CELLS AND ORGANELLES 2

Cells and Organelles

Cells, Organelles and Homeostasis


ALL LIVING THINGS ARE MADE OF CELLS.

The cell theory
  • Cell is basic unit of living things.
  • All organisms are made of cells.
  • All cells come from other cells.
IMAGE OF PLANT CELL


IMAGE OF ANIMAL CELL



There are two BASIC CELL TYPES: eukaryote and prokaryote.


INTERACTIVE ANIMATION
PROKARYOTE VS EUKARYOTE

Eukaryote cells have nucleus-
Prokaryote cells DO NOT have a nucleus.
ONLY bacteria are prokaryote.

Functions of some cells in eukaryote organisms(The roles that some of your cells play in the body)
  • red blood cells carry oxygen to cells and carry carbon dioxide to the lungs.
  • White blood cells fight germs like viruses and bacteria.
  • Muscle cells specialize in contraction and are used for movement.
  • Nerve cells carry nerve signals or nerve impulses that are used for communication.

Organelles are membrane bound structures found inside eukaryotic cells. (Little organs inside the cell)

HERE ARE SOME OF THE ORGANELLES FOUND INSIDE THE CELL.
THE NUCLEUS
Nucleus: Holds the DNA and directs or controls all activities. (found in both in plant and animal cells) 
Nucleolus: makes ribosomes (located inside the nucleus)



THE RIBOSOMES

Ribosomes: make proteins or is involved in protein synthesis.(found in all cells) looks like dots


THE MITOCHONDRIA



Mitochondria: converts glucose and oxygeninto a form of energy usable by the cell called ATP. (found in both plant and animal cells).  This is the structure where cell respiration occurs.

Cell respiration: is the process that occurs inside the mitochondria where glucose is converted into a form of energy usable by the cell called "ATP".

The formula for cell respiration is: 
 O2 + glucose Change to: ATP + CO2 + H2O 

THE CHLOROPLAST

Chloroplast: a structure found in plant cells that converts sunlight, carbon dioxide and water into glucose and oxygen. This process is called photosynthesis.
(found only in photosynthetic organisms, mostly plants)




 Light + CO2 + H2O Change to O2+ glucose



Cell Membrane: controls what goes in and out of the cell. (found in all cells).  It is able to to do that because it is selectively permeable.  That is, it has small holes. Therefore, small molecules such as water, oxygen and carbon dioxide are able to go through,while larger molecules must go through a protein channel.

CHECK THIS INTERACTIVE 

Cell Wall: structure that makes up the outside border of plant cells, which helps the cell maintain its shape. (found in plant cells)
THE VACUOLE

Vacuole: structure found in plant cells that stores materials. (found in plant cells and some animal cells)


Lysosomes: have digestive enzymes that breakdown things like bacteria, viruses and old organelles.

Golgi Apparatus: Is considered the post office of the cell. It receives, stores, modifies, packages and ships newly synthesized or newly made proteins to different destinations in the cell. VIDEO OF THE GOLGI



THE ROUGH ENDOPLASMIC RETICULUM


Rough Endoplasmic Reticulum(RER): Organelle that forms a network of tubules. The RER is an extension of the nuclear envelop. It appears grainy because it is studded with ribosomes. This structure is involved in protein synthesis and export.

Smooth Endoplasmic Reticulum(SER): This structure is involved in lipid and steroid synthesis, metabolizes carbohydrates and steroids, regulates calcium concentration and is also involved in detoxification. 

Receptors: are special proteins found on cell surface and they are used for communications. They interact with hormones from the endocrine glands and neurotransmitters from nerve cells.

Transport Through the cell

The word transport refers to how things are taken from one place and carry to another.

Diffusion: 
is defined as the movement of molecules from an area of high concentration to an area of low concentration and it requires no energy.  In nature, molecules are always vibrating.  When vibrating molecules collide they move in opposite directions and spread apart.  Small molecules like water, oxygen and carbon dioxide can diffuse freely through the cell membrane. 

Osmosis:
is the diffusion of water through the cell membrane.

Active Transport:
Active transport occurs when molecules move from an area of low concentration to an area of high concentration through the cell membrane with the use of energy (ATP).  This type of transport requires the assistance of a transport protein.


Both diffusion and active transport can be observed with the aid of an indicator.

Indicator:
An indicator is a chemical that changes color when it comes in contact with certain substances. 

Starch Indicator:
When starch comes in contact with iodine, it turns black.  Therefore,iodine is a starch indicator.


Glucose indicator:
When Benedict's solution comes in contact with glucose and the solution is heated up, it turns creamish green or orange.  Therefore, Benedict's solution is a glucose indicator.










Enzymes: 
are special proteins that make it easier for chemical reactions to occur inside an organism. How well an enzyme works depends on environmental factors such as pH and temperature.  Improper pH and improper temperature can denature the enzyme by changing its shape.


WHAT PROCESSES CONTROL THE FLOW OF MATERIALS IN AND OUT OF THE CELL?
  • Diffusion is a process that allows materials to move in and out of the cell based on their concentration. Diffusion occurs when molecules move from an area of high concentration to an area of low concentration without using any energy. The molecules bounce against each other and spread. The molecules must be small enough to go through the holes in the cell membrane.
  • Active transport is a process that allows molecules to move in and out of the cell from an area of low concentration to an area of high concentration.  It requires energy and the assistance of a transport protein.


To learn more, click this link. CELL ANIMATION VIDEO

Another cell animation CELL ANIMATION

  • Compare plant cells to animal cells
  • What is it that plant cells make, animal cells cannot make and they both use?



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