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Parabasalids

A second Excavata subgroup, the parabasalids, also exhibits semi-functional mitochondria. In parabasalids, these structures function anaerobically and are called hydrogenosomes because they produce hydrogen gas as a byproduct. Parabasalids move with flagella and membrane rippling. Trichomonas vaginalis , a parabasalid that causes a sexually transmitted disease in humans, employs these mechanisms to transit through the male and female urogenital tracts. T . vaginalis causes trichamoniasis, which appears in an estimated 180 million cases worldwide each year. Whereas men rarely exhibit symptoms during an infection with this protist, infected women may become more susceptible to secondary infection with human immunodeficiency virus (HIV) and may be more likely to develop cervical cancer. Pregnant women infected with T . vaginalis are at an increased risk of serious complications, such as pre-term delivery.

Euglenozoans

Euglenozoans includes parasites, heterotrophs, autotrophs, and mixotrophs, ranging in size from 10 to 500 µm. Euglenoids move through their aquatic habitats using two long flagella that guide them toward light sources sensed by a primitive ocular organ called an eyespot. The familiar genus, Euglena , encompasses some mixotrophic species that display a photosynthetic capability only when light is present. In the dark, the chloroplasts of Euglena shrink up and temporarily cease functioning, and the cells instead take up organic nutrients from their environment.

The human parasite, Trypanosoma brucei , belongs to a different subgroup of Euglenozoa, the kinetoplastids. The kinetoplastid subgroup is named after the kinetoplast    , a DNA mass carried within the single, oversized mitochondrion possessed by each of these cells. This subgroup includes several parasites, collectively called trypanosomes, which cause devastating human diseases and infect an insect species during a portion of their life cycle. T . brucei develops in the gut of the tsetse fly after the fly bites an infected human or other mammalian host. The parasite then travels to the insect salivary glands to be transmitted to another human or other mammal when the infected tsetse fly consumes another blood meal. T . brucei is common in central Africa and is the causative agent of African sleeping sickness, a disease associated with severe chronic fatigue, coma, and can be fatal if left untreated.

 The life cycle of  T. brucei begins when the tetse fly takes a blood meal from a human host, and inject the parasite into the bloodstream. T. brucei multiplies by binary fission in blood, lymph and spinal fluid. When another tsetse fly bites the infected person, it takes up the pathogen, which then multiplies by binary fission in the fly’s midgut. T. brucei transforms into an infective stage and enters the salivary gland, where it multiplies. The cycle is completed when the fly takes a blood meal from another human.
Trypanosoma brucei , the causative agent of sleeping sickness, spends part of its life cycle in the tsetse fly and part in humans. (credit: modification of work by CDC)

Watch this video to see T . brucei swimming.

Chromalveolata

Current evidence suggests that species classified as chromalveolates are derived from a common ancestor that engulfed a photosynthetic red algal cell, which itself had already evolved chloroplasts from an endosymbiotic relationship with a photosynthetic prokaryote. Therefore, the ancestor of chromalveolates is believed to have resulted from a secondary endosymbiotic event. However, some chromalveolates appear to have lost red alga-derived plastid organelles or lack plastid genes altogether. Therefore, this supergroup should be considered a hypothesis-based working group that is subject to change. Chromalveolates include very important photosynthetic organisms, such as diatoms, brown algae, and significant disease agents in animals and plants. The chromalveolates can be subdivided into alveolates and stramenopiles.

Questions & Answers

what difference between animal cell and plant cell
Lazarus Reply
what is animal call
Rita
what is fertilization?
Muhamed Reply
What kind of nutrients is composed of plants
Annie Reply
phosphorus,potassium,nitrogen
Kritika
what is hormones
Igwe Reply
hormon is the chemical messanger
Sneha
Genes can make someone dull?
Taperah
21ecological instrument and their diagrams
Ayomide Reply
cell biology
Muhamed
I am sorry
onuoha
for wat
ezeadaugo
no reason
KP
nothing but speculate
KP
what are the kidney disease
Immaculate Reply
kidney stones
Gracelyne
it is a disease that affects the kidney
Miriam
what are some lung diseases
Gracelyne
what is micro-organism
Jackson Reply
what is the hypothesis
Jackson
hypothesis is a proposed explanation for a phenomenon
Miriam
hypothesis is raw materials
KP
what is biology
KP
biology is the study of living things and their interaction with their environment
Miriam
what is zyogot?
Muhamed
what is fertilization?
Muhamed
zygote is an unfertilized eggs
KP
fertilization refers to the fusion of a sperm and ovum
KP
what does mean stigma
Amira Reply
what is the full of the MOST dangerous disease in the world where one stops sleeping and just dies :Hint ; FFI
God Reply
fatal familial insomnia which affects the thalamus
Miriam
there are other dangerous diseases like CAD i.e coronary artery disease
Miriam
what is matter
Thomas Reply
it is any thing that has weight and occupies space
Anye
matter is any substances that occupies spaces and has mass
Jackson
describe photosynthesis
Mavis Reply
What is equilibrium
Mavis
What is equilibrium
Mavis
like corporal intern balance right?
FRANCISCA
on my own understanding is just a balanced state
Stanley
photosynthesis is the process by which plants and other organisms convert light energy to chemical energy
Miriam
what is a chromosome?
Wise Reply
Are thread-like structures located inside the nucleus of animal and plant cells.
Canab
thx
Wise
what are the difference between Biotic community and Ecological nitche.
Ganiyat Reply
what is the celll
KAMOLIKA Reply
A cell is the simplest bit of living matter that exist independently
Ganiyat
cell is the basic unit of life
Shadrack
what is ecdysis
Shadrack
what is genetics
Sebastian Reply
The cell is the simplest bit of living matter that can exist independently.
Ganiyat

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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