Post on 22-Feb-2016
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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???