D A N I L H A M M O U D I . M D

The cells

Chemical Structure of the Plasma Membrane

14. Describe the plasma membrane according to the fluid mosaic model. Include glycolipids, glycoproteins,phospholipids, cholesterol, integral proteins, and peripheral proteins.

Membrane Transport

15. Define the following terms: intracellular fluid, extracellular fluid, and interstitial fluid.

16. Define diffusion and describe how molecules diffuse across a plasma membrane. Include the following terms inyour description: passive process, simple diffusion, facilitated diffusion, carriers, and channels.

17. Define and describe osmosis. Include the following terms in your description: solvent, solute, solution, hypertonic,hypotonic, and isotonic.

18. Explain what happens to a cell placed in a hypertonic, hypotonic, or isotonic solution.

19. List and explain the five factors that affect the rate of transport of substances across cell membranes. These factorsare size of the material, temperature, the presence or absence of channels or other facilitating devices, particle charges,and the concentration gradient for the material being transported.

20. Define and describe active processes by which materials move across cell membranes.Active processes include active transport and vesicular transport. Include the following terms

in your description: ATP, pumps, exocytosis, endocytosis, phagocytosis, and receptormediated endocytosis.

Cellular Structures

21. Describe the structures and functions of the following membrane junctions: tight junctions, desmosomes,and gap junctions

Cell Theory

The cell is the basic structural and functional unit of life Organismal activity depends on individual and collective activity of cells Biochemical activities of cells are dictated by subcellular structure Continuity of life has a cellular basis

Fundamentally there are two basic types of cells

Eukaryotic cellular structure is more complex due to organellesOrganelles segregate functions, allows cell size to increase

A typical eukaryotic cell

Figure 3.2

Secretion being releasedfrom cell by exocytosis

Peroxisome

Ribosomes

Roughendoplasmicreticulum

NucleusNuclear envelopeChromatin

Golgi apparatus

Nucleolus

Smooth endoplasmicreticulum

Cytosol

Lysosome

Mitochondrion

CentriolesCentrosomematrix

Microtubule

Microvilli

Microfilament

Intermediatefilaments

Plasmamembrane

Plasma Membrane

Separates intracellular fluids from extracellular fluids Plays a dynamic role in cellular activityGlycocalyx is a glycoprotein area abutting the cell that provides highly

specific biological markers by which cells recognize oneanother, unique to each cells

• Act as an ID tag• Block cancer signal• Embryo growth• Cell protection• Immunity to infection• Cell adhesion• Fertilization

glycocalyx perturbation occurs when the circulation gets exposed to atherogenic stimuli such as oxidized lipoproteins,hyperlipidemia, and hyperglycemia.

Glycocalyx: Definition & Function - Video & Lesson Transcript | Study.com

Membranes define cellular and organelle boundaries•How does chemistry dictate function?•Why are there different lipid types?•How does material get across membranes?

Fluid Mosaic ModelDouble bilayer of lipids with imbedded, dispersed proteins Bilayer consists of phospholipids, cholesterol, and glycolipids Glycolipids are lipids with bound carbohydrate Phospholipids have hydrophobic and hydrophilic bipoles

Membrane Structure

Fluid Mosaic Model

Figure 3.3

hydrophilic means “water loving”

hydrophobic means “water repelling

Functions of Membrane Proteins

Transport

Enzymatic activity

Receptors for signaltransduction

Figure 3.4.1

Receptor Proteins

Enzymes

Transport Protein

Functions of MembraneProteins

Intercellularadhesion

Cell-cell recognition

Attachment tocytoskeleton andextracellular matrix

Figure 3.4.2

Plasma Membrane Surfaces

Differ in the kind and amount of lipids they contain

Glycolipids are found only in the outer membrane surface

20% of all membrane lipid is cholesterol

Lipid Rafts Make up 20% of the outer membrane surface

Composed of sphingolipids and cholesterol

Are concentrating platforms for cell-signaling molecules

Membrane Junctions

Tight junction – impermeable junction thatencircles the cell

Desmosome – anchoring junction scattered alongthe sides of cells

Hemidesmosomes : basalmembrane to cell

Gap junction – a nexus that allows chemicalsubstances to pass between cells

Membrane Junctions: Tight Junction

Figure 3.5a

Tight junction

Tight junctions are found in all tissues, but those ofparticular relevance to drug delivery include: Nasal tissue Gastrointestinal tissue - where oral drugs are

absorbed Blood vessels Blood-brain barrier

Tight junctions consist of proteins, for example,claudins, occludins and junctional adhesion

Membrane Junctions: Desmosome

Figure 3.5b

Membrane Junctions: Gap Junction

Figure 3.5c

A gap between adjacent cell membranescontaining very fine latticelike connectionsthat allow physiologic components to passdirectly from cell to cell. Also called nexus.

Gap Junction

Protienaceous tubes that connect adjacentcells. These tubes allow material to pass from one

cell to the next without having to passthrough the plasma membranes of the cells. Dissolved substances such as ions or glucose

can pass through the gap junctions. Large organelles such as mitochondria

connot pass. Ca++ control of gap junction opening

Passive Membrane Transport: Diffusion

II/ Facilitated diffusion

I/ Simple diffusion

Passive Membrane Transport: Diffusion

Simple diffusion – nonpolar and lipid-solublesubstances

Diffuse directly through the lipid bilayerDiffuse through channel proteins

Diffusion

Passive Membrane Transport: Diffusion

Facilitated diffusion Transport of glucose, amino acids, and ions Transported substances bind carrier proteins or pass

through protein channels

Carrier Proteins

Are integral transmembrane proteins Show specificity for certain polar molecules including

sugars and amino acids

Diffusion Through the Plasma Membrane

Figure 3.7

Extracellular fluid

Cytoplasm

Lipid-solublesolutes

Lipidbilayer

Lipid-insolublesolutes

Watermolecules

Small lipid-insolublesolutes

(a) Simple diffusiondirectly through thephospholipid bilayer

(c) Channel-mediatedfacilitated diffusionthrough a channelprotein; mostly ionsselected on basis ofsize and charge

(b) Carrier-mediated facilitateddiffusion via protein carrierspecific for one chemical; bindingof substrate causes shape changein transport protein

(d) Osmosis, diffusionthrough a specificchannel protein(aquaporin) orthrough the lipidbilayer

Passive Membrane Transport: Osmosis

Osmosis is the diffusion of water through a cellmembrane from a solution of low solute concentration toa solution with high solute concentration, up a soluteconcentration gradient.

It is a physical process in which a solvent moves, withoutinput of energy, across a semi permeable membrane(permeable to the solvent, but not the solute) separatingtwo solutions of different concentrations.

Osmosis releases energy, and can be made to dowork, as when a growing tree-root splits a stone.

Passive Membrane Transport: Osmosis

Occurs when the concentration of a solvent isdifferent on opposite sides of a membraneDiffusion of water across a semipermeable

membrane

Osmolarity – total concentration of solute particles ina solution Tonicity – how a solution affects cell volume

It has been estimated that an amount of water equivalent to roughly 250times the volume of the cell diffuses across the red blood cell membraneevery second; the cell doesn't lose or gain water because equal amountsgo in and out.

Osmotic pressure affects cell shape and life

Why this is important biologically

Kidney function is dependent upon ion and water transport

Effect of Membrane Permeability on Diffusionand Osmosis

Figure 3.8a

Effect of Membrane Permeability on Diffusion and Osmosis

Figure 3.8b

Passive Membrane Transport: Filtration

The passage of water and solutes through amembrane by hydrostatic pressure Pressure gradient pushes solute-containing fluid

from a higher-pressure area to a lower-pressure area

Effects of Solutions of Varying Tonicity

Isotonic – solutions with the same soluteconcentration as that of the cytosol

Hypertonic – solutions having greater soluteconcentration than that of the cytosol

Hypotonic – solutions having lesser soluteconcentration than that of the cytosol

Figure 3.10

Cytoplasm

Extracellular fluidK+ is released andNa+ sites are ready tobind Na+ again; thecycle repeats.

Cell ADP

Phosphorylationcauses theprotein tochange its shape.

Concentration gradientsof K+ and Na+

The shape changeexpels Na+ to theoutside, andextracellular K+ binds.

Loss of phosphaterestores the originalconformation of thepump protein.

K+ binding triggersrelease of thephosphate group.

Binding of cytoplasmicNa+ to the pump proteinstimulates phosphorylationby ATP.Na+

Na+

Na+

Na+Na+

K+K+

K+

K+

Na+

Na+

Na+

ATPP

P

Na+

Na+Na+

K+

K+

P

Pi

K+

K+

Active Transport

Uses ATP to move solutes across a membraneRequires carrier proteins

Types of Active Transport

Symport system – two substances are movedacross a membrane in the same direction

Antiport system – two substances are movedacross a membrane in opposite directions

Types of Active Transport

Primary active transport – hydrolysis of ATPphosphorylates the transport protein causingconformational change

Secondary active transport – use of anexchange pump (such as the Na+-K+ pump)indirectly to drive the transport of other solutes[ATP-ASE]

Types of Active Transport

Figure 3.11

Vesicular Transport

Transport of large particles and macromoleculesacross plasma membranes

Exocytosis – moves substance from the cell interior to theextracellular space

Endocytosis – enables large particles and macromolecules toenter the cell

Vesicular Transport

Transcytosis – moving substances into, across, andthen out of a cell

Vesicular trafficking – moving substances fromone area in the cell to another

Phagocytosis – pseudopods engulf solids and bringthem into the cell’s interior

Vesicular Transport

Fluid-phase endocytosis – the plasma membraneinfolds, bringing extracellular fluid and solutes intothe interior of the cell

Receptor-mediated endocytosis – clathrin-coated pits provide the main route forendocytosis and transcytosis

Non-clathrin-coated vesicles – caveolae that areplatforms for a variety of signaling molecules

Exocytosis

Figure 3.12a

Clathrin-Mediated Endocytosis

Figure 3.13a

Recycling ofmembrane andreceptors (if present)to plasma membrane

CytoplasmExtracellularfluid

Extracellularfluid

Plasmamembrane

Detachmentof clathrin-coatedvesicle

Clathrin-coatedvesicle

Uncoating

Uncoatedvesicle

Uncoatedvesiclefusing withendosome

To lysosomefor digestionand releaseof contents

Transcytosis

Endosome

Exocytosisof vesiclecontents

Clathrin-coatedpit

Plasmamembrane

Ingestedsubstance

Clathrinprotein

(a) Clathrin-mediated endocytosis

2

1

3

Phagocytosis

Figure 3.13b

Receptor Mediated Endocytosis

Figure 3.13c

Passive Membrane Transport – Review

Process Energy Source Example

Simple diffusion Kinetic energy Movement of O2 throughmembrane

Facilitateddiffusion Kinetic energy Movement of glucose into cells

Osmosis Kinetic energy Movement of H2O in & out ofcells

Filtration Hydrostaticpressure Formation of kidney filtrate

Active Membrane Transport – Review

Process Energy Source Example

Active transport of solutes ATP Movement of ions acrossmembranes

Exocytosis ATP Neurotransmitter secretion

Endocytosis ATP White blood cellphagocytosis

Fluid-phase endocytosis ATP Absorption by intestinal cells

Receptor-mediatedendocytosis ATP Hormone and cholesterol

uptake

Endocytosis via caveoli ATP Cholesterol regulation

Endocytosis via coatomervesicles ATP Intracellular trafficking of

molecules

Membrane Potential

Voltage across a membraneResting membrane potential – the point where K+

potential is balanced by the membrane potential Ranges from –20 to –200 mV Results from Na+ and K+ concentration gradients

across the membrane Differential permeability of the plasma membrane to Na+

and K+

Steady state – potential maintained by activetransport of ions

Generation and Maintenance of Membrane Potential

InterActive Physiology ®:Nervous System I: The Membrane Potential

Figure 3.15

Cell Adhesion Molecules (CAMs)

Anchor cells to the extracellular matrix Assist in movement of cells past one anotherRally protective white blood cells to injured or

infected areas

Roles of Membrane Receptors

Contact signaling – important in normaldevelopment and immunityElectrical signaling – voltage-regulated “ion

gates” in nerve and muscle tissueChemical signaling – neurotransmitters bind

to chemically gated channel-linked receptors innerve and muscle tissueG protein-linked receptors – ligands bind to a

receptor which activates a G protein, causing therelease of a second messenger, such as cyclic AMP

Operation of a G Protein

An extracellular ligand (first messenger), binds to aspecific plasma membrane protein The receptor activates a G protein that relays the

message to an effector protein

Operation of a G Protein

The effector is an enzyme that produces a secondmessenger inside the cell The second messenger activates a kinase The activated kinase can trigger a variety of cellular

responses

Operation of a G Protein

Figure 3.16

Extracellular fluid

Cytoplasm

Inactivesecondmessenger

Cascade of cellular responses(metabolic and structural changes)

Effector(e.g., enzyme)

Activated(phosphorylated)kinases

First messenger(ligand)

Activesecondmessenger(e.g., cyclicAMP)

Membranereceptor

G protein

1

2

3 4

5

6

Cytoplasm

Cytoplasm – material between plasma membraneand the nucleus

Cytosol – largely water with dissolved protein, salts,sugars, and other solutes

The cytosol (cf. cytoplasm, which also includes the organelles) is theinternal fluid of the cell, and where a portion of cell metabolism occurs.Proteins within the cytosol play an important role in signal transductionpathways and glycolysis. They also act as intracellular receptors and formpart of the ribosomes, enabling protein synthesis.

Cytoplasm

Cytoplasmic organelles – metabolic machinery of thecell Inclusions – chemical substances such as

glycosomes, glycogen granules, and pigment

Cytoplasmic Organelles

Specialized cellular compartmentsMembranous Mitochondria, peroxisomes, lysosomes, endoplasmic

reticulum, and Golgi apparatus

Nonmembranous Cytoskeleton, centrioles, and ribosomes

Mitochondria

Doublemembranestructure withshelf-like cristaeProvide most of

the cell’s ATP viaaerobic cellularrespirationContain their

own DNA andRNA

Mitochondria

Figure 3.17a, b

Ribosomes

Granules containing protein and rRNA Site of protein synthesis Free ribosomes synthesize soluble proteinsMembrane-bound ribosomes synthesize proteins to

be incorporated into membranes

Endoplasmic Reticulum (ER)

Interconnected tubes and parallel membranesenclosing cisternae Continuous with the nuclear membrane Two varieties – rough ER and smooth ER

Endoplasmic Reticulum (ER)

Figure 3.18a, c

Rough (ER)

External surface studded with ribosomesManufactures all secreted proteinsResponsible for the synthesis of integral membrane

proteins and phospholipids for cell membranes

Signal Mechanism of Protein Synthesis

The protein folds into a three-dimensionalconformation The protein is enclosed in a transport vesicle and

moves toward the Golgi apparatus

Signal Mechanism of Protein Synthesis

Figure 3.19

Cytosol

Ribosomes

mRNA

Coatomer-coatedtransportvesicle

Transportvesiclebudding off

Releasedglycoprotein

ERcisterna

ERmembrane

Signal-recognitionparticle(SRP)

Signalsequence

Receptorsite

Sugargroup

SignalsequenceremovedGrowing

polypeptide

1

2

34

5

Smooth ER

Tubules arranged in a looping network Catalyzes the following reactions in various organs

of the body In the liver – lipid and cholesterol metabolism, breakdown of

glycogen and, along with the kidneys, detoxification of drugs In the testes – synthesis of steroid-based hormones

Smooth ER

Catalyzes the following reactions in various organsof the body (continued) In the intestinal cells – absorption, synthesis, and transport

of fats In skeletal and cardiac muscle – storage and release of

calcium

Cytosolic Protein Degradation

Nonfunctional organelle proteins are degraded bylysosomesUbiquitin attaches to soluble proteins and they are

degraded in proteasomes

Extracellular Materials

Body fluids and cellular secretions Extracellular matrix

Developmental Aspects of Cells

All cells of the body contain the same DNA butdevelop into all the specialized cells of the body Cells in various parts of the embryo are exposed to

different chemical signals that channel them intospecific developmental pathways

Developmental Aspects of Cells

Genes of specific cells are turned on or off (i.e., bymethylation of their DNA) Cell specialization is determined by the kind of

proteins that are made in that cell

Developmental Aspects of Cells

Development of specific and distinctive features incells is called cell differentiation Cell aging Wear and tear theory attributes aging to little chemical insults

and formation of free radicals that have cumulative effectsthroughout life

Genetic theory attributes aging to cessation of mitosis that isprogrammed into our genes

Golgi Apparatus

Stacked and flattened membranous sacs Functions in modification, concentration, and

packaging of proteins Transport vessels from the ER fuse with the cis face

of the Golgi apparatus

Golgi Apparatus

Proteins then pass through the Golgi apparatus to thetrans face Secretory vesicles leave the trans face of the Golgi

stack and move to designated parts of the cell

Golgi Apparatus

Figure 3.20a

Cell trafficking Golgi is the distribution center forproteins and lipids from the ER to the vesicles andplasma membrane.Modifies N-oligosaccharides on asparagine.Adds O-oligosaccharides on serine andthreonine.Adds mannose-6-phosphate to proteins fortrafficking to lysosomes.

Endosomes are sorting centers for material fromoutside the cell or from the Golgi, sending it tolysosomes for destruction or back to themembrane/Golgi for further use.

Role of the Golgi Apparatus

Figure 3.21

Secretion by exocytosisExtracellular fluid

Plasma membrane

Vesicle incorporatedinto plasma membrane

Coatomercoat

Lysosomes containing acidhydrolase enzymes

PhagosomeProteins in cisterna

Membrane

Vesicle

Pathway 3

Pathway 2

Secretory vesicles

Proteins

Pathway 1

Golgiapparatus

CisternaRough ER

Lysosomes

Spherical membranous bags containing digestiveenzymesDigest ingested bacteria, viruses, and toxinsDegrade nonfunctional organelles Breakdown glycogen and release thyroid hormone

Lysosomes

Breakdown nonuseful tissue Breakdown bone to release Ca2+

Secretory lysosomes are found in white blood cells,immune cells, and melanocytes

I-cell disease (inclusion cell disease/mucolipidosis type II)—inherited lysosomal storagedisorder; failure of the Golgiproteins are secreted extracellularly rather than delivered to lysosomes. Results in coarsefacial features, clouded corneas, restricted joint movement, and high plasma levels oflysosomal enzymes. Often fatal in childhood.

Endomembrane System

System of organelles that function to: Produce, store, and export biological molecules Degrade potentially harmful substances

System includes: Nuclear envelope, smooth and rough ER, lysosomes, vacuoles,

transport vesicles, Golgi apparatus, and the plasmamembrane

PLAY Endomembrane System

Endomembrane System

Figure 3.23

Peroxisomes

Membranous sacs containing oxidases and catalasesDetoxify harmful or toxic substancesNeutralize dangerous free radicals Free radicals – highly reactive chemicals with unpaired electrons (i.e., O2

–) Peroxisome Membrane-enclosed organelle involved in catabolism of very-long-

chain fatty acids (through β-oxidation), branched-chain fatty acids, amino acids,and ethanol.

Barrel-shaped protein complex that degrades damaged or ubiquitin-tagged proteins.

Defects in the ubiquitin-proteasome system have been implicated insome cases of Parkinson disease.

Proteasome

Cytoskeleton

The “skeleton” of the cellDynamic, elaborate series of rods running through

the cytosol Consists of microtubules, microfilaments, and

intermediate filaments

Cytoskeleton

Figure 3.24a-b

Cytoskeleton

Figure 3.24c

Microtubules

Dynamic, hollow tubes made of the spherical proteintubulinDetermine the overall shape of the cell and

distribution of organelles

Microfilaments

Dynamic strands of the protein actin Attached to the cytoplasmic side of the plasma

membrane Braces and strengthens the cell surface Attach to CAMs and function in endocytosis and

exocytosis

Intermediate Filaments

Tough, insoluble protein fibers with high tensilestrengthResist pulling forces on the cell and help form

desmosomes

Motor Molecules

Protein complexes that function in motility Powered by ATP Attach to receptors on organelles

Motor Molecules

Figure 3.25a

Motor Molecules

Figure 3.25b

Centrioles

Small barrel-shaped organelles located in thecentrosome near the nucleus Pinwheel array of nine triplets of microtubulesOrganize mitotic spindle during mitosis Form the bases of cilia and flagella

Centrioles

Figure 3.26a, b

Cilia

Whip-like, motile cellular extensions on exposedsurfaces of certain cellsMove substances in one direction across cell surfaces

PLAY Cilia and Flagella

Cilia

Figure 3.27a

Cilia

Figure 3.27b

Cilia

Figure 3.27c

Nucleus

Contains nuclear envelope, nucleoli, chromatin, anddistinct compartments rich in specific protein setsGene-containing control center of the cell Contains the genetic library with blueprints for

nearly all cellular proteinsDictates the kinds and amounts of proteins to be

synthesized

Nucleus

Figure 3.28a

Nuclear Envelope

Selectively permeable double membrane barriercontaining pores Encloses jellylike nucleoplasm, which contains

essential solutes

Nuclear Envelope

Outer membrane is continuous with the rough ERand is studded with ribosomes Inner membrane is lined with the nuclear lamina,

which maintains the shape of the nucleus Pore complex regulates transport of large molecules

into and out of the nucleus

Nucleoli

Dark-staining spherical bodies within the nucleus Site of ribosome production

Chromatin

Threadlike strandsof DNA andhistonesArranged in

fundamental unitscalled nucleosomesForm condensed,

barlike bodies ofchromosomeswhen the nucleusstarts to divide

Figure 3.29

The double helix of DNA has these features:It contains two polynucleotide strands wound around each

other.

The backbone of each consists of alternating deoxyribose andphosphate groups.

The phosphate group bonded to the 5' carbon atom of onedeoxyribose is covalently bonded to the 3' carbon of the next.

The two strands are "antiparallel"; that is, one strand runs 5′to 3′ while the other runs 3′ to 5′.

The DNA strands are assembled in the 5′ to 3′ direction and,by convention, we "read" them the same way.

The purine or pyrimidine attached to each deoxyriboseprojects in toward the axis of the helix.

Each base forms hydrogen bonds with the one directlyopposite it, forming base pairs (also called nucleotide pairs)

In DNA, four different bases are found:•two purines, called adenine (A) and guanine (G)

•two pyrimidines, called thymine (T) and cytosine (C)

RNA contains:•The same purines, adenine (A) and guanine (G).

RNA also uses the pyrimidine cytosine (C), but instead ofthymine, it uses the pyrimidine uracil (U).

DNA Replication

DNA helices begin unwinding from the nucleosomesHelicase untwists the double helix and exposes

complementary strands The site of replication is the replication bubble Each nucleotide strand serves as a template for

building a new complementary strand

DNA Replication

The replisome uses RNA primers to begin DNAsynthesisDNA polymerase III continues from the primer and

covalently adds complementary nucleotides to thetemplate

PLAY DNA Replication

DNA Replication

Since DNA polymerase only works in one direction: A continuous leading strand is synthesized A discontinuous lagging strand is synthesized DNA ligase splices together the short segments of the

discontinuous strand

Two new telomeres are also synthesized This process is called semiconservative replication

DNA Replication

Figure 3.31

Cell Division

Essential for body growth and tissue repair

Mitosis – nuclear division

Cytokinesis – division of the cytoplasm

Mitosis

G1

E R I CN I E D E R H O F F E R

S I U - S O M

Cell Cycle

G0

6-8 hDNA, RNA,Protein

3-4 h

RNA, Protein

1 h

Mitosis, Cytokinesis

S

G2 Cyc D’sCDK4,6

Cyc B/ACDK1

Cyc ACDK2

M

Cyc ECDK2

6-12 h RNA, Protein

p53pRb

LaminH1Abl

Mitosis

The phases of mitosis are: Prophase Metaphase Anaphase Telophase

Cytokinesis

Cleavage furrow formed in late anaphase bycontractile ring Cytoplasm is pinched into two parts after mitosis

ends

Early and Late Prophase

Asters are seen as chromatin condenses intochromosomesNucleoli disappear Centriole pairs separate and the mitotic spindle is

formed

Early Prophase

Figure 3.32.2

Late Prophase

Figure 3.32.3

Metaphase

Chromosomes cluster at the middle of the cell withtheir centromeres aligned at the exact center, orequator, of the cell This arrangement of chromosomes along a plane

midway between the poles is called the metaphaseplate

Metaphase

Figure 3.32.4

Anaphase

Centromeres of the chromosomes splitMotor proteins in kinetochores pull chromosomes

toward poles

Anaphase

Figure 3.32.5

Telophase and Cytokinesis

New sets of chromosomes extend into chromatinNew nuclear membrane is formed from the rough ERNucleoli reappearGenerally cytokinesis completes cell division

Telophase andCytokinesis

Figure 3.32.6

Figure 3.30

Cell Cycle

Interphase Growth (G1),

synthesis (S),growth (G2)

Mitotic phase Mitosis and

cytokinesis

Interphase

G1 (gap 1) – metabolic activity and vigorous growthG0 – cells that permanently cease dividing S (synthetic) – DNA replicationG2 (gap 2) – preparation for division

PLAY Late Interphase