1. Cell Structure
Life Science Chapter 4

2. Cell Membranes Each Cell is surrounded by a Cell Membrane
The membrane is a thin covering that makes the outer boundary of the cell.
Keeps the insides in and the surroundings out.
Membranes sense and respond to the changes in the surrounding environment.

3. Membrane Structure
There seems to be ONE basic design found in ALL cells.
Membranes are composed of molecules of lipids and proteins.
Many variations to this one primary design
Model of the Cell membrane – Fluid Mosaic Model
Lipids form a flexible fluid
Proteins embeded in a two-layered film
Makes different patterns (mosaics)

4. Membrane Properties
By learning some properties of membranes, we learn much about how the cell operates.
Selectively Permeable- certain molecules go through them, and others do not.
Not all materials permeable to the same molecule.

5. Membrane Properties cont…
Active Transport- movement by use of the cell’s own energy.
Passive Transport- movement of substances through a membrane without the use of a cell’s own energy.
Diffusion
Osmosis

6. Passive Transport
Diffusion- The movement of molecules from a place with a lot of them (high concentration) to a place where there are few of them (low concentration)
Diffusion can be accelerated by things such as heat, movement, and pressure
Sugar passes from our blood to our cells by diffusion.

7. Passive Transport Cont..
Osmosis- diffusion of water through a selectively permeable membrane.
A type of diffusion
Moving from an area of LOW concentration to HIGH concentration
Primary means by which a plant obtains water

8. Osmosis Cont…
Some organisms have to control the amount of water that osmosis brings into their cells.
Cell could swell and burst if it did not regulate this.

9. Typical Parts of a Cell Cells are like tiny factories
In different cells, the basic structures come in different shapes, sizes, and quantities.
All cells have THREE basic parts
Cellular boundaries
Cytoplasm
Genetic Material

10. Cellular Boundries
All factories have walls that protect the machinery.
Cell membrane is like that factory wall
Some factories have further protection (fences, boundaries, gates)
Some cells also have additional boundaries
Cell Walls- substances found in this boundary are made by the cell and assembled just outside of the membrane.
The cell wall supports and protects the cell

11. Cytoplasm Cytoplasm- a thick fluid that contains many small organelles
Organelles- parts of a cell that perform many of the functions needed to keep the cell alive.

12. Types of organelles Mitochondria- The Powerhouse of the cell
Usually long oval structures made of two membranes
Outer membrane smooth, inner has ridges
Stores and uses energy

13. Types of organelles
Endoplasmic Reticulum (ER) – passageways (canals) formed by a folded membrane passing throughout the cytoplasm.
Connects the nucleus to the cell membrane
Cell’s Delivery System

14. Types of organelles
Ribosomes – Tiny organelles that direct the assembling of proteins.
Scattered throughout the cytoplasm
Receive coded instructions from the nucleus to form proteins.

15. Types of organelles
Golgi Apparatus- Collect Chemicals from the cytoplasm.
Sometimes they process these chemicals and make them complex.
Connected with the ER

16. Types of organelles
Vacuoles- organelles that look like bubbles and serve as containers inside the cytoplasm of some cells.
Made of a membrane and may contain food, water, waste, fats, or chemicals.

17. Types of organelles Lysosomes- tiny enzyme filled capsules
Use their enzymes as a “demolition crew”
Dissolve structures that are no longer needed, or invading bacteria or viruses.
Can also be used for digestion.

18. Types of organelles
Chloroplasts – made of an outer membrane and stacks of inner membranes that contain the green pigment chlorophyll.
Many plant cells and some other cells have chloroplasts

19. Types of organelles
Cilia and Flagella- Propels the cell, or moves material by the cell.
Cilia- tiny hair-like structures on the outside of the cell that are extentions of the membrane.
Short and many
Flagella- Hair like structures that are smaller and the cell has fewer.
Usually one or two.

20. Genetic Material.
Nucleus- compact roundish structure that functions as the control center for the cell.
Main office
Surrounded by a nuclear membrane which has larger pores that allow substances to pass back and forth between the nucleus and the cytoplasm.

21. Nucleus Cont… Inside the nucleus are chromosomes.
Chromosomes – composed of DNA and other molecules.
Chromosomes control the “plans” for all of the “machines” of the “factory”

22. Cell Comparison
Some cells may completely lack organelles and some may be packed with one particular type.
Bacteria cells lack a nuclear membrane among other organelles.
Prokaryotes- lack a nuclear membrane
Eukaryotes- cells that have a nuclear membrane.

23. What to Cells tell us about our God?
When you view a piece of art, you not only appreciate the piece, but the creator of the piece.
Cells show marvelous complexity, design, and efficiency.
This should point to the Creator of life!
And some people still believe this all happened from a big bang and evolution?!?!?

24. Anton van Leeuwenhoek Microscopist of the late 1600’s and 1700’s
Viewed many tiny things with lenses he made himself.
Other scientists had difficulty believing that the organisms Leeuwenhoek saw actually existed.