Prokaryote Characteristics

Questions and Answers

Some prokaryotes have ______, which allow them to stick to their substrate or other individuals in a colony

fimbriae

Pili (or sex ______) are longer than fimbriae and allow prokaryotes to exchange DNA

pili

Many bacteria exhibit ______, the ability to move toward or away from a stimulus

taxis

Bacterial ______ are composed of a motor, hook, and filament

flagella Signup and view all the answers

Many prokaryotes form metabolically inactive ______, which can remain viable in harsh conditions for centuries

endospores Signup and view all the answers

Three factors contribute to their genetic diversity: rapid reproduction, mutation, and genetic ______

recombination Signup and view all the answers

Most of the genome consists of a circular ______ located in the nucleoid region

chromosome Signup and view all the answers

Some species of bacteria also have smaller rings of DNA called ______

plasmids Signup and view all the answers

Archaea share certain traits with bacteria and other traits with ______

eukaryotes Signup and view all the answers

Methanogens live in swamps and marshes and produce ______ as a waste product

methane Signup and view all the answers

Phototrophs obtain energy from ______.

light Signup and view all the answers

In ______, some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3).

nitrogen fixation Signup and view all the answers

Cyanobacteria are ______ that generate O2

photoautotrophs Signup and view all the answers

Prokaryotes can be categorized by how they obtain energy and ______.

carbon Signup and view all the answers

Spirochetes are helical ______

heterotrophs Signup and view all the answers

A ______ cell attaches to a recipient by a pilus, pulls it closer, and transfers DNA.

donor Signup and view all the answers

Chlamydia trachomatis causes ______ and nongonococcal urethritis by sexual transmission

blindness Signup and view all the answers

In the cyanobacterium Anabaena, photosynthetic cells and nitrogen-fixing cells called ______ exchange metabolic products.

heterocysts Signup and view all the answers

Extreme halophiles live in highly ______ environments

saline Signup and view all the answers

Extreme thermophiles thrive in very ______ environments

hot Signup and view all the answers

Obligate ______ require O2 for cellular respiration.

aerobes Signup and view all the answers

Prokaryotes play a major role in the recycling of ______ elements between the living and nonliving components of ecosystems

chemical Signup and view all the answers

A piece of DNA called the F ______ is required for the production of pili.

factor Signup and view all the answers

[Blank] is the movement of genes between bacteria by bacteriophages (viruses that infect bacteria).

Transduction Signup and view all the answers

Fungi are essential for the well-being of most ______ ecosystems.

terrestrial Signup and view all the answers

Fungi use enzymes to break down a large variety of complex molecules into smaller ______ compounds.

organic Signup and view all the answers

Conidia are not formed inside ______; they are produced asexually at the tips of specialized hyphae called conidiophores

sporangia Signup and view all the answers

Symbiotic relationships between fungi and animals are examples of ______ mutualism.

fungus-animal Signup and view all the answers

Neurospora crassa, a ______ mold, is a model organism with a well-studied genome

bread Signup and view all the answers

Mycorrhizae are symbiotic relationships between fungi and ______.

plants Signup and view all the answers

The phylum Basidiomycota is defined by a clublike structure called a ______

basidium Signup and view all the answers

Basidiomycetes are a group of fungi that include ______ and mushrooms.

rusts Signup and view all the answers

Fungi are efficient decomposers of organic material including ______ and lignin

cellulose Signup and view all the answers

Decomposition performed by fungi is important in an ecosystem because it helps ______ vital nutrients.

recycle Signup and view all the answers

Fungal cell walls contain ______.

chitin Signup and view all the answers

The life cycle of a basidiomycete usually includes a long-lived ______ mycelium

dikaryotic Signup and view all the answers

A mycelium's structure maximizes its surface ______-to-volume ratio.

area Signup and view all the answers

Mushrooms are examples of ______ fruiting bodies

basidiocarps Signup and view all the answers

Fungi perform essential recycling of chemical ______ between the living and nonliving world

elements Signup and view all the answers

Fungi are also used in ______ projects to clean up pollutants

bioremediation Signup and view all the answers

Most fungi have hyphae divided into cells by ______, with pores allowing cell-to-cell movement of organelles

septa Signup and view all the answers

Coenocytic fungi lack ______ and have a continuous cytoplasmic mass with hundreds or thousands of nuclei

septa Signup and view all the answers

Some fungi have ______ specialized to capture prey

hyphae Signup and view all the answers

Mycorrhizal fungi deliver ______ ions and minerals to plants

phosphate Signup and view all the answers

The body is made of a mycelium, which is an interwoven mass of ______

hyphae Signup and view all the answers

A unique feature that helps identify the fungus is the presence of ______ cell walls

chitinous Signup and view all the answers

Foresters inoculate pine seedlings with ______ to promote growth

mycorrhizae Signup and view all the answers

Mycorrhizae are mutually beneficial relationships between fungi and ______ roots

plant Signup and view all the answers

Study Notes

Prokaryotic Structures and Functions

Some prokaryotes have fimbriae, which allow them to stick to their substrate or other individuals in a colony.
Pili (or sex pili) are longer than fimbriae and enable prokaryotes to exchange DNA.

Locomotion

Many bacteria exhibit taxis, the ability to move toward or away from a stimulus.
Chemotaxis is the movement toward or away from a chemical stimulus.
Most motile bacteria propel themselves by flagella scattered about the surface or concentrated at one or both ends.
Bacterial flagella are composed of a motor, hook, and filament.

Internal Organization

Prokaryotic cells usually lack complex compartmentalization.
Some prokaryotes have in-foldings of the plasma membrane that perform metabolic functions.
Most of the genome consists of a circular chromosome located in the nucleoid region.
Some species of bacteria also have smaller rings of DNA called plasmids.

Prokaryotic Reproduction

Prokaryotes reproduce by binary fission, which takes around 1-3 hours.
They have short generation times, which contributes to their genetic diversity.
Many prokaryotes form metabolically inactive endospores, which can remain viable in harsh conditions for centuries.
Genetic diversity in prokaryotes is also contributed by rapid reproduction, mutation, and genetic recombination.
Mutation rates during binary fission are low, but rapid reproduction allows mutations to accumulate rapidly in a population.

Genetic Recombination

Transformation is the process where a prokaryotic cell takes up and incorporates foreign DNA from the surrounding environment.
Transduction is the movement of genes between bacteria by bacteriophages (viruses that infect bacteria).
Horizontal gene transfer is the movement of genes among individuals from different species.

Conjugation

Conjugation is the process where genetic material is transferred between prokaryotic cells.
During conjugation, a donor cell attaches to a recipient by a pilus, pulls it closer, and transfers DNA.
A piece of DNA called the F factor is required for the production of pili.

Metabolism and Nutrition

Prokaryotes can be categorized by how they obtain energy and carbon.
Phototrophs obtain energy from light, while chemotrophs obtain energy from chemicals.
Autotrophs require CO2 as a carbon source, and heterotrophs require an organic nutrient to make organic compounds.
Energy and carbon sources are combined to give four major modes of nutrition.

Nitrogen Metabolism

Nitrogen is essential for the production of amino acids and nucleic acids.
In nitrogen fixation, some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3).
In the cyanobacterium Anabaena, photosynthetic cells and nitrogen-fixing cells called heterocysts exchange metabolic products.

Prokaryotic Metabolism

Prokaryotic metabolism varies with respect to O2.
Obligate aerobes require O2 for cellular respiration, while obligate anaerobes are poisoned by O2 and use fermentation or anaerobic respiration.
Facultative anaerobes can survive with or without O2.

Prokaryotic Diversity

Domain Archaea shares certain traits with bacteria and other traits with eukaryotes.
Some archaea live in extreme environments and are called extremophiles.
Extreme halophiles live in highly saline environments, while extreme thermophiles thrive in very hot environments.
Methanogens live in swamps and marshes and produce methane as a waste product.

Domain Bacteria

Proteobacteria include photoautotrophs, chemoautotrophs, and heterotrophs.
Some proteobacteria are anaerobic, while others are aerobic.
Chlamydia are parasites that live only within animal cells.
Spirochetes are helical heterotrophs, which can be parasitic.
Cyanobacteria are photoautotrophs that generate O2.

Gram-Positive Bacteria

Actinomycetes decompose organic matter.
Bacillus anthracis causes anthrax, while Clostridium botulinum causes botulism.
Some Staphylococcus and Streptococcus can be pathogenic.
Mycoplasms are the smallest known cells.

Ecological Importance

Prokaryotes play a major role in the recycling of chemical elements between the living and nonliving components of ecosystems.
Chemoheterotrophic prokaryotes function as decomposers, breaking down dead organisms and waste products.
Prokaryotes can increase the availability of nitrogen, phosphorus, and potassium for plant growth.

Symbiosis

Symbiosis is an ecological relationship in which two species live in close contact: a larger host and smaller symbiont.

Fungal Characteristics

Fungi are diverse and widespread, with approximately 100,000 described species and an estimated 1.5 million total species
They are essential for terrestrial ecosystems, breaking down organic material and recycling vital nutrients
Fungi are heterotrophs, absorbing nutrients from outside their bodies using enzymes to break down complex molecules
They exhibit diverse lifestyles, including decomposers, parasites, and mutualists

Morphology

Fungi grow as either filaments (hyphae) or yeasts, with some species capable of growing as both
Multicellular fungi have a morphology that enhances their ability to absorb nutrients
Fungi consist of mycelia, networks of branched hyphae adapted for absorption
A mycelium's structure maximizes its surface area-to-volume ratio
Fungal cell walls contain chitin
Most fungi have hyphae divided into cells by septa, with pores allowing cell-to-cell movement of organelles
Coenocytic fungi lack septa and have a continuous cytoplasmic mass with hundreds or thousands of nuclei

Specialized Hyphae

Some fungi have hyphae specialized to capture prey
Some unique fungi have specialized hyphae called haustoria, allowing them to penetrate the tissues of their host
Most vascular plants have mycorrhizae, mutually beneficial relationships between fungi and plant roots
Mycorrhizal fungi deliver phosphate ions and minerals to plants
Types of mycorrhizal fungi include ectomycorrhizal fungi (do not penetrate root cells) and arbuscular mycorrhizal fungi (penetrate root cells)

Phylum Basidiomycota

Includes mushrooms, puffballs, and shelf fungi, mycorrhizae, and plant parasites
Defined by a clublike structure called a basidium, a transient diploid stage in the life cycle
Also called club fungi
Many basidiomycetes are decomposers of wood
Life cycle usually includes a long-lived dikaryotic mycelium that reproduces sexually by producing elaborate fruiting bodies called basidiocarps
Mushrooms are examples of basidiocarps
Basidia in a basidiocarp are sources of sexual spores called basidiospores

Conidia

Not formed inside sporangia, but produced asexually at the tips of specialized hyphae called conidiophores

Ecological Roles of Fungi

Decomposition: fungi are efficient decomposers of organic material, including cellulose and lignin
Recycling: fungi perform essential recycling of chemical elements between the living and nonliving world
Bioremediation: fungi are used in bioremediation projects

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Description

This quiz covers the unique features of prokaryotes, including fimbriae, pili, and locomotion mechanisms such as taxis and flagella.