chapter 25 Flashcards
how do prokaryotic and eukaryotic cells differ?
prokaryotes
- simple and small
- no nucleus
- no organelles
eukaryotes
- more complex and larger
- have a nucleus (chromosomes are inside)
- have organelles
eukaryotes are defined by the presence of a nucleus more features include :
- a dynamic cytoskeleton
- the membrane system ( which explains their evolutionary)
what do eukaryotic cells with dynamic features provide?
new possibilities for movement and feeding
what does sexual reproduction promote?
it promotes genetic diversity in eukaryotic populations
give me 2 examples how sex promotes genetic variation:
- meiotic cell division results in gametes or spores
- in fertilization, new combinations of genes are brought together by the fusion of gametes
what’s the difference of eukaryotic life cycle between animals and plants?
- in animals, the zygote divides many times to form a multicellular diploid body before a small subset of cells within the body undergoes meiotic cell division to form haploid gametes (eggs and sperm).
- plants have two multicellular phases in their life cycle: haploid and diploid
many single-celled eukaryotic organisms have evolved complex life cycles that include sexual reproduction. ”sexual reproduction” means that:
A. genetic material from two haploid cells is combined.
B. diploid cells must undergo mitotic cell division in order to reproduce.
C. haploid cells must undergo meiotic divisions to form gametes.
D. complex mating behavior likely evolved at the same time as sexual reproduction.
the answer is A. genetic material from two haploid cells is combined
what does mitochondria harness to convert it to what?
it harness energy from organic molecules such as sugars and convert it into ATP in plant and animal cells.
what does chloroplast capture to do what?
it captures the energy of sunlight to fix atmospheric carbon and synthesize simple sugars in plant cells and photosynthetic organisms.
where did chloroplast originate from?
cyanobacteria, red algal chloroplasts, and plant chloroplasts ( they have similar structures and biochemical features )
why are chloroplast genomes so small compared to cyanobacteria?
- the cyanobacteria most closely related to chloroplasts have thousands of genes, while the chloroplast itself has only a few hundred.
- some genes may have been lost. many other genes migrated to the nucleus of the host cell.
which of the statements is evidence supporting the hypothesis that eukaryotic chloroplasts originated from cyanobacteria?
A. chloroplasts and cyanobacteria have similar DNA sequences for shared genes.
B. chloroplasts and cyanobacteria both have cell walls.
C. chloroplasts can leave the cell and function freely on their own.
D. chloroplasts and cyanobacteria have the same number of genes.
the answer is A. chloroplasts and cyanobacteria have similar DNA sequences for shared genes
what is a proteobacteria?
bacteria that has similar DNA to mitochondria
what is the main difference between the two hypotheses—endosymbiosis and infolding of the cellular membrane—for the origin of the eukaryotic cell?
A. one attributes the formation of the endoplasmic reticulum and nuclear envelope to infolding of the plasma membrane.
B. only one involves the conversion of a proteobacterium to a mitochondrion.
C. one hypothesizes that eukaryotic cells evolved from an archaeon rather than a bacterium.
D. one hypothesizes that engulfment of a proteobacterium occurred after the formation of the nuclear envelope rather than before.
the answer is D: the competing hypotheses differ on which membrane organelle evolved first. it is difficult to determine the origin of the nuclear envelope, so these two hypotheses continue to be a source of debate.
what are opisthokonts?
the most successful group of eukaryotes including animal and fungi
what are choanoflagellates? and what do they share in common with animals?
- choanoflagellates are a group of unicellular protists characterized by a ring of microvilli that forms a collar around the cell’s single flagellum.
- they share many genes, and they also share similar structures called collar cells which are found in sponges
what member is archaeplastids?
members of this clade are photosynthetic, contains the green algae and the land plants
what is the theory of endosymbiosis?
it suggests that mitochondria and chloroplasts were once independent prokaryotes that were engulfed by another cell.
imagine there is a mutation in a eukaryotic cell that affects the cell’s ability to produce microtubules. Which of the answer options would you expect to be a characteristic of cells with this mutation compared to cells without the mutation?
A. ATP productions would be slower
B. productions of vesicles by the golgi would be slower
C. response rates in cell-signaling pathways would be slower
D. transport rates of mRNA out of the nucleus would be slower
the answer is C. since microtubules function is cell motility and determine cell shape
green algae are most closely related to:
A. diatoms
B. red algae
C. land plants
D. brown algae
the answer is C. land plants
chloroplasts are though to have evolved from:
A. cyanobacteria
B. mitochondria
C. autotrophic protists
D. proteobacteria
E. algae
the answer is A. cyanobacteria
how do eukaryotic cells generate and maintain genetic diversity?
A. by allowing more mutations
B. through horizontal gene transfer
C. through asexual reproduction
D. through sexual reproduction
the answer is D. through sexual reproduction
which of these features is responsible for the evolutionary success of eukaryotes?
A. having complex patterns of gene regulation
B. all of these choices are correct
C. possessing a dynamic cytoskeleton
D. possessing a dynamic endomembrane system
E. localizing where energy metabolism takes place
the answer is B. all choices are correct
in animals, the egg and sperm cells are:
A. none of these are correct
B. polypoid
C. diploid
D. haploid
the answer is D. haploid
