Cell Structures

What are the functions of the major cell structures?

Cell Wall• Found in plants, algae, fungi and

nearly all prokaryotes

• Lie outside the cell membrane

• Made up of fibers of carbohydrate and protein– Plant cell walls made of cellulose

• MAIN FUNCTION: provide support and protection for the cell

Image from: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/PlantCell.html

Plant Cell Wall Structure

Image from: http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/cellwall.htm

Bacterial cell walls

• Made up of peptidoglycan

• Different structures for different types of bacteria

Fungal and Algal cell walls

• Fungal cell walls–Composed of

chitin and cellulose

• Algal Cell Walls– Composed of

polysaccharides– Which

polysaccharides depends on the algae

Nucleus

• Controls most of the cell processes and contains the hereditary information (DNA)

• Parts of the nucleus–Chromatin and chromosomes–Nucleolus–Nuclear envelope

Image from: http://sun.menloschool.org/~birchler/cells/animals/nucleus/

                                                                          

Image from: http://www.daviddarling.info/encyclopedia/N/nucleusc.html

Image from: http://cellbio.utmb.edu/cellbio/nucleus.htm

Chromatin and Chromosomes

• Chromatin– The granular material visible within the

nucleus– Consists of DNA bound to proteins

• Chromosomes– Chromatin condenses into chromosomes

before cell division– Contain genetic information

Nucleolus

• Assembly of ribosomes begins here

Nuclear envelope

• Double membrane layer surrounding the cell

• Has pores which allows material into and out of the cell

Cytoskeleton• Network of protein filaments

that help the cell maintain it’s shape

• Involved in many forms of cell movement

Parts of the Cytoskeleton• Microtubules

–Hollow tubes of protein that maintain shape

–Serve as “tracks” for moving organelles–Important in cell division–Make up centrioles in animal cells–Also make up flagella and cilia in some

cells

Microtubules

Images from: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Cytoskeleton.html

Parts of the Cytoskeleton

• Microfilaments–Long, thin fibers that function

in the movement and support of the cell

–Much smaller than microtubules

Microfilaments

Ribosomes

• Small particles of RNA and protein

• Function: assemble proteins• Prokaryotic and Eukaryotic

ribosomes have different structures

Ribosomes consist of a

small subunit

and a large subunit

Image from: http://cellbio.utmb.edu/cellbio/ribosome.htm

Endoplasmic Reticulum• Function: Components of the cell

membrane are assembled and some proteins are modified

• Rough ER: Synthesis of proteins: chemical modification; Studded with ribosomes

• Smooth ER: synthesis of lipids

Image from: http://www.winterwren.com/apbio/cellorganelles/er.html

Image from: http://biology.about.com/library/weekly/aa041300a.htm

Golgi Apparatus

• Function: enzymes in the Golgi attach carbohydrates and lipids to proteins

• From Golgi proteins are packaged and sent to their final destinations

Image from: http://cellbio.utmb.edu/cellbio/GOLGI.HTM

Image from: http://cellbio.utmb.edu/cellbio/GOLGI.HTM

Lysosomes

• Small organelles filled with enzymes

• Function: break down lipids, carbohydrates and proteins from food particles

• Break down old organelles and other cellular debris

Image from: http://cellbio.utmb.edu/cellbio/lysosome.htm

Vacuoles

• Function: Store materials such as water, salts, proteins, and carbohydrates

• In plants, a large central vacuole filled with fluid is used for support in the cell

Image from: http://micro.magnet.fsu.edu/cells/plants/images/plantvacuolesfigure1.jpg

Chloroplasts

• Function: use energy from the sun to make energy-rich food molecules in photosynthesis

• Bound by two envelope membranes

• Stacks of photosynthetic membranes contain chlorophyll

Image from: http://www.daviddarling.info/images/chloroplast.jpg

Mitochondria

• Function: use energy from food to make high energy compounds

• Powerhouse of the cell• Bound by two envelope

membranes• Inner membrane is folded

Image from:http://micro.magnet.fsu.edu/cells/mitochondria/images/mitochondriafigure1.jpg

Organelle DNA

• Chloroplasts and mitochondria contain their own DNA

• Endosymbiotic theory:mitochondria and chloroplasts the result of endocytosis of bacteria and blue-green algae whichbecame symbiotic

Endosymbiotic theory

Image from: http://www.msnucleus.org/membership/html/k-6/lc/organ/5/images/wpeA.gif

Venn Diagram

• Use your notes and the venn diagram handout to compare and contrast prokaryotic and eukaryotic cells and plant and animal cells

Cell as a Factory

• See page 182