part i: cells

PART I: CELLS

Textbook pages 65-74

PowerPoint® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

PART A3

Cells and Tissues

Cells and Tissues

• Carry out all chemical activities needed to sustain life

• Cells are the building blocks of all living things• Tissues are groups of cells that are similar in

structure and function

Anatomy of the Cell

• Cells are not all the same• All cells share general structures• All cells have three main regions– Nucleus– Cytoplasm– Plasma membrane

Figure 3.1a

The Nucleus

• Control center of the cell– Contains genetic material (DNA)

• Three regions– Nuclear envelope (membrane)– Nucleolus– Chromatin

The Nucleus

Figure 3.1b

The Nucleus

• Nuclear envelope (membrane) – Barrier of the nucleus– Consists of a double membrane– Contains nuclear pores that allow for exchange of

material with the rest of the cell

The Nucleus

• Nucleoli– Nucleus contains one or more nucleoli– Sites of ribosome assembly– Ribosomes migrate into the cytoplasm through

nuclear pores

The Nucleus

• Chromatin – Composed of DNA and protein– Present when the cell is not dividing– Scattered throughout the nucleus– Condenses to form chromosomes when the cell

divides

Plasma Membrane

• Barrier for cell contents• Double phospholipid layer– Hydrophilic heads– Hydrophobic tails

• Also contains proteins, cholesterol, and glycoproteins

Plasma Membrane

Figure 3.2

Plasma Membrane Specializations

• Microvilli– Finger-like projections that increase surface area

for absorption


• Membrane junctions– Tight junctions • Impermeable junctions • Bind cells together into leakproof sheets

– Desmosomes • Anchoring junctions that prevent cells from being

pulled apart– Gap junctions • Allow communication between cells


Figure 3.3

Cytoplasm

• Cytoplasm is the material outside the nucleus and inside the plasma membrane

Cytoplasm

• Contains three major elements– Cytosol• Fluid that suspends other elements

– Organelles• Metabolic machinery of the cell • “Little organs” that perform functions for the cell

– Inclusions• Chemical substances such as stored nutrients or cell

products

Cytoplasmic Organelles

Figure 3.4


• Mitochondria– “Powerhouses” of the cell– Change shape continuously– Carry out reactions where oxygen is used to break

down food– Provides ATP for cellular energy


• Ribosomes– Made of protein and RNA– Sites of protein synthesis– Found at two locations• Free in the cytoplasm• As part of the rough endoplasmic reticulum


• Endoplasmic reticulum (ER)– Fluid-filled tubules for carrying substances– Two types of ER• Rough endoplasmic reticulum

– Studded with ribosomes– Synthesizes proteins

• Smooth endoplasmic reticulum– Functions in lipid metabolism and detoxification of drugs and

pesticides

Rough Endoplasmic Reticulum

Figure 3.5

Ribosome

Protein

Protein insidetransport vesicle

Transportvesicle buds off

mRNA

Rough ER

As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern.

In the cistern, the protein foldsinto its functional shape. Shortsugar chains may be attachedto the protein (forming aglycoprotein).

The protein is packaged in atiny membranous sac called atransport vesicle.

The transport vesicle buds fromthe rough ER and travels to theGolgi apparatus for furtherprocessing or goes directly tothe plasma membrane where itscontents are secreted.


Figure 3.5, step 1

Ribosome

Protein

mRNA

Rough ER



Figure 3.5, step 2

Ribosome

Protein

mRNA

Rough ER




Figure 3.5, step 3

Ribosome

Protein


mRNA

Rough ER





Figure 3.5, step 4

Ribosome

Protein

Protein insidetransport vesicle


mRNA

Rough ER




The transport vesicle buds fromthe rough ER and travels to theGolgi apparatus for furtherprocessing or goes directly tothe plasma membrane where itscontents are secreted.


• Golgi apparatus– Modifies and packages proteins– Produces different types of packages• Secretory vesicles• Cell membrane components• Lysosomes

Figure 3.6Extracellular fluid

Plasma membrane

Golgi vesicle containingmembrane componentsfuses with the plasmamembrane

Golgi vesicle containingdigestive enzymesbecomes a lysosome

Proteins in cisterna

Lysosome fuses withingested substancesMembrane

Transportvesicle

Pathway 3

Pathway 2

Secretory vesicles Pathway 1

Golgiapparatus

Golgi vesicle containingproteins to be secretedbecomes a secretoryvesicle

Cisterna

Rough ER

Proteins

Secretion byexocytosis

Figure 3.6, step 1Extracellular fluid

Plasma membrane


Membrane

Golgiapparatus

Cisterna

Rough ER


Plasma membrane


Membrane

Transportvesicle

Golgiapparatus

Cisterna

Rough ER

Pathway 1


Plasma membrane


Membrane

Transportvesicle

Secretory vesicle Pathway 1

Golgiapparatus


Cisterna

Rough ER


Plasma membrane


Membrane

Transportvesicle


Golgiapparatus


Cisterna

Rough ER

Proteins



Plasma membrane


Membrane

Transportvesicle

Pathway 2Golgiapparatus

Cisterna

Rough ER


Plasma membrane


Membrane

Transportvesicle


Cisterna

Rough ER


Plasma membrane



Membrane

Transportvesicle


Cisterna

Rough ER


Plasma membrane


Membrane

Transportvesicle

Pathway 3

Golgiapparatus

Cisterna

Rough ER


Plasma membrane



Membrane

Transportvesicle

Pathway 3

Golgiapparatus

Cisterna

Rough ER


Plasma membrane




Transportvesicle

Pathway 3

Golgiapparatus

Cisterna

Rough ER


Plasma membrane





Transportvesicle

Pathway 3

Pathway 2


Golgiapparatus


Cisterna

Rough ER

Proteins



• Lysosomes– Contain enzymes that digest worn-out or

nonusable materials within the cell


• Peroxisomes– Membranous sacs of oxidase enzymes• Detoxify harmful substances such as alcohol and

formaldehyde• Break down free radicals (highly reactive chemicals)

– Replicate by pinching in half


• Cytoskeleton– Network of protein structures that extend

throughout the cytoplasm– Provides the cell with an internal framework

Figure 3.7a

Figure 3.7b–d

Cytoplasmic Organelles• Cytoskeleton– Three different types of

elements• Microfilaments (largest)• Intermediate filaments• Microtubules (smallest)


• Centrioles– Rod-shaped bodies made of microtubules– Direct the formation of mitotic spindle during cell

division

Cellular Projections

• Not found in all cells• Used for movement– Cilia move materials across the cell surface• Located in the respiratory system to move mucus

– Flagella propel the cell • The only flagellated cell in the human body is sperm

Cell Diversity

Figure 3.8a

Cell Diversity

Figure 3.8b

Cell Diversity

Figure 3.8c

Cell Diversity

Figure 3.8d

Cell Diversity

Figure 3.8e

Cell Diversity

Figure 3.8f

Cell Diversity

Figure 3.8g

Cell Physiology

Cell Physiology: Membrane Transport

• Membrane transport—movement of substances into and out of the cell

• Two basic methods of transport– Passive transport• No energy is required

– Active transport• Cell must provide metabolic energy (ATP)

Solutions and Transport

• Solution—homogeneous mixture of two or more components– Solvent—dissolving medium; typically water in the

body– Solutes—components in smaller quantities within

a solution• Intracellular fluid—nucleoplasm and cytosol• Interstitial fluid—fluid on the exterior of the

cell

Selective Permeability

• The plasma membrane allows some materials to pass while excluding others

• This permeability influences movement both into and out of the cell

Passive Transport Processes

• Diffusion– Particles tend to distribute themselves evenly within a

solution– Movement is

from high concentration to low concentration, or down a concentration gradient

Figure 3.9


• Types of diffusion– Simple diffusion• An unassisted process• Solutes are lipid-soluble materials or small enough to

pass through membrane pores


Figure 3.10a


• Types of diffusion (continued)– Osmosis—simple diffusion of water• Highly polar water molecules easily cross the plasma

membrane through aquaporins


Figure 3.10d


• Facilitated diffusion• Substances require a protein carrier for passive

transport• Transports lipid-insoluble and large substances


Figure 3.10b–c


• Filtration– Water and solutes are forced through a membrane

by fluid, or hydrostatic pressure– A pressure gradient must exist

• Solute-containing fluid is pushed from a high-pressure area to a lower pressure area

Active Transport Processes

• Substances are transported that are unable to pass by diffusion – Substances may be too large– Substances may not be able to dissolve in the fat

core of the membrane– Substances may have to move against a

concentration gradient• ATP is used for transport


• Two common forms of active transport– Active transport (solute pumping)– Vesicular transport• Exocytosis • Endocytosis

– Phagocytosis– Pinocytosis


• Active transport (solute pumping)– Amino acids, some sugars, and ions are

transported by protein carriers called solute pumps

– ATP energizes protein carriers– In most cases, substances are moved against

concentration gradients

Figure 3.11

Extracellular fluid

Cytoplasm

Loss of phosphate restoresthe original conformation ofthe pump protein. K+ isreleased to the cytoplasm andNa+ sites are ready to bind Na+

again; the cycle repeats.

Binding of cytoplasmic Na+

to the pump proteinstimulates phosphorylationby ATP, which causes thepump protein to change itsshape.

The shape change expelsNa+ to the outside.Extracellular K+ binds,causing release of thephosphate group.

ADP

Na+

Na+

Na+

Na+

Na+

Na+

K+

K+

K+

K+

P

PP

ATP

Figure 3.11, step 1

Extracellular fluid

Cytoplasm



ADP

Na+

Na+

Na+ P

ATP

Figure 3.11, step 2

Extracellular fluid

Cytoplasm




ADP

Na+

Na+

Na+

Na+

Na+

Na+

K+

K+

P

PP

ATP

Figure 3.11, step 3

Extracellular fluid

Cytoplasm

Loss of phosphate restoresthe original conformation ofthe pump protein. K+ isreleased to the cytoplasm andNa+ sites are ready to bind Na+

again; the cycle repeats.




ADP

Na+

Na+

Na+

Na+

Na+

Na+

K+

K+

K+

K+

P

PP

ATP


• Vesicular transport– Exocytosis• Moves materials out of the cell• Material is carried in a membranous vesicle• Vesicle migrates to plasma membrane• Vesicle combines with plasma membrane• Material is emptied to the outside

Active Transport Processes: Exocytosis

Figure 3.12a

Active Transport Processes: Exocytosis

Figure 3.12b


• Vesicular transport (continued)– Endocytosis• Extracellular substances are engulfed by being enclosed

in a membranous vescicle– Types of endocytosis• Phagocytosis—“cell eating”• Pinocytosis—“cell drinking”

Active Transport Processes: Endocytosis

Figure 3.13a

Recycling of membraneand receptors (if present)to plasma membrane

CytoplasmExtracellularfluid

Extracellularfluid

Plasmamembrane

Detachmentof vesicle

Vesicle containingingested material

Vesicle

Vesicle fusingwith lysosomefor digestion

Release ofcontents tocytoplasm

Lysosome

Transport to plasmamembrane andexocytosis ofvesicle contents

Plasmamembrane

Ingestedsubstance

Pit

(a)


Figure 3.13a, step 1


Extracellularfluid

Plasmamembrane

Plasmamembrane

Ingestedsubstance

Pit

(a)




Extracellularfluid

Plasmamembrane



Plasmamembrane

Ingestedsubstance

Pit

(a)




Extracellularfluid

Plasmamembrane



Vesicle


Lysosome

Plasmamembrane

Ingestedsubstance

Pit

(a)




Extracellularfluid

Plasmamembrane



Vesicle



Lysosome

Plasmamembrane

Ingestedsubstance

Pit

(a)




Extracellularfluid

Plasmamembrane



Vesicle



Lysosome


Plasmamembrane

Ingestedsubstance

Pit

(a)



Recycling of membraneand receptors (if present)to plasma membrane


Extracellularfluid

Plasmamembrane



Vesicle



Lysosome


Plasmamembrane

Ingestedsubstance

Pit

(a)


Figure 3.13b–c

Cell Life Cycle

• Cells have two major periods– Interphase• Cell grows• Cell carries on metabolic processes

– Cell division • Cell replicates itself• Function is to produce more cells for growth and repair

processes

DNA Replication

• Genetic material is duplicated and readies a cell for division into two cells

• Occurs toward the end of interphase• DNA uncoils and each side serves as a

template

DNA Replication

Figure 3.14

Events of Cell Division

• Mitosis—division of the nucleus– Results in the formation of two daughter nuclei

• Cytokinesis—division of the cytoplasm– Begins when mitosis is near completion– Results in the formation of two daughter cells

Stages of Mitosis

• Prophase– First part of cell division– Centrioles migrate to the poles to direct assembly

of mitotic spindle fibers– DNA appears as double-stranded chromosomes– Nuclear envelope breaks down and disappears

Stages of Mitosis

• Metaphase– Chromosomes are aligned in the center of the cell

on the metaphase plate

Stages of Mitosis• Anaphase– Chromosomes are pulled apart and toward the

opposite ends of the cell– Cell begins to elongate

Stages of Mitosis

• Telophase– Chromosomes uncoil to become chromatin– Nuclear envelope reforms around chromatin – Spindles break down and disappear

Stages of Mitosis

• Cytokinesis– Begins during late anaphase and completes during

telophase– A cleavage furrow forms to pinch the cells into

two parts

Stages of Mitosis

Figure 3.15

Centrioles

PlasmamembraneInterphase Early prophase Late prophase

NucleolusNuclearenvelope

Spindlepole

ChromatinCentrioles

Formingmitoticspindle

Centromere

Chromosome,consisting of twosister chromatids

Fragments ofnuclear envelope

CentromereSpindlemicrotubules

Metaphase Anaphase Telophase and cytokinesisDaughterchromosomes

Sisterchromatids

Nuclearenvelopeforming

NucleolusformingSpindleMetaphase

plate

Cleavagefurrow

Stages of Mitosis

Figure 3.15, step 1

Centrioles

Plasmamembrane

InterphaseNucleolus

Nuclearenvelope

Chromatin

Stages of Mitosis

Figure 3.15, step 2

Centrioles

Plasmamembrane

Interphase Early prophaseNucleolus

Nuclearenvelope

ChromatinCentrioles


Centromere


Stages of Mitosis

Figure 3.15, step 3

Centrioles

Plasmamembrane

Interphase Early prophase Late prophaseNucleolus

Nuclearenvelope

Spindlepole

ChromatinCentrioles


Centromere




Stages of Mitosis

Figure 3.15, step 4

Metaphase

Sisterchromatids

Spindle Metaphaseplate

Stages of Mitosis

Figure 3.15, step 5

Metaphase Anaphase

Daughterchromosomes

Sisterchromatids


Stages of Mitosis

Figure 3.15, step 6

Metaphase Anaphase Telophase and cytokinesis

Daughterchromosomes

Sisterchromatids


Nucleolusforming


Cleavagefurrow

Stages of Mitosis

Figure 3.15, step 7

Centrioles

PlasmamembraneInterphase Early prophase Late prophase

NucleolusNuclearenvelope

Spindlepole

ChromatinCentrioles


Centromere




Metaphase Anaphase Telophase and cytokinesisDaughterchromosomes

Sisterchromatids


NucleolusformingSpindleMetaphase

plate

Cleavagefurrow

Protein Synthesis

• Gene—DNA segment that carries a blueprint for building one protein

• Proteins have many functions– Building materials for cells– Act as enzymes (biological catalysts)

• RNA is essential for protein synthesis

Role of RNA

• Transfer RNA (tRNA)– Transfers appropriate amino acids to the ribosome

for building the protein• Ribosomal RNA (rRNA)– Helps form the ribosomes where proteins are built

• Messenger RNA (mRNA)– Carries the instructions for building a protein from

the nucleus to the ribosome

Transcription and Translation

• Transcription– Transfer of information from DNA’s base sequence

to the complimentary base sequence of mRNA– Three-base sequences on mRNA are called codons

Transcription and Translation

• Translation– Base sequence of nucleic acid is translated to an

amino acid sequence– Amino acids are the building blocks of proteins

Protein Synthesis

Figure 3.16

Nucleus(site of transcription)

DNA

mRNA specifyingone polypeptideis made onDNA template

mRNA leavesnucleus andattaches toribosome, andtranslationbegins

Synthetaseenzyme

Amino acids

Cytoplasm(site of translation)

Correct aminoacid attachedto each speciesof tRNA by anenzyme

Growing polypeptide chain

Nuclear pore

Nuclear membrane

mRNA

As the ribosomemoves along themRNA, a new aminoacid is added tothe growing proteinchain

Released tRNAreenters thecytoplasmicpool, ready tobe rechargedwith a newamino acid

Direction of ribosomeadvance; ribosome movesthe mRNA strand alongsequentially as each codonis read

Small ribosomalsubunit

Portion ofmRNA alreadytranslated

tRNA “head” bearinganticodon

Large ribosomal subunit

Peptide bond

Incoming tRNArecognizes acomplementarymRNA codon callingfor its amino acid bybinding via itsanticodon to thecodon

Codon

AlaPhe

Ser

GlyMet

C G G

GU UU C UCC AA G CCA U

Protein Synthesis

Figure 3.16, step 1


DNA



Nuclear pore

Nuclear membrane

mRNA

Protein Synthesis

Figure 3.16, step 2


DNA




Nuclear pore

Nuclear membrane

mRNA



Codon

U G CCA U

Protein Synthesis

Figure 3.16, step 3


DNA



Synthetaseenzyme

Amino acids


Correct aminoacid attachedto each speciesof tRNA by anenzymeNuclear pore

Nuclear membrane

mRNA



Codon

U G CCA U

Protein Synthesis

Figure 3.16, step 4


DNA



Synthetaseenzyme

Amino acids


Correct aminoacid attachedto each speciesof tRNA by anenzymeNuclear pore

Nuclear membrane

mRNA





Codon

U G CCA U

Protein Synthesis

Figure 3.16, step 5


DNA



Synthetaseenzyme

Amino acids




Nuclear pore

Nuclear membrane

mRNA






Peptide bond


Codon

AlaPhe

Ser

GlyMet

C G G

G C UC A G CCA U

Protein Synthesis

Figure 3.16, step 6


DNA



Synthetaseenzyme

Amino acids




Nuclear pore

Nuclear membrane

mRNA


Released tRNAreenters thecytoplasmicpool, ready tobe rechargedwith a newamino acid



Portion ofmRNA alreadytranslated



Peptide bond


Codon

AlaPhe

Ser

GlyMet

C G G

GU UU C UCC AA G CCA U

part i: cells

Documents

groups of cells

sameall cells

protein foldsinto

general structuresall

apartgap junctions

cell little organs

exchange of material

rough er cistern