Cell diffintion and function of cell and structure and types of cell

1. CELL

2. Introduction
 All living thing composed of cells
 Basic structural and functional unit
 space outside cell is extracellular space; contain
fluids and matrixes

3. General characteristics
 Each cell of body
 Need nutrition and oxygen
 Produce energy of its own, req for growth, repair
 Eliminate waste
 Maintain healthy environment
 Shows response to antigens
 Reproduce by division

4. Some points….
 Tissues (group of cells having same function)
 Muscle
 Nervous
 Epithelial
 Connective
 Organ (Structures having two or more tissues)
 Hollow organ; stomach, intestine, gall bladder, urinary bladder
 compact organ; heart, liver, kidneys
 System
 Group of organ work together to perform specific activity
 Digestive , cardiovascular, respiratory, reproductive

5. Structure of cell
 Membrane
 Cytoplasm
 Nucleus

6. a

7. CELL MEMBRANE
 A protective sheath
 Differentiate extra and intracellular environment
 Permeable for certain substances
 Thickness is 7.5 to 10 nm
 Composition
 Proteins 55%
 Lipids 40%
 Carbohydrates 5%

8. Structure
 Structurally called unit membrane
 Three layers
 Centrally lipid bilayer
 Other two layers surrounds central layer, formed by proteins
and carbohydrates

10. 1. Lipid bilayer
 Fluid in nature; movement
 Major lipids
Phospholipids
 Head portion; hydrophilic faces ECF
 Tail portion; non polar, inside the membrane
Cholesterol
 Present b/w phospholipids; maintains structural
integrity
 b/c phospholipids are oily

11. Function of lipid layer
 Permeable to fat soluble substances
 Oxygen
 CO2
 Alcohol
 Substances which cannot pass
 Glucose
 Urea
 Electrolytes

13. 2. Protein layer of cell membrane
 Covers lipid layer
 Gives protection to lipid layer
 Mostly glycoprotein
 Two types of proteins present
1. Integral protein
2. Peripheral protein

15. Function of proteins in cell membrane
 Structural integrity
 Channels allows water soluble substances
 Transport protein
 Act as a pump
 Receptor proteins
 Enzymes
 Antigen proteins

16. 3. Carbohydrates in cell membrane
 Make a thin covering around membrane; Glycocalyx
 Attach to proteins and lipids
 Glycoproteins and glycolipids
 Function of carbohydrates
1. Are negatively charged; restrict movement of neg charged
ions in and out of cell
2. Glycocalyx helps tight fixation of cell
3. Act as receptors

18. Function of cell membrane
 Protective function
 Selective permeability
 Absorptive
 Excretory
 Exchange of gases
 Maintainance of shape and size of cell

20. CYTOPLASM
 Jelly like substance; 80% water and other substances
 Carbohydrates
 Lipids
 Proteins
 Electrolytes
 Organelles
2- TYPES
 Ectoplasm
 Endoplasm

21. Cell organelles in cytoplasm
1. Endoplasmic reticulum
 Rough ER
 Protein synthesis
 Degradation of worn-out organelles
 Smooth ER
 Lipids and steroid synthesis
 Role in cellular metabolism
 Storage and metabolism of calcium
 Catabolism , detoxification of toxic subs

23. 2. Golgi apparatus
 Membrane bound organelles
 Have flattened membrane sac; cisternae
 Present near the nucleus
 Functions
 Processing
 Packaging (granules, vesicles, lysosomes)
 Labeling
 Delivery
Of proteins and lipids

26. 3. lysosomes
 Membrane bound vesicle
 Formed by golgi apparatus
 Garbage system
 Has the thickest covering membrane
 Contain hydrolytic enzymes
 Proteases
 Lipase
 Amylase
 Nuclease
 Types
 Primary (inactive)
 Secondary (active)

28. Function
 Degradation of
 Macro-molecule (endocytosis; phago & pinocytosis)
 Worn-out organelles
 Removal of excess of secretory products
 Secretion of enzymes
 T-lymphocytes
 Natural killer cells
 Melanocyte cell
 Mast cell

29. Pino/phagocytosis

30. Peroxisomes
 Vesicles formed by endoplasmic reticulum
 Contain oxidative enzymes
 Catalase
 Urate oxidase
 Amino acid oxidase

32. Function
 Break down of excess fatty acids (beta-oxidation)
 Detoxification of hydrogen peroxide/metabolic waste
 Oxygen utilization
 Gluconeogenesis
 Formation of myelin
 Formation of bile acid

33. Mitochondria
 Rod or oval shaped
 Double membrane
 Outer membrane; enzyme acetyl-CoA synthetase,
acetyltransferase
 Inner membrane; called cristae… enzyme and
proteins for cellular respiration

35. Functions
Energy production
 Substrates used: protein, fats, carbohydrates
 By oxidation reaction  release CO2 water and
energy.
 Energy stored in mitochondria

36. Synthesis of ATP
 Synthesized by electron transport chain
 Stores as ATP
 Cleaved and energy released as needed
 Apoptosis
Storage of calcium
Detoxification of ammonia in liver

37. Step 1.
• Carbohydrates are converted
into glucose
• Proteins are converted into
amino acids
• Fats are converted into
fatty acids
Step 2.
• Glucose, AA, and FA are
processed into AcetylCoA
Step 3.
•AcetylCoA reacts with O2 to
produce ATP
A maximum of 38 molecules of
ATP are formed per molecule of
glucose degraded.
ATP production

38. The Use of ATP for Cellular Function
1. Membrane
transport
2. Synthesis of
chemical
compounds
3. Mechanical
work
Figure 2-15

39. Ribosomes
 Organelle without limiting membrane
 Made of protein and ribonucleic acid called RNA
(rRNA)
TYPES
 Attached to rough EPR
 Free in cytoplasm

41. Function
 Called protein factories
 Role in protein synthesis
 mRNA carries genetic code for P.S from nucleus to
ribosome
 Arrange amino acid into small protein
 Attached ribosome synthesize
 Enzymatic protein
 Hormonal
 Lysosomal
 Cell membrane protein

42.  Free ribosome synthesize
 Proteins in haemoglobin
 Peroxisome
 Mitochondria

43. Cytoskeleton
 Present throughout the cytoplasm
 Determine shape
 Provide support
 Formed by globular protein, alpha & beta subunits
Types
 Microtubule
 Intermediate filament
 Microfilament

45. The Cytoskeleton
Intermediate Filaments:
•Comprised of cell-specific fibrillar monomers
(e.g. vimentin, neurofilament proteins, keratins, nuclear
lamins)
Microtubules:
• Heterodimers of  and  tubulin
• Make up spindle fibers, core of axoneme structure
Thin Filaments:
• F-Actin
• Make up “stress fibers” in non-muscle cells
Thick Filaments:
• Myosin (types I and II)
•Together with actin support cellular locomotion and
subcellular transport

46. NUCLEUS
 Largest organelle, occupies 10% of total cell volume
 Present in all types of cells except haemoglobin
 Uni-nucleated cell
 Multinucleated cell
 Present in the center
 Spherical in shape

47. Structure
 Covered by nuclear membrane
 Nucleoplasm
 Chromatin
 Chromosome
 Nucleolus

48. Nuclear membrane
 Doubled layered
 Porous
 Outer layer is continous with ER
 Exchange of material or signals is through these
pores

50. Chromatin
 Thread like material
 Made of large molecule of DNA
 DNA-histone complex
 DNA wraps around 8-mol of histone nucleosome
 Nucleosome are packed together by histone called
chromatin fiber
 Which converts to chromosome just before division

52. Chromosome
 Formed by wrapping DNA around histone molecule
 Rod shaped
 Contain all genetic information of an individual
 Appear during cell division only on microscope
 Diploid and haploid cell
 Sex chromosomes and autosomes

54. FUNCTION OF NUCLEUS
Brain of cell, Control center
 Controll of all cell activities i.e metabolism, protein
synthesis, reproduction
 Synthesis of RNA
 Sending signal to cytoplasm for protein synthesis
 Storge of hereditary material
 Controll of cell division through genes

55. Cell Death
 Autophagy
 Apoptosis
 Necrosis

56. Autophagy
 Normal physiological process
 Old cell are replaced by new cells
 Formation of autophagosomes
 Attached with lysosomes
 Protein degradation
 Protein fragments re-used for formation of new cells
 Non-apoptotic cell death

57. Apoptosis
 Natural/Programmed cell death by genetic control
 Cell suicide
 Normal phenomena, essential for normal
development
 Doesn't produce inflammation in the adjacent tissue
Examples
 Web fingers
 Neuron
 Falling leaves in autumn

58. Significance
 Cellular homeostasis
 Useful for unrepairable damaged cell
 Essential event in development and in adult
Examples
 Removal of neuron in developmental phase
 Removal of tissue; web
 Disappearance of ducts system in sex differentiation
 Sloughing of endometrium in menstrual cycle
 Removal of auto aggressive T-cells

59. Activation of apoptosis
 Withdrawal of positive signals
 Nerve growth cells for neurons
 Interleukins for lymphocytes
 Arrival of negative signals
 In normal developmental procedures
 Cellular stress
 Increase in intracellular oxidants
 Viral infection
 Damage to DNA
 Exposure; chemo drugs, X-rays, UV rays etc

60. Death receptor ligand and death receptor
Ligands
 Subs bind on cell mem receptor initiate
apoptosis
 E.g. TNF-alpha, TNF-beta and Fas ligand
Receptors
 Which receives ligands
 TNF receptor-1

61. Role of mitochondria in apoptosis
 Internal/ external stimulus initiate apoptosis by
activating caspasis, a cysteine dependent aspartate
specific proteases (normally suppressed by AIF)
 MITOCHONDRIA release cytochrome-C and SMAC
 SMAC and C-C inactivate AIF and initiate apoptosis.
 Caspasis induced damage to cytoskeleton cell
shrinkage chromatin degradation nuclear
membrane discontinuous  DNA cleaved 
chromatin bodies cell membrane breaks
apoptotic bodies engulf by macrophages

62. Necrosis
 Uncontrolled/ Unprogrammed cell death
 Cell murder
 Cause inflammation and damage to neighbor cells.
 Induced by external factors
 Infection
 Inflamation
 Heat
 Radiation
 Trauma
 Hypoxia
 Toxins

63. Pathophysiology
 Stimulus
 Cell swelling
 Porous cell membrane
 Leakage of intra cellular content
 Altered intra cellular environment
 Ca release by mitochondria
 Inc Ca affects the action of proteins and release of toxic
material
 Activation of lysosomes
 Degradation of cellular component
 Cell death
 Products ingested by neighboring cells

64. Surrounding Tissues reaction after necrosis
 Tissue reacts with breakdown product of necrotic cell
 Phospholipids likes arachadonic acid; cause
 Dilation of capillaries, inc blood flow
 Increase of temperature
 Release of histamine, induce pain
 Migration of leucocytes and macrophages
 Local edema
 Engulfing of debris
 Activation of immune system; removal of foreign
material
 Formation of pus
 Finally tissue growth and healing

65. Cell adaptation
 Changes in cell in response to external stimulus
 External stimulus
 Stress
 Chemical agents
 Disease
 Environmental factors
 Mechanisms
 Atrophy
 Hypertrophy
 Hyperplasia
 Dysplasia
 Metaplasia

66. Atrophy
 Dec in size of cell, tissue, organ
2. types
Physiological
 Thymas of child
 Tonsils in adolescence
Pathological
 Atrophy of skeletal, cardiac, sex organ, brain

67. Hypertrophy
 Inc in size of cell
 Physiological
 Muscular
 Ventricular
 Pathological
 Compensatory

68. Hyperplasia
 Inc in number of cell by mitosis
 Results gross enlargement of organ
Physiological
 Momentary adaptive response e.g. in menstrual cycle
Compensatory
 Inc in number of cell to replace damaged cell or organ
 Cells in liver, intestine, epidermis
Pathological
 Abnormal inc in cell due to over production of hormones
 Gigantism, inc growth hormone, inc body growth
 BPH

69. Metaplasia
 Replacement of one type of cell with another one
Physiological
 Replacement in normal condition
 Cartilage to bones
Pathological
 Irreversible replacement due to constant exposure to
stimulus
 Chronic smoking ciliated columnar epithelial cell
to non ciliated columnar cells

70. a