Tour Of The Cell

Microscopy

• What is the difference between magnification and resolving power?

• Magnification is how much larger the object can now appear.

• Resolving power is the ability to distinguish between two points, it is limited by the wavelength of visible light.

The different microscopes:• Light microscope - resolving power is limited

by the wavelengths of light.• Specimen should be stained, but can be

alive– Compound microscope– stereomicroscope

• Electron microscope - resolving power is greater since wavelengths of electrons is smaller than those of light.– SEM - 3D image– TEM - flat image

• electron microscopes cannot use live specimens

How did scientists first discover the different cell parts?

As Organisms Get Larger, Why do They Become

Multicellular?

It’s all about

the surface area to volume ratio!

Prokaryotic vs. Eukaryotic CellsProkaytotic cells:

• monerans• genetic material not in

a nucleus• no membrane bound

organelles

Eukaryotic cells:• Protists, Plants, Fungi

and Animals• true nucleus with

genetic material • has membrane boun

organelles

The Prokaryotic Cell:

The Plasma Membrane:

General Eukaryotic Cells:

Two Areas of the Eukaryotic Cell:

• What is the space between the cell membrane and the nucleus called?

• The cytoplasm. This includes the organelles and the cytosol.

• The cytosol is the fluid medium found in the cytoplasm

The nucleus

Nuclear Components:

• Envelope =

Nuclear Components:

• Envelope = double layered membrane that has pores for molecular transport.

• Chromatin =

Nuclear Components:

• Envelope = double layered membrane that has pores for molecular transport.

• Chromatin = DNA + protein complex of threadlike fibers that make up the eukaryotic chromosome.

• Chromosome =

Nuclear Components:

• Envelope = double layered membrane that has pores for molecular transport.

• Chromatin = DNA + protein complex of threadlike fibers that make up the eukaryotic chromosome.

• Chromosome = Chromatin fibers condense into visible chromosomes during cell division.

Ribosomes:

• Prokaryotic ribosomes differ from eukaryotic ribosomes

• Function =

Ribosomes:

• Prokaryotic ribosomes differ from eukaryotic ribosomes

• Function = Site of Protein synthesis

The Endomembrane system:• Related through direct continuity or by

transfer on membrane segments through vesicles.

• Structure of membranes is not identical• Includes:• Nuclear envelope --> Endoplasmic

reticulum --> Golgi apparatus --> lysosomes --> vacuoles -->plasma membrane

Transport vessicle from ER

New vessicle forming

Transport vessicle from golgi

Function of Golgi:

• Modifies stores and routes products of ER

• Alters membrane phsopholipids• Targets products for parts of the cell

Vacuoles

• Larger than vessicles• food vacuoles =

Vacuoles

• Larger than vessicles• food vacuoles = formed by phagocytosis• contractile vacuole =

Vacuoles

• Larger than vessicles• food vacuoles = formed by phagocytosis• contractile vacuole = found in fresh

water protozoans, keep water balance• central vacuole =

Vacuoles

• Larger than vessicles• food vacuoles = formed by phagocytosis• contractile vacuole = found in fresh water

protozoans, keep water balance• central vacuole = found in most plant cells

stores organic compounds, has enzymes to break macromolecules, has poisonous and unpalatable compounds,etc...

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Mitochondria and Chloroplasts

• Not part of endomembrane system• their membrane proteinsare made by

free ribosomes and their own ribosomes• Both have small amount of DNA• Grow and reproduce on their own within

the cell• Involved in Energy transformation

Plastids

• Amyplasts - store starch, in roots and tubers

• chromoplasts - non-chlorophyll pigments responsible for non-green colors.

• Chloroplasts - chlorophyll containing plastids

Peroxisome• Contains enzymes that transfer hydrogen from

substrates to oxygen, producing hydrogen peroxide.

• Some use oxygen to fuel the breakdown of fatty acids to smaller molecules that can be used in the mitochondrion.

• In liver they detoxify alcohol and other poisons, by transferring hydrogen from poison to oxygen

• Hydrogen peroxide is toxic, what enzyme can be used to break this down?

Cytoskeleton

• Provides structural support

• Functions in motility and motion

Microtubules

• Cellular support• provides tracks for movement within the

cell: e.g. transport vessicles• Composes cilia and flagella, locomotive

appendages of certain cells.• separation of chromosomes during cell

division (spindle fiber)• composes centrioles in animal cells

Microfilaments

• Smaller than microtublues• participates in muscle contraction• support• localized cell contractions

The Cell Surface

• Cell Walls in plant cells• membrane linked channel -

plasmodesmata that connects cytoplasm between cells

Animal Cell Surfaces

• Glycocalyx - strengthens cell surface, helps glue animal cells together

• tight junctions - holds cells together to block transport

• desmosomes - rivets cells together into strong sheets but permits transport

• gap junctions - analogous to plasmodesmata in plant cells

Let’s Review:Name the cell structure and its

function.Be able to tell if this structure is found in prokaryote, eukaryote,

plant and/or animal cells

Take a closer look!

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