Cells

Structure and Function

ทนพ. สุวิทย์ คล่องทะเล วท.บ. (เทคนิคการแพทย์) เกียรตินิยม

มหาวิทยาลัยมหิดล

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2 Campbell et al, Biology; 2009.

Sizes of Living Things

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Minimum resolution of a LM 2 microns, the size of a small bacterium LM can magnify effectively to 1,000 times the size of the actual specimen.

http://amazedatbio.wordpress.com/2012/09/17/life-is-cellular/

Properties of life Reproduction :

o sexual : genetic variation, fertilization

o asexual : genetically identical, e.g. sporulation, budding,

regeneration, binary fission

Metabolism : anabolism Vs. catabolism

Growth and Development

Response to environment

Homeostasis : regulated via organ system

Organization : Cell, tissue, organ, organ system, organism

o acellular

o unicellular : bacteria, yeast

o multicellular : plant, animal

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Cell Theory All organisms are composed of cells

All cells come only from preexisting cells (Rudolf Virchow)

Cells are the smallest structural and functional unit of organisms

Cells carry genetic information in the form of DNA

5 Robert Hooke (1665) Matthias Jacob

Schleiden (1838) plant

Theodor Schwann (1839) animal

Antony van Leeuwenhoek (1673)

Light microscope

6 Campbell et al, Biology; 2009.

Electron microscope To resolve smaller structures we use EM, which focuses a beam

of electrons through the specimen (TEM) or onto its surface

(SEM)

TEM are used to study the internal ultrastructure of cells.

A TEM aims an electron beam through a thin section of the

specimen.

o The image is focused and magnified by electromagnets.

o To enhance contrast, the thin sections are stained with

atoms of heavy metals.

SEM are useful for studying surface structures.

The SEM has great depth of field, resulting in an image that

seems three-dimensional.

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8 Campbell et al, Biology; 2009.

Prokaryotic and eukaryotic cells

All cells

o surrounded by a plasma membrane.

o have cytosol, containing the organelles.

o contain chromosomes

o have ribosomes

A major difference

o eukaryotic cell: chromosomes are contained in the nucleus (within a membranous nuclear envelope)

o prokaryotic cell: the DNA is concentrated in the nucleoid

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A major difference...

Cytoplasm

o All the material within the plasma membrane of a prokaryotic

cell is cytoplasm.

o Within the cytoplasm of a eukaryotic cell is a variety of

membrane-bounded organelles of specialized form and

function.

Eukaryotic cells are generally much bigger than prokaryotic

cells.

o smallest bacteria, mycoplasmas, are 0.1 to 1.0 micron. (most

bacteria: 1-10 microns)

o Eukaryotic cells are typically 10-100 microns in diameter

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Not present in bacteria nucleus, membrane bounded organelle, cytoskeleton, centriole

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Eukaryotic Cells Prokaryotic Cells

“complex” organisms, including all

plants, protists, fungi and animals

“Simple” organisms, including

bacteria and cyanobacteria

Contain nucleus and membrane bound

organelles

Several chromosome

Lack nucleus and other

membrane-encased organelles.

Single chromosome (DNA + non-

histone protein)

Can specialize for certain functions,

multicellular organs and organisms

Usually exist as single, virtually

identical cells

Cellular respiration occur in

mitochondria

Cellular respiration occur in

mesosome (extended membrane)

Ribosome: 40s, 60S Ribosome: 30S, 50S

Photosynthesis occur in chloroplast Photosynthesis occur in

chlorophyll located region

Cell Wall present in Plants & Fungi only Cell Wall

Cyanobacteria (blue-green algae) e.g. Nostoc, Oscillatoria, Anabaena, Spirulina

Cells

Cell coat: Cell wall, Cell membrane

Protoplasm

o Nucleus : nuclear membrane, nucleoplasm (chromatin fiber, nucleolus)

o Cytoplasm

• cytosol

• organelle

– no membrane bounded: ribosome, centriole, cytoskeleton

– single membrane bounded: ER, Golgi complex, lysosome, peroxisome, vacuole

– double membrane bounded: mitochondria, chloroplast

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Animal Cell Anatomy

14 http://traddude.blogspot.com/2008/06/cells-compendium-1.html

Plant Cell Anatomy

15 http://minhalogia.blogspot.com/2013_03_01_archive.html

Plasma membrane

Fluid mosaic model

o Phospholipid bilayer acts

more like a fluid than a

liquid

Contains integral and

peripheral proteins

Semi permeable membrane

Like a city border they

surround the cell and are able

to regulate entrance and exit

16 Campbell et al, Biology; 2009.

Phospholipid bilayer

polar heads face outward towards the watery environments both inside and outside the cell

non polar tails face inward away from the watery environment 17

http://alevelnotes.com/content_images/i38_phospholipid.gif http://online.morainevalley.edu/WebSupported/BIO111-Gibbons/membra29.jpg

18 control fluidity of

membrane

recognition of cell

Campbell et al, Biology; 2009.

Function of membrane protein

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Campbell et al, Biology; 2009.

Function of membrane protein

Enzyme

Mediate the passage of ions and most biological molecule

Selective traffic of molecule

Control the interactions between cells of multicellular organisms

Serve as sensor (e.g. receptors, signal transductions) 20

Chandar et al, Lippincott’s Illustrated Reviews: Cell and Molecular Biology; 2010.

Transport through membrane

Passive transport: need no energy, downhill

o simple diffusion

o facilitated diffusion: channel protein, carrier protein

Active transport: need energy, uphill

o primary active : direct hydrolysis of ATP

o secondary active : symporters, antiporters

Vesicle transport

o endocytosis: receptor mediated, phagocytosis, pinocytosis

o exocytosis

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External environment

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Gas Hydrophobic molecules

Small polar molecules

Large polar molecules

Charged molecules

CO2

O2 Benzene

H2O

Ethanol Glucose Amino acid

Ions

H+ Cl-

Na+

Ca2+

Cytoplasm

Diffusion

23 Campbell et al, biology; 2011.

Osmosis

24 Campbell et al, biology; 2011.

Passive transport

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Chandar et al, Lippincott’s Illustrated Reviews: Cell and Molecular Biology; 2010.

Active transport

26 Na+-Ca2+antiporter in

cardiac muscle Na+-glucose transporter in intestinal epithelial cell

Chandar et al, Lippincott’s Illustrated Reviews: Cell and Molecular Biology; 2010.

Vesicle Transport

27 http://www.shayda.us/WebCT/AP1/AP1_Ex2_Materials/GA_Pag2.jpg

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Phagocytosis of microbes

Abbas et al, Cellular and Molecular Immunology; 2012.

29 Russell et al, Biology the dynamic science; 2008.