Has resolution that is sufficient to view images up to 0.2 micrometers, due to the limitations of the wavelength of light. Scientists ran in to problems when they wanted to see smaller things, such as in Figure 1. New technology was needed, and thus came the Electron Microscope Figure 1. Image from

Uses beams of electrons, rather than light, so a much clearer resolution can be achieved. Useful to view images down to 1 nm (0.001 micrometers) Useful to see images such as those of viruses and small organelles.

Prokaryotes

Prokaryotes are cells that have no membrane-bound organelles Smaller than animal or plant cells Very Old! ~3.5 billion years old

One BIG compartment

Vs.

Cell wall – provides structure, protection for the cell Cell membrane – provides shape, allows materials in and out of the cell (selectively permeable) Pili – allow attachment to other bacteria in order to share DNA Ribosomes – synthesize proteins for the cell Nucleoid – region containing DNA, instructions for cell processes Cytoplasm – space in which metabolic reactions can take place Flagella – utilize whip-like motion to move the cell

Prokaryotes use a method of asexual reproduction termed Binary Fission. Binary fission allows prokaryotes to divide in to two identical bacterium

Eukaryotes

SizeDNANucleusOrganelleRibosomesMitochondr ia Prokaryote1-3 micrometer Closed loop DNA in cytoplasm “cell parts”70S (small)No Eukaryotes micrometer Double helix Has nuclear membrane Membrane bound 80S (big)yes

Draw overall structure and label the following based on the diagram: Golgi Apparatus Lysosome Mitochondrion Free Ribosomes Chloroplast Vacuoles Microtubules Centrioles Cilia/flagella (not pictured) Rough ER Nucleus

vs.

Eukaryotic cells are compartmentalized Advantages of being so include: Enzymes and substrates for a particular process can be much more concentrated than if they were spread out Potentially harmful substances can be quarantined pH and other homeostatic levels can be managed much more effectively Organelles with their contents can be moved around within the cell

Nucleus – contains chromosomes, which are organized raw DNA Most of the time, they are visible as chromatin, an unorganized form of DNA

Consists of flattened sacs – cisternae Ribosomes attach to them, and fulfill protein synthesis

Consists of flattened membrane sacs called cisternae, similar to the rough ER These cisternae are shorter, have no ribosomes attached, and have many vesicles nearby Golgi Apparatus processes proteins brought to it from the rER

Little spherical organelles, formed out of golgi vesicles Have a high concentration of protein, mostly digestive enzymes that they use to break down food particles Also responsible for breaking down “old” organelles and intruders, such as bacteria

Double membrane! – inner membrane is invaginated (folded inwards) to form structures called cristae Produce ATP (energy for the cell) by aerobic respiration

No membrane! – same size as ribosomes attached to the rER, only 20 nm in length Synthesize proteins for the cell and its surroundings Produced in the nucleolus

Only found in photosynthetic cells Double membrane! – performs photosynthesis Photosynthesis produces a wide variety of compounds, including glucose

Vacuoles vary widely in size – Very small in animals (generally) Very large in plants (generally) Used for a variety of purposes, including digestion, water balance, transport What do you think the function of this palisade mesophyll cell is?

Small, cylindrical fibers called microtubules that provide structure to the cell Centrioles are present in animal cells, and provide an anchoring point for microtubules during mitosis

Whip-like structures that allow the cell to move Comprised of a ring of double microtubules and two central ones While cilia and flagella can both be used for locomotion, cilia can also be used to create a current next to the cell

What do you think these structures indicate about the cell’s function in Figure 1? SOC What about the cell in Figure 2? SOC Figure 1. Figure 2.

Eukaryotic, and therefore have all the characteristics of a eukaryotic cell In addition to the organelles present in animal cells, plant cells also have chloroplast, a cell wall, and an enlarged vacuole.

plant SOC