Cytology I Study of Cells - · PDF fileCytology I –Study of Cells ... concentrated at both ends of the cell. a) A eukaryotic animal cell has a large ... –Plasmolysis • Cell membrane

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Cytology I – Study of Cells

Biology 20


Which cell type has organelles such as

mitochondria, nuclues, Golgi bodies, etc?

• A) prokaryotic

• B) eukaryotic

• C) bacterial

• D) viral

• E) none of these


Cellular Basis of Life

1. Basic unit of Life

2. Composed of one or more cells

3. Arises from pre-existing cells

Asexual (Mitosis)/Sexual (Meiosis)

4. Surrounded by a membrane

5. Transform energy

6. Information retention (genes)

Cell Theory


What level in life’s hierarchy possess all the

attributes of life?

• A) molecular

• B) organ

• C) tissue

• D) cellular

• E) all of these


Cell Doctrine

• All living things are composed of cells

• Cell is the smallest unit that exhibits all of

the attributes of life

• All cells come only from preexisting cells


Two Basic Cell Types Classified by

Internal Organization

Prokaryotic Cells

• Plasma membrane

• No nucleus

• Cytoplasm: fluid

within membrane

• No true organelles

• 1 – 10 um

Eukaryotic Cells

• Plasma membrane

• Nucleus: information

center

• Cytoplasm: fluid within

membrane

• Organelles:

compartments with

specialized functions

• 10 – 100 um

What type of cell do you have?


Figure 3.6

Ribosomes

Cytoplasm

Nucleoid

(DNA)Cell

membraneCell wall Capsule Flagellum

SEM (false color) 2 μm SEM (false color) 2 μm SEM (false color) 2 μm

a.

b. c. d.


Figure 3.2

Range of electron microscope

Range of light microscope

Range of human eye

AtomsSmall

moleculesProteins Viruses Most bacteria and

archaeaMost plant and

animal cellsFrog eggs Ant

© 2012 Pearson Education, Inc. Figure 3.1

b) Prokaryotic cells such as this bacterium have arigid cell wall surrounding the plasma membrane.The genetic material is not surrounded by amembrane, and there are no organelles in the cell.The elongated bacterium in the center of the photois about to divide in two, as its genetic material isconcentrated at both ends of the cell.

a) A eukaryotic animal cell has a largenucleus and numerous small organelles.The cytoplasm is enclosed by a flexibleplasma membrane.

Nucleus

Organelles

Cytoplasm

Cell wall

Plasmamembrane


Cell structure reflects eukaryotic cell’s function

Figure 3.2

a) A portion of several musclecells of the heart (X 1,500).

b) Nerve cells of the centralnervous system (X 830).

c) Cells lining a tubule of a kidney (X 250).

• How are these cells similar?

• What makes these cells different?


Figure 3.23

40 µm 35 µm 50 µmLM LM LM400 µmLMa. b. c. d.

Cell structure reflects eukaryotic cell’s function


Why are cells so small?

• Efficiency in:• Acquisition of nutrients

• Disposal of wastes

• What makes this possible?• High surface areas to volume ratio


The cells of an ant and an elephant are,

on average, the same small size; an

elephant just has more of them. What is

the advantage of small cell size?

a) small cells are less likely to burst than large cell;

b) small cells are less likely to be infected by bacteria;

c) small cells can better take up what they need from their environment;

d) it takes less energy to make an organism out of small cells;

e) small cells can "morph" more easily than larger cells.


Figure 3.5

Receptor protein

Channelprotein(always open)

Gatedchannelprotein(closedposition)

Carbohydrategroups

Cytoskeletonfilaments

Phospholipid

Cytoplasm

Lipidbilayer

Transportprotein

Glycoprotein

Extracellular environment

Cholesterol

Plasma or cell membrane

• Hydrophobic

interactions

• Fluid Mosaic Model

• 8 hm

• Boundary

• Selectively

permeable


Water

Water

Phospholipid

bilayer

Hydrophilic

Hydrophobic

Hydrophilic

Phospholipid

bilayer

Ions and large, polar,

or charged molecules

Lipids and small,

nonpolar molecules

Figure 3.11

Plasma or cell membrane

02_MH05_MembraneTransport_TheLipidBilayerCC.swf


Fluid Components

• 1) Phospholipid

– Hydrophilic

– Hydrophobic

– Amphipathic

• 2) Cholesterol

– Cold prevents packing

– Hot limits movement


Mosaic Components

• 3) Proteins

– Intergral: w/in membrane

– Peripheral: inside cell (cytoplasmic)


Membrane Protein Functions

• 1) Transport• In or out of the cell

• Molecule specific

• 2) Ion channel• Na+, K+, Ca++, Cl-.

http://www.csupomona.edu/~seskandari/GABA_transporter_page.html


Membrane Protein Function

• 3) Enzymatic

– Chemical rxn

– Energy production



• 4) Receptor site• For chemical messengers

• Signal transduction

• Cell recognition



• 5) Cytoskeleton attachment• Cell shape

• Coordinate extracellular &

intracellular changes



6) Cell adhesion


Figure 3.27

GAP JUNCTION

CELLS OF SMALL INTESTINE

TIGHT JUNCTION

ANCHORING (ADHERING)

JUNCTION


6) Cell adhesion


Mosaic Components

• 4) Carbohydrates• Glycoproteins

• glycolipids

• Function:• Cell-cell recognition

• Ex. Blood type


Which component of the cell membrane is

the cell’s ID tag (or identifies the cell as its

particular type?

A) cholesterol

B) carbohydrates

C) phospholipids

D) proteins

E) All of these


Which of the following allows for cell to cell

recognition?

A) cholesterol

B) carbohydrates

C) phospholipids

D) proteins

E) I think it’s two of these


Membrane Permeability

• Size:• Small molecules

• Charge:• Uncharged easy

• Charged: can not

• Lipid solubility• Hydrophobic molecules

• Carrier proteins• Assist small charged

• Assist non-soluble


Membrane Transport

• Simple Diffusion• [High] [Low]

• Down its [gradient]

• Passive no energy

Passive_diffusion.swf


Membrane Transport

• Facilitated diffusion• Carrier protein

• Passive no energy

• Ions, water

http://www.youtube.com/watch?v=s0p1ztrbXPY

http://www.csupomona.edu/~seskandari/GABA_transporter_page.html


Table 4.2

Membrane Transport


Lower

concentration

Diffusion through the lipid

layer. Lipid-soluble molecules

such as O2 and CO2 diffuse

freely through the plasma

membrane.

Diffusion through channels.

Some polar and charged

molecules diffuse through

protein channels that span

the membrane. Water

is a typical example.

Facilitated transport. Certain

molecules bind to a protein,

triggering a change in protein

shape that transports the

molecule across the membrane.

Glucose typically enters cells by

this method.

Higher

concentration

3 types of passive transport


Sodium ions (Na+) diffuse across the cell

membrane, but they need assistance.

This would be an example of:

a) simple diffusion

b) facilitated diffusion;

c) active transport;

d)osmosis;

e) huh?


Membrane Transport

• Osmosis• Diffusion of water

• Across a selectively

permeable membrane

• Passive

• Hypotonic• Lower [solute] & High [H2O]

• Isotonic• Equal/same [solute] &

equal/same [H2O]

• Hypertonic• Higher [solute] & Low [H2O]

Hypotonic hypertonic


Membrane Transport - Osmosis


Figure 4.16




• Isotonic solution

– Equal/same [solute]

– Ex.

• Inside cell: 3% NaCl, 97% H2O

• Beaker: 3% NaCl, 97% H2O

– Animal cells Normal

– Plant cells normal

3% NaCl

97% H2O



• Hypotonic solution

– Lower [solute], has more water



– H2O: more IN than out

– Animal cells burst/lyse

– Plant cells turgid (stiff)

– Why?

0% NaCl

100% H2O

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



• Hypertonic solution

– Higher [solute], less water



– H2O: more OUT than in

– Animal cells shrinks

– Plant cells plasmolysis 50% NaCl

50% H2O

http://www.youtube.com/watch?v=c8nhJBw_So8


Osmosis – hypertonic solutions

• Animal cells

– Shrinks/shrivels

• Plant cells

– Plasmolysis

• Cell membrane separates

from cell wall

5% NaCl

95% H2O


The amount of water movement is indicated by the sizes of the arrows.

Scanning of electron micrographs of red blood cells

placed in similar solutions.

0.9% salt 10% salt DI water

HypotonicHypertonicIsotonic


Figure 4.17

HypotonicHypertonicIsotonic


Figure 4.18


Tonicity & the potato

Initial (3 cm)

Hypertonic

Isotonic

Hypotonic


You're rushed to the ER and given an IV

(intravenous) saline (salt) solution to rehydrate

you. The nurse was not sleeping during

biology this time and happened to give you an

isotonic IV solution. What would happen to

your RBC's (red blood cells) in your blood

vessels?

a) shrivel;

b) lyse/burst;

c) nothing;

d) you're thinking lawsuit aren't you?


Membrane Transport

• Active Transport• [lower] [higher]

• Against [gradient]

• Carrier protein

• REQUIRES energy

Active_transport.swf


Active Transport – Na+/K+ pump

http://www.youtube.com/watch?v=STzOiRqzzL4


Membrane Transport

• Bulk transport Large molecules• Endocytosis = in take

1. Phagocytosis = cell eating

2. Pinocytosis = cell drinking

Endo_Exocytosis.swf

http://www.youtube.com/watch?v=fpOxgAU5fFQ


Figure 4.20

Membrane Transport


Membrane Transport

• Large molecules• Endocytosis = in take

1. Phagocytosis = cell eating

2. Pinocytosis = cell drinking

3. Receptor mediated

Substance triggers receptor protein

http://www.youtube.com/watch?v=PifagmJRLZ0


Figure 4.21

Membrane Transport


Membrane Transport

• Bulk Transport Large molecules

• Exocytosis

– Getting rid of substances

– Transport vessicle fuses w/ cell

membrane

Contractile

vacuole

http://www.youtube.com/watch?v=7_frccgVAWQ&feature=related

http://www.youtube.com/watch?v=iG6Dd3COug4


c) Photomicrograph showingvarious stages of endocytosis.

a) Endocytosis. In endocytosis, material is surrounded bythe cell membrane and brought into the cell.

Extracellular environment

Plasma membrane

Cytoplasm

Vesicle

b) Exocytosis. In exocytosis, a membranous vesicle fuseswith the plasma membrane, expelling its contents outsidethe cell.

Comparison of endocytosis & exocytosis

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Cytology I Study of Cells - · PDF fileCytology I –Study of Cells ... concentrated at both ends of the cell. a) A eukaryotic animal cell has a large ... –Plasmolysis • Cell membrane