Cell Structure & Function

Cell Theory

• All living things are made up of cells.

• Cells are the smallest working units of all living things.

• All cells come from pre-existing cells through cell division.

Definition of Cell

A cell is the smallest unit that is capable of performing life functions.

Examples of Cells

Amoeba Proteus

Plant Stem

Red Blood Cell

Nerve Cell

Bacteria

Two Types of Cells

•Prokaryotic

•Eukaryotic

1

2

Prokaryotes

Cell membrane

Cytoplasm

Prokaryotic

They are the simplest form of life. No nucleus.

Do not have structures surrounded by membranes (organelles)

Few internal structures

They are unicellular_(One-celled organisms).

Example: Bacteria

are the most complex form of life.

They have nucleus

Contain organelles surrounded by membranes

They are multicellular organisms (composed of many cells).

Most living organisms

Examples: animals and plants.

Eukaryotic

Common Characteristics

• All cells are surrounded by a barrier called the cell membrane

• They contain the molecule that carries biological information-DNA

Eukaryotic

Plant Animal

Compare and contrast Prokaryotes vs. Eukaryotes

DifferencesProkaryote

DifferencesEukaryote

Similarity

“Typical” Animal Cell

“Typical” Plant Cell

Differentia between animal and plant cells

Cell Parts

Organelles

CELL STRUCTURE AND FUNCTIONCELL STRUCTURE AND FUNCTION

ORGANELLESORGANELLES• Cytoplasm lies Cytoplasm lies

between the cell between the cell membrane and membrane and nucleus and nucleus and contains the contains the organelles.organelles.

• Cytosol is a gelatin Cytosol is a gelatin like aqueous fluid like aqueous fluid that contains salts, that contains salts, minerals and minerals and organic moleculesorganic molecules

MitochondriaMitochondria• Sites of chemical reactions that transfer Sites of chemical reactions that transfer

energy from organic compounds to ATPenergy from organic compounds to ATP• ATP- main energy source for cellsATP- main energy source for cells• Cells with high energy requirements Cells with high energy requirements

have more mitochondria ex: muscle have more mitochondria ex: muscle and liver cellsand liver cells

• Have 2 membranesHave 2 membranes• Smooth outer membrane serves as a Smooth outer membrane serves as a

boundary between the mitochondria boundary between the mitochondria and the cytosoland the cytosol

• Inner membrane has many folds called Inner membrane has many folds called Cristae – they enlarge the surface area Cristae – they enlarge the surface area for more chemical reactionsfor more chemical reactions

• Have their own DNA ( for reproduction)Have their own DNA ( for reproduction)

They are called the They are called the ““POWER HOUSE” POWER HOUSE” of the cellof the cell

RibosomesRibosomes• Most numerousMost numerous• Not surrounded by a Not surrounded by a

membranemembrane• Made up of proteins and RNAMade up of proteins and RNA• RNA is packaged into the RNA is packaged into the

ribosomes then transported to ribosomes then transported to the cytosolthe cytosol

• Some ribosomes are freeSome ribosomes are free• Some are attached to the Some are attached to the

endoplasmic reticulum endoplasmic reticulum • Protein is synthesized Protein is synthesized

(produced) in the ribosomes(produced) in the ribosomes• Proteins to be used in the Proteins to be used in the

cytosol – free ribosomescytosol – free ribosomes• Proteins to be exported or Proteins to be exported or

inserted in the cell membrane inserted in the cell membrane – ribosomes on the ER– ribosomes on the ER

Endoplasmic ReticulumEndoplasmic Reticulum• System of membranous tubules and System of membranous tubules and

sacssacs• Intracellular Highway – molecules Intracellular Highway – molecules

move from one part of the cell to move from one part of the cell to anotheranother

• 2 types – rough and smooth2 types – rough and smooth• Rough covered by ribosomes – Rough covered by ribosomes –

prominent in cells that make large prominent in cells that make large amounts of proteins to be exported amounts of proteins to be exported from the cellfrom the cell

• Smooth – no ribosomesSmooth – no ribosomes• Synthesis of steriods in gland cellsSynthesis of steriods in gland cells• Regulation of calcium in muscle cellsRegulation of calcium in muscle cells• Breakdown of toxic substances in liver Breakdown of toxic substances in liver

cellscells

Golgi ApparatusGolgi Apparatus

• Processing, Processing, packaging and packaging and secreting organllesecreting organlle

• System of System of membranesmembranes

• Series of flattened Series of flattened sacs with convex sacs with convex shapeshape

• Works with the ER to Works with the ER to modify proteinsmodify proteins

LYSOSOMESLYSOSOMES• Small spherical Small spherical

organellesorganelles• Enclose hydrolytic Enclose hydrolytic

enzymes within single enzymes within single membranesmembranes

• Digest proteins, Digest proteins, carbohydrates, lipids, carbohydrates, lipids, DNA and RNADNA and RNA

• Digest old organelles, Digest old organelles, bacterias, viruses bacterias, viruses

• Rare in plant cellsRare in plant cells

CYTOSKELETONCYTOSKELETON• Maintains the shape and size of Maintains the shape and size of

cellcell• Network of long protein strandsNetwork of long protein strands• Not surrounded by a membraneNot surrounded by a membrane• Participates in the movement of Participates in the movement of

organellesorganelles• 2 major components – 2 major components –

microfilaments and microtubulesmicrofilaments and microtubules• Microfilaments – threads made of Microfilaments – threads made of

actin (protein) – smallest strandsactin (protein) – smallest strands• Microtubules – largest strands Microtubules – largest strands

that are hollow tubes – help the that are hollow tubes – help the cell divide by forming spindle cell divide by forming spindle fibers that extend across the cellfibers that extend across the cell

CILIA AND FLAGELLACILIA AND FLAGELLA

• Hairlike organelles Hairlike organelles that extend from the that extend from the surface of the cellsurface of the cell

• Assist in movementAssist in movement• Cilia – short and Cilia – short and

present in large present in large numbersnumbers

• Flagella – long and Flagella – long and less numerousless numerous

NucleusNucleus• Most prominent structureMost prominent structure• Maintains its shape with a Maintains its shape with a

protein skeleton called the protein skeleton called the nuclear matrixnuclear matrix

• Double membrane – nuclear Double membrane – nuclear envelopeenvelope

• Inside the envelope – Inside the envelope – chromation (DNA & protein)chromation (DNA & protein)

• When the cell is about to When the cell is about to divide it forms the divide it forms the chromosomeschromosomes

• Stores hereitary information in Stores hereitary information in its DNAits DNA

• RNA is copied from DNARNA is copied from DNA• RNA travels from nucleus to RNA travels from nucleus to

the cytosol through small holes the cytosol through small holes in the envelope – nuclear in the envelope – nuclear porespores

• Contains the nucleolus – the Contains the nucleolus – the site where ribosomes are site where ribosomes are synthesizedsynthesized

Nucleolus

• Inside nucleus• Contains RNA to build

proteins • Site where ribosome

are synthesized

Cell Wall

• Most commonly found in plant cells & bacteria

• Supports & protects cells

Chloroplast

• Usually found in plant cells

• Contains green chlorophyll

• Where photosynthesis takes place

Label the parts of the cell

http://www.phschool.com/atschool/phbio/activities/cbd-3072/simbase.htmhttp://www.phschool.com/atschool/phbio/activities/cbd-3072/simbase.htmhttp://www.harcourtschool.com/activity/cell/cell.htmhttp://www.harcourtschool.com/activity/cell/cell.htm

Cytoplasm

Ans. The cell structure and function

• Cytoplasm

Mitochondria• ATP

• Muscle and liver 2

• Crytal

• Cristae

• They enlarge the surface area for more

• Reproduction

• Ribosome• Membrane• Proteins• Cytosol• Endoplasmic rediculum• Protein• Produced

Endoplasmic Reticulum (ER)HyghwayRought and smoothRibosomeProtein steroidssteroids

Ans.• Fedex, DHL

Lysosome• Animal

Cytoskeloeton• Shape and size

• Membrane

• Microfilament & microtubule

• Spindel fiber

Cilial and Flagella• Movement

• Nucleus• Nuclear envelop• DNE and protein• Heridity

NucleusNuclear envelopDNE and proteinHeridity

NuleoulusRibosome

Name: ___________ Date:_____ 1/12/11

Quiz: cell structure and function

Multiple choice 1-22

No note can be used

Color and label parts of cell:

Animal and plant cells

ANIMAL CELL

PLANT CELL

The Human Cheek Cell

http://www.biologycorner.com/worksheets/cheekcell.html

The Human Cheek Cell

Materials

Microscope

Methylene blue

Toothpick

Slide

Cover slide

The Human Cheek CellProcedure

• 1. Put a drop of methylene blue on a slide. Caution: methylene blue will stain clothes and skin.

• 2. Gently scrape the inside of your cheek with the flat side of a toothpick. Scrape lightly.

• 3. Stir the end of the toothpick into the stain and throw the toothpick away.

• 4. Place a cover slip onto the slide• 5. Use the SCANNING objective to focus. You probably will not see

the cells at this power.• 6. Switch to low power. Cells should be visible, but they will be small

and look like nearly clear purplish blobs. If you are looking at something dark purple, it is probably not a cell

• 7. Once you think you have located a cell, switch to high power and refocus.(Remember, do NOT use the coarse adjustment knob at this point)

The Human Cheek Cell

Low High

Sketch

Scanning

---Sketch the cell at low and high power. Label the nucleus, cytoplasm, and cell membrane. Draw your cells to scale.

The Human Cheek CellQuestions

1.  This cell is which cell type?

A. animal B. plant C. prokaryotic

2.  The shape of this cell, overall, is:

A. round B. rectangular C. other

3. What stain did you use to see this cell type?

4. What material does this particular stain reveal?

5.  Which organelles were apparent in this cell?

A. nucleus B. chloroplast C. central vacuole

6. Which cells are larger?

A. cheek B. bacteria

7. Is the cheek cell a eukaryote or prokaryote? How do you know?

8. Cheek cells do not move on their own, so you will not find two organelles that function for cell movement. Name these organelles.

The Human Cheek CellQuestions

• 1. Why is methylene blue necessary?• 2. Cheek cells do not move on their own, so you will not find two

organelles that function for cell movement. Name these organelles.• 3. The light microscope used in the lab is not powerful enough to

view other organelles in the cheek cell. What parts of the cell were visible?

• 4. List 2 organelles that were NOT visible but should have been in the cheek cell.

• 5. Is the cheek cell a eukaryote or prokaryote? How do you know• 6. Keeping in mind that the mouth is the first site of chemical

digestion in a human. Your saliva starts the process of breaking down the food you eat. Keeping this in mind, what organelle do you think would be numerous inside the cells of your mouth?

Surrounding the Cell

Cell Membrane

• Outer membrane of cell that controls movement in and out of the cell

• Double layer

Inside the Cell

Nucleus

• Directs cell activities

• Separated from cytoplasm by nuclear membrane

• Contains genetic material - DNA

Nuclear Membrane

• Surrounds nucleus• Made of two layers• Openings allow

material to enter and leave nucleus

Chromosomes

• In nucleus• Made of DNA• Contain instructions

for traits & characteristics

Cytoplasm

• Gel-like mixture

• Surrounded by cell membrane

• Contains hereditary material

Endoplasmic Reticulum• Moves materials around

in cell• Smooth type: lacks

ribosomes• Rough type (pictured):

ribosomes embedded in surface

Ribosomes

• Each cell contains thousands

• Make proteins• Found on ribosomes

& floating throughout the cell

Mitochondria

• Produces energy through chemical reactions – breaking down fats & carbohydrates

• Controls level of water and other materials in cell

• Recycles and decomposes proteins, fats, and carbohydrates

Golgi Bodies

• Protein 'packaging plant'

• Move materials within the cell

• Move materials out of the cell

Lysosome• Digestive 'plant' for

proteins, fats, and carbohydrates

• Transports undigested material to cell membrane for removal

• Cell breaks down if lysosome explodes

Vacuoles

• Membrane-bound sacs for storage, digestion, and waste removal

• Contains water solution

• Help plants maintain shape

CELL WALLCELL WALL

• Lies outside of the Lies outside of the cell membranecell membrane

• Helps support and Helps support and protect the plant cellprotect the plant cell

• Contains long chains Contains long chains of cellulose – hardens of cellulose – hardens the entire structurethe entire structure

• Pores in the cell wall Pores in the cell wall allow ions to enter or allow ions to enter or exit the cellexit the cell

VACUOLES

•Fluid filled organelles that store enzymes and metabolic wastes•Some vacuoles may make up 90% of the cell

ChloroplastChloroplast• Surrounded by 2 Surrounded by 2

membranes and contain membranes and contain DNADNA

• Some store starch or fats Some store starch or fats • Some contain pigments Some contain pigments

that absorb visible light – that absorb visible light – chlorophyll chlorophyll

• Ex Chloroplasts – energy Ex Chloroplasts – energy of sunlight is converted of sunlight is converted into chemical energy each into chemical energy each chloroplast encloses a chloroplast encloses a system of membranous system of membranous sacs called thylakoidssacs called thylakoids

INTERACTIVE ACTIVITYINTERACTIVE ACTIVITY• http://www.phschool.com/atschool/phbio/activities/cbd-3072/simbase.htmhttp://www.phschool.com/atschool/phbio/activities/cbd-3072/simbase.htm• http://www.harcourtschool.com/activity/cell/cell.html (label)http://www.harcourtschool.com/activity/cell/cell.html (label)• http://www.cellsalive.com/quiz1.htm (Quiz)http://www.cellsalive.com/quiz1.htm (Quiz)• http://library.thinkquest.org/12413/structures.html (note)http://library.thinkquest.org/12413/structures.html (note)• http://www.sp.uconn.edu/~bi107vc/fa02/terry/cells.html (Prok vs Euk.)http://www.sp.uconn.edu/~bi107vc/fa02/terry/cells.html (Prok vs Euk.)• http://www.biology4kids.com/files/cell_main.html http://www.biology4kids.com/files/cell_main.html