Question

Design and submit a concept map on what you have learned. It should include concepts and connections between concepts including: Bacteria Structure Bacteria Function Transmission and replication Types

Answer 1

Bacteria are microscopic, single-celled organisms that exist in both inside and outside other organisms.

Some bacteria are harmful, but most serve a useful purpose. They support many forms of life, both plant and animal, and they are used in industrial and medicinal processes.

Bacteria are thought to have been the first organisms to appear on earth, about 4 billion years ago. The oldest known fossils are of bacteria-like organisms.Bacteria can use most organic and some inorganic compounds as food, and some can survive extreme conditions.

A growing interest in the function of the gut microbiome is shedding new light on the roles bacteria play in human health.

Bacteria are prokaryotes, lacking well-defined nuclei and membrane-bound organelles, and with chromosomes composed of a single closed DNA circle. They come in many shapes and sizes, from minute spheres, cylinders and spiral threads, to flagellated rods, and filamentous chains. They are found practically everywhere on Earth and live in some of the most unusual and seemingly inhospitable places.Bacteria are classified into 5 groups according to their basic shapes: spherical (cocci), rod (bacilli), spiral (spirilla), comma (vibrios) or corkscrew (spirochaetes). They can exist as single cells, in pairs, chains or clusters. Artwork of bacterial cells becoming resistant to antibiotics.

Each bacterium is enclosed by a rigid cell wall composed of peptidoglycan, a protein-sugar molecule. The wall gives the cell its shape and surrounds the cytoplasmic membrane, protecting it from the environment. It also helps to anchor appendages like the pili and flagella, which originate in the cytoplasm membrane and protrude through the wall to the outside. The strength of the wall is responsible for keeping the cell from bursting when there are large differences in osmotic pressure between the cytoplasm and the environment.

Cell wall composition varies widely amongst bacteria and is one of the most important factors in bacterial species analysis and differentiation. For example, a relatively thick, meshlike structure that makes it possible to distinguish two basic types of bacteria.The cytoplasm, or protoplasm, of bacterial cells is where the functions for cell growth, metabolism, and replication are carried out. It is a gel-like matrix composed of water, enzymes, nutrients, wastes, and gases and contains cell structures such as ribosomes, a chromosome, and plasmids. The cell envelope encases the cytoplasm and all its components. Unlike the eukaryotic cells, bacteria do not have a membrane enclosed nucleus.

There are three basic shapes of bacteria

1.Spherical: Bacteria shaped like a ball are called cocci, and a single bacterium is a coccus. Examples include the streptococcus group, responsible for “strep throat.”

2.Rod-shaped: These are known as bacilli (singular bacillus). Some rod-shaped bacteria are curved. These are known as vibrio. Eg.rod-shaped bacteria include Bacillus anthracis (B. anthracis), or anthrax.

3.Spiral: These are known as spirilla (singular spirillus). If their coil is very tight they are known as spirochetes. Leptospirosis, Lyme disease, and syphilis are caused by bacteria of this shape.

There are many variations within each shape group.

Structure

Bacterial cells are different from plant and animal cells. Bacteria are prokaryotes, which means they have no nucleus.

A bacterial cell include

Capsule: A layer found on the outside of the cell wall in some bacteria.

Cell wall: A layer that is made of a polymer called peptidoglycan. The cell wall gives the bacteria its shape. It is located outside the plasma membrane . The cell wall is thicker in some bacteria, called Gram positive bacteria.

Plasma membrane: Found within the cell wall, this generates energy and transports chemicals. The membrane is permeable, which means that substances can pass through it.

Cytoplasm: A gelatinous substance inside the plasma membrane that contains genetic material and ribosomes.

DNA: This contains all the genetic instructions used in the development and function of the bacterium. It is located inside the cytoplasm.

Ribosomes: This is where proteins are made, or synthesized. Ribosomes are complex particles made up of RNA-rich granules.

Flagellum: This is used for movement, to propel some types of bacteria. There are some bacteria that can have more than one.

Pili: These hair-like appendages on the outside of the cell allow it to stick to surfaces and transfer genetic material to other cells. This can contribute to the spread of illness in humans.

Replications of bacteria Bacteria reproduce by binary fission. In this process the bacterium, which is a single cell, divides into two identical daughter cells. Binary fission begins when the DNA of the bacterium divides into two.

Most circular bacterial chromosomes are replicated bidirectionally, starting at one point of origin and replicating in two directions away from the origin.