Chapter 3 - Cells

Cells vary greatly in SIZE and STRUCTURE

Cytology =

Cells have 3 main parts

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The cell membrane is SELECTIVELY PERMEABLE = controls what enters and leaves the cell, it this its main function.

The cell membrane is a double layer of phospholipids with embedded proteins. Sketch the membrane to remember what it looks like.

 

 

 

CYTOPLASM - the area between the plasma membrane and nucleus. Where most metabolic reactions/activities take place.

(Review) What is metabolism?

The cytoplams many structures called ORGANELLES ("little organs")

ORGANELLES

1. ENDOPLASMIC RETICULUM (E.R.) - complex system or network of interconnected membranes, canals, or channels.

Function =

A. Rough ER - where ribosomes are located

Ribosomes function to:

B. Smooth ER - no ribosomes, where lipid synthesis takes place

smooth er

2. GOLGI APPARATUS (BODIES) - series of flattened membranes

Function =

golgi body

The droplets on the edges of the G.A. are vesicles

3. MITOCHONDRIA (-ion = sing.) - the "powerhouse" of the cell

Function =

This process is called CELLULAR RESPIRATION

mitochondria

What does respiration have to do with metabolism?

4. LYSOSOMES -. Contain powerful digesting enzymes, sometimes called the "suicide sac"

What is the purpose of enzymes?

What organ of your body is most like the lysosome?

5. CENTROSOME (central body) -Composed of 2 "cylinders" called CENTRIOLES ( which lie perpendicular to each other)

Involved in cell reproduction - SPINDLE forms from the centrioles

What is the purpose of the spindle?

 

Sketch the spindle and the centrioles.

 

 

6. CYTOSKELETON

Made of microtubules and microfilaments that give the cell support and shape.

What two structures function in movement? Describe or sketch them

 

9. NUCLEUS

- directs the activities of a cell.
- Contains GENETIC material = chromatin which condenses to form chromosomes (made of DNA)
- has a nucleolus which makes ribosomes
- tiny pores in the nuclear membrane allows RNA to leave the nucleus

More analogies

What part of the cell is most like the:

1. Stomach
2. Circulatory System
3. Brain
4. Bones
5. Skin


LABEL THE CELL

Movement of Substances Through the Cell Membrane

Passive Transport (no energy required)

DIFFUSION - molecules move spontaneously (no cellular energy used) from an area of higher concentration to an area of lower concentration
FACILITATED DIFFUSION - molecules diffuse through a membrane with the help of proteins
OSMOSIS - the diffusion of water through a selectively permeable membrane

SOLUTIONS

Hypertonic Solution |                 |  Hypotonic Solution |                  | Isotonic Solution

 

 

 

 

ACTIVE TRANSPORT - molecules are moved against the concentration gradient. This requires the use of cellular energy, also usually involves a carrier molecule.

Exocytosis = transport of particles out of the cell | Endocytosis = transport of particles into the cell

Pinocytosis - liquids taken in, cell engulfs a droplet of water
Phagocytosis -solids taken in. a vesicle forms.

Where does the energy come from to power this type of transport?

The Life Cycle of a Cell

A. Mitosis (nuclear division)
B. Cytoplasmic Division (cytokinesis)
C. Interphase (growth)
D. Differentiation - cells become specialized, developing characteristics in structure and function

MITOSIS

A. PROPHASE
1.
2.
3.
4.
5.

B. METAPHASE
1.

C. ANAPHASE
1.

D. TELOPHASE
1.
2.
3.
4.
5.

E. CYTOKINESIS


INTERPHASE - growth of cell occurs, chromosomes are duplicated and other structures and organelles are produced
DIFFERENTIATION - occurs as cells multiply and organism develops and grows

mitosis