1.2 – Ultrastructure of cells

(with special thanks to Stephen Taylors “Draw the Core” and topic 2

presentations)

The invention of electron microscopes led to greater understanding of cell structure

Look at that resolution!

All organisms can be divided into two groups according to their cell structure.

Organisms

EukaryotesProkaryotes

Cell wall with peptidoglycan

Cell wall with cellulose (plants), chitin (fungi),

or no cell wall (animals)

70s ribosomes 80s ribosomes

Cell membrane on inside of cell wall –

no organelles

Cell membrane on inside of cell wall and

all throughout cell surrounding organelles

Prokaryotes have a simple cell structure without compartmentalization and divide by binary

fission.

Drawing of the ultrastructure of prokaryotic cells based on electron micrographs: cell wall, pili and flagella, and plasma membrane enclosing cytoplasm that contains 70S ribosomes and a nucleoid with naked DNA.

A Terrible Drawing…

http://sciencevideos.wordpress.com Draw the Core 6

A Terrible Drawing…

http://sciencevideos.wordpress.com Draw the Core 7

Too lightUnlabeled

Messy

Tiny

A Rubbish Drawing…

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A Rubbish Drawing…

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Where are these labels pointing?The arrow heads are unnecessary

Unclear labels

Outside the scanning box

Messy shading

Criss-crossed label linesWiggly label lines

Drawing of the ultrastructure of prokaryotic cells based on electron micrographs: cell wall, pili and flagella, and plasma membrane enclosing cytoplasm that contains 70S ribosomes and a nucleoid with naked DNA.

A Good Drawing…

http://sciencevideos.wordpress.com Draw the Core 11

A Good Drawing…

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• Good use of space• Clear strong lines• Label lines are straight• Labels clearly written• Scale bar if appropriate

• Lines touch the labeled structure

• No unnecessary shading or colouring

http://sciencevideos.wordpress.com Draw the Core 13

1µm

cell wallProtects cell, holds structure

plasma membraneControls what goes in and out of the cell

FlagellumMovement

PiliAttachment, Exchange of DNA

70S ribosomesProtein synthesis

CytoplasmContains solutes, enzymes for metabolic reactions

NucleoidContains:Plasmids/ Loops of DNAGenetic information

Drawing of the ultrastructure of eukaryotic cells based on electron micrographs: plasma membrane enclosing cytoplasm that contains 80S

ribosomes and a nucleus, mitochondria and other membrane-bound organelles are present in the cytoplasm. Some eukaryotic cells have a cell

wall.

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10µm

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10µm

Plasma membrane

Mitochondria

Free 80S ribosomes

Lysosomes

Cytoplasm

Golgi apparatus Rough Endoplasmic Reticulum

Nucleus

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10µm

Plasma membrane Controls what enters and leaves the cell

MitochondriaCell respiration

Free 80S ribosomesProtein synthesis for use within the cell

LysosomesContain enzymes for intracellular digestion

CytoplasmSolutes and enzymes for metabolic pathways

Golgi apparatusModifies and packages proteins for export

from the cell. Produces vesicles for exocytosis

Rough Endoplasmic ReticulumAttached 80S ribosomes produce proteins for export from the cell

NucleusContains DNA in the form of chromosomes

Structure and function of organelles within exocrine gland cells of the pancreas and within palisade

mesophyll cells of the leaf.

Structure and function of organelles within exocrine gland cells of the pancreas and within

palisade mesophyll cells of the leaf.

What is its function?

Structure and function of organelles within exocrine gland cells of the pancreas and within

palisade mesophyll cells of the leaf.

Structure and function of organelles within exocrine gland cells of the pancreas and within

palisade mesophyll cells of the leaf.

Interpretation of electron micrographs to identify organelles and deduce the function of

specialized cells.

Red Blood Cell

• Small and flexible to fit through tiny tubes.• NO nucleus to make more room for more oxygen

Nerve Cell

Long and branching arms to send messages quickly from any part of the body to the brain.

Muscle Cell

• Long and skinny to contract and extend for movement. • Lots of nuclei to help large cell communicate.• Lots of mitochondria because cells need lots of energy.

White Blood Cell

Can change shape to fit between tissues to find and fight infections.

Form

DNA is replicated only a few pieces at time.

Function

What DNA structure regulates the replication? DNA has sections that signal for the beginning of a coding sequence as well as a DNA section that signals for the ending of a coding sequence. The possibility of damage to the DNA is minimized by having only small sections opened up at any time.

Form

Hummingbirds often feed from flowers that do not have a place for them to perch.

Function

How do hummingbirds access their food? Hummingbirds can beat their wings fast enough to hover in midair and they have long bills and tongues which allow them to drink from the nectar of flowers.

Form

In vertebrate organisms, the nervous system must establish an effective system of communication.

Muscle tissue responds to electrical charges which causes them to contract, resulting in movement.

Chlorophyll and other pigments needs isolation from the cytosol in order to perform its function.

Function

What structure of nerve cells (neurons) allows for communication throughout the body?

How does skeletal muscle respond to the nervous signals to result in movement?

What organelle isolates these pigments?

Form

The cell membrane must be flexible enough for transport, but sturdy enough to withstand the impact of external factors.

Hemoglobin is a globular protein that carries multiple oxygen molecules throughout the blood stream.

Proper cell function requires the ability to digest old organelles/metabolic wastes that take up space, waste valuable resources, and may be toxic to the cell.

Most fungi do not have a system of transport for water and food.

Function

What component of the cell membrane provides stability?

How does the structure of hemoglobin allow it to carry oxygen?

What organelles perform this function and what specific toxin do they eliminate?

As heterotrophic organisms, how do fungi “find” their food?

Form

Some proteins are destined to stay in the cell while others are destined to leave the cell (secretion).

ER, Golgi body and other membrane bound organelles often work together to produce a finished functional product.

Cellular respiration (specifically the electron transport chain) requires a very specific proton concentration in order to allow production of ATP. Amoeba is a unicellular protozoan that would not survive if it were to feed only by diffusion.

Function

Are these two types of proteins produced in loose ribosomes? Explain.

What structure connects them?

What feature of the mitochondrion allows isolation of the proton gradient?

What type of cellular transport do they use for large molecules? What features of the cell membrane permit it?

Form

Eukaryotic cells have a small surface area to volume ratio compared to prokaryotic cells.

The evolution of plants from aquatic environments to land resulted in adaptations for vertical growth and to store water.

Some cells depend on the ability to move in order to survive.

Function

What compensates for that?

How do land plants gain stability without the buoyancy of water to keep them upright?

What do they use for such movement?