CHAPTER 7Cells and Organelles

Background

Every living thing is made of cells Robert Hooke coined the term

“cells” Antonie van Leeuwenhoek

discovered the 1st living cell

Cell Theory The Cell Theory states that: All organisms are composed of one or more cells.

The cell is the basic unit of organization in all organisms.

All cells come from pre-existing cells

Levels of organization Smallest living unit is the cell

Cells

Tissues

Organs

OrganSystem

Types of cellsTwo types of cells

Prokaryotes – simple cells, bacteria

Eukaryotes – complex cells, animal and plant

Inside the cellInside the cell there are smaller parts called organelles Organelle means ‘little organ’

Plasma Membrane The plasma membrane, aka

the cell membrane, surrounds the cell It is present in all cells Function – controls what enters

and leaves the cell Selectively permeable – selects what moves through it

Plasma membraneStructure

Phospholipid bilayer

Cell WallSurrounds some cells

Plant cells, fungi cells, and bacteria cells

Tough and ridged Made of cellulose

Nucleus Controls everything in the cell

Reproduction, movement, eatingOnly present in eukaryotic cellsContains all genetic information

Nucleus Surrounding the nucleus is the nuclear envelope

Inside the nucleus is the nucleolus The nucleolus produces an organelle called the ribosomes

Ribosome Ribosomes are the site of

protein synthesis Found all over the cell

In cytoplasm On Rough ER

Endoplasmic Reticulum Two types: smooth and rough Smooth – stores lipids Rough – after the ribosomes

make proteins the rough ER packages them in vesicles to move around, or out of, the cell

Rough because it is covered in ribosomes

Golgi Apparatus Modifies and sorts proteins before they are sent out of the cell

Notice increased Surface areaStacked like pancakes

Production of Proteins Each organelle has a role to play in the

production of proteins

Vacuole Main function is storage In both plant and animal cells,

but they are much larger in plant cells

Mitochondria Produces energy for the cell Does this through a process

called cellular respiration Many folds to increase surface

area called Cristae

Chloroplast Produce sugar, or food, by using

light energy This process is called photosynthesis

Found in plant cells and protist cells

LysosomeThe lysosomes job is to digest things that are no longer needed by the cell Contain special enzymes to do this

Animal VS Plant Cell

Stem cells Eukaryotic organisms begin as a

mass of cells Each cell has the same DNA so how

do we end up with hundreds of cell types?

It has to do with the DNA!!

Stem Cells Cell differentiation- happens only

specific parts of the DNA are activated. the parts of the DNA that are activated determine the function and specialized structure of a cell.

Once a cell is differentiated it can not be reversed.

Stem Cells Stem cells have not differentiated yet They have the ability to become any

cell! Embryonic stem cells – found in the embryo Adult stems cells – found in adult living

organisms (example – bone marrow) Both types have potential to be come

specialized cells Important because it can turn into ANY

cell!!!! CONTROVERSIES???