CONNECTIVE TISSUE

HYALIN CARTILAGE:

STRUCTURE:

1.Firm and flexible                                                             

2.Chondrocytes(alive)

3.Cell of cartilage within lacunae

DISTRIBUTION:

1.Tachea 

2.Bronchi

FUNCTIONS

1.Covers the ends of bonds and reduces friction between joints during movement 

2.It  forms tge embryonic skeleton in many bony vertebrates

COMPACT BONE

STRUCTURE:

1.Living tissue 

2.Consist 

 (a)Osteocytes:Mature Osteoblasts

  

 ( b)Osteoblast:Form new bone and release calcium phosphate

  (c)Canaliculi:Contain cytoplasmic strands which connect the lacuna to each other

FUNCTIONS

1.Storage for calcium phosphorus

2.protect organ

3.Red blood cell production site

   

SODIUM-POTASSIUM PUMP CYCLE

 

The sodium-potassium pump transports sodium out of and potassium into the cell in a repeating cycle of conformational (shape) changes. In each cycle, three sodium ions exit the cell, while two potassium ions enter. This process takes place in the following steps:

1. To begin, the pump is open to the inside of the cell. In this form, the pump really likes to bind (has a high affinity for) sodium ions, and will take up three of them.
2. When the sodium ions bind, they trigger the pump to hydrolyze (break down) ATP. One phosphate group from ATP is attached to the pump, which is then said to be phosphorylated. ADP is released as a by-product.
3. Phosphorylation makes the pump change shape, re-orienting itself so it opens towards the extracellular space. In this conformation, the pump no longer likes to bind to sodium ions (has a low affinity for them), so the three sodium ions are released outside the cell.
4. In its outward-facing form, the pump switches allegiances and now really likes to bind to (has a high affinity for) potassium ions. It will bind two of them, and this triggers removal of the phosphate group attached to the pump in step 2.
5. With the phosphate group gone, the pump will change back to its original form, opening towards the interior of the cell.
6. In its inward-facing shape, the pump loses its interest in (has a low affinity for) potassium ions, so the two potassium ions will be released into the cytoplasm. The pump is now back to where it was in step 1, and the cycle can begin again.

This may seem like a complicated cycle, but it just involves the protein going back and forth between two forms: an inward-facing form with high affinity for sodium (and low affinity for potassium) and an outward-facing form with high affinity for potassium (and low affinity for sodium). The protein can be toggled back and forth between these forms by the addition or removal of a phosphate group, which is in turn controlled by the binding of the ions to be transported.

ACTIVE TRANSPORT
 Active transport is the movement of molecules across a cell membrane from a region of their lower concentration to a region of their higher concentration in the direction against some gradient or other obstructing factor (often a concentration gradient). Unlike passive transport, which uses the kinetic energy and natural entropy of molecules moving down a gradient, active transport uses cellular energy to move them against a gradient, polar repulsion, or other resistance. Active transport is usually associated with accumulating high concentrations of molecules that the cell needs, such as ions, glucose and amino acids. If the process uses chemical energy, such as from adenosine triphosphate (ATP), it is termed primary active transport. Secondary active transport involves the use of an electrochemical gradient. Examples of active transport include the uptake of glucose in the intestines in humans and the uptake of mineral ions into root hair cells of plants

Electrochemical gradients

 

We have already discussed simple concentration gradients, in which a substance is found in different concentrations over a region of space or on opposite sides of a membrane. However, because atoms and molecules can form ions and carry positive or negative electrical charges, there may also be an electrical gradient, or difference in charge, across a plasma membrane. In fact, living cells typically have what’s called a membrane potential, an electrical potential difference (voltage) across their cell membrane.

PASSIVE TRANSPORT

Naturally, molecules move from an area of high concentration to low concentration without the need of energy. This type of movement is passive transport. Molecules with strong electrical charges such as ions cannot simply diffuse across the cell membrane. Irrespective of their size, their charge prevents them from moving freely across the cell membrane. Other molecules such as proteins, starch and sugar are simply too large to diffuse across the membrane. Sometimes, some of these large molecules are transported across the cell membranes by carrier proteins; this does not require energy and as a result is a form of passive transport. There are three types of passive transport;

Simple diffusion: Hydrocarbons, carbon dioxide, and oxygen are hydrophobic substances that can pass easily across the cell membrane by diffusion and travel down the concentration gradient (Figure 8). This type of diffusion relies on the thermal motion energy intrinsic to the molecule in question. It is a form of passive transport because the cell expends no energy in moving the substances.

Figure 8: Diffusion of molecules across a semi-permeable membrane from an area of high concentration to an area of low concentration in order to achieve a balanced concentration.

Osmosis: The movement of water across a selectively permeable membrane is osmosis. A cell has one of three water relationships with the environment around it.

• In an isotonic solution there will be no net movement of water across the plasma membrane. Water crosses the membrane, but at the same rate in both directions.
• In a hypertonic solution the cell will lose water to its surroundings. The hyper - prefix refers to more solutes in the water around the cell, hence, the movement of water to the higher (hyper-) concentration of solutes. In this case the cell loses water to the environment, shrinks, and may die.
• In a hypotonic solution water will enter the cell faster than it leaves. The hypo - prefix refers to fewer solutes in the water around the cell, hence, the movement of water into the cell where the solutes are more heavily concentrated. In this case the cell will expand and may burst, unless protected by a cell wall such as that found in bacteria and plant cells.

Facilitated diffusion: Ions and polar molecules cannot pass easily across the membrane. The process by which ions and hydrophilic substances travel across the cell membrane with the help of transport proteins is called facilitated diffusion (Figure 9). Transport proteins are specific (like enzymes) for the substances they transport. They work in one of two ways:

• They provide a hydrophilic channel through which the molecules in question can pass.
• They bind loosely to the molecules in question and carry them through the membrane.

                       STUCTURE AND FUNCTION OF ORGANELLE 

                                             

                                                  NUCLEUS

    >Sphere or oval

    >Double membrane organelle 

    >Carry genetic information 

    >Direct protein synthesis 

    >Consist nuclear envelope,nuclelous and chromatin

Nuclear envelope:>Double membrane separate nuclear content 
                                            from surrounding cytoplasm

Nucleoplasm:>Interior part of nucleus with full of chromatin

Nuclelous:>A mass of densely stained granules and fibres
                   adjoining part of chromatin

                 >Spherical in shape 

                 >Non membranous

                 >Function:Produce rRNA,form ribosome 

ENDOPLASMIC RETICULUM

   >Network of membranous sacs and tubes 

   >Continues with nuclear envelope

     

Smooth ER:>Has lack of ribosome on its outer surface

                    >Synthesis of lipid

                    >Metabolism of carbohydrate 

                    >Detoxification of drugs and poison 

                    >Storage of calcium ions 

Rough ER :>Studded with numerous Ribosome 
                   >Process and transport protein synthesizes by ribosomes

GOLGI BODY

  >Consist of flattened memmranous sacs 
  >Function:Modifies processes or store the substance 

Cis Face:>Located near the ER to transport vesicle from ER to Golgi Body
               >Recive vesicle containing ER products from transport vesicles

Trans Face:>packages molecules in vesicles and transport them out of Golgi Body

LYSOSOME

>Spherical sacs 
>Surrounded by single membrane
>Contining hydrolytic enzyme 
>Function:Intercellular digestion such as Phagocytosis and Autophagy

Phagocytosis:>digesting food particle by engulfing

Autophagy:> digesting damage organelle

RIBOSOME

>Small granule 
>Consist of two subunit which is small and large 
>Non membranous
>Manufactured in nuclelous of nucleus
>Function:The site of protein synthesis.
                 Responsible for then formation of peptide bond

MITOCHONDRIA

>Double membrane
>Outer membrane:smooth 
 Inner membrane: convulated with enfolding called cristae
>Function:Site of cellular respiration

Cristae:>increase large surface are to make gaseous exchange more efficient

  CHLOROPLAST

>Double membrane
>Contain chlorophyll
>Contain its own DNA and Ribosome
>Function:Site of photosynthesis 
>Thylakoid:combination of grana(light reaction occurs)
>Stroma(dark reaction occurs)
>Integranal Lamella:connented thylakoid of adjacent grana

CENTROSOME AND CENTRIOLE

Centosome:region usually located near the nucleus

Centriole:A pair of short microtubules each composed of nine sets of triplets 
                 microtubules arranged in a ring 

>Function:Microtubule organizing centre and and important in cell division of animal cells.
                  Initiate the spindle that organizes and separates the chromosomes

VACOULE

>Single membrane 
>Membrane bound sacs containing water or dilute solution of salts and other solute
   called Cell Sap
>Function:> structural support
                  >storage for nutrient
                  >waste disposal
                  >protection
                  >growth