Ch.1 Cell Structures and Functions

The Cell

Cell Parts

• Cell Membrane, Cell Wall, Cell Membrane, Cell Wall, CytoplasmCytoplasm

• Protein ProductionProtein Production- - Nucleus, Nucleus, Nucleolus, Endoplasmic Nucleolus, Endoplasmic Reticulum, Ribosomes, Golgi Reticulum, Ribosomes, Golgi Bodies, LysosomesBodies, Lysosomes

• Energy-Energy- Mitochondrion, Mitochondrion, Chloroplasts Chloroplasts (Energy- Mitochondrion, Energy- Mitochondrion, Chloroplasts)Chloroplasts)

• Miscellaneous- Microtubules, Microfilaments, Plastids

Cell MembraneIt also connects the the endoplasmic reticulum, and the nuclear membrane. In the image below we have colored the membrane to highlight its composition. The yellow represents the phospholipids. The purple represents the membrane proteins

Cell Membrane• The Cell membrane performs a number of critical functions for the cell. It regulates all that enters and leaves the cell; in multicellular organisms it allows self recognition. In order to understand the function of the cell membrane you must understand its structure.

phospholipids

Cell MembraneClose-up

• Here we see a cross section of Here we see a cross section of the cell membrane you should the cell membrane you should notice two different structures: notice two different structures: The The phospholipidsphospholipids are the are the round round yellowyellow structures with the structures with the blue blue tailstails, the , the proteinsproteins are the are the lumpy lumpy structuresstructures that are scattered that are scattered around among the phospholipids.around among the phospholipids.

This is a simple representation of a phospholipid. the yellow structure represents the HYDROPHILLICHYDROPHILLIC or water loving section of the phospholipid. The blue tails that come off of the sphere represent the HYDROPHOBICHYDROPHOBIC or water fearing end of the Phospholipid. Below is a structural model of a phospholipid that explains what these terms mean.

Cell Wall•Cell walls are the rigid structure found surrounding plant cells. They provide support for the plant

Cytoplasm•The term cytoplasm refers to everything between the cell membrane and the nuclear envelope. It consists of primarily of water. It also contains various organelles as well as salts, dissolved gasses and nutrients.

CytoplasmCytoplasm• Protein Producing Organelles: Protein Producing Organelles:

Endoplasmic Reticulum, Endoplasmic Reticulum, Ribosomes, Golgi Apparatus, Ribosomes, Golgi Apparatus, LysosomesLysosomes

• Energy Producing Organelles -Energy Producing Organelles -Mitochondrion, ChloroplastsMitochondrion, Chloroplasts

• Specialty Structures -centrioles, vacuoles, cell walls, cilia, flagella, plastids

NUCLEUS- NUCLEUS- nuclear envelopenuclear envelope

The nuclear envelope is a double The nuclear envelope is a double membrane. Is has 4 phospholipid membrane. Is has 4 phospholipid layers. It is also has large layers. It is also has large pores through which materials pores through which materials pass back and forth.pass back and forth.

Nucleus

The headquarters of the cell. It The headquarters of the cell. It is a large dark spot in is a large dark spot in EUKARYOTIC EUKARYOTIC cells. It controls all cells. It controls all cell activity. Close up you will cell activity. Close up you will see that the nuclear membrane has see that the nuclear membrane has many pores. many pores. The nuclear membrane The nuclear membrane is continuous with the E.R.is continuous with the E.R.

The thick ropy The thick ropy strands are the strands are the CHROMATINCHROMATIN. The . The large solid spot large solid spot is the is the NUCLEOLUSNUCLEOLUS. . The nucleolus is a The nucleolus is a knot of chromatin. knot of chromatin. It manufactures It manufactures ribosomes.ribosomes.

With the outer membrane removed it With the outer membrane removed it is much easier to see the contents is much easier to see the contents of the nucleus.of the nucleus.

Chromatin

Within the nucleus are found chromatin Within the nucleus are found chromatin and a structure called the nucleolus. and a structure called the nucleolus. Chromatin is DNA in its active form. Chromatin is DNA in its active form. It consists of DNA looped around It consists of DNA looped around histone proteins. The nucleolus is a histone proteins. The nucleolus is a knot of chromatin. It is the knot of chromatin. It is the nucleolus that manufactures ribosomesnucleolus that manufactures ribosomes .

Endoplasmic Reticulum

•Smooth, no ribosomes

•rough, has ribosomes

Smooth E.R.• The endoplasmic reticulum is a series of double membranes that loop back and forth between the cell membrane and the nucleus.

• These membranes fill the cytoplasm but you cannot see them because they are very transparent. There are two distinct types of E.R.: The rough E.R.rough E.R. has ribosomesribosomes and is the site of protein synthesis; the smooth E.R.smooth E.R. has no ribosomesno ribosomes

•

R.E.R.

The endoplasmic reticulum is a series of double membranes that loop back and forth between the cell membrane and the nucleus. These membranes fill the cytoplasm but you cannot seecannot see them because they are very transparent.

R.E.R.

Ribosome•The ribosomes are the organ-elles which manufacture proteins. They are made of two separate parts. These structures are both made of ribosomal RNA.

GOLGI BODY

Golgi ApparatusThe golgi body is responsible for packaging proteins for the cell. Once the proteins are produced by the rough E.R. they pass into the sack- like cisternae that are the main part of the golgi body.

These proteins are then squeezed off into the little blebs which drift off into the cytoplasm.

LysosomeLysosomes are called suicide sacks. They are produced by the golgi body. They consist of a single membrane surrounding powerful digestive enzymes. From this screen you can cut the lysosome and move it around.

Lysosomes• With the outer

membrane removed it is much easier to see the contents of the lysosome. Those lumpy brown structures are digestive enzymes.

"suicide sacks” • They dissolve bacteria and other foreign bodies. Under some conditions the lysosomes in a cell will break open and a cell will self destruct in a process called autolysis (giving rise to the name "suicide sacks").

Vacuole Vacuoles are large empty appearing areas found

in the cytoplasm. They are usually found in plant cells where they store waste. As a plant cell ages they get larger. In mature cells they occupy most of the cytoplasm.

CENTRIOLE ENLARGED

MicrofilamentThese are hair like extensions off of the cell membrane. Cilia tend to be small and numerous and flagella tend to be large &few. They beat back and forth rhythmically. In unicellular organisms their job is locomotion. In large multicell organisms their role is to move fluid past the cell. Notice the 9+2 arrangement of the microtubles.

Microtubule

• Centrioles are found only in animal cells. They function in cell division. Zoom in and notice the 9 groups of 3 arrangement of the

protein fibers.

The MITOCHONDRION is the powerhouse of the cell. It is the site of respiration. It has a double membrane. From this view you can see very little >>>>>>>>>>

The outer membrane is cut to get a better look. With the outer membrane removed it is much easier to see the contents of the mitochondrion. The white folded structure is the inner membrane. Most of AEROBIC RESPIRATION occurs along this membrane. Get a really good look by cutting the inner membrane. >>>next slide>>>>>

The inner membranes is ruffled. It has

a very large surface area. These ruffles are

called cristae. Mitochondria have their

own DNA and manufacture some their

own proteins. It is thought that the

mitochondrion evolved from symbiotic

bacteria that took up residence inside

the first eukaryotic cells.

INSIDE THE INNER MITOCHONDRION

Plastids• Plastids are large organelles found on plants and some protists but not in animals or fungi. They can easily be seem through a light microscope. The other class of plastid are called leucoplasts (colorless plastids); they usually store food molecules. Included in this group are amyloplasts or starch plastids shown here in potato root cell.

PLASTIDS- ChloroplastChloroplast

• Chloroplasts Chloroplasts represent one represent one group of group of plastids called plastids called chromoplasts chromoplasts (colored (colored plastids).plastids).

•

With the outer membrane removed it is much easier to see the contents of the chloroplast. The stacks of disk-like structures are called the GRANA. The membranes connecting them are the THYLAKOID MEMBRANES.

The chloroplast is the site of photosynthesis. It consists of a double membrane. Cut the outer membrane to get a better look inside.

Grana and Thylakoid Grana and Thylakoid MembranesMembranes

• The membranes The membranes that you see here that you see here are the site of are the site of photosynthesis. photosynthesis. It is here that It is here that the energy the energy harnessing harnessing process of process of photosynthesis photosynthesis occurs. occurs.

Dissolve the Dissolve the RemainingRemaining membrane and zoom membrane and zoom in in to get a better to get a better look.look.