1. Cell Structure & Function
Source:

2. Definition of Cell
A cell is the smallest unit that is capable of performing life functions.

3. Examples of Cells Muscle Cell Skin Cell Bacteria Red Blood Cell
Nerve Cell

4. Prokaryotic Eukaryotic
Two Types of Cells
Prokaryotic
Eukaryotic

5. Prokaryotic Do not have structures surrounded by membranes
Few internal structures
One-celled organisms, Bacteria

6. Prokaryotic Cell

7. Eukaryotic Contain organelles surrounded by membranes
Most living organisms
Plant
Animal

8. Eukaryotic Cells
Eukaryotic cells -possess a membrane-bound nucleus -are more complex than prokaryotic cells -compartmentalize many cellular functions within organelles and the endomembrane system -possess a cytoskeleton for support and to maintain cellular structure

9. “Typical” Animal Cell

10. Eukaryotic Cells

11. Eukaryotic Cells Nucleus
-stores the genetic material of the cell in the form of multiple, linear chromosomes
-surrounded by a nuclear envelope composed of 2 phospholipid bilayers
-in chromosomes – DNA is organized with proteins to form chromatin

12. Eukaryotic Cells

13. Cell Parts
Organelles

14. Surrounding the Cell

15. Cell Membrane
Outer membrane of cell that controls movement in and out of the cell
Phospholipid bilayer
Composed of multiple types of proteins

16. Function of Cell Membrane
Cell membrane provides gateway to most of the body’s metabolic reactions
Major Processes: Passive and Active Transport
Passive Diffusion: Diffusion and Filtration
Diffusion: process by which molecules move away from region of high concentration to low concentration (concentration gradient)
Simple Diffusion: Molecules can move freely through the membrane (osmosis: diffusion of water)
Facilitated Diffusion: Provides passage of larger molecules too big to move through membrane

17. Function of Cell Membrane
Active Transport: requires ATP to move molecules across membrane
Molecules can move across gradient
Sodium-Potassium Pump: carries ions into nerve cells via ATP
Exocytosis: moves substances out of the cell
Endocytosis: moves substances in the cell

18. Inside the Cell

19. Nucleus Directs cell activities
Separated from cytoplasm by nuclear membrane
Contains genetic material - DNA

20. Nuclear Membrane Surrounds nucleus Made of two layers
Phospholipid bilayer
Openings allow material to enter and leave nucleus

21. Nucleolus Inside nucleus Site of ribosome production
Contains RNA to build proteins
Site of translation

22. Cytoplasm Gel-like mixture (cytosol) Surrounded by cell membrane
Mostly composed of water
Anchors organelles within the cell
Surrounded by cell membrane
Where most of the human body’s metabolic reactions occur

23. Mitochondria
Produces energy through chemical reactions – breaking down fats & carbohydrates
Controls level of water and other materials in cell
Found in higher concentrations in higher energy organs (i.e. liver, muscle)

24. Mitochondria

25. Endoplasmic Reticulum
Moves materials around in cell
Smooth type: lacks ribosomes; involved in lipid metabolism
Rough type (pictured): ribosomes embedded in surface
Functions to fold and transport proteins across the cell

26. Ribosomes Each cell contains thousands of ribosomes
Site of protein synthesis
Found on ribosomes & floating throughout the cell

27. Golgi Bodies Protein 'packaging plant' Move materials within the cell
Move materials out of the cell

28. Lysosome Digestive 'plant' for proteins, fats, and carbohydrates
Transports undigested material to cell membrane for removal
Cell breaks down if lysosome structure is disrupted.

29. Peroxisomes Membranous sacs that contain oxidase enzymes
Work to detoxify harmful substances
Most numerous in liver and kidney cells

30. Endomembrane System (4.6 – 4.9)
Series of organelles responsible for:
Modifying protein chains into their final form
Synthesizing of lipids
Packaging of fully modified proteins and lipids into vesicles for export or use in the cell
And more that we will not cover!

31. Cell Structure All Cells have: an outermost plasma membrane
genetic material in the form of DNA
cytoplasm with ribosomes

33. Why Are Cells So Small? (4.2)
Cells need sufficient surface area to allow adequate transport of nutrients in and wastes out.
As cell volume increases, so does the need for the transporting of nutrients and wastes.

34. Why Are Cells So Small?
However, as cell volume increases the surface area of the cell does not expand as quickly.
If the cell’s volume gets too large it cannot transport enough wastes out or nutrients in.
Thus, surface area limits cell volume/size.

35. Why Are Cells So Small?
Strategies for increasing surface area, so cell can be larger:
“Frilly” edged…….
Long and narrow…..
Round cells will always be small.