Prokaryotic and Eukaryotic Cells

What is a prokaryote?

A prokaryote is any organism - usually single-celled - whose DNA is suspended freely in the cytoplasm. The word means 'before the nucleus.'

what are actin filaments?

A secondary element of the cytoskeleton is a network of very fine actin filaments. These are not made of microtubules but work with them to maintain or change the cell's shape.

how are ribosomes involved in protein synthesis?

Ribosomal RNA (rRNA) is transcribed in the nucleolus. tHis does not form a template for a protein, but folds up into subunits that pair up to make ribosomes. Translation: most ribosomes attach to the rough endoplasmic reticulum (ER), where they translate mRNA into proteins. These then are transported by the flattened sacs, or the cisternae, of the ER.

how is smooth ER involved in protein synthesis?

Smooth ER has no ribosomes but is involved in the transport of proteins. It also has an important role in the production and storage of carbohydrates, lipids, and other molecules.

How are Golgi vesicles involved in protein synthesis?

Some Golgi vesicles are lysosomes, containing enzymes that break down old organelles or infectious bacteria. Others transport proteins to elsewhere in the cell or eject them by exocytosis.

how are transport vesicles involved in protein synthesis?

The membrane of the ER continually buds off to form vesicles. These are packages of proteins and other molecules formed on the ER for transport to the Golgi apparatus.

what is the capsule?

a mucous-like protective layer that surrounds many pathogenic bacteria.

what do all prokaryotic cells have in common?

all prokaryotes share the same basic structure.

what is the mitochondrion?

an energy-generating organelle. it is surrounded by two membranes. the inner layer folds inward to form the cristae. the cristae project into a liquid called the matrix. The inner membrane is coated in enzymes which catalyze the reactions of aerobic respiration to produce ATP.

Eukaryotes include:

animals, plants, fungi, and a diverse group known as the protists (or protoctists). All eukaryotic cells contain a large number of specialized, membrane-bound organelles.

what is a eukaryote?

any organism consisting of one or more cells that contain DNA is a membrane-noun nucleus, separate from the cytoplam.

what two groups can prokaryotes be divided into?

bacteria and archaea.

what are plasmids?

bacterial cells often contain plasmids - small continuous loops of DNA. plasmids are replicated independently of a bacterium's genophore the chromosome of a bacterium), and may confer an advantage such as antibiotic resistance. Plasmids commonly are used in genetic engineering to make copies of genes or large quantities of proteins or hormones.

how does the capsule protect bacteria from viruses or attack from a host organism's immune system?

by hiding antigens on the cell surface

what are chloroplasts?

chloroplasts use carbon dioxide, water, and light energy to build sugars. They are present in all green plants. The chloroplast is surrounded by a double membrane. It is filled with a liquid called the stroma and contains stacks of thylakoid membrane called grans. The thylakoid membranes are the sites of photosynthesis.

what are cilia?

cilia are short (5-10) hair-like outgrowths on the surface of a cell. Cilia beat to power cell movement (e.g. white blood cells) or to move fluid across the cell's surface (e.g. in respiratory epithelium).

what are pili?

hollow protein structures used during bacterial conjugation - the transfer of genetic material from one bacterium to another

what organelles are involved in protein synthesis?

many of a cell's organelles are involved in protein synthesis, which is central to all life's processes.

what are microtubules and why are they important?

microtubules are hollow filaments of the protein tubulin. they give a cell structural support as part of the cytoskeleton and form organelles such as centrioles and cilia.

what are microtubules?

microtubules are the main component of a cell's cytoskeleton. they connect the cell's organelles to each other to keep them in place. they also can alter their length to affect the shape of the cell or cause it to move.

the DNA of prokaryotes

not associated with proteins like eukaryotic DNA but is freely suspended in the cytoplasm. it usually is coiled up and referred to as the nucleoid or genophore.

what do plant cells share with animal cells?

plant cells contain all the common features of animal cells but also contain some additional organelle. plants gain all their energy from sunlight; cells in the leaves contain many chloroplasts to convert this into a useful form. Every plant cell is surrounded by a cell wall and contains one or more permanent vacuoles.

what is the capsule composed of?

polysaccharides and also contains water to protect against desiccation

what is the cell membrane?

similar in structure to that of a eukaryotic cell. it consists of a phospholipid bilayer containing other molecules such as proteins and lipids.

What is the cytoplasm?

similar to that of a eukaryote; comprises a liquid, known as as cytosol, and everything suspended in it, including the cell's DNA, since it is not bound in a nucleus.

what are flagella?

some prokaryotic cells feature one or more flagella. these are long helical toques extending out of the cell wall which rotate to provide locomotion. flagella are powered by protein motors and can propel bacteria at a rate of more than 50 lengths per second.

does the cell wall seal off a cell completely from its neighbors?

the cell does not seal off a cell completely from its neighbors. There are pores within the walls called plasmodesmata. These connect two cells together by their cytoplasms, enabling substances to be exchanged and transported between them.

what is the cell wall?

the cell wall of a plant cell gives it support and structure. it is made of the polysaccharide cellulose and can function as a carbohydrate store by varying the amount of cellulose it holds.

what are centrioles?

the centrioles coordinate the nucleation and growth of microtubules in all eukaryotes excel the higher plants. They are an example of a microtubule organizing center (MTOC).

how is the nucleus involved in protein synthesis?

the nucleus consists of genetic material, chromatin, bound in a nuclear membrane. It contains one or more denser areas called nucleoli. The nucleus is the site of the first stage of protein synthesis: transcription. during this process, a molecule of messenger RNA (mRNA), coding for a protein, is created from a DNA template.

what do ribosomes do?

translate mRNA into protein. prokaryotic ribosomes are smaller than those found in eukaryotes but perform the same function.

are prokaryotes simpler than eukaryotes?

yes. prokaryotes have simpler structure than eukaryotes, lacking organelles such as the nucleus, ER and Golgi.

how is the Golgi apparatus involved in protein synthesis?

The Golgi apparatus modifies molecules and packages them for specific destinations inside or outside the cell. Vesicles fuse with the cistern at one end and new ones bud off at the other.