Biology 1408
Ch. 3 Notes Outline

Cellular Level of Organization

Cells are the smallest units of life Must exhibit all of the _________________ of life. Ex:

All are highly ____________________ Ex:

Many are specialized Ex:

Cell Theory All living things are composed of cells Cells are the basic units of __________________ & _______________________ of living things All cells come from _________________________ cells

Discovery of Cells

Anton Von Leeuwenhoek invented the _______________ __________________ in the 1600’s. He was a Dutch lens maker who made eye glasses for a living. Robert Hooke – 1st to observe _____________ cells under the microscope Why did he call them “cells”?

Matthias Schleiden and Theodore Schwann proposed the cell theory after making many observations of plant and animal tissues.

Cell Size

Most cells are smaller than ___________ mm in diameter. Surface area to volume ratio determines cell _______________. Volume increases as the cube of the radius of the cell while surface area increases by the __________________ of the radius.

Ex: cell with 5 mm diameter S. A. = V =

cell with a 10 mm diameter S.A. = V =

Calculate the surface area to volume ratio of the above cells.

Calculate the surface area to volume ratio of two cube shaped cells, one with sides of 1 cm in length and the other with sides of 2 cm in length.

Conclusion from above calculations: Small cells have a greater S. A. to V. ratio than larger cells. Nutrients from the environment must cross the cell membrane to enter the cell. Cells must be small in order for the surface area to be adequate to supply nutrients to the cell by absorption or diffusion.

So, why are cells so small?

The ________________ the cell, the greater the surface area to volume ratio and therefore, the _________________ the rate of diffusion of nutrients, wastes, oxygen, & carbon dioxide.

EUKARYOTIC CELLS

Have a membrane bound _____________________. Nucleus contains ____________________. All plant and animal cells, protists and fungi are eukaryotic. Plasma membrane: outer boundary of cell Composed of a phosopholipid bilayer with ____________________ embedded in it. Also has glycolipids associated with its surface and cholesterol within it.

Hydrophilic = ___________________________ Hydrophobic = ___________________________ Phospholipids have a hydrophilic end and a hydrophobic end.

Sketch and label the phospholipid bilayer:

Functions of the cell (plasma) membrane: Barrier between the cell and its ____________________________. Regulates the ___________________ of substances into and out of the cell. Contains ____________________ that enable the cell to respond to its environment. Contains proteins that are important to the ________________ response. Dynamic, fluid structure (not stiff or rigid- proteins “float” in phospholipid bilayer like icebergs in the sea. Plant cells have a cell membrane surrounded by a _________________ ________________. Cell wall provides rigidity and is typically composed of _______________________ Some plant cells have a secondary cell wall composed of ________________________. Where have we heard of lignin? Organelles “tiny organs”

Subcellular structures which perform specific life functions for the cell. Found in animal and plant cells. Chloroplasts and a central ____________________ are found only in plant cells. Centrioles are found only in _______________ cells and are seen during mitosis.

Compare the diagrams of the plant cell and animal cell and note the differences between them.

Nucleus

Contains the genetic material ________________. ___________________ - thread-like DNA which has a grainy appearance. It is the uncoiled state of DNA seen in cells during interphase. It is the