CAMPBELL AND REECE

Chapter 6A Tour of the Cell

Cell Theory

All living organisms are made of cellsCells are the smallest unit of structure &

function in living organismsAll cells come from other cells

Microscopes

1665: Hooke sees cell walls

Anton van Leewenhoek

made best lenses of his day

pond water: animalcules

Light Microscopy

light goes through specimen and is refracted by glass lenses so image is magnified as it is projected toward eye

magnification: ratio of image size to real size

resolution: a measure of clarity , the minimum distance 2 pts can be separated & seen as 2 pts (can’t do better than 200 nm)

contrast: accentuate pts in different parts of specimen

Light Microscopy

TEM SEM

beam e- thru specimen

beam e- across surfaces

Electron Microscopy

Size Range of Cells

Cell Fractionation

Common to all cells

1. cytosol2. ribosomes3. DNA4. plasma membrane

Prokaryotic Cell Eukaryotic Cell

DNA concentrated in nucleoid

smallersimpler(-) internal

membranesolderasexual

reproduction

DNA in nucleuslarger more complex(+) internal

membranesasexual or sexual

reproduction

Compare & Contrast

ProkaryoticNucleoid

EukaryoticNucleus

Images

Cell Size Limitations

Prokaryotic Cell Details

Eukaryotic Cell Details: Plant Cell

Eukaryotic Cell Detail: Animal Cell

Nucleus

contains most of the DNA5 microns across on averageenclosed by dbl membrane: nuclear

envelope

Chromatin

Nucleus Nucleolus

Nucleolus

Ribosomes

rRNA & proteinscarry out protein synthesisfree ribosomes or ribosomes embedded

in membranepolysomes: string of ribosomes

Ribosomes Polysomes

Anatomy of a Ribosome

The Endomembrane System

includes all membranes in cellnuclear envelopeEndoplasmic reticulumGolgi apparatusvesicles, vacuoles lysosomesplasma membrane

http://www.google.com/imgres?q=endomembrane+structure&hl=en&biw=1366&bih=499&tbm=isch&tbnid=76flkeXqTwmh1M:&imgrefurl=http://endomembrane.wikispaces.com/&docid=gNDcCN4ctEk3jM&imgurl=http://endomembrane.wikispaces.com/file/view/002.JPG/101480769/576x298/002.JPG&w=576&h=298&ei=C0JeUJXvKIKC8ATyvICgBg&zoom=1&iact=hc&vpx=591&vpy=209&dur=4560&hovh=161&hovw=312&tx=149&ty=110&sig=102733850649124752380&page=2&tbnh=114&tbnw=221&start=12&ndsp=18&ved=1t:429,r:15,s:12,i:159

The Endomembrane System

functions:synthesis of proteins (ribosomes in

membrane) transport of proteins into membranes

& organelles (or out of cell)movement of lipids detoxification of poisonsall membranes “related” either by

proximity or by transfer of membrane segments via vesicles

The Endomembrane System

Endoplasmic Reticulum

>50% of membrane in a cell“endoplasmic” means within the

cytoplasm“reticulum” means little netmade of network of tubules & sacs

Endoplasmic Reticulum

cisternae spaces contiguous with nuclear envelope

RER & SER Contiguous

RER

ribosomes on outer surface of membranemost proteins made shipped out of cellas polypeptide grows (into cisternae) it

folds into its 2’ then 3’ structuremost secretory proteins are glycoproteins

so that carbohydrate attachment is done by enzymes in RER membrane

RER

protein made for use in cytosol kept separate from those meant for export

transport vesicles carry new secretory protein/glycoprotein away from RER

Secretory Vesicles

SER

functions: lipid synthesismetabolism of carbohydratesdetoxification of drugs & poisonsstorage of Ca++ (muscle fibers)

SER

cells with lots SER: endocrine glands

synthesize steroid hormonesovaries, testes, adrenals

hepatocytes detoxify by adding –OH, increases solubility cleared by kidneys

alcohol, drug abusers (legal or not) have increased amts of SER in their hepatocytes (also increases drug tolerance)

Detox by SER

SER Stores Ca++ in Muscle Fibers

Golgi Apparatus

receives, sorts, packages, ships also does a little modifying of proteinsextensive in cells that secrete made of flattened membranous sacs with

a curve (has directionality cis & trans)internal space = cisternae

Golgi Apparatus

Golgi Apparatus

ER products modified on trip thru Golgicisternae membrane has unique

“team”of enzymes that moves from cis to trans

modifies the monomers in carb part of glycoproteins

modifies phospholipids destined for membrane

makes some macromolecules: polysaccharides

Golgi Apparatus

Golgi Apparatus Vesicles

when leave trans vesicles have molecular ID tags that indicates where they are going

vesicles have receptor proteins on external surface that “recognize” where vesicle is supposed to dock (other organelles, plasma membrane)

Lysosomes

membranous sac filled with hydrolytic enzymes

digests macromolecules use acidic pHmade in RER Golgi cytosol

Lysosome Functions

digest food vacuoles ingested by phagocytosis in protists or by macrophages (WBCs that ingest bacteria or debris and recycle nutrients in them)

autophagy: hydrolytic enzymes in lysosomes recycle cell’s own organic material in worn out organelles

http://www.google.com/imgres?q=cell+biology+cartoons&start=130&hl=en&biw=1366&bih=499&tbm=isch&tbnid=ask5vj79u6_XJM:&imgrefurl=http://www.ascb.org/index.php?option=com_content&view=article&id=877&Itemid=361&docid=pXPawxVv0F67gM&imgurl=https://www.ascb.org/meetings/images/CellDance2012Poster.png&w=800&h=1200&ei=LxhfUJeQJon68QShtIDADg&zoom=1&iact=hc&vpx=398&vpy=95&dur=798&hovh=275&hovw=183&tx=91&ty=179&sig=102733850649124752380&page=8&tbnh=152&tbnw=117&ndsp=18&ved=1t:429,r:8,s:130,i:156

Lysosomes

Lysosmes

Lysosomal Storage Diseases

autosomal recessive diseaseslack a functioning hydrolytic enzyme

whatever that enzyme would have chemically broken down builds up in lysosome (called a residual body) lysosomes fill up interferes with cell functions example: Tay Sachs disease

lipid-digesting enzyme malfunction affects neurons autosomal recessive

Vacuoles

are large vesicles from ER or Golgisolution inside different from cytosol due

to its selectively permeable membraneTypes:

food vacuolescontractile vacuoles

remove excess water in plant cells act like

lysosomes storage bins

Large Central Vacuoles in Plant Cells

develops by coalescence of smaller vacuoles

solution inside it called cell sap

http://www.google.com/imgres?q=cell+biology+cartoons&start=130&hl=en&biw=1366&bih=499&tbm=isch&tbnid=-oh5VRXkoHE3SM:&imgrefurl=http://franczyk.yolasite.com/&docid=OggVq4sIwRNkuM&imgurl=http://franczyk.yolasite.com/resources/Cartoon.gif&w=240&h=286&ei=LxhfUJeQJon68QShtIDADg&zoom=1&iact=hc&vpx=112&vpy=142&dur=8377&hovh=228&hovw=192&tx=82&ty=158&sig=102733850649124752380&page=8&tbnh=152&tbnw=128&ndsp=18&ved=1t:429,r:6,s:130,i:150

Endosymbiont Theory

early ancestor of eukaryotic cells engulfed an oxygen-using nonphotosynthetic prokaryotic cell = mitochondrion

over time prokaryotic cell became an endosymbiont (a cell living w/in another cell)

some time later some or 1 of these engulfed a photosynthetic prokaryotic cell and developed same relationship = chloroplast

Endosymbiosis Theory

Mitochondria

in nearly all cells, 1- 10 microns# correlates with metabolic activity of celldbl membraneinner membrane folded (cristae) & divides

mitochondria into 2 separate inner compartments (intermembrane space & matrix)

matrix contains enzymes for cellular respiration, DNA, ribosomes

cristae has enzymes that make ATP

Mitochondrion Structure

Chloroplasts

a plastiddbl membrane separates inside 2 parts3-6 micronsin green parts of plants (chlorophyll)thylakoids: inner membrane folds in disc-

shapes: 1 stack of discs = granumfluid in inner folds = stroma

Plastids

group of plant organelles other examples:1. amyloplast

colorless in roots & tubers stores starch

2. chromoplast1. pigments that give fruits & flowers

their colors

http://www.google.com/imgres?q=chloroplasts&hl=en&biw=1366&bih=499&tbm=isch&tbnid=_UIt3N_3UO9ehM:&imgrefurl=http://www.s-cool.co.uk/a-level/biology/cells-and-organelles/revise-it/organelles&docid=xm5Q_LHjYa1H3M&imgurl=http://www.s-cool.co.uk/a-level/assets/learn_its/alevel/biology/cells-and-organelles/organelles/chloroplast-b.gif&w=400&h=261&ei=NitfUN2gC4OS9QTuxoGgAw&zoom=1&iact=hc&vpx=92&vpy=184&dur=5351&hovh=181&hovw=278&tx=125&ty=109&sig=102733850649124752380&page=2&tbnh=121&tbnw=186&start=13&ndsp=18&ved=1t:429,r:0,s:13,i:181

Peroxisomes

specialized metabolic compartment with 1 membrane

contain enzymes that remove H atoms from various molecules to O2 H2O2

H2O2 2 H2O by enzymes in liver peroxisomes

functions:break down fatty acids in hepatocytes detoxify alcohol,

poisons

Glyoxysomes

specialized peroxisomes in fat-storing tissues of plant seeds

contain enzymes that start catabolism of fatty acids sugars

seed uses these sugars for energy to plant

http://www.google.com/imgres?q=peroxisomes&hl=en&biw=1366&bih=499&tbm=isch&tbnid=0wOpUY_6xRQxvM:&imgrefurl=http://course1.winona.edu/sberg/308s09/Lec-note/IntracellularCompB.htm&docid=E71WYH744Y7bqM&imgurl=http://course1.winona.edu/sberg/ILLUST/peroxisomeCartoon.gif&w=362&h=360&ei=CTFfUOSIN-nu0gH0g4HADg&zoom=1&iact=hc&vpx=429&vpy=146&dur=7752&hovh=224&hovw=225&tx=126&ty=132&sig=102733850649124752380&page=2&tbnh=140&tbnw=141&start=14&ndsp=19&ved=1t:429,r:8,s:14,i:209

Cytoskeleton

organizes the structure & activities of a cell

3 types:1. Microtubules2. Microfilaments3. Intermediate Filaments

Functions of the Cytoskeleton

1. mechanical support2. maintain cell shape3. provides anchor for organelles & cytosol

enzymes4. cell motility

Cytoskeleton & Cell Motility

involves interaction between cytoskeleton & motor proteinsboth work with plasma membrane to

move cellmake flagella or cilia movemuscle fiber contractionmigration of neurotransmitter vesicles

to axon tips

Motor Protein Animation

https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1WLXB_enUS512US585&ion=1&espv=2&ie=UTF-8#q=motor%20protein%20animation

Types of Cytoskeleton

Cell Surface Projections Formed by Cytoskeleton

http://www.sinauer.com/cooper5e/micrograph1202.html

Microvilli

https://www.youtube.com/watch?v=iK8MOA32vAY

Cytoskeleton Animation

http://www.bmc.med.utoronto.ca/bmc/images/stories/videos/eddy_xuan.mov

Microtubules

in all eukaryotic cellshollow rods 25 nm across, 200 nm – 25

microns longmade from a globular protein: tubulin, a

dimer (made of 2 subunits)

Microtubules

Assembly of Microfilaments

http://sites.sinauer.com/cooper6e/animation1203.html

Microtubule Functions

shape & support cell (compression-resistant role)

serve as tracks other organelles with motor proteins can move along

guide secretory vesicles from Golgi plasma membrane

in mitotic spindle to separate chromosomes

in animal cells: microtubules made in centrosome

Centrioles

pair w/in each centrosomeeach made of 9 sets of triplet

microtubulesonly in animal cells

Centrioles

https://vimeo.com/58347006

Cilia

locomotor appendage on some cellsmove fluid over surfaceare usually many on cell surface0.25 microns across & 2 – 20 microns

longmove like oars (alternating power

/recovery strokes)generate force perpendicular to cilium’s

axis

Cilia & Flagella Structure

locomotor appendage share common structure with cilia: 9

doublets of microtubules in ring with 2 single microtubules in center then covered with plasma membrane

Cilia & Flagella Structure

dyneins: large motor proteins extending from one microtubule doublet to adjacent doublet

ATP hydrolysis drives changes in dynein shape so cilia or flagella bend

Flagella & Cilia Animation

http://biology-animations.blogspot.com/2008/02/flagell-and-cilia-animation-video.html

Microfilaments

are really actin: globular protein that links with others into chains, which twist helically around each other, forming microfilaments

in all eukaryotic cellsfunction: bears tensionmany found just inside plasma

membrane (support cell shape) which gives cytosol gel-like consistency just inside plasma membrane

make up core of microvilli

Microfilaments

with myosin (another contractile protein) make muscle fibers contractAmoeboid movement (pseudopods)

Intermediate Filaments

8 – 12 nm acrosstension bearingnot assembled/disassembled like

microtubules & microfilamentsmade of proteins, one is keratinline interior of nuclear envelope, axonssupport framework of cell shape

Intermediate Filaments

Extracellular

materials made by cell but put into extracellular space:

Cell WallExtracellular MatrixCell Junctions

Plant Cell Walls

functions:protectionmaintains shapeprevents excessive uptake of waterDetailsexact chemical composition varies

from species to speciesall have microfibrils made of cellulose

Plant Cell Wall Basic Design

Plant Cell Walls

secreted by cell membraneyoung plant cell secretes primary cell

wall: thin, flexiblemiddle lamella: lies between primary

cell walls of adjacent cells made of pectin: glues adjacent cells together

Plant Cell Walls

when cell stops growing either:1. secrete hardening substances into

primary wall2. secrete a secondary wall between

plasma membrane & primary cell wall has strong & durable matrix wood is mostly secondary cell wall

Primary & Secondary Cell Walls

Extracellular Matrix (ECM)

in animals main ingredient: glycoproteins

collagen embedded in proteoglycans (protein with many carbohydrates attached) 40% of all the protein in human body is collagen

ECM

fibronectin: ECM glycoprotein binds to cell-surface receptor proteins called integrins

integrins: span plasma membrane transmitting signals from ECM microfilaments on inner border of plasma membrane

ECM

Cell Junctions

1. plasmodesmata: perforations in plant cell walls lined with plasma membrane, filled with cytoplasm

cytosol flows from cell to cell plasma membranes of adjacent

cells contiguous

Plasmodesmata

Cell Junctions in Animal Cells

3 main types1. Tight Junctions

plasma membranes of adjacent cells tightly pressed against each other

bound together by proteins form continuous seal around cell example: tight jcts around skin cells

make skin water proof

Tight Junctions

Cell Junctions in Animal Cells

2. Desmosomes function like rivets fastens cells together anchored in cytoplasm by

intermediate filamentsexample: attach muscle cells to each

other

Desmosomes

Cell Junctions in Animal Cells

3. Gap Junctionscytoplasmic channels from 1 cell to

anothermade of membrane proteins that

surround a pore open to ions, sugars, a.a.

necessary for communication between cells like cardiac muscle and in animal embryos

Gap Junctions

Cell Animation

http://vcell.ndsu.nodak.edu/animations/flythrough/movie-flash.htm