FSN 1500 Week 7, 8 The Cell

Introduction The study of biological cells and the potential applications (e.g., stem cell research, cloning, gene therapy) is one of the most exciting, and controversial, scientific pursuits Everyone should have functional knowledge of these topics

Cell Theory and Function Cell - the smallest structural and functional unit capable of carrying out all the functions necessary to support life. Cell Theory - all living things are composed of cells Cells are viewed by different types of microscopy, including the light, scanning electron microscope (SEM) and transmission electron microscope (TEM)

Microscopy All microscopes have a particular resolving power (resolution). Optical resolution - measure of the ability to distinguish two separate points. (see slide)

Optical resolution - measure of the ability to distinguish two separate points.

1 nanometer (nm) = m (one billionth) Light microscope: 200 nm resolution (best); SEM: nm resolution; TEM: 0.5 nm resolution The SEM and TEM focus electrons (not light); the SEM electrons produce a “backscatter” image whereas the TEM electrons pass through the specimen Microscopy

The SEM provides a 3-D view of the object; the TEM a detailed interior view (see figures) SEM Microscope Example

Microscopy Researchers will likely continue to develop better microscopes and better microscopy techniques

The Cell In addition to microscopy, our knowledge of cell structure and function has been acquired from manipulating/removing components of the cell and other means e.g., the 2008 Nobel Prize in chemistry was awarded to three researchers who developed a fluorescent green protein that can be used to monitor the movement of substances inside the cell

The Cell The average animal cell is inches in diameter The average adult body contains an estimated 30 – 40 trillion human cells! Unsettling thought? An estimated 200 trillion microbes live within the human body! There are approximately 220 different human cell types in our body

The Cell Cells are generally classified into two broad groups: prokaryotes and eukaryotes; prokaryotes are present in primitive organisms (e.g., all bacteria) and lack a membrane-bound nucleus; eukaryotes possess a membrane- bound nucleus

Cell Structure and Function Organelles - bodies within cells that carry out a specific function - see figures Organelles commonly grouped into five categories - see figures and handout; know the job that these organelles perform The cell membrane (animal cells) and cell membrane plus cell wall (plant cells) are not classified as organelles but have important functions.

Cell Structure and Function The cell organelles reside in the cytosol (or cytoplasm) – a semi fluid substance composed mostly of water, carbohydrates and proteins - the proteins play a critical role in cell function facilitating the conduction of cellular instructions and containing intracellular receptors which act like ushers

Cell Membrane and Substance Transport

Cell Structure and Function A good online review of these topics is available via the Cells Alive home page (

The Cell Lastly: make sure you know the major differences not just between eukaryotic plant and animal cells but also between eukaryote and prokaryote cells (see figure)