I. A Tour of the Cell
A. All living organism have cell.
B. Microscopes provide windows to the world of the cell.
1. A light microscope is the first microscope and it works by passing visible light through a specimen.
2. Then Electron microscope came that uses beam of light. It’s much powerful then the light microscope about small as 1nm can be seen. Then scanning electron microscope came out to study the detailed architecture of cell surface. It also uses electron beam to scan the surface of a cell or group of cells that have been coated with metal.
3. Transmission electron microscope is used to study the details of internal cell structure. With the cut specimens the electromagnets bend the electron beams to magnify and focus an image onto a viewing screen or photo.
C. Cell sizes vary with their function. They have different function depending their size because for example muscles are long they are to pull different body parts together. Also red blood cells are only 8um in diameter so it can fit through tiniest blood vessels.
1. 1cm =1/100m 1mm = 1/1000m 1um = 1/1000000m 1nm = 1000000000m
D. Natural laws limit cell size.
1. At minimum, a cell must be able to house DNA< protein molecules, and internal structures to survive.
2. The maximum size of a cell is limited by its requirement for enough surface area to obtain adequate nutrients from the environment and dispose of waste. Lager the cell more surface area it have, but have less surface area relative to their volume then small cells.
E. Prokaryotic cells are small and structurally simple.
1. Bacteria and archaea are prokaryotic cells. When other life are composed of eukaryotic cells that have membrane-enclosed nucleus.
2. Then DNA is coiled into an uncleoid region, but membrane doesn’t surround the DNA. Ribosome assembles amino acids into polypeptides that make up protein.
3. Plasma membrane surrounds the contents of the prokaryotic cells. Outside of it is prokaryotic cell wall. Also another layer that some prokaryotes have is a sticky outer coat called capsule. Also some has short projections called pili that help attach to surface. Longer projections are called prokaryotic flagella a propel that is used to move through its liquid environment.
F. Eukaryotic cells are partitioned into functional compartments. All eukaryotic cells all organisms are similar to one another and profoundly different from prokaryotic cells.
1. Cytoplasm a fluid-fulfilled region between the nucleus and plasma membrane.
The spaces are important as the slither where specific chemical conditions are maintained it’s varying from one organelle to another it’s called cellular metabolism.
2. The structures that are in the cells are called organelles they have specific function in the cell.
3. Plant cell have central vacuole, chloroplast, and cell wall, but animal’s cell doesn’t. Animal cell have flagellum, lysosome, and centriole, but not plant cell.
G. The nucleus is the cell’s genetic control center. Cell’s hereditary blueprint is Dan like a prokaryote’s DNA. DNA is attached to the proteins, forming long fibers called chromatin. Its fiber is a chromosome. Enclosing the uncles is a nuclear envelope. Adjoining the chromatin within the nucleus is mass of fibers and granules called nucleolus.
H. Many cell organelles are related through the end membrane system. End membrane system is a network of membranous organelles that partition the cytoplasm eukaryotic cell. Some organelles are connected to each other when others are separate, but functionally connected.
I. Rough endoplasmic reticulum makes membrane and protein. Rough ER is a network of interconnected flattened sacs with two main functions.
1. To make more membrane. ER membrane will get the proteins made by ER ribosomes and it wills later ends up in other organelles.
2. Rough ER is to make proteins that are secreted by the cell.
a. For example secretary protein is an antibody.
3. Synthesis and packaging of a secretary protein made of a single polypeptide. As the polypeptide is synthesized, it passes into ER. Then short chains of sugars are then linked to the polypeptide, making the molecule a glycoprotein. When molecules are ready to be export ER packages it and then it’s called transport vesicle. IT buds off from the ER then travel to Golgi apparatus more process.
J. Smooth endoplasmic reticulum has a variety of functions. Smooth ER is a network of interconnected tubules that lack ribosome. It has many functions is the synthesis of lipids, phospholipids, and steroids. Can destruction of toxic substances, and storage of calcium ions (regulate muscle).
K. The Golgi apparatus finishes, sorts, and ships cell products. It serve as a molecular warehouse and finishing factory, it receives and modifies substances manufactured by the ER. It takes materials and then modifies them chemically/ the finish products may become part of the plasma membrane or part of another organelle.
L. Lysosomes digest the cell’s food and wastes. It is produced by rough ER and the Golgi apparatus. Its digestive enzyme helps to digest larger molecules to ATP. It can also destroy bacteria and recycle damaged organelles. Also function in embryonic development.
1. Abnormal lysosomes can cause fatal disease. If the person is missing one of the hydrolytic enzymes of the lysosomes they are afflicted with lysosmal storage diseases. It can be engorged with indigestible substance that affects cellular functions.
M. Vacuoles function in the general maintenance of the cell. Vacuoles are membranous sacs larger then vesicles. Belong to end membrane system.
1. Central vacuole in the plant cell can be large lysosomes. They also can help plant cell to grow in size by absorbing water. Also store vital chemicals or waste of cell metabolism.
a. In flower petals central vacuoles may contain pigments that attract pollinating insects. Other contains poisons that protect from animals.
N. Chloroplast converts solar energy to chemical energy. Chloroplasts are the photosynthesizing organelles of plant and protests. It uses light energy from sun to make chemical energy of sugar molecules.
1. Think fluid called stroma and a network of tubules and interconnected hollow disked formed membrane. The each stack is called granum.
a. Granum is the chloroplast’s solar power packs. Where it makes energy.
O. Mitochondria harvest chemical energy from food. Mitochondria are organelles that convert energy from one chemical form to another. It carries to cellular respiration.
1. The intermembrane space forms one fluid-filled compartment. Inner membrane enclosed the 2nd compartment, contains mitochondrial matrix. Many chemical reactions of cellular respiration occur in matrix. The folds of the inner membrane is called cristae, it increase the membrane’s surface area.
It improves ATP production.
P. The cell’s internal skeleton helps organize its structure and activities.
1. Cytoskeleton is involved in cell movement. It help regulate cellular activates. There are 3 kinds that make up the cytoskeleton.
a. Microfilaments are solid helical rod composed mainly of a globular protein called actin. It helps cells change shape and more by adding subunits at one end while losing subunits at the other.
b. Intermediate filaments are a varied group. Made of fibrous proteins then globular ones that have a rope like structure. It serves as reinforcing rods for bearing tension and helps anchor certain organelles.
c. Microtubules are straight, hollow tubes composed of globular proteins called tub lines. They act as track for organelle movement.
Q. Cilia and flagella move when microtubules bend. Eukaryotic flagella and cilia have a common structure and mechanism of movement. Flagella are longer, but cilia are shorter. They use theses to move. They are composed of a core of microtubules wrapped by plasma membrane. It proves support and contributes to the locomotors mechanism underlying the whipping action of these organelles. They use dynein arms to bend to move.
R. Cell surfaces protect, support, and join cells. Cell’s have additional surface like cell war and capsules.
1. Cell wall protects the cell and skeletal support that keeps plants upright on land. Its 10-100 thicker then plasma membrane. They are multilayered. Cell have cell junctions that connects them to one another even the walls are thick. Plasmoesmata are channels between adjacent plants cells so the water is other molecules can pass through.
2. Animal cell lack rigid cell wall, but they are mostly embedded in a sticky layer of glycoprotein, the extracellular matrix. It helps to hold tissue together and protective, and support functions. Helps to regulate cell behavior.
a. Tight junctions bind cells together, forming a leak proof sheet like for digestive tract.
b. Anchoring junctions attach adjuncts cells to each other or to the extracellular matrix. Rivet cells together with cytoskeletial fibers, but allow materials to pass through spaces.
c. Communication junctions are channels similar in function to the plasmodesmata of plants that allow water and small molecules to flow between neighboring cells.
S. Eukaryotic organelles comprise four fictional categories.
1. Manufacturing. For example Ribosome manufactures protein.
2. It breakdown molecules. For example Lysosmes break down larger molecules to smaller molecules.
3. Energy processing. For example chloroplast converts light energy to make sugar for energy.
4. Support, movment, and communication between cells. For example cell walls maintained clef’s shape and shop port skeletical structures
T. Extraterrestrial life-forms may share features with life on earth. In earth all living things have cells and DNA. Also carry out metabolism. If they have another life on earth they might have similar features like life in earth.
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