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Chapter 27 Eukaryotic Cells
Terms in this set (57)
defining characteristics of eukaryotes
nucleus and membrane bound organelles
bacteria and archaeons reply primarily on what to support the cell?
cells wall and framework of proteins within the cytoplams
eukaryotes reply primarily on what to support the cell?
internal scaffolding of proteins such as actin filaments and microtubules - cytoskeleton
found in all eukaryotic cells, can be remodeled quickly which enables the cell to change shape and engulf particles or other cells
engulfing a particle, packaging it in membrane-lined vesicles, transporting it to be processes inside the cell body
vacuoles package newly formed molecules or cytoplasmic waste in vesicles and move them to the cell surface for excretion by molecular motors in the cytoskeleton
dynamic membranes that include...
1. the nuclear envelope
2. an assembly of membranes that run through the cytoplasm called the rough endoplasmic reticulum and golgi apparatus
3. a cell or plasma membrane that surrounds the cytoplasm
all members of the endomembrane are...
interconnected directly or by the movement of vesicles, many capable of changing shape
compared to prokaryotes, eukaryotes are ______ in the way they obtain carbon and energy
engulfing food particles and packaging them inside a membrane vesicle which is then transported into the cytoplasm where enzymes break it down into molecules that can be used by the mitochondria
allows for predation
selection favors strains of bacteria and archaea that only retain the genetic material vital to the organism because...
speed of replication of the circular dna chromosome allows for speed of reproduction
what relieves the evolutionary pressure to minimize genome size in eukaryotes
multiple linear chromosomes that can be replicated at many sites at once
regulatory DNA gives eukaryotes...
fine control of gene expression that is required for multicellular development and complex life cycles
Diversity in Eukaryotes: why so much more
diversity in size, shape, type than prokaryotes?
• Membrane dynamics
• Compartmentalized metabolism
• Genome organization
• Genetic diversity by means of sex
• Life cycles
how do bacteria and archaea generate genetic diversity?
horizontal gene transfer
sex cells with half the chromosome number (haploid cells), produced in meiosis
2 ways sex promotes genetic variation
1. meiotic cell division results in daughter cells that are genetically unique, combination of alleles is different than that in the parent cells
2. in fertilization, new combinations of genes are brought together by the fusion of gametes
cells with one set of chromosomes, 1n
cells with two sets of chromosomes, 2n
many single celled eukaryotes exist in the....
haploid state and reproduce through mitotic division
two haploid cells fusing to create a diploid cell
single celled eukaryotes that are mostly diploid and reproduce asexually by mitotic cell division, becoming smaller with each asexual division
two multicellular phases in the life cycle of plants
one haploid, one diploid
only haploid stage of life in animals
when its a gamete
an organism that lives in closely evolved association with another species
association between two species
how did chloroplast originate?
as a symbiotic cyanobacteria that through time became permanently incorporate into their hosts because of their photosynthetic membranes, resulting in a double membrane
a symbiosis in which one partner lived within the other
cyanobacteria most closely related to chloroplast have 2000-3000 genes but now chloroplast only have 60-200 genes. where did it go?
lost through evolution, genes that were similar to nuclear gene were no longer needed
most was transported to the nucleus of the eukaryote on viruses
how did mitochondria originate?
as endosymbiotic bacteria originally called proteobacteria
human mitochondria only code for 13 proteins and 24 RNAs
most single-celled eukaryotes in oxygen-free environments do not have mitochondria. why?
once had them but lost then and gained hydrogenosomes that generate ATP by an anaerobic process, they have little dna but it is the remnant of mitochondrial dna
mitosomes do the same thing and are also the remnant of mitochondria
2 hypotheses of why archaeon genes are inside eukaryotes
1. some believe that the host for mitochondrion-producing endosymbiosis was a true eukaryotic cell but only limited ability to derive energy from organic molecules - host cell evolved from archaea
2. others believe that no eukarytic cell existed before there were mitochondria, believe eukaryotic cell began as a symbiotic association between a proteobacteria and an archaeon
domain is divided into four kingdoms
organisms that have a nucleus but lack other features specific to plants, animals, or fungi
protists live within these houses constructed on organic molecules
how protists move
flagella or pseudopodia
7 groups of eukarya
humans are in opisthokonts
land plants are in archaeplastids
75% of species
"posterior pole" cell movement is propelled by a singular flagellum (sperm)
group of mostly unicellular protists characterized by a ring of microvilli, fingerlike projections that form a collar around the cell's single flagellum
most closely related to animals
single-celled opisthokonts that are closely related to fungi
parasites that live inside animal cells
smallest genome of any eukaryote
superkingdom, group of eukaryotes with amoeba-like cells that move and gather food by means of pseudopodia
entamoeba histolytica causes dysentery
haploid cells fuse together to form a zygote which subsequently undergoes repeated rounds of mitosis but not cell division
structure that slime molds form, can move and seek out food
contains many nuclei within one giant cell
stocks that plasmodia slime molds form when ready to reproduce
starvation causes cellular slime molds to aggregate together after the release of cAMP which is good at finding food
superkingdom of land plants, all photosynthetic
2. red algae
superkingdom that includes unicellular organisms, giant kelps, algae, protozoa, free living cells, and parasite
all have unusual flagellum that bear two rows of stiff hairs and a second smooth flagellum
diatoms are responsible for half of all primary production in ocean and a quarter of all photosynthesis on earth
superkingdom that includes dinoflagellates (red tide), ciliates, heterotrophic protists
all have cortical alveoli
why was photosynthesis found in multiple areas of the tree?
eukaryotes acquired it multiple times by repeated episodes of endosymbiosis
sedimentary rocks from 1800-1400 mya that contain microscopic fossils
when did the eukaryotic domain first appear?
when did the first fossils that can be linked to one of the superkingdoms appear?
FW, single-celled, the highest
number of features linking to the ancestral
Peptidoglycan and biliprotein pigments that are
Green Algae Diversity
differences in form, chlorophyll
a and b, 2-membrane chloroplasts, phytoplankton,