2.1.2 Prokaryotic Cells

What can some viruses have for protection?

A lipid envelope

What is a prokaryote?

A prokaryote is an organism which is made of prokaryotic cells. They are usually single-celled organisms like bacteria.

Describe viral cells with two terms.

A-cellular and non-living

What extra feature do all prokaryotes have and what is this for?

All prokaryotes have a cell wall. This protects against mechanical damage and prevents certain substances entering or leaving the cell. It also prevents lysis which is when the cell bursts after swelling up with water. In this way it has a similar function to the cell wall of a plant.

What are pili for?

Bacterial conjugation

Describe four extra features that a bacterium may have which a eukaryotic one wouldn't.

Cell wall - for protection Flagella - for movement Mucilaginous Capsule - for protection Plasmid - for extra genetic information storage

Which organelles do prokaryotes not have?

Most membrane bound organelles are not found in prokaryotic cells - golgi, mitochondria, ER, chloroplasts, lysosomes etc.

What is a prokaryotic cell wall made of?

Murein - a polysaccharide

Why is flagella called "irreducibly complex"?

No part of it can be removed or altered without it not being able to function completely.

What are the main differences between eukaryotic and prokaryotic cells?

Prokaryotic cells are much smaller and much simpler than eukaryotic ones. They have no true membrane bound nucleus and no other membrane bound organelles. They also have a cell wall, smaller ribosomes and may have other features.

How are eukaryotic ribosomes different from prokaryotic ribosomes?

Prokaryotic ribosomes are 70S while eukaryotic ones are 80S so prokaryotic ones are smaller.

What helps some kinds of bacteria move?

Some bacteria have a long tail called a flagellum. This is a protein strand made of 9 ringed microtubules which is rotated by a protein motor to propel the bacterium through the medium it is in.

((What is bacterial conjugation?))

The mechanism by which bacteria share DNA. This process uses pili and is used to share useful genes

What is the mucilaginous capsule for?

The mucilaginous slime capsule protects the bacteria from other cells by hiding antigens on the surface of the bacterial cell to make it less recognizable. It also prevents desiccation (drying out).

What's the main difference between viruses and bacteria?

Viruses are much smaller

When can a virus reproduce?

Viruses have no metabolic functions of their own. They can only reproduce when they inhabit a host cell.

How is genetic information contained within a virus?

As strands of a nucleic acid - RNA or DNA. For example, HIV contains its genes as two strands of RNA.

What are the two types of prokaryotic cells?

Bacteria and Viruses

What are plasmids and what are they used for?

Plasmids are extra loops of DNA used for containing extra genetic information. Often, useful characteristics such as antibiotic resistance are contained in the plasmids, so that they may be shared between bacteria in bacterial conjugation.

How is genetic material contained in a bacterium?

The DNA in a bacterium is shorter than in a eukaryote. It is contained in a circular loop of DNA which is free in the cytoplasm (ie, not bound in a nucleus). It may also be contained as plasmids which are extra loops of DNA.

What other structure can flagella be compared to?

The flagellum is essentially a longer cilia as it is made of the same material (microtubules)