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DPT 1, Lec 6

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Page 1: DPT 1, Lec 6
Page 2: DPT 1, Lec 6

Learning objectives

• Functions of mitochondria.• Locomotion of cells

Page 3: DPT 1, Lec 6

Extraction of energy from nutrients

• Energy is extracted from foodstuffs.• Oxygen reacts with carbohydrates, fats and

proteins under the influence of enzymes.• All these reactions occur in mitochondria.• ATP is formed.

Page 4: DPT 1, Lec 6
Page 5: DPT 1, Lec 6

Functional characteristics of ATP

• ATP is a nucleotide composed of:- 1-The nitrogenous base adenine 2-The pentose sugar ribose 3-Three phosphate radicals

Page 6: DPT 1, Lec 6
Page 7: DPT 1, Lec 6

Each high energy bonds contains about 12,000 calories of energy per mole of ATP.

When ATP releases its energy, a phosphoric acid radical is split away and ADP is formed.

ATP is called Energy currency of cell as it can be spent and remade continually.

Page 8: DPT 1, Lec 6

Chemical process in the formation of ATP

• Glycolysis• Citric acid cycle• The overall process of formation of ATP is

called Chemiosmotic mechanism.

Page 9: DPT 1, Lec 6

Uses of ATP for cellular function

• ATP is used for 3 major categories of functions:-

1-Transport of substances through multiple membranes of the cell

2-Synthesis of chemical compounds3-Mechanical work

Page 10: DPT 1, Lec 6
Page 11: DPT 1, Lec 6

Locomotion of cells

• 2 types of movements are present:-1- Ameboid movement2- Ciliary movement

Page 12: DPT 1, Lec 6
Page 13: DPT 1, Lec 6

Types of cells that exhibit ameboid movement

• WBC• Fibroblasts• Germinal cells of skin• Movement of embryonic cells

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Control of ameboid movement

• Chemotaxis- Initiates movement• Chemotactic substances• Positive chemotaxis• Negative chemotaxis

Page 15: DPT 1, Lec 6

Ciliary movements

• Whiplike movement of cilia• Occurs in two places in humans:-1-Respiratory airways2-Movement of ovum from ovary to uterus

Page 16: DPT 1, Lec 6

• Cilium has the appearance of a sharp pointed straight or curved hair that projects 2-4 micrometers from the surface of cell.

• Almost 200 cilia on the surface of each epithelial cell inside respiratory passages.

Page 17: DPT 1, Lec 6
Page 18: DPT 1, Lec 6

• Cilium is covered by an outcropping of CM.• It is supported by 11 microtubules – 9 double

tubules located around the periphery of the cilium, and 2 single tubules down in the center.

Page 19: DPT 1, Lec 6
Page 20: DPT 1, Lec 6

• Each cilium is an outgrowth of a structure that lies immediately beneath the CM, called the basal body of the cilium.

• Flagellum of a sperm is similar to a cilium.• Difference is that flagellum is much longer and

moves in quasi-sinusoidal waves .

Page 21: DPT 1, Lec 6
Page 22: DPT 1, Lec 6

• Cilium moves forward with a sudden , rapid whiplike stroke 10-20 times per second, bending sharply where it projects from the surface of the cell.

• Then it moves backwards slowly to its initial position.

• The fluid is continually propelled in direction of fast of fast forward stroke.

Page 23: DPT 1, Lec 6
Page 24: DPT 1, Lec 6

Mechanism of ciliary movement

1-Nine double tubules and two single tubules are linked by complex of protein cross linkages to one another.

This whole complex is called axoneme.2-If membrane is removed and other elements

of cilium besides axoneme is destroyed, the cilium can still beat under appropriate conditions.

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3-After destruction beating depends on:- -Availability of ATP -Appropriate ionic conditions esp Mg and Ca4-During forward movement, the double

tubules on the front edge of the cilium slide outwards towards the tip of cilium and those on back edge remain in place.

Page 26: DPT 1, Lec 6

5-Multiple protein arms composed of protein Dynein which has ATPase enzymatic activity, project from each double tubule toward an adjacent double tubule.

Page 27: DPT 1, Lec 6