Presentation on theme: "Surface Area: Volume Ratio Lab Think about your cell city…(think/pair/share) What is your nucleus? How many people or beings could be supported by your."— Presentation transcript:
Surface Area: Volume Ratio Lab Think about your cell city…(think/pair/share) What is your nucleus? How many people or beings could be supported by your nucleus? How well can your cell membrane/cell wall protect the structures and function of your cell? What would happen if your cell or institution doubled in size but your nucleus did not?
Importance of SA:V ratio As a cell grows, the surface area cannot maintain the contents of the cell. To compensate: elongate and thin or have surface folds to increase SA:V. Or, it will divide.
Surface Area: Volume Ratio Surface area: volume ratio - restriction of cell size based on its ability to carry out functions.
Surface area = cell membrane (membrane surrounding cell) Regulates what nutriens (food, oxygen) can enter and how much waste can exit Volume = the endomembrane area (cytoplasm and organelles) The amount of “stuff” the DNA needs to control and the cell membrane needs to be able to maintain
Surface to Volume Ratio Diameter (cm): Surface area (cm 2 ): Volume (cm 3 ): Surface- to-volume ratio:13:16:1 4:1 Surface area: cm 2 Volume: cm 3
Demands of an oversized cell DNA overload – DNA does not increase as cell increases Therefore, DNA cannot support the amount of work the large cell demands Decreased efficient of nutrient and waste transport In today’s lab, apply this concept! You will see what I mean!
Compound Light Microscope Two or more sets of glass lenses bend light bounced off of a specimen Forms an enlarged image through the eyepiece 1000x magnification ~200 nm (small bacteria)
Fig. 4.5a, p. 56
path of light rays (bottom to top) to eye Ocular lens enlarges primary image formed by objective lenses Objective lenses (those closest to specimen) form the primary image. Most compound light microscopes have several stage (holds microscope slide in position) Condenser lenses focus light rays through specimen illuminator microscope base housing source of illumination Fig. 4.5b, p. 56
Light microscope – Euglena (protist)
Electron Microscopes SEM Scanning Electron Microscope Specimen is coated with a thin layer of metal Beam of electrons scan the cell surfaces Produces detailed 3D images of cell surfaces 0.1 nm – 100 um
accelerated electron flow (top to bottom) condenser lens to focus beam of electrons onto specimen objective lens intermediate lens projector lens viewing screen (or photographic film) specimen Fig. 4.5c, p. 56
Electron Microscopes TEM Transmission Electron Microscope Used to study details of internal cell structures Magnetic field acts as the “lens” Accelerated electrons directed through a specimen 0.1 nm – 100 um
frog egg 3 mm Typical plant cell µm mitochondrion 1-5 µm chloroplast 2-10 µm human red blood cell 7-8 µm diameter Trypanosoma (protozoan) 25 µm long Chlamydomonas (green alga) 5-6 µm long Poliovirus 30 nm HIV (AIDS virus) 100 nm T4 bacteriophage 225 nm long tobacco mosaic virus 300 nm long DNA molecule 2 nm diameter UNAIDED HUMAN EYE ELECRON MICROSCOPES (DOWN TO 0.5 NM) LIGHT MICROSCOPE (DOWN TO 200 NM) Escherichia coli (bacterium) 1-5 µm long 1 centimeter (cm) = 1/100 meter, or 0.4 inch 1 millimeter (mm) = 1/1,000 meter 1 micrometer (µm) = 1/1,000,000 meter 1 nanometer (nm) = 1/1,000,000,000 meter 1 meter = 10 2 cm = 10 3 mm = 10 6 µm = 10 9 nm 1mm100 µm10 µm1 µm100 nm10 nm1 nm0.5 nm Fig. 4.6, p. 57
Light micrograph (phase-contrast process) Light micrograph (Nomarski process) Transmission electron micrograph, thin section Scanning electron micrograph Fig. 4.7, p. 57
Golgi body vesicle microfilaments (components of cytoskeleton) mitochondrion chloroplast central vacuole rough endoplasm reticulum (rough ER) ribosomes (attached to rough ER) ribosomes (free in cytoplasm) smooth endoplasmic reticulum (smooth ER) DNA + nucleoplasm nucleolus nuclear envelope NUCLEUS plasma membrane cell wall Plant Cell
microfilaments microtubules components of cytoskeleton plasma membrane mitochondrion nuclear envelope nucleolus DNA + nucleoplasm NUCLEUS vesicle lysosome rough ER ribosomes (attached to rough ER and free in cytoplasm) smooth ER vesicle Golgi body pair of centrioles Animal Cell
In the left hand column are the major organelles of a cell, with their essential function within the cell listed below them. Your job is to choose another organization of your interest: 1) Government 2) School 3) Sports Team 4) Your place of employment 5) Family 6) A city List the members or things within your choice that serve the same purpose as the corresponding organelle.
You and a partner will research and prepare a short presentation on your chosen organelle: You will have time in class to research your organelle and discuss your presentation layout with your partner, as well as computer lab time to put together your powerpoint. Your presentation should include: a) Structure of the organelle b) Function and location of the organelle c) An image of the organelle d) You must include information from your text and one other resource. e) An assessment – how will you know the class comprehends the characteristics of your organelle?