1. Chapter 3: Cell Structure & Function
The cell is the smallest structure capable of performing all of the functions of life.
smallest living organisms; made up of only 1 cell (Ex. Bacteria)
Multicellular: composed of many cells
(Ex. Humans)
Can be prokaryotic or eukaryotic

2. Discovery of the Cell Antonie van Leeuwenhoek
made 1st microscope in late 1600’s
Robert Hooke
Looked at thin slice of cork under microscope
1st to use the term “cell”

3. The Cell Theory
1. All living organisms are made up of 1 or more cells. 2. Cells are the basic unit of life. 3. All cells come only from other cells.

4. Common Features of Cells
Most cells have these common features:
Plasma membrane: boundary that separates cell from its environment
Cytoplasm: semifluid substance inside cell made up of water, salts, organic molecules
Ribosomes: where proteins are made
DNA: genetic material

5. Cell Size
ASurface area of a cell is important for carrying out the cell’s functions, such as acquiring adequate nutrients and oxygen
A small cell has more surface area relative to its cell volume and is more efficientt larger
Cells must be small to move substances quickly into or out of cell.
creasesface area affecget material into and out of cell surface area = faster exchange of nutrient & wastes

6. Prokaryotic Cells
Lack membrane bound nucleus and organelles (cell parts)
Bacterial cells
Found in Bacteria and Archaea Domains
DNA is shaped like rings & stored in cytoplasm
Some have cell walls & sticky capsules

7. Anatomy of a Prokaryotic Cell

8. Eukaryotic Cells All living cells other than bacteria
Ex. Plants, animals, fungi, protists
DNA is found in the nucleus & is enclosed by a nuclear membrane
Can be multicellular or unicellular
Contain tiny structures that perform specific functions called organelles (“little organs”)

9. Eukaryotic Animal Cell

10. Eukaryotic Plant Cell

11. Nucleus Contains DNA Contains nucleoplasm (like cytoplasm)
Nuclear envelope
Double membrane that separates nucleus from cytoplasm
Has permanent nuclear pores where substances can leave nucleus
Contains DNA
Chromosomes: DNA & proteins coiled up
Chromatin: threadlike form of DNA & proteins
Contains nucleoplasm (like cytoplasm)
Contains nucleolus (another organelle)
Where rRNA is made

12. May be attached to endoplasmic reticulum Found in the cytoplasm
Ribosomes
Made up of two subunits that are composed of ribosomal RNA (rRNA) and proteins
Large subunit
Small subunit
Proteins are made here
May be attached to endoplasmic reticulum
Found in the cytoplasm

13. The Endomembrane System
EThe membranes within a eukaryotic cell are physically connected and compose the endomembrane system
The endomembrane system includes the nuclear envelope, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, vacuoles, and the plasma membrane

14. The Endomembrane System
Some components of the endomembrane system are able to communicate with others with formation and transfer of small membrane segments called vesicles
One important result of communication is the synthesis, storage, and export of molecules

15. The Endoplasmic Reticulum
There are two kinds of endoplasmic reticulum—smooth and rough
Smooth ER lacks attached ribosomes
Rough ER lines the outer surface of membranes
They differ in structure and function
However, they are connected

17. Rough Endoplasmic Reticulum
Some RER is continuous with the outer envelope of the nuclear membrane
Once a growing protein is inside the RER, there are enzymes there which help to fold newly form proteins
Some proteins also have carbohydrate segments added to them in the RER to make glycoproteins

18. Smooth Endoplasmic Reticulum
SER is also a series of membrane tubes without ribosomes attached, continuous with the RER at the periphery, with a number of very important functions.
Functions
In cells in testes produces testosterone
Make phospholipids needed for all membranes in cell
In liver cells, detoxifies some poisons
Release free glucose from glycogen (liver)
Assist in recycling of old, worn out cell parts

19. Golgi
Golgi is a series of flattened membrane sacs, like a stack of malformed pancakes, curling slightly toward the nucleus and toward the plasma membrane.
Functions of Golgi
Modify proteins:
Add carbohydrate portions (glycoproteins)
Add lipid portions (lipoproteins)
And/or cut into smaller piecesce of cell because it collects, sorts, packages, and distributes materials like proteins & lipids

20. Vesicles and Vacuoles
These are membrane sacs containing material being stored or transported.
May be formed from the Golgi, lysosomes, the ER or by endocytosis.
Vacuoles are usually larger than vesicles
Vacuoles are used for storage
Water, sugar, salt, pigments, toxic substances
Vesicles are used more for transporting substances either into or out of cell.

21. Lysosomes Lysosomes are membrane bound sacs of hydrolytic enzymes
Enzymes were made by ribosomes
The integral membrane proteins of lysosomes pump H+ into the sac, making the inside of a lysosome have a very low pH, when compared to the cytoplasm.
The enzymes are in their most active at low pH, so if a lysosome breaks, the enzymes will do little damage to the cells parts because they don’t work at high pH
Functions
Recycle old, worn out cell parts
Digest materials brought into cell by endocytosis

22. Peroxisomes Peroxisomes are membrane sacs, similar to lysosomes.
Most abundant in liver and kidney cells.
Functions:
Breakdown of hydrogen peroxide (a powerful oxidant damaging to cells ) into water & oxygen
In liver, break down fats & produce bile salts
Detoxify ethyl alcohol in liver
In plant leaves, they use up oxygen & release CO2

23. Mitochondria
An endosymbiont, with its own DNA, ribosomes and internal membrane network.
Double membrane
Outer membrane surrounds organelle
inner membrane is called the cristae
Inner membrane is ‘bacteria-like’
Site of cellular respiration
Found in plant & animal cells
Outer compartment is the space between outer and inner membrane
Matrix, fluid inside inner membrane

24. Chloroplasts
Use energy from sun to make carbohydrates by the process of photosynthesis
Solar energy + carbon dioxide + H2O  glucose + oxygen
Found in plants and algae
Plastid
Amyloplasts= found in roots; store starch
Chromoplasts= found in leaves; contain red & orange pigments
Chloroplasts= contains green pigment chlorophyll

25. Chloroplast cont. Bound by 2 membranes Stroma: fluid-filled space
Contains DNA, ribosomes, enzymes
Thylakoids: interconnected flattened sacs of membrane
Grana: stacks of thylakoids that contain pigment chlorophyll used in photosynthesis

26. Cytoskeleton
The cytoskeleton is a series of proteins that give the cell its shape, much of its function, and mobility in cells that move.
3 basic types:
Microfilaments: smallest in diameter, often contractile. Responsible for movement of cytoplasm and of some cell components.
Examples: actin and myosin
Intermediate filaments: permanent. Responsible for holding cell contents, especially the nucleus, in place.
Microtubules: largest diameter. Responsible for transport within the cell and, as part of cilia/flagella, along the outside of cells, too.

27. “MtOC”s Microtubule Organizing Centers
Microtubules are small hollow cylinders that make up the cytoskeleton, cilia, flagella, & centrioles
Centrosome: main area where microtubules are assembled found near nucleus
No surrounding membrane
Centrioles produce the spindle fibers that move chromosomes around during nuclear division (mitosis & meiosis)

28. Cilia and Flagella
Hair-like structures on the surface of cells, growing out of the plasma membrane
Movement is the function of both
Cilia are short, there are usually many on the surface of one cell, and in humans, are found on surfaces where they move materials along the cells’ surface.
Found in respiratory tract and female reproductive tract.
A flagellum is a longer version, and there is usually only one or a few per cell. It moves the cell of which it is a part.
Only one flagellate cell type in humans: sperm