Basic types of cells1. Prokaryotes-

a. lack a membrane bound nucleus and membrane bound organellesb. have DNA is concentrated in the Nucleoidc. have two domains: Archaea and Bacteria

2. Eukaryotes-a. Organisms made up of one or more cells that have a nucleus and membrane-bound organelles b. have a variety of sub cellular structures called organellesc. tend to be much larger than prokaryotes

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Cellular Organization

Cells are specialized and unable to survive independently

Cells Tissues organs Organ systemMuscle cells muscle tissues Heart

circulatory system

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Cell organelles and features

Plasma membrane:- it allows for only certain molecules to enter or leave the cell- it separates internal metabolic reactions from the external environment-excretes waste- interaction with environment

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Membrane LipidsMade of phospholipidsThey have both a polar (hydrophilic) phosphate

head and two non polar (hydrophobic) fatty acid tails

Double layer is called phospholipid bilayer

Eukaryotes also have lipids called sterols located between the tails of the phospholipids (most common is cholesterol, prevent the membrane from freezing at low temps)

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Membrane Proteins1. Integral proteins- specific proteins that are

located in the lipid bilayer2. Peripheral proteins- located on the outside of

the membrane not embedded in itFluid mosaic model- phospholipid bilayer behaves like a fluid more

than it behaves like a solid- Proteins can mover laterally within the bilayer

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Nucleus• Houses and protects genetic information• Chromatin- DNA, long thin fibers• Chromosomes- condensed DNANuclear Envelope- double membrane that

surrounds the nucleusNuclear pores- protein-lined holes, passageways

for RNA and other materials to enter or exit the nucleus

Nucleolus- dense area, where DNA is concentrated and it is making ribosomal RNA

Ribosomes- organelles made of protein and protein synthesis in the cytoplasm

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Mitochondria• Tiny organelles that transfer energy from organic

molecules to ATP• Powers most of the cell’s chemical reactions• Highly active cells-muscles cells have hundreds of them• Fat storing cells have few• Inner and outer phospholipid membrane• Inner membrane has many folds- cristae, which contain

proteins that carry out energy harvesting chemical reactions

• Contain own DNA• Can reproduce only by the division of preexisting mitochondria• Originated from prokaryotic cells- symbiotic relationship

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Ribosome• Small, roughly spherical organelles that

are responsible for protein synthesis• Do not have a membrane• Made of protein and RNA molecules• Developed in the nucleolus and completed

in the cytoplasm• Some float freely in cytosol other in R-ER

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Endoplasmic Reticulum• System of membranous tubes and sacs

(cisternae)• Intracellular highway- particles move

from one part to another • Amount depends on the cells activityTwo types1. Rough2. Smooth

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Rough Endoplasmic Reticulum

• Interconnected, flattened sacs covered with ribosomes

• Produces phospholipids and proteins• Proteins are exported from the cell-

digestive enzymes• Abundant in cells that produce large

amounts of protein for export , digestive glands, antibody-producing cells

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Smooth ER• Has no ribosomes• Most cells have few S-ER• Builds lipids- cholesterol• Ovaries/testes- produce steroid hormone

estrogen and testosterone• Skeletal and heart muscles- release

calcium stimulates contraction• Abundant in liver and kidney- detoxify

drugs/poisons

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Golgi Apparatus

• System, flattened membranous sacs• Packaging system- UPS

1. receive vesicles from ER with new proteins or lipids2. travel in the Golgi- modify them3. redirected to various parts of the cell

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VesiclesCan be small, spherically shaped sacs that

are surrounded by a single membrane 1. Lysosomes- vesicles that bud from the

Golgi and contain digestive enzymes2. Peroxisomes- abundant in liver and

kidney (H2O2)3. Other-glyoxysomes, endosome,

contractile vacuoles4. Protein synthesis

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Vesicles cont:4. Protein synthesis

a. proteins are assembled by ribosomes on the rough ERb. Vesicles transport proteins to the golgi apparatusc. the golgi modifies protein and packages them in new vesiclesd. vesicles release protein that have destinations outside the celle. vesicles containing enzymes remain inside the cell as lysosomes, peroxisomes, endosomes

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CytoskeletonNetwork of thin tubes and filaments that

crisscrosses the cytosol, give it shape1. Microtubules- hollow tubes made of protein

called tubulin, anchor, shape2. Microfilaments- long threads of the beadlike

protein actin, double strands3. Intermediate filaments- rods that anchor the

nucleus, shape of nucleus 4. Cilia and flagella- hair like structures that

extend from the surface of the cell5. Centrioles- occur in animal cells , organize for

cell division

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Plant cells p 87Plants have 3 structures that are extremely

important to plant function:1. cell walls2. large central vacuoles3.chloroplast

Plants are different than animals- plant make their own carbon-containing molecules from the carbon in the environment (photosynthesis)

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Parts:1. Cell wall- rigid layer that lies outside the

plasma membrane, made of carbohydrates called cellulose

2. Central vacuole- stores water, metabolic wastes, other materials, 90% of cell, if the cell shrinks the plant wilts

3. Chloroplast- organelles that have own DNA, have a double membranea. chloroplast- light energy to make carbs, (thylakoids, chlorophyll)b. chromoplast- colorful pigments

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Prokaryotes vs Eukaryotes

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Plant vs Animal

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What do all cells have?

Common features:1.

2.

3.

4.

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Animations• http://www.cellsalive.com/cells/cell_model.htm• http://www.scsc.k12.in.us/SMS/Teachers/Martin/intro.htm#Resources• http://www.biology4kids.com/files/cell_main.html• http://www.ibiblio.org/virtualcell/tour/cell/cell.htm• http://projects.edtech.sandi.net/miramesa/Organelles/animal.html• http://library.thinkquest.org/12413/structures.html#centrioles• http://learn.genetics.utah.edu/content/begin/cells/insideacell/• http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookCELL2.html

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