Cell Structure

I. Looking at Cells  A. Scientists only became aware of cells after the invention of the microscope.  :Robert Hooke observed cork cells and called them “little boxes”. and called them “little boxes”. 1675:Anton van Leeuwoenhoek used a 1675:Anton van Leeuwoenhoek used a microscope and observed pond water. He microscope and observed pond water. He discovered many living creatures. discovered many living creatures.

B. Measuring Cell Structures 1111. Measurement taken by scientists are expressed in Metric Units. The official name of the metric system is International System of Measurements. TTTThe metric system is based on powers of 10.

fill in the metric chart. fill in the metric chart.

C. Types of Microscopes  1. Compound Light Microscope The most powerful Light microscopes can magnify up to 2000X.  2. Electron Microscope Electron microscopes can magnify up to 200,000X.  Transmission Electron Microscopes (TEM) reveal internal details.  Scanning Electron Microscopes (SEM) shows 3-D images of surface.

Eyepiece Body Tube Revolving Nosepiece Arm Stage Clip Stage Course Adjustment Fine Adjustment Base Objectives Light Diaphragm

EEEEyepiece – lens closest to the viewers eye BBBBody Tube – directs light from the objective to the eye RRRRevolving nosepiece – hold the objectives AAAArm – holds the base of the microscope with the objectives and eyepiece SSSStage Clips – hold the slide in place SSSStage – supports the slide

CCCCourse Adjustment – used to bring an object into focus under LOW power FFFFine Adjustment – used to fine tune the focus under LOW and HIGH power BBBBase – holds the light source, connects to the arm to hold the other parts of the microscope together OOOObjective – more magnification of the objective LLLLight source – light source DDDDiaphragm – controls the amount of light that travels through the specimen

*******TAKS QUESTION******  The English scientist Robert Hooke used a crude microscope to examine  A. individual atomsC. single-celled organisms  B. electronsD. cork cells

II. Cell Theory  A. Whose observations helped form the CELL THEORY?  Mattias Schleiden concluded that cells make up every part of the Plant.  Theodor Schwann concluded that animals are made up of cells.  Rudolph Virchow determined that cells only come from other cells.

B. 3 parts of the Cell Theory  1. All living things are made up of one or more cells.  2. Cells are the basic units of structure and function in organisms.  3. All cells arise from existing cells.

CELL SIZE  Small cells function more efficiently than large cells.  How many cells are our bodies made up of? 100 trillion  The advantage of cells being smaller is that substances that enter or leave a cell must cross that cell’s surface; if the cell is small they can exchange substances more readily than large ones. substances that enter or leave a cell must cross that cell’s surface; if the cell is small they can exchange substances more readily than large ones.

Relationship between Surface area and Volume Relationship between Surface area and Volume

Common Features of Cells  Cell Membrane-outer boundary of cell  Function- regulates what enters and leaves the cell  Made up of- phosphoplipids and proteins  Cytoplasm- fills the cell;cellparts are suspended in this  Function- same as above  Made up of- water and salts

CCCCytoskeleton- a system of microscopic fibers FFFFunction- provides framework, shape and support MMMMade up of- protein fibers

 Ribosomes-proteins are made here  DNA- found in the nucleus  Function- provides instructions for making proteins, regulates cell activities  Made up of- nucleotides

5. Prokaryotes  Smallest and simplest cells.  Prokaryote- is a single-celled organism that LACKS a nucleus and other compartments  They were the only organisms on Earth for 2 billion years. They are very simple and small. The familiar prokaryotes that cause infection and cause food to spoil are commonly called Bacteria.

Characteristics of Prokaryotes  They can live everywhere.  They can cause infection in humans and grow and divide very rapidly.  Some do not need oxygen survive.  Some can make their own food.  Prokaryotic cells have cytoplasm,cell wall, ribosomes, cell membrane & DNA (circular). Some have flagella for movement.  Some prokaryotic cell walls are surrounded by a capsule that enables the cell to cling to almost anything.

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6. Eukaryotic Cells  A eukaryote is an organism whose cells have a nucleus.  Organelle-parts of the cell that carry out specific activities  Nucleus-internal compartment that holds DNA Function- controls cells activities Function- controls cells activities

 Cilia-short hair-like structures  Function-used for movement  Cytoskeleton- provides interior framework  Function- support and shape of the cell  Made up of- protein fibers: microfilaments, microtubules, intermediate fibers

6. Cell Membrane  Cell Membrane- selective permeability (barrier)  Made up of- phospholipids and proteins  Draw a picture below of the Cell Membrane- Phospholipid and a Lipid bilayer:

7. Membrane Proteins  Serve many roles including: as markers; as receptors to recognize and bind to substances; as enzymes; as transport proteins to move substances across the membrane  ***************TAKS Question: ****************  A bacterium that lost its flagella would be unable to  A. divideC. maintain its shape  B. moveD. make proteins

III. Cell Organelles  The Nucleus –Contains Hereditary information- DNA & RNA –RNA- made in nucleus; used to make proteins –DNA- wound tightly into chromosomes –Humans have 46 chromosomes. Garden peas have 14 chromosomes.

B. Endoplasmic Reticulum-system of internal membranes  Function- moves proteins and other substances through the cell  Made up of- lipid bilayer & embedded proteins  Rough ER- contains ribosomes  Smooth ER- (lacks ribosomes)-makes lipids and breaks down toxins

 C. Golgi Apparatus- flattened membrane- bound sac  Function- package and distribution center (UPS)  Made up of- proteins  D. Lysosomes- vesicles that bud off of Golgi Apparatus  Function-contains cell digestive enzymes  E. Mitochondria- “MIGHTY MITOCHONDRIA”- site of cell metabolism  (more mitochondria=more energy) Function-makes energy ATP for the cell Function-makes energy ATP for the cell  Made up of- 2 membranes-inner is folded out and outside is smooth.

F. Structures of Plant Cells structures found only in PLANT CELLS.  1. Cell Wall- surrounds the cell membrane  Function- support & maintains shape of the cell  Made up of- proteins, carbohydrates->cellulose  2. Chloroplasts- found in plant cells as well as algae  Function-use light energy to make Carbohydrates ->glucose (sugar) Carbohydrates ->glucose (sugar)  Made up of- 2 membranes; has own DNA  3. Central vacuole- takes up most of a plant cell’s volume  Function-stores water,nutrients, wastes (when full cell wall is rigid)

******** TAKS Question****** ******** TAKS Question******  Which organelle serves as the packaging and distribution center of a eukaryotic cell? A. NucleusC. Mitochondrion B. LysosomeD. Golgi Apparatus A. NucleusC. Mitochondrion B. LysosomeD. Golgi Apparatus