Ahmad ata 1 Anatomy & physiology of cells Chapter 3.

ahmad ataahmad ata 11

Anatomy & physiology Anatomy & physiology of cellsof cells

Chapter 3Chapter 3


Objectives Objectives 1. 1. label the components, name a term that label the components, name a term that

describes the cell.describes the cell.

2. Distinguish between passive and active 2. Distinguish between passive and active transport processes. transport processes.

3. Define the terms 3. Define the terms diffusion, osmosis, filtrationdiffusion, osmosis, filtration

and and facilitated diffusionfacilitated diffusion, and give an example , and give an example of each.of each.

4. Define the terms 4. Define the terms active transport, endocytosisactive transport, endocytosis, , and and exocytosisexocytosis..

5. List a function(s) for each cellular component 5. List a function(s) for each cellular component and/or organelle.and/or organelle.

6. Describe the structure of each cellular organelle.6. Describe the structure of each cellular organelle.


INTRODUCTIONINTRODUCTION

The cell is the basic unit of structure and The cell is the basic unit of structure and function in living things. Cells vary in their function in living things. Cells vary in their shape size, and arrangements but all cells have shape size, and arrangements but all cells have similar components, each with a particular similar components, each with a particular function.function.

Some of the 100 trillion of cells make up human Some of the 100 trillion of cells make up human body.body.

All human cell are microscopic in size, shape All human cell are microscopic in size, shape and function.and function.

The diameter range from 7.5 micrometer (RBC) The diameter range from 7.5 micrometer (RBC) to 150 mm (ovum). to 150 mm (ovum).


Introduction Introduction

- Cell is defined as the fundamental living unit Cell is defined as the fundamental living unit of any organism.of any organism.

- Cell is important to produce energy for Cell is important to produce energy for metabolism (all chemical reactions within a metabolism (all chemical reactions within a cell)cell)

- Cell can mutate (change genetically) as a Cell can mutate (change genetically) as a result of accidental changes in its genetic result of accidental changes in its genetic material (DNA).material (DNA).

- Cytology: the study of the structure and Cytology: the study of the structure and functions of cells.functions of cells.


Cell structure Cell structure

1) THE CELL (PLASMA) MEMBRANE1) THE CELL (PLASMA) MEMBRANE The cell membrane is a thin, dynamic The cell membrane is a thin, dynamic

membrane that encloses the cell and membrane that encloses the cell and controls what enters and leaves the controls what enters and leaves the cell.cell.

Fluid Mosaic ModelFluid Mosaic Modelcomposed of a double layer (bilayer) composed of a double layer (bilayer) of phospholipid molecules with many of phospholipid molecules with many protein molecules dispersed within it;protein molecules dispersed within it;


Fluid Mosaic ModelFluid Mosaic Model

a.a. The surfaces of the The surfaces of the membrane are "hydrophilic" due membrane are "hydrophilic" due to the polar phosphate heads;to the polar phosphate heads;

b.b. The internal portion of the The internal portion of the membrane is "hydrophobic" due membrane is "hydrophobic" due to the non-polar fatty acid tails;to the non-polar fatty acid tails;

c.c. The membrane proteins also The membrane proteins also have both hydrophilic and have both hydrophilic and hydrophobichydrophobic


PLASMA MEMBRANEPLASMA MEMBRANE


PLASMA MEMBRANEPLASMA MEMBRANE

hydrophillic phosphate head hydrophobic fatty acid tails

• Chemical attractions are Chemical attractions are the forces that hold the forces that hold membranes togethermembranes together


Function of plasma membraneFunction of plasma membrane

Serves as boundary of the cell.Serves as boundary of the cell. Serve as markers that identify the Serve as markers that identify the

cells.cells. Play significant role in Play significant role in

transportation.transportation. Cell recognition proteins-allow cell Cell recognition proteins-allow cell

to recognize other cells.to recognize other cells.


Membrane proteinsMembrane proteins

– Some membrane proteins have Some membrane proteins have carbohydrates attached to them, carbohydrates attached to them, forming glycoproteins that act as forming glycoproteins that act as identification markersidentification markers

– Some membrane proteins are Some membrane proteins are receptors that react to specific receptors that react to specific chemicals, sometimes permitting a chemicals, sometimes permitting a process called signal transductionprocess called signal transduction


CytoplasmCytoplasm

Is a gel-like matrix of water, enzymes, Is a gel-like matrix of water, enzymes, nutrients, wastes, and gases and nutrients, wastes, and gases and contains cell structures (organelles).contains cell structures (organelles).

Fluid around the organelles called Fluid around the organelles called cytosol.cytosol.

Most of the cells metabolic reactions Most of the cells metabolic reactions occur in the cytoplasm.occur in the cytoplasm.


2) Endoplasmic 2) Endoplasmic reticulum reticulum network of interconnected parallel membranes network of interconnected parallel membranes

(maze), that is continuous with the nuclear (maze), that is continuous with the nuclear membrane; membrane;

2.2. Two types: Two types: a.a. Rough Endoplasmic Reticulum (RER)Rough Endoplasmic Reticulum (RER)1.1. ER studded with ribosomes;ER studded with ribosomes;2.2. Function = Function = protein synthesis and intraceluar protein synthesis and intraceluar

transportation of molecules transportation of molecules ;; b.b. Smooth Endoplasmic Reticulum (SER)Smooth Endoplasmic Reticulum (SER)lacks ribosomes;lacks ribosomes;1.1. Function = Function = lipid & cholesterol synthesis and lipid & cholesterol synthesis and

Stores calcium.Stores calcium.


Rough Endoplasmic Reticulum (RER)Rough Endoplasmic Reticulum (RER)


3) Ribosomes 3) Ribosomes

Every cell contains thousand of ribosome's Every cell contains thousand of ribosome's and many of them attached to the RER.and many of them attached to the RER.

Each ribosome is nonmembranous structure, Each ribosome is nonmembranous structure, made of two pieces large unit and small unit made of two pieces large unit and small unit and each subunit composed of rRNA.and each subunit composed of rRNA.

Function: protein synthesisFunction: protein synthesis Protein released from the ER are not Protein released from the ER are not

mature, need further processing in Golgi mature, need further processing in Golgi complex before they are able to perform complex before they are able to perform their function within or outside the cell.their function within or outside the cell.


3) 3) Golgi ApparatusGolgi Apparatus

1.1. flattened membranous sacs (cisternae).flattened membranous sacs (cisternae).

2.2. arranged in stacks ("stack of pancakes") arranged in stacks ("stack of pancakes") associated with many vesicles associated with many vesicles (membrane bound sacs containing (membrane bound sacs containing proteins);proteins);

2.2. Function = Function = modification, packaging, modification, packaging, and transport of proteinsand transport of proteins;;

3.3. Encloses digestive enyzymes into Encloses digestive enyzymes into membranes to form lysosomes. membranes to form lysosomes.


4) Lysosomes4) Lysosomes

1.1. spherical membranous sacs containing spherical membranous sacs containing digestive enzymes;digestive enzymes;

2.2. "suicide sacs" which destroy anything "suicide sacs" which destroy anything the cell no longer wants or needs.the cell no longer wants or needs.

3.3. AutolysisAutolysis is the process by which worn is the process by which worn cell parts are digested by autophagy.cell parts are digested by autophagy.


PeroxisomesPeroxisomes::

1.1. membranous sacs membranous sacs containing oxidase enzymes;containing oxidase enzymes;

2.2. Function = Function = detoxification detoxification of harmful or toxic substancesof harmful or toxic substances (i.e. alcohol, formaldehyde, (i.e. alcohol, formaldehyde, oxygen free radicals);oxygen free radicals);

H2O2 (peroxide) ----> waterH2O2 (peroxide) ----> water


MitochondriaMitochondria

1.1. kidney-shaped kidney-shaped organelle whose inner organelle whose inner membrane is folded membrane is folded into shelf-like partitions into shelf-like partitions called called cristaecristae;;

2.2. ""PowerhousePowerhouse" of " of the cell = site of the cell = site of cellular respiration cellular respiration where energy is where energy is released from glucose.released from glucose.


NUCLEUSNUCLEUS

the central core, control center or "brain" of the cell.the central core, control center or "brain" of the cell.

1.1. the largest organelle of the cell;the largest organelle of the cell;2.2. filled with nucleoplasm;filled with nucleoplasm; Nuclear MembraneNuclear Membrane (or nuclear envelope) is a double (or nuclear envelope) is a double

membrane that separates the contents of the nucleus membrane that separates the contents of the nucleus from the cytoplasm;from the cytoplasm;

At various point, these two membranes fuse = At various point, these two membranes fuse = nuclear nuclear

porepore..

The nuclear membrane is "selectively permeable"; The nuclear membrane is "selectively permeable"; pores serve as sites where mRNA can pass out of the pores serve as sites where mRNA can pass out of the nucleus during protein synthesis, and how ribosomes nucleus during protein synthesis, and how ribosomes exit the nucleus. exit the nucleus.


NucleoliNucleoli

Nucleolus (s) = a spherical body Nucleolus (s) = a spherical body within the nucleus;within the nucleus;

composed of RNA and proteins;composed of RNA and proteins; Function = synthesis of Function = synthesis of

ribosomes.ribosomes.


Cytoskeleton :Cytoskeleton : The cytoskeletonThe cytoskeleton

– Is a network of fibers extending Is a network of fibers extending throughout the cytoplasmthroughout the cytoplasm

– Fibers appear to support the Fibers appear to support the endoplasmic reticulum, endoplasmic reticulum, mitochondria, and “free” ribosomesmitochondria, and “free” ribosomes

Microtubule

0.25 µm Microfilaments


The cytoskeletonThe cytoskeleton

– Gives mechanical support to the cellGives mechanical support to the cell

– Is involved in cell motility, which Is involved in cell motility, which utilizes motor proteinsutilizes motor proteins

– Rodlike pieces that provide support Rodlike pieces that provide support and allow movement and mechanisms and allow movement and mechanisms that can move the cell or its partsthat can move the cell or its parts


Components of cytoskeleton: Components of cytoskeleton: 1) Microfilaments1) Microfilaments

Solid rods of Solid rods of globular proteins.globular proteins.

Important Important component of component of cytoskeleton which cytoskeleton which offers support to offers support to cell structure.cell structure.

Microfilaments can Microfilaments can slide past each slide past each other, causing other, causing shortening of the shortening of the cellcell


Components of cytoskeleton: Components of cytoskeleton:

2) 2) Intermediate filamentsIntermediate filaments

– Intermediate filaments are twisted Intermediate filaments are twisted protein strands slightly thicker than protein strands slightly thicker than microfilaments; they form much of the microfilaments; they form much of the supporting framework in many types of supporting framework in many types of cellscells


Components of cytoskeleton: Components of cytoskeleton: 3) Microtubules3) Microtubules

MicrotubulesMicrotubules– Shape the cellShape the cell– Guide movement of organelles (Guide movement of organelles (their their

function is to move things around in the function is to move things around in the cell)cell)

– Help separate the chromosome copies in Help separate the chromosome copies in dividing cellsdividing cells


Components of cytoskeleton: Components of cytoskeleton: 4) Microtubules4) Microtubules

Centrosomes and CentriolesCentrosomes and Centrioles The centrosomeThe centrosome

– An area of the cytoplasm near the nucleus An area of the cytoplasm near the nucleus that coordinates the building and breaking that coordinates the building and breaking of microtubules in the cellof microtubules in the cell

– Its considered to be a “microtubule-Its considered to be a “microtubule-organizing center”organizing center”

– Plays an important role during cell divisionPlays an important role during cell division– Contains a pair of centriolesContains a pair of centrioles


Components of cytoskeleton: Components of cytoskeleton:

Centrioles Self-replicatingSelf-replicating Made of bundles of Made of bundles of

microtubules.microtubules. Help in organizing Help in organizing

cell division.cell division.


Cell Membrane Surface ModificationsCell Membrane Surface Modifications 1.1. Cilia / CiliumCilia / Cilium

a.a. short, hair-like cellular extensions (eyelashes);short, hair-like cellular extensions (eyelashes);b.b. help move substances through passageways;help move substances through passageways;c.c. located in lining of respiratory tract & fallopian tube.located in lining of respiratory tract & fallopian tube.

2.2. FlagellaFlagella

a.a. tail-like projection;tail-like projection;b.b. only one per cell in humans;only one per cell in humans;c.c. aids in cell aids in cell locomotionlocomotion; ; d.d. sperm cell.sperm cell.

3.3. MicrovilliMicrovilli::

a. small finger-like extensions of the external surface of the cell a. small finger-like extensions of the external surface of the cell membrane; membrane;

b.b. Function = to Function = to increase surface areaincrease surface area..c.c. located in the lining of the digestive tract.located in the lining of the digestive tract.


Membrane JunctionsMembrane Junctions

Tight junctionTight junction – impermeable junction that – impermeable junction that encircles the cell & prevents leakageencircles the cell & prevents leakage

– – Blood brain barrierBlood brain barrier - Skin - Skin Desmosome Desmosome – anchoring junction scattered – anchoring junction scattered

along the sides of cells. Prevents tissues from along the sides of cells. Prevents tissues from fraying fraying

Stomach, uterus , bladderStomach, uterus , bladder Gap junctionGap junction – allows chemical substances to – allows chemical substances to

pass between cellspass between cells HeartHeart


Tight JunctionTight JunctionDesmosomeDesmosome


Gap JunctionGap Junction


Transport Across the Plasma Transport Across the Plasma MembraneMembrane

– 2 types 2 types

– Passive transport Passive transport

– Active TransportActive Transport

require no ATP( energy)require no ATP( energy)Substances move High to low conc. Substances move High to low conc.

Examples include Examples include Simple diffusionSimple diffusion OsmosisOsmosis facilitated diffusionfacilitated diffusion filtrationfiltration


Simple diffusionSimple diffusion

random mixing of random mixing of particles in solutionparticles in solution

substances move substances move down concentration down concentration gradient-gradient-

particles eventually particles eventually become evenly become evenly distributed - distributed - Equilibrium reachedEquilibrium reached


Simple diffusionSimple diffusion


Facilitated DiffusionFacilitated Diffusion

Diffusion Through channel Diffusion Through channel proteins or transport proteinsproteins or transport proteins

allow passage of allow passage of – small inorganic ions – Na+ , K+, small inorganic ions – Na+ , K+,

Ca+2Ca+2– Glucose, water soluble vitamins(B,C)Glucose, water soluble vitamins(B,C)generally slower than diffusion across generally slower than diffusion across

lipid portionlipid portion Depends upon the number of Depends upon the number of

transporters available transporters available


Diffusion Through the Plasma MembraneDiffusion Through the Plasma Membrane


OsmosisOsmosis

passive processpassive process diffusion of water across a diffusion of water across a

selectively permeable membraneselectively permeable membrane from Hi. Conc. of WATER ( low solute)from Hi. Conc. of WATER ( low solute)

to to

lower concentration of WATER( Hi. lower concentration of WATER( Hi. solute)solute)


Membrane Permeability on Diffusion Membrane Permeability on Diffusion and Osmosisand Osmosis


TonicityTonicity

Describes how a solution affects cell volumeDescribes how a solution affects cell volume hypertonichypertonic

– solution with more solutessolution with more solutes– Blood cells shrink and crenateBlood cells shrink and crenate

hypotonichypotonic– solution with less solutessolution with less solutes– Blood cells swell up and hemolyse Blood cells swell up and hemolyse

isotonicisotonic– both solutions have similar concentrations of both solutions have similar concentrations of

solutes. solutes. – Cell size is unchangedCell size is unchanged


Active transport Active transport - movement of - movement of a substance from a lower a substance from a lower concentration to a higher concentration to a higher concentration using a carrier and concentration using a carrier and energyenergy

Endocytosis Endocytosis - brings substances - brings substances into the cellsinto the cells


solutes moving against solutes moving against concentration gradient-Uses concentration gradient-Uses carrier proteins carrier proteins

– can be driven by ATP use or via can be driven by ATP use or via energy stored in ionic concentrationenergy stored in ionic concentration

Types : Types : – Primary active transport Primary active transport – Secondary active transport Secondary active transport 1.1. Endocytosis Endocytosis 2.2. Exocytosis Exocytosis 3.3. TanscytosisTanscytosis


Primary active Primary active transporttransportuses ATP and transporter proteins sodium potassium pump


Transport in Vesicles- Transport in Vesicles- EndocytosisEndocytosis A form of active transport.A form of active transport.

Transport of large particles Transport of large particles across the plasma membraneacross the plasma membrane

Types : Types : 1.1.PhagocytosisPhagocytosis

1.1.Pinocytosis Pinocytosis


PhagocytosisPhagocytosis

only a few body cells are capableonly a few body cells are capable Ex. WBC (macrophages , neutrophils)Ex. WBC (macrophages , neutrophils) particle binds to plasma membraneparticle binds to plasma membrane pseudopodspseudopods extend and surround extend and surround

particle forming phagosomeparticle forming phagosome phagosome fuses with lysosomes phagosome fuses with lysosomes

which destroy invaderwhich destroy invader


PhagocytosisPhagocytosis


PinocytosisPinocytosis

Also called cellular drinking Also called cellular drinking most body cells carry out processmost body cells carry out process

– especially absorptive cells in especially absorptive cells in intestines and kidneysintestines and kidneys

tiny droplets of extracellular fluid tiny droplets of extracellular fluid taken into celltaken into cell

lysosomes fuse and degrade lysosomes fuse and degrade particles into smaller useable particles into smaller useable particlesparticles


PinocytosisPinocytosis


ExocytosisExocytosis

releases materials form a cellreleases materials form a cell all cells carry out processall cells carry out process Ex. i. secretory cellsEx. i. secretory cells

release digestive enzymes, hormones, mucus, release digestive enzymes, hormones, mucus, or other secretionsor other secretions

– Ii. nerve cellsIi. nerve cells release neurotransmittersrelease neurotransmitters

vesicles fuse with plasma membrane vesicles fuse with plasma membrane and release contents into extracellular and release contents into extracellular fluidfluid


ExocytosisExocytosis

vesicle fuses with the plasma membrane vesicle fuses with the plasma membrane and then ruptures; used in hormone and and then ruptures; used in hormone and neurotransmitter releaseneurotransmitter release


ExocytosisExocytosis - -

Ahmad ata 1 Anatomy & physiology of cells Chapter 3.

Documents

Transcript of Ahmad ata 1 Anatomy & physiology of cells Chapter 3.