Chapter 4: Eukaryotic Cells Flashcards
Endosymbiotic Theory
series of sequentail, cell merging events between an ancient eukaryotic ancestor and certain prokaryotes; mitochondria evolved from an engulfed nonphotosynthetic prokaryote; chloroplast evolved from an engulfed photsynthetic prokaryote (cyanobacterium)
What is some of the evidence supporting endosymbiotic theory?
mitochondria and chloroplasts have their own circular DNA;, 70S ribosomes, double membrane structures, similar size to bacteria, ability to replicate by a process similar to binary fission, genes resembling certain bacterial gnees
Eukaryotic Cells
plants, animals, protists, fungi, larger in size and more complex than prokaryotic cells; larger genomes; multiple linear chromosomes
Membrane Bound Organelles
eukaryotic cells have a defined nucleus; a variety of other membrane bound organelles; mitochodria, chloroplast
Cell Division in Eukaryotes
eukaryotic cells can exhibit sexual or asexual reproduction; before a cell divides it must copy it genetic material; cell division is longer in eukaryotes because they have a larger genome and organelles to replicate
Mitosis
generates two genetically identical offspring from one parent cell; offspring cells maintain the same number of chormosomes as the parent cell; clones
Meiosis
involved in sexul reproduction; consists of two cell division stages; one parent cell produces four gametes; gametes are haploid; crossing over allows for genetic recombination
Endocytosis
imports things into the cell; plasma membrane fold around extracellular substances; membrane pinches off forming endocytic vesicles containing substances; pinocytosis, phagocytosis, and receptor mediated endocytosis
Exocytosis
exports things out of the cell; vesibles deliver their contents to the plasma membrane
Pinocytosis
cell drinking; endocytosis of dissolved substances in small vesicles
Phagocytosis
cell eating; endocytosis of undissolved substances
Phagocytosis (cont)
specialized immune system cells (macrophages); cells engulfs its target (the phagosome); phagosome fuses with a lysosome containing hydrolytic enzymes; fusion = phagolysosome; hydrolytic enzymes destroys most cells and viruses; waste products are expelled
Receptor Mediated Endocytosis
ligands (hormones, nutriens, pathogens, etc) bind to specific cell surface receptors; inner surface of the plasma membrane is coated with clathrin; clathrin polymerizes forming a pit; clathrin-coated pit pinches off; forms a clathrin coated vesicle; sheds the clathrin coat; fuses with an endosome; altered pH separates ligand and receptor; ligand and recepteor are sorted and delivered
Animals
multicellular organisms; do not carry out photosyntehsis; obtain organie carbon from nutrients; ~7.5 million animal species; include parasitic worms (helminths) and arthropods
Helminths
paraisitc worms (roundworms and flat worms); complex life cycles; usually spead in a microscopic form; WHO estimates half the worlds population is infected with some type of helminth
Plants
multicellular organisms; more than290000 species; carry out photosynthesis (contain chloroplasts); make their own organic carbon using light energy; vegetation can serve as a vehibcle for infectious pathogens
Fungi
mroe than 600000 different species; most are multicellular; yeasts are unicellular; do not carry out photosynthesis; absorb nutrients from their environemt; include pathogens and saprobes
Hyphae
most fungi grow as a collecion of tubular structures
Septate Hyphae
divisions between each cell in the filament so it appears as a string of individual cells
Aseptate Hyphae
do not have divisions and appear as a long continuous chain with amny nuclei
Dimorphic Fungi
cycle between having hypahe and living as a yeast like form; many pathogenic fungi are dimorphic
Asexual Spores
arise from mitosis (no genetic variation); include conidiospores and sporangiospores
Sexual Spores
arise from meiosis (results in genetic variation); include: zygospores, ascospores, and basidospores
ADD IN EUKARYOTIC CHARTS INCLUDING HELMINTHS AND FUNGI
Fungal Diseases
called mycoses; occur in immunocompromised individuals (ex pneumocystis pneumonies AIDS patients), people who experience a disruption of their normal microbiota (ex yeast infections caused by candida)