AP Biology 2011-2012

Tour of the Cell 1

http://www.studiodaily.com/main

/searchlist/6850.html

AP Biology

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Cytology: science/study of cells

To view cells:Light microscopy

resolving power: measure of clarity

Electron microscopy – electron beam

TEM: to study cell internal ultrastructure

SEM: to study cell surfaces

AP Biology

To isolate organelles:

Cell fractionation: to separate major organelles

Ultracentrifuge: cell fractionation;

130,000rpm or 1,000,000 g

Cytology: science/study of cells

http://www.youtube.com/watch?v=8BnES4T1RDk

AP Biology

http://learn.genetics.utah.edu/content/begin/cells/scale/

AP Biology

Cell Size

http://learn.genetics.utah.edu/content/begin/cells/scale/

AP Biology

Cell Radius 1 2 3 4

SA (r2) 1 4 9 16

V (r3) 1 8 27 64

SA = 4 r2

V = 4/3 r3

SA/V (r2/r3) 1 1/2 1/3 1/4

Cell Size

V > SA

r Vand SA

r SA/V

AP Biology

Cell Size

As cell size increases, the SA to V ratio

decreases

Rates of chemical exchange may then be

inadequate for cell size

Cell size, therefore, remains small

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Prokaryote

bacteria cellsTypes of cells

Eukaryote

animal cells

- no organelles

- organelles

Eukaryote

plant cellshttp://www.yellowtang.org/animations/cell_features_v2.swf

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Cell Types: Prokaryotic

Nucleoid: DNA

concentration

No organelles with

membranes

Ribosomes:

protein synthesis

Plasma membrane:

(all cells); semi-permeable

Cytoplasm/cytosol (all cells)

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Cell types: Eukaryotic

Nucleus:membrane enclosed organelle

containing chromosomes

Membrane bound organelles of

specialized form and function

Generally larger than prokaryotic cells

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Why organelles? Specialized structures

specialized functions

cilia or flagella for locomotion

Containers

partition cell into compartments

create different local environments

separate pH, or concentration of materials

distinct & incompatible functions

lysosome & its digestive enzymes

Membranes as sites for chemical reactions

unique combinations of lipids & proteins

embedded enzymes & reaction centers

chloroplasts & mitochondria

mitochondria

chloroplast

Golgi

ER

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Cells must work to live! What jobs do cells have to do?

make proteins

proteins control every

cell function

make energy

for daily life

for growth

make more cells

growth

repair

renewal

AP Biology 2007-2008

Building Proteins

AP Biology

Proteins do all the work!

cells

DNA

proteins

organismRepeat after me…

Proteins do all the work!

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Cells functions Building proteins

read DNA instructions

build proteins

process proteins

folding

modifying

removing amino acids

adding other molecules

e.g, making glycoproteins

for cell membrane

address & transport proteins

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Building Proteins

Organelles involved

nucleus

ribosomes

endoplasmic reticulum (ER)

Golgi apparatus

vesicles

nucleus ribosome ERGolgi

apparatusvesicles

The Protein Assembly Line

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nuclearpores

nuclearpore

nuclear envelope

nucleolus

histone protein

chromosome

DNA

Function

protects DNA

Structure

nuclear envelope

double membrane

membrane fused in spots to create pores

allows large macromolecules to pass through

Nucleus

What kind of molecules need to

pass through?

AP Biology

DNA

NucleusmRNA

nuclearmembrane

smallribosomal

subunit

largeribosomal

subunit

cytoplasm

mRNA

nuclear pore

production of mRNA

from DNA in nucleus

mRNA travels from

nucleus to ribosome

in cytoplasm through

nuclear pore

1

2

http://www.dnalc.org/resources/3d/12-transcription-basic.html

http://www.dnalc.org/view/15481-Translation-RNA-to-

protein-3D-animation-with-no-audio.html

http://www.youtube.com/watch?v=I9ArIJWYZHI

http://www.youtube.com/watch?v=4jtmOZa

IvS0&feature=related

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AP Biology

Nucleolus

Function

ribosome production

build ribosome subunits from rRNA & proteins

exit through nuclear pores to cytoplasm &

combine to form functional ribosomes

smallsubunit

large subunit

ribosome

rRNA &proteins

nucleolus

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smallsubunit

largesubunitRibosomes

Function

protein production

Structure

rRNA & protein

2 subunits combine 0.08mm

Ribosomes

RoughER

SmoothER

AP Biology membrane proteins

Types of Ribosomes

Free ribosomes

suspended in cytosol

synthesize proteins that

function in cytosol

Bound ribosomes

attached to endoplasmic

reticulum

synthesize proteins

for export or

for membranes

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Endoplasmic Reticulum Function

processes proteins

manufactures membranes

synthesis & hydrolysis of many compounds

Structure

membrane connected to nuclear envelope &

extends throughout cell

http://www.youtube.com/watch?v=PUy_Em5dXmc

AP Biology

Types of ER

rough smooth

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Smooth ER function

Membrane production

Many metabolic processes

synthesis

synthesize lipids

oils, phospholipids, steroids & sex hormones

hydrolysis

hydrolyze glycogen into glucose

in liver

detoxify drugs & poisons

in liver

ex. alcohol & barbiturates

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Membrane Factory

Build new membrane

synthesize phospholipids builds membranes

ER membrane expands bud off & transfer

to other parts of cell that need membranes

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Rough ER function

Produce proteins for export out of cell

protein secreting cells

packaged into transport vesicles for export

Which cellshave lot of rough ER?

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Synthesizing proteins

cytoplasm

cisternalspace

mRNA

ribosome

membrane ofendoplasmic reticulum

polypeptide

signalsequence

ribosome

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Golgi Apparatus

Which cellshave lots of Golgi?

transport vesicles

secretoryvesicles

Function

finishes, sorts, tags & ships cell products

like ―UPS shipping department‖

ships products in vesicles

membrane sacs

―UPS trucks‖

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Golgi Apparatus

http://www.youtube.com/watch?v=rvfvRgk0MfA

http://www.dnatube.com/video/1594/Protein-Modification-Golgi

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Vesicle transport

vesiclebuddingfrom roughER

fusionof vesiclewith Golgiapparatus

migratingtransportvesicle

protein

ribosome

Regents Biology

DNA

RNA

ribosomes

endoplasmic

reticulum

vesicle

Golgi

apparatus

vesicle

proteinon its way!

protein finishedprotein

Making Proteins

TO:

TO:

TO:

TO:

nucleus

AP Biology

proteins

transportvesicle

Golgiapparatus

vesicle

smooth ER

rough ER

nuclear porenucleus

ribosome

cellmembrane protein secreted

cytoplasm

making proteinsPutting it together…

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Putting it together…making proteins

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AP Biology 2007-

2008

Tour of the Cell 2

AP Biology

Food & water storage

plant cells

central vacuole

contractile

vacuole

food vacuoles

animal cells

AP Biology

Lysosomes

Function

little ―stomach‖ of the cell

digests macromolecules

―clean up crew‖ of the cell

cleans up broken down

organelles

Structure

vesicles of digestive

enzymes

only in

animal cells

synthesized by rER,

transferred to Golgi

Where old organellesgo to die!

AP Biology

Lysosomes

white blood cells attack

& destroy invaders =

digest them in

lysosomes1974 Nobel prize: Christian de Duve

Lysosomes discovery in 1960s

1960 | 1974

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Cellular digestion

Lysosomes fuse with food vacuoles

polymers

digested into

monomers

pass to cytosol

to become

nutrients of

cellvacuole

lyso– = breaking things apart

–some = body

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Lysosomal enzymes

Lysosomal enzymes work best at pH 5

organelle creates custom pH

how?

proteins in lysosomal membrane pump H+ ions from

the cytosol into lysosome

why?

enzymes are very sensitive to pH

why?

enzymes are proteins — pH affects structure

why evolve digestive enzymes which function at

pH different from cytosol?

digestive enzymes won’t function well if some leak into

cytosol = don’t want to digest yourself!

AP Biology

When things go bad…

Diseases of lysosomes are often fatal

digestive enzyme not working in lysosome

picks up biomolecules, but can’t digest one

lysosomes fill up with undigested material

grow larger & larger until disrupts cell &

organ function

lysosomal storage diseases

more than 40 known diseases

example:

Tay-Sachs disease

build up undigested fat

in brain cells

AP Biology

Lysosomal storage diseases

Lipids

Gaucher’s disease

Niemann-Pick disease

Tay Sachs

Glycogen & other polysaccharides

Farber disease

Krabbe disease

Proteins

Schindler’s disease

AP Biology

Lysosomal storage disease

Hepatosplenomegaly courtesy

of The National MPS Society,

Inc.

http://www.lysosomallearning.co

m/healthcare/about/lsd_hc_abt_

niemann.asp