Chapter 28 Flashcards
(78 cards)
Are protists paraphyletic or monophyletic?
paraphyletic
What were the first eukaryotes?
Protists
Eukaryotic differences from Prokaryotes
Presence of a complex skeleton
Compartmentalization (nucleus and organelles).
Appearance of eukaryotes in microfossils occurred about what time?
1.5 BYA
The word Eukaryote derived from Greek words means what?
True nucleus
Which ways did Eukaryotic cells evolve?
Horizontal Gene Transfer
Infoldings of membranes
engulfing other cells
Out of the three ways that Eukaryotic cells evolved to what they are today, which method is the way that the nuclear envelope and endoplasmic reticulum arose?
Membrane Infoldings
Bacteria that live within other cells and provide some benefit for their host cells are called?
endosymbiotic bacteria (endosymbiosis means “living together in close association”)
How to we know the mitochondria came first when Eukaryotes were first evolving?
It is the most widespread common trait in Eukaryotes
Who championed the Theory of Endosymbiosis in 1970?
Lynn Margulis
Who first proposed the theory of endosymbiosis in 1905?
Konstantin Mereschkowsky
What facts serve as evidence to support the theory of endosymbiosis?
DNA inside mitochondria and chloroplasts. (Circular DNA, similar to bacteria DNA in size and character.)
the MRNAs produced from the genes of the mitochondrial genome are translated using ribosomes that are very much like bacterial ribosomes in size and structure
Many antibiotics that inhibit protein synthesis in bacteria also inhibit protein synthesis in mitochondria and chloroplasts
Chloroplasts and mitochondria replicate by binary fission – not mitosis.
How does the theory of endosymbiosis believe the mitochondria became a part of the Eukaryotic cell?
Energy producing bacteria may have to come to reside within larger bacteria or archaebacteria, eventually evolving into what we now know as mitochondria
How does the theory of endosymbiosis believe the chloroplast became a part of the Eukaryotic cell?
Photosynthetic bacteria were likely engulfed by other, larger bacteria leading to the evolution of chloroplasts. All chloroplasts are likely derived from a single line of cyanobacteria.
How is it assumed Brown algae obtained their chloroplasts?
by engulfing one or more red algae, a process called secondary endosymbiosis. this why chloroplasts in brown algae have four membranes
How do prokaryotes carry genes?
on a single DNA molecule
How do eukaryotes carry genes?
On multiple chromosomes, which are usually present in pairs
Mitosis in Eukaryotes
Mitosis is the separation of chromosomes while cytokinesis is the division of the cytoplasm
In fungi and some protist groups the nuclear envelope does not dissolve so mitosis occurs in the nucleus rather than the cytoplasm like in most eukaryotes. Then two daughter nuclei form and then the cell will split.
How could you distinguish the difference between primary and secondary symbiosis by looking at micrographs of cells with chloroplasts?
Counting the number of cell membranes of chloroplasts indicates primary or secondary endosymbiosis
Protist Overview
Most diverse of the four eukaryotic kingdoms and are united on the basis that they are not fungi, plants, or animals (classified by exclusion)
Unicellular, colonial, and multicellular groups.
Most are microscopic but some are huge.
Many forms and symmetries.
All types of nutrition.
They are not monophyletic, they are paraphyletic
Are protists present in all 5 eukaryotic supergroups? What are they?
Yes,
Excavata
S A R
Archaeplastida
Amoebozoa
Ophisthokonta
What is being used to test different hypothesis regarding evolutionary relationship controversies in protist phylogeny?
DNA sequence data
Do protists have a varied array of cell surfaces?
Yes (Plasma Membrane and/or extracellular matrix (ECM))
Some protists, such as amoebas are surrounded by only what cell surface?
Plasma Membrane