Biology 131 Ch. 24 Protists

evolved from engulfed photosynthetic bacteria

Chloroplasts

Protists possess a varied array of cell surfaces:

Some protists, such as amoebas, are surrounded only by their plasma membrane, while all other protests have a plasma membrane with an extracellular matrix (ECM) on the outside of the membrane.

Endosymbiosis is:

Suggest that a critical stage and the evolution of eukaryotic cells involved endo symbiotic relationships with prokaryotic organisms.

A likely evolved into the mitochondria and a likely evolved to be the chloroplast.

aerobic bacterium, photosynthetic bacterium

Many antibiotics that inhibit protein synthesis in bacteria inhibit protein synthesis and mitochondria and chloroplasts, but not in the cytoplasm.

also

In endosymbiosis, energy producing bacteria come to reside within larger bacteria, eventually evolving into what we know now as mitochondria. Possibly the original host cell was:

anaerobic with hydrogen dependent metabolic pathways.

The grouping of protists into the kingdom Protista is

artificial (paraphyletic, polyphyletic)

Endosymbiotic bacteria are:

bacteria that live within other cells and perform specific functions for their host cells

Chloroplasts and mitochondria replicate via , not mitosis.

binary fission

Some autotrophic protists are photosynthetic, whereas others are

chemoautotrophic

Mitochondria evolved from .

engulfed aerobic bacteria.

Some of the earliest free-living eukaryotes with functional mitochondria were the ____.

euglenozoans

Mitosis involved in:

eukaryotes.

Stramenopiles are a branch of SAR that are distinguished from other members based on the presence of ____.

fine hairs on their flagella

About a third of the 40 genera of euglenoids ____.

have chloroplasts and are fully autotrophic

Euglenids are among the earliest free living eukaryotes that possessed functional for cellular respiration.

mitochondria

For as long as the mitochondria has existed as endosymbionts within eukaryotic cells,

most of their genes have been transferred to the chromosomes of the host cells, but not all.

Diplomonads are unique because they possess two

nuclei

All chloroplasts are likely derived from a , but the organisms that host these chloroplasts are not monophyletic.

single line of cyanobacteria

Vorticella is a protist and

unicellular.

The genes that encode the essential proteins of oxidative metabolism are transcribed within the mitochondrion,

using mitochondrial ribosomes that are smaller than those of eukaryotic cells, very much like bacterial ribosomes in size and structure.

In rocks about , the first microfossils that are noticeably different than prokaryote fossils appeared.

1.5 billion years old

Indirect chemical traces hint that eukaryotes may go as far back as?

2.7 billion years

Prokaryotic microfossils were no larger than .

6 micrometers.

Which of the following are structures that protists utilize to swim?

Cilia, Flagella

cells are much larger than those of prokaryotes and have internal membranes and thicker walls.

Eukaryotic

Choose the 5 main supergroups of protists, according to our current understanding of protist phylogeny.

Excavata Opisthokonta SAR Archaeplastida Amoebozoa

Which of the following protozoans is mismatched with the disease that it causes?

Giardia intestinalis—malaria. Entamoeba histolytica—amoebic dysentery. Trypanosoma brucei—sleeping sickness. Trichomonas vaginalis—vaginitis and urethritis.

intestinalis is a diplomonad parasite that can pass from human to human via contaminated and causes diarrhea.

Giardia, water

Protists can be:

Heterotrophic or autotrophic.

Mitosis and cytokinesis did not evolve all at once as there are traces of intermediate mechanisms in some eukaryotes. Such as:

In fungi and in some groups of protists the nuclear membrane does not dissolve, as it does in plants, animals, and most other protests, in which mitosis is confined to the nucleus. When mitosis completes, the nucleus divides into two daughter nuclei and then the rest of the cell divides.

For protists phagotrophs to digest their food, they:

Lysosomes fuse with the food vacuoles, introducing enzymes that digest the food particles within. Digested molecules are absorbed across the vacuolar membrane

Protests are highly variable with no unifying features:

Many are unicellular, but there are numerous colonial and multicellular groups. Most are microscopic, but some are as large as trees.

Protests move using diverse mechanisms:

Many protists wave one or more flagella to propel themselves through the water whereas other protests use cilia to create water currents for their feeding or propulsion. Among amoebas, large blunt extensions of the cell body called pseudopodia are the main means of locomotion.

Do any fossils support that eukaryotes appeared 2.7 billion years ago?

No.

Protist heterotrophs obtain energy from

Organic molecules synthesized by other organisms

Some heterotrophic protists are phagotrophs;

Organisms that ingest particles of food into vesicles called food vacuoles or phagosomes.

Some parabasalids live in a symbiotic relationship in the gut of termites. How do they aid in the digestion of cellulose, the main component of termites diet?

Parabasalids have a symbiotic relationship with bacteria that secrete enzymes which aid digestion of cellulose.

Mixotrophs are:

Protists that are both phototrophic and heterotrophic.

According to our current understanding, stramenopiles and alveolates are members of the supergroup

SAR

According to our current understanding, stramenopiles and alveolates are members of the supergroup .

SAR

reproduction allows for frequent genetic recombination which generates genetic variation - the starting point of evolution.

Sexual

Protests are the most ancient eukaryotes and are classified on the basis of a single negative characteristic:

They are not fungi, plants, or animals.

How are the members of Protists related and what is the implication of their relationship for their grouping in the kingdom Protista?

They are only distantly related; grouping is artificial

Which of the following are characteristics of the symbiotic parabasalids that inhabit the guts of termites?

They have a symbiotic relationship with bacteria which aid in the digestion of cellulose. They can digest cellulose.

Select all features of diplomonads.

They lack mitochondria. They have two nuclei. They are unicellular.

True or false: Euglenids reproduce only asexually by mitotic cell division.

True

Each mitochondrion still has its own genome, , on which are located genes encoding the essential proteins of oxidative metabolism.

a circular closed molecule of DNA similar to that found in bacteria

Chloroplasts are the:

photosynthetic organelles of plants and algae.

In evidence of endosymbiosis is that present day organelles such as mitochondria and chloroplasts contain their own DNA, which is:

remarkably similar to the DNA of bacteria in size and character.

Fertilization, or the union of two haploid cells, is a defining feature of ____.

sexual reproduction

Cilia is

short flagella-like structure