CH 4 CELL 1010 Dr. V Tulane University

Light Microscope

Uses light for illumination

Can only see single nuclear membrane- see one point

Electron microscope

uses electron beam

can see double nuclear membrane - see two points

Light microscopes have ... resolution than electron microscopes

lower (0.2 nanometers vs 2 nanometers)

Electron microscopes have stronger resolution than light microscopes due to its use of...

e- emitting smaller wavelengths than light

the naked eye can see

100 micrometers

Magnification serves to

enlarge

ratio between the size of an image produced by a microscope and its actual size

*Resolution is synonymous with

clarity

ability to observe two objects separated by the shortest distance as DISTINCT from each

*Contrast is synonymous with

visualizing

how DIFFERENT one structure looks from another

florescent light

absorbs light at a certain pigment and then reflects light at a larger wavelength

focuses on what emitted the light

Confocal microscope

the best microscope for resolution among light microscopes

Transmission Electron Microscope (TEM)

the best resolution among ALL microscopes

how do transmission electron microscopes work?

e- flow through the sample to form an image

Scanning electron microscope

give a 3D topography of the membrane

e- are scattered out from the membrane to form an image

Two types of electron microscopes

transmission electron microscope

scanning electron microscope

Cell fractionation

emables scientists to determine the functions of organelles

breaks up cells and separates the components using centrifugation

which two domains are prokaryotic cells?

bacteria and archaea

3 bacteria shapes

spirilla (spirals)

coccus (spherical)

Bacilli (elongated rod)

Components of a Bacterial Cell

Plasma membrane

Cell wall

Glycocalyx

Capule

Plasmid

Naked DNA

Nucleoid Region

Pilli

Flagella

Ribosome

Cytosol

Plasma membrane (bacteria cell)

Semipermeable formidable phospholipid bilayer

Invaginated to increase SA of cell, allowing for more special proteins and pigments. Accounts for the lack of membrane bound organelles.

Arranged via hydrophobic exclusion (polar heads vs nonpolar tails)

Contains transport, receptor, adhesive proteins

Where photosynthesis and the ETC occurs

Cell wall (bacterial cell)

rigidity gives shape and protects

porous to absorb nutrients

cell wall composition of gram positive and gram negative indicates whether the bacteria is virulent or nonvirulent

Gram positive cell wall

Typically nonvirulent - except anthrax

Stain purple

Form: Thick, mesh layer of peptidoglycans (proteins + carbs)

Gram negative cell wall

Virulent

Stain pink

Form: Thin layer of peptidoglycan + thick layer of lippolysaccharide (lipids + carbs) on top

Virulent

cannot be broken down by antibodies

requires antibiotics

Glycocalyx

The outermost layer of bacterial cell

Viscous layer - contains a lot of water, constantly absorbs water

Made of carbohydrates

Function: protects against dehydration

(form: syrup-like)

Capsule

Modified versions of the glycocalyx

(form: jelly-like)

not essential but helpful. Function: virulence factor, protects cell from engulfment

Nucleoid region

the space surrounding the single circular naked DNA

NOT the direct DNA itself

DNA (bacterial cell)

single circular ring of naked DNA

located directly in the cytoplasm

Plasmid (bacterial cell)

outside the nucleoid region

ENHANCES the survival of bacterial cell in toxic environments

Presence of a plasmid usually indicates the presence of pilli

pilli

extensions of the prokaryotic cell surface membrane

allow for attachment, genetic recombination, and conjugation

NOT REPRODUCTION; rapid horizontal gene transfer

conjugation

In bacteria, the direct transfer of DNA between two cells that are temporarily joined via sex pilus

ribsomes

protein synthesis

what happens when bacteria are exposed to harmful situations?

turn into an endospore. once normal conditions return, cell reverts away from endospore and undergoes binary fission

Endospore

A thick-walled, non reproductive, protective spore that forms inside a bacterial cell and resists harsh conditions.

Flagella

A long, whip-like filament that helps in cell movt.

corkscrew-like movt

coils up like a spring (large PE) and when released, creates large spurts of motion

smaller cell

larger surface area to volume ratio

better cell communication

cytosol

Fluid portion of cytoplasm

OUTSIDE the organelles but inside the plasma membrane

cytoplasm

EVERYTHING inside the plasma membrane: cytosol, organelles, endomembrane system

cytosol vs cytoplasm

cytosol is the fluid itself...cytoplasm is everything within the plasma membrane except the nucleus

Endomembrane system

membranes that enclose the nucleus, ER, golgi apparatus, lysosomes, vacuoles, peroxisomes

includes the PM

*Do individuals have the same gene sequence in every part of the body?

Yes, just certain genes are expressed more in areas where their function is most necessary

Differentiation and diversification of proteins occurs in these 4 ways

1. differential gene regulation

2. difference in stability and concentration of protein

3. changes in amino acid composition - alternative splicing

4. covalent modifications of proteins

differential gene regulation

in specific cell types, certain genes will be UP REGULATED (produce more) and non-necessary ones are DOWN REGULATED

difference in stability and concentration of protein

alternative splicing

Splicing of introns in a pre-mRNA that occurs in different ways, leading to different mRNAs that code for different proteins or protein isoforms. Increases the diversity of proteins.

covalent modifications of proteins

change in the proteome

what is an anabolic activity that takes place in the cytosol?

translation/protein synthesis

anabolic = building larger molecule through combination of smaller molecules and energy

what is a catabolic activity that takes place in the cytosol?

glycolysis (splitting of larger glucose molecule into pyruvates)

catabolic = splitting larger molecules into smaller ones, giving off energy

complexes found IN the cytosol

ribosomes

mitochondria and the nucleus ARE NOT found IN cytosol because cytosol doesn't include organelles