cell structure
DESCRIPTION
Cell Structure. Enormous variety in the size and shape of different cells Smallest cells belong to group of organisms Mycoplasma Only about 0.2 µm in diameter So small that often beyond the limit of resolution of light microscopes. Cell Structure. Large cells (giant amoeba) Chaos chaos - PowerPoint PPT PresentationTRANSCRIPT
CELL STRUCTURE
CELL STRUCTURE Enormous variety in the size and shape
of different cells Smallest cells belong to group of
organismsMycoplasma Only about 0.2 µm in diameter So small that often beyond the limit of
resolution of light microscopes
CELL STRUCTURE Large cells (giant amoeba)Chaos chaos
About 1000 µm in diameter
Larger cellsyolks of bird eggs Single cells containing stored food for the
developing bird for the most part, cells are between 5 &
50 µm in diameter
CELL STRUCTURE certain structures are common to most
cells plants, animals, and related organisms
have 3 basic structures: cell membrane-outer boundary nucleus-control center cytoplasm-material between the cell membrane
and nucleus
CELL MEMBRANE all cells are separated from their
surroundings by a cell membrane regulates what enters and leaves the cell aids in the protection and support of the
cell similar to cell walls that surround a house
CELL MEMBRANE it must communicate with other cells, take
in food, and water and eliminate wastes composed of several kinds of molecules
lipids, proteins, cho’s
LIPIDS• double layer of lipid molecules, known as a
‘bilayer’ forms the basic unit from which cell membranes are constructed
PROTEIN some proteins stick to the surface of
the lipid bilayer, others are free to move around within the bilayer
some act as channels through which molecules can pass
others act like small pumps, actively pushing molecules from one side of the membrane to the other
CARBOHYDRATES cho’s are attached to proteins or lipids
at the membrane surface many act like chemical id cards,
allowing cells to recognize and interact with each other
CELL WALL in organism such as plants, algae, and
some bacteria, the cell membrane is surrounded by a cell wall
helps to protect and support the cell very porouswater, oxygen, carbon
dioxide, and other substances can pass through easily
made up of two or more layers layers form in a series of steps
PRIMARY CELL WALL 1st layer to form develops where two
plant cells meet Contains a gluey substance called
pectin, that helps hold the cells together
Each of these cells then forms a primary cell wall on its side of this gluey layer
Made up of cellulose (a fibrous material)
Make the cell wall elasticstretch as it grows
SECONDARY CELL WALL Plants that have woody stems,
another layer secondary cell wall, develops
Composed of cellulose and lignin Lignin makes cellulose more rigid Wood consists mainly of secondary
cell walls
NUCLEUS Nucleus-info center of the cell
Seen in many cells as a large dark structure
1st described by Robert Brown Not all cells have nuclei Small unicellular organismbacteria and
several other kinds of organisms, do not have nuclei
PROKARYOTES / EUKARYOTES The absence or presence of a nucleus can
be used to divide organisms into two categories:
Prokaryotes-lack nuclei Eukaryotes-contain nuclei
Karyon=nucleus Pro=before Eu=true
PROKARYOTES Prokaryotic organism
Bacteria and their relatives Usually small and unicellular
EUKARYOTES Eukaryotic organisms
Both unicellular and multicellular
NUCLEUS Nucleus is the information center of the
cell Contains DNA=instructions for making
thousands of different molecules Directs all the activities that occur in a
living cell
NUCLEUS Nuclear envelope
Composed of two membranes that form boundary around nucleus
Insidedozens of nuclear pores Molecules move in and out of nucleus through
nuclear pores
NUCLEUS Nucleolus
Most nuclei contain a small region called nucleolus
Made up of RNA and proteins Where ribosomes are made
NUCLEUS Chromosomes
The DNA in the nucleus of eukaryotic cells is attached to special proteins and forms large structures called chromosomes
Contain genetic information that must be passed to each new generation of cells
CYTOPLASM Cytoplasm
Area between the nucleus and the cell membrane
Contains important structures
TOMORROW We will discuss the organelles found
within the cytoplasm!!!!!!!!!!!!