Transcript
THEORYTYPES OF CELL
ULTRASTRUCTURE OF CELLDIFFUSSIONOSMOSIS
ACTIVE TRANSPORT SYSTEM
OBJECTIVES:By the end of the lesson, student
should be able to :
• Define terms cell.• Understand the structure and
functions of the animal and plant cells.
THEORY:
• Cells form the building blocks of living organism.• Cells arise only by the division of existing cells.• Cells contain inherited information which control
their activities.• Cells is the functioning unit of life metabolism
(the chemical reaction of life) take place in cells.• Given suitable conditions, cells are capable of
independent existence.
• Cells are the basic building blocks of all living creatures. However, they didn't always exist as cells.
• Each cell is formed from a varieties of molecules that can be classified into several major families such as Nucleic Acids and Amino Acids.
• Through cycles of selection from environmental pressures, these molecules come together to form the first primitive cell, for the sole purpose of ultimate survival.
TYPES OF CELLS
PLANT CELLANIMAL CELL
DIFFERENT BETWEEN ANIMAL AND PLANT CELL:
ANIMAL CELL PLANT CELL
SHAPE No fixed shape. Fixed shape.
CELL WALL Does not have. Has a cellulose cell wall.
CHLOROPLAST Does not have. Has chloroplast which contain chlorophyll.
VACUOLE Usually exists as numerous small vacoules in lower animal cell.
Usually has a large vacuole.
GRANULES Contain glycogen granules.
Contain starch granules.
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STRUCTURE COMPOSITION FUNCTION
Plasma membrane
Bilayer phospholipid with embedded proteins.
Selective passage of molecules into and out of cell.
Nucleus Nuclear envelope surrounding nucleoplasm, chromatin and nucleolus.
Storage of genetic information.
Nucleolus Concentrated area of chromatin, RNA and proteins
Ribosomal formation
STRUCTURE COMPOSITION FUNCTION
Ribosome
Protein and RNA in two submits.
Protein synthesis.
Endoplasmic reticulum
(ER)
Membranous saccules and canals.
Synthesis and/or modification of protein and other substances and transport by vesicles formation.
Rough ER Studded with ribosome.
Proteins synthesis.
Smooth ER No ribosome. Lipid synthesis.
STRUCTURE COMPOSITION FUNCTION
Vacuole and vesicle
Membranous sacs. Storage of substances.
Lysosome Membranous vehicle containing digestive enzymes.
Intracellular digestion.
Mitochondria Inner membrane (cristae) within outer membrane.
Cellular respiration.
Golgi apparatus Stack of membranous Processing, packaging & distributing molecules
STRUCTURE COMPOSITION FUNCTION
Cytoskeleton Microtubels, actin filaments
Shape of cells
Cilia and flagella
9+2 of microtubules Cell movement
Centrioles 9+0 pattern of microtubules
Formation of basal bodies
OBJECTIVES:By the end of the lesson, student
should be able to :
• Define main group of cells.• Understand the roles and
responsibilities of prokaryotes and eukaryotes cells.
MAIN GROUP OF CELLS
• There are two main groups of cells, prokaryotic and eukaryotic cells.
• They differ not only in their appearance but also in their structure, reproduction, and metabolism.
• However, all of the cells belong to one of the five life kingdoms. The greatest difference lies between cells of different kingdoms.
• The following group shows the five kingdoms: monera, protista, plantae, fungi, and animalia.
• The cells in the 5 kingdoms can all be classified as either prokaryotic or eukaryotic.
• Eukaryotes are generally more advanced than prokaryotes.
• There are many unicellular organisms which are eukaryotic, but all cells in multicellular organisms are eukaryotic.
CHARACTERISTICS:
• Nuclear membrane surrounding genetic material. • Numerous membrane-bound organelles. • Complex internal structure. • Appeared approximately one billion years ago. • Examples: • Paramecium • It is hypothesized that a primitive bacterium once
surrounded its food after releasing its digestive enzymes.
• The membrane folded inward and pinched off, creating the first digestive membrane-bound organelle.
• Prokaryotes are unicellular organisms, found in all environments.
• Prokaryotes are the largest group of organisms, mostly due to the bacteria which comprise the bulk of the prokaryote classification.
CHARACTERISTICS:
• No nuclear membrane (genetic material dispersed throughout cytoplasm).
• No membrane-bound organelles.• Simple internal structure.• Most primitive type of cell (appeared about four
billion years ago). • Examples: • Staphylococcus • Escherichia coli (E. coli) • Streptococcus
Part What it does?
Nucleus The “brains” of the cell, the nucleus directs cell activities and contains genes.
Mitochondria Make energy out of food
Ribosomes Make protein
Vacuole Used for storage of water or food.
Plant cells also have:
Chloroplast Use sunlight to create food by photosynthesis
Cell wall For support
• Bacteria have a very simple internal structure, and no membrane-bound organelles.
• Do not have a nucleus • Are the smallest of cell
types • Lack internal
membrane bound organelles
• e.g. bacteria
• Have a nucleus • Are 10 to 1000 times
larger than prokaryotic cells
• Have many kinds of organelles, many of which are membrane bound
• e.g. all other cells
OBJECTIVES:By the end of the lesson, student should be
able to :
• Identify the structure of cell membrane.• Understand the functions of cell
membrane.• Identify the important types of protein
consists in cell membrane.
• Mainly composed: a) Lipids b) Proteins• Consist of a double layer of phospholipids.• Have different types of molecules of cell
membrane: a) Phospholipids b) Fibrous protein• Example: Globular shaped protein:
» Glycoprotein» Pore protein» Channel protein
• Cell membrane mostly lipids, it only allows lipid-soluble substances such as O2,CO2 and steroids to go through.
• Water soluble substance such as glucose, amino acid, ions and water need the help of the various part of transport.
• 2 layers of phospholipids molecules self-assemble so that their water soluble (hydrophilic) head from the surface and interior of the membrane and the water soluble (hydrophobic) tails face each other.
• STRUCTURE:– The fluid mosaic model of the membrane shows
the membrane is composed of a number of proteins which are similar to shifting tiles.
– The spaces between the tiles are filled with fluid-like phospholipids.
– The phospholipids consists of hydrophilic heads, which point towards the outside environment and the cytoplasm.
– The hydrophobic tails repel the water and point in.
• STRUCTURE:– Thus, the phospholipids form a bilayer that
acts like a barrier between the cell and the environment.
– The phospholipids bilayer also contains cholesterol, which makes the bilayer stronger, more flexible and more permeable.
– There are a number of important proteins in the plasma membrane which will be discussed later.
• FUNCTIONS:• The purpose of the membrane is to control what
goes in and out of the cell. • The items that go in are highly regulated. It also
communicates with other cells for example with receptors on the surface or cell to cell adhesion.
• Proteins that are found in the bilayer are receptor proteins, which deal with communication, recognition proteins and transport proteins that regulate the movement of water and soluble molecules through the membrane.
• In order to regulate the transport of molecules, there are two types of proteins in the cell: carrier proteins and transport proteins.
• FUNCTIONS:• The two types of transport proteins are channel
and carrier protein. Transport is either active or passive.
• Active transport is moving molecules against the concentration gradient and energy is required in the form of ATP.
• Passive transport is moving molecules down the concentration gradient and no energy is required.
• Examples of passive transport are diffusion, which moves from high concentration to low concentration and osmosis, which is the diffusion of water molecules.
• FUNCTIONS:• The cell membrane is important for the
connections between cells. • There are four different types of these
connections: – Attach cells together like "glue".– A tight junction consists of fusing the cells together. – A gap junction consists of pairs of channels fused. – Finally, plasmodesma consists of binding plants
together.
• FUNCTION (SURFACE CELL):– Controlling the passage of materials in and
out of cells.– Recognition of other cells.– Receptor sites for hormones and
neurotransmitters.– Transmission of nerve impulses.– Insulation of nerves.
• FUNCTION (INSIDE CELL):– Acting as a reaction surface.– Acting as an intercellular compartments,
isolating different chemical reactions.
THE IMPORTANT PROTEINS:
• The fibrous protein may span the entire membrane and serve as receptors for the cell.
• The pore protein to allow lipid insoluble water molecules to pass through.
• Other integral protein sure as channel proteins and selectively transport ions for the cell.
OBJECTIVES:By the end of the lesson, student
should be able to :
• Define the diffusion process.• Understand the FICK’S LAW concept.• Understand the relation of diffusion
and facilitated diffusion.
• DEFINITION:– Diffusion is the movement of molecules, other
than water, from an area of high concentration to an area of low concentration.
– No ATP energy is used. – Molecules move like this naturally, so no
chemical or cellular energy is needed.
• THE RATE OF DIFFUSION:– 1) Is directly proportional to the area of the
surface.– 2) Is directly proportional to the concentration
gradient.– 3) Is inversely proportional to the distance.
(the length of the diffusion pathway)
• Rate of diffusion is proportional to: Surface area X difference conc.
Length of diffusion path
* INCREASING the factors on the top line of the equation will make diffusion faster, while increasing that on the bottom will slow it down.
• Applies to situations where there is no barrier to the movement of substances.
• Eg: The diffusion of a dye in a container of water, the diffusion of a substance into or out of a cell is a of passive transport.
• Diffusion through a cell membrane is affected by the nature membrane (its permeability) and the size and type of molecule or ion diffusing through it.
• ADAPTATION FOR DIFFUSION:
– Refer to FICK’S LAW cellular diffusion is a very slow process unless there is large concentration gradient over a short distance.
– Tissues such as those in the lungs and small intestine are especially adapted to maximize the rate of diffusion by:
• Maintaining a steep concentration gradient• Having a high surface area to volume ratio• Being thin, minimizing the distance over which the
diffusion takes place.
• MEMBRANE PERMEABILITY:
– Cell membrane are partially permeable: many substances can pass through them, but some substances cannot.
FACILITATED DIFFUSION
• Sometimes, proteins are used to help move molecules more quickly. It is a process called facilitated diffusion.
• It could be as simple as bringing in a glucose molecule. Since the cell membrane will not allow glucose to cross by diffusion, helpers are needed.
• The cell might notice outside fluids rushing by with free glucose molecules.
• The membrane proteins then grab one molecule and shift their position to bring the molecule into the cell.
• That's an easy situation of passive transport because the glucose is moving from higher to lower concentration.
• It's moving down a concentration gradient. If you needed to remove glucose, the cell would require energy.
OBJECTIVES:
By the end of the lesson, student should be able to :
• Define the osmosis process.• Identify several terms use in osmosis.• Understand the concept of isotonic,
hypotonic and hypertonic concept.• Differentiate the osmosis in animal
and plant cells.
PASSIVE TRANSPORT:
• While active transport requires energy and work, passive transport does not.
• There are several different types of this easy movement of molecules.
• It could be as simple as molecules moving freely such as osmosis or diffusion.
• May also see proteins in the cell membrane that act as channels to help the movement along.
• There is an in-between transport process where very small molecules are able to cross a semi-permeable membrane.
• DEFINITION:– Osmosis is the movement of water from a
region of high water concentration to a region of lower water concentration through a semi permeable membrane.
SELECTIVE PERMEABLE MEMBRANE
WATER MOLECULES
TERMS IN OSMOSIS:
• SELECTIVELY PERMEABLE MEMBRANE Allowing some materials to pass through more easily than others.
• SOLVENT Liquid substance, such as water, in which other materials may be dissolved.
• SOLUTE The dissolved substance in a solution.
• SOLUTION Solute plus solvent.
EXAMPLE:
• A Red Blood Cell (RBC) which has an internal solute concentration of approximately 0.9% salt (equivalent) and place it in various solutions of varying salt and concentrations.
• The concentration of particles in solution is lower than in the cell therefore, the concentration of water is lower in the cell.
• Water will diffuse into the cell and the cell will swell up
• -> animal cells may explode.
• -> plant cells held intact by cell wall.
• The concentration of particles in solution is higher than in the cell therefore the concentration of water is higher in the cell.
• Water will diffuse out of the cell and the cell will shrivel up
• -> animal cells lose cytoplasm and shrivel up
• -> plant cells maintain shape due to cell wall but lose cytoplasm (wilting of unwatered plants)
• The concentration of particles inside and outside the cell is the same therefore so is the concentration of water.
• No change in the cell.
SOLUTION ANIMAL CELL PLANT CELL
ISOTONIC •No changes in the volume of the cell.•Water potential inside and outside the cell is the same and there is the same.
HYPOTONIC •Fresh water.•Tends to enter the cell causing the cell volume to increase.
TURGID CELL:•Water enters the plant cell, filling the vacuole to capacity.•The cell surface membrane pushes against the cell wall, making the cell very rigid.
HYPERTONIC •External solution is of a sufficiently high solute concentration.•Water will tend to be drawn out of the cell causing it to shrink and shrivel.
PLASMOLYSED CELL:
Water moves out of a plant cell, the cell vacuole shrinks and the cell surface membrane pulls away from the cell wall.
OBJECTIVES:By the end of the lesson, student
should be able to :
• Define active transport system.• Understand the concept of sodium
and potassium moves in and out of the cell.
• Active Transport is the process whereby molecules or ions are moved from an area of lower concentration to an area of higher concentration through a semi-permeable membrane.
• The cell's own energy is required for this process.
• Protein molecules in cell membrane called channel proteins are involved in this process.
• Through active transport the cell may: – gather nutrients it needs. – dispose of waste. – create electric potential across membrane
(nerves and muscles).
• There are three ways molecules can be transported through channel proteins.
OBJECTIVES:By the end of the lesson, student
should be able to :
• Define cell division.• Understand the differentiate of
mitosis and meiosis process.
• Cell division is a process by which a cell, called the parent cell, divides into two cells, called daughter cells.
• Cell division is usually a small segment of a larger cell cycle. I
• n meiosis however, a cell is permanently transformed and cannot divide again.
• This process of cellular division is unique to eukaryotic cells.
• The following illustrations depict only the replication of chromosomes and their division.
• The process of mitosis involves the entire cell which includes a multitude of organelles.
• All gametes have half the number of chromosomes that regular cells have.
• Gametes are created through the process of meiosis.
• Meiosis involves two divisions which create four haploid cells.
STAGE DESCRIPTION
Interphase I Chromosome are copied to into 2 identical chromatids joined at the centromere.
Prophase I Spindle apparatus forms around chromosomes.
Metaphase I The identical chromosomes (homologous chromosomes) line up together in the center of the cell. They form tetrads which are paired chromosome structures. Some get crossed over.
Anaphase I The chromosomes pairs are pulled apart from each other to either side of the cell.
Telophase I The outer membrane pinches the cell in half and a nuclear membrane forms around chromosomes.
Late Interphase, which produce 2 daughter cells.
STAGE DESCRIPTION
Prophase II Spindle apparatus forms around chromosomes.
Metaphase II The homologous chromosomes line up together in the center of the cell.
Anaphase II The chromosomes pairs are pulled apart from each other to either side of the cell.
Telophase II The outer membrane pinches the cell in half and a nuclear membrane forms around chromosomes
2 daughter cell produced with same number of chromosomes as parent cell.
4 daughter cells produced with half the number of chromosomes as parent cell.
Daughter cells are genetically identical to or clones of parent cell and each other.
Daughter cells show genetic variation to parent cell and to each other.
Occurs in the formation of: - body- non sex cells - some spores- basis of asexual reproduction
Occurs in the formation of:-Gametes- Spores- Some stage in the life of sexually reproducing organism.
1 main stage. 2 stage : 1) Meiosis I
2) Meiosis II
Homologous chromosomes do not pair up in prophase.
Homologous chromosomes pair up or form bivalents in prophase I.
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