Cell Structure and Function Chapter 4 xenophilius.wordpress.com/2008/09/21/ commons.wikimedia.org/wiki/File:SEM_blood_cel...

What is a Cell? The smallest unit of matter that can carry all processes of life. Structure directly related to Function ≈ trillion cell in the human body All cells are not created equal cell diversity-cells differ in shape, size, and organization Limited in size by surface area to volume ratio Shape indicates function At least 200 cell types in your body!

Background Check Cell Discovery: ◦ Possible by development of microscope ◦ Robert Hooke-examined cork ◦ Anton van Leeuwenhoek-1 st to observe living cells Cell Theory: 1.All living things 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 askabiologist.asu.edu/.../rhooke.html

Eukaryotes Vs. Prokaryotes Eukaryotes: ◦ Membrane-bound nucleus and organelles ◦ Example(s): YOU, animals, plants, fungi, protists Prokaryotes: ◦ Lack nucleus and membrane- bound organelles ◦ Example(s): bacteria

Cell Membrane Surrounds entire cell Selectively permeable – some substances pass with ease while others cannot pass at all Made of: -- Lipids and proteins Fluid Mosaic Model commons.wikimedia.org/wiki/File:Cell_membrane...

Membrane Lipids and Proteins Phospholipids ◦ Polar head: hydrophilic ◦ Nonpolar tails: hydrophobic ◦ Forms lipid bilayer Steroids ◦ Cholesterol main steroid in animal cells ◦ Stabilize membrane/maintain fluidity Proteins ◦ Peripheral proteins: on exterior or interior surface of cell membrane ◦ Integral proteins: embedded in lipid bilayer  Carbohydrates: involved with self recognition and attachment  Transport of molecules through bilayer (channels or pores)

Cytoplasm/Cytosol Cytoplasm: ◦ Area between cell membrane and nucleus contains organelles Cytosol:  Gelatin-like aqueous in cytoplasm  Salts, minerals, organic molecules

Mitochondria Site of chemical reactions producing ATP – “power house” Own DNA and grow and divide on own 2 membranes ◦ Smooth outer: boundary ◦ Inner: cristae (folds)- enlarge surface area for reactions

Ribosomes No membrane Two compounds- proteins and RNA Assembled in nucleus Free or attached to Endoplasmic reticulum Role: protein synthesis

Endoplasmic Reticulum (ER) System of membranous tubules and sacs Function: intracellular highway 2 types: ◦ Rough- has ribosomes  cells with high rate of proteins being exported out or inserted into membrane ◦ Smooth- no ribosomes  calcium regulation in muscle cells  Breaks down toxic materials

Golgi Apparatus The UPS of the cell ◦ Packaging, processing, and secreting proteins System of membranes/sacs ◦ Works closely with ER

Lysosomes Small and spherical ◦ Enclose hydrolytic enzymes Enzyme use: ◦ Digest- proteins, carbohydrates, lipids, RNA, DNA ◦ Digest- old organelles, viruses, and bacteria Common in: ◦ Animals, fungi, and protists ◦ RARE in plants

Cytoskeleton Long protein strands in cytosol ◦ maintain cell shape and size ◦ support and movement ◦ No membrane 2 Components: ◦ Microfilaments-  Actin polymer chains  Smallest  Contribute to movement and contraction of muscle ◦ Microtubules-  hollow tubes  Largest  Active role in cell division- spindle fibers

Cilia and Flagella Cilia ◦ Hair-like organelles ◦ Numerous on cell ◦ Crawling motion  Help unicellular bacteria search for food/escape  On surface of respiratory tract Flagella ◦ Hair-like organelles ◦ Long, less numerous ◦ Swimming/whipping motion  Quick movement for unicellular organisms

Nucleus- “the brain” Nuclear matrix ◦ Protein skeleton ◦ Maintains shape Nuclear envelope ◦ Double membrane ◦ Chromatin within  DNA and protein combination  Coil for cell division forming chromosomes Nuclear Pores-visible ◦ Holes in envelope Nucleolus-visible ◦ Ribosome synthesis/partially assembled

Cell Wall- Plant cells Outside cell membrane Rigid- support and protection ◦ Long chains of cellulose ◦ Pores-allow passage of ions and molecules 2 types ◦ Primary- when cell being formed ◦ Secondary- when cell reaches full size  Between primary wall and membrane  Tough and woody

Vacuoles- Plant cells Fluid-filled Often large can occupy up to 90% of cell volume Storage: ◦ Store enzymes and metabolic waste ◦ Some waste toxic- can be a defense

Plastids- Plant cells Double membrane and contains DNA Store: ◦ Starch, fats, or pigments Chloroplast- most common ◦ Chlorophyll- green pigment ◦ Thylakoids: system of flattened, membranous sacs  Sunlight converted to chemical energy- Photosynthesis Other plastids contian pigments that give fruit and flowers color