Question

Compare and contrast prokaryotes and eukaryotes in terms of structures

Answer 1

Eukaryotic cells contain membrane-bound organelles, such as the nucleus, while prokaryotic cells do not. Differences in cellular structure ofprokaryotes and eukaryotes include the presence of mitochondria and chloroplasts, the cell wall, and thestructure of chromosomal DNA.

Answer 2

                  Eukaryotic Cell                                           Prokaryotic Cell

Nucleus Present                                                                    Absent

Number of chromosomes More than one One--but not true chromosome: Plasmids

Cell Type Usually multicellular Usually unicellular (some cyanobacteria may be multicellular)

True Membrane bound Nucleus Present Absent

Example Animals and Plants Bacteria and Archaea

Genetic Recombination Meiosis and fusion of gametes Partial, undirectional transfers DNA

Lysosomes and peroxisomes Present Absent

Microtubules Present Absent or rare

Endoplasmic reticulum Present Absent

Mitochondria Present Absent

Cytoskeleton Present May be absent

DNA wrapping on proteins. Eukaryotes wrap their DNA around proteins called histones. Multiple proteins act together to fold and condense prokaryotic DNA. Folded DNA is then organized into a variety of conformations that are supercoiled and wound around tetramers of the HU protein.

Ribosomes larger smaller

Vesicles Present Present

Golgi apparatus Present Absent

Chloroplasts Present (in plants) Absent; chlorophyll scattered in the cytoplasm

Flagella Microscopic in size; membrane bound; usually arranged as nine doublets surrounding two singlets Submicroscopic in size, composed of only one fiber

Permeability of Nuclear Membrane Selective not present

Plasma membrane with steroid Yes Usually no

Cell wall Only in plant cells and fungi (chemically simpler) Usually chemically complexed

Vacuoles Present Present

Cell size 10-100um 1-10um