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)
Dermatophytes
fungal disease; true pathogens; infect skin, hair and nails; dermatophytic infections are tinea; tinea ungium aka dermatophytic onychomycosis; tinea pedia aka athletes foot
Some fungi can stimulate allergies or produce…
mycotoxins; ex clavicep purpurea produces ergot toxin which is a potent neurotoxin that can lead to seizures, psychosis, nausea, vomiting, and even death
Protists
diverse group of eukaryotes; unicellular, multicellular or multinucleated masses; autotrophs or heterotrophs; asexual or sexual reproduction; cell wall or no cell wall
Examples of Protists
algae, slime molds, protozoans; though to represent evolutionary link to plants, fungi, and animals
Examples of Protozoan Pathogens
toxoplasma gondii, trichomonas vaginalis, giardia spp.
How are protozoans grouped?
based on their means of motility in their mature form; amoeboid, flagellated, ciliated, spore forming
Amoeboid Protozoans
use pseudopods for movement; some are free living (amoeba proteus) and some are pathogenic (naeglera fowleri, acanthamoeba); entamoeba histolytica is the most common amoeboid infection in humans
Flagellated Protozoans
flagella for motility; some are free living (euglena) and some are parasitic (trichomonas vaginalis, trypanosoma spp. , giardia lamblia)
Ciliated Protozoans
ciliophora; use cilia for motility; common in aquatic environments; some are free living (paramecium) and some are parasites; balandtidium coli is the ciliated protozoan known to cause human disease
Apicomplexa
spore forming protozoans; largest phyla of protozoans; move by gliding (no flagella, cilia, or pseudopodia); most are obligate intracellular parasites; complex life cycles that include sexual and asexual stages; three phases- mergony, gamogony, and sporogony
Merogony
asexual stage of repoduction; merozoites are made by repeated asexual cell division
Gamogony
sexual phase of reproduction; merozoites produce male and female haploid gametes by meiosis
Sporogony
zygote made by gamete fusion divides to make sporozoites; typically the infective stage; then cycle starts again
Apicomplexans are notorious…
human pathogens; toxoplasmosis (often spread by cats); malaria; cryptosporidiosis; microsporidiosis ; some members require arthropod vectors (like mosquitos) for part of their life cycle
Plasma Membrane
serves as selective barrier; phospholipid bilayer structure; eukaryotic membranes contain many sterols
Cell Wall
external to plasma membrane; helps maintain cell shpae; protects against mechanical and osmotic stress; fungi, plants, and certain protists have cell walls; lack peptidoglycan
Eukaryotic Glycocalyx
most eukaryotes have a sticky extracellualr layer called a glycocalyx as their outermost layer; contains a diverse collection of carbohydrates, glycoproteins, and glycolipids
Eukaryotic Flagella
built from tubulin; has microtubules (9+2 arrangement); surrounded by plasma membrane; microtubules sprout from a centriole; wave like motion (whips back and forth)
Prokaryotic Flagella
flagellin protein; no microtubules; not membrane enclosed; hook and filament structure anchored by rings; rotatry/propeller movement
Ribosomes
makes proteins; made of protein and ribosomal RNA (rRNA); eukaryotes have 80S ribosomes that are made of 40S and 60S subunit
Ribosomes can be free or membrane associated
free in cytoplasm or bound to ER; can change from free to bound based on the protein production needs of the cell
Bound Ribosomes
produce proteins that are destined for secretion from the cell
Free Ribsomes
produces cytosolic proteins
Cytoskeleton
dynamic (constantly being rebuilt and moved) and responsive intracellular network of protein fibers; helps maintain shape, facilitates movement, protects against external forces, directs transportation, coordinated cell division; made of microtubules, intermediate filaments and microfilaments
Microtubules
hollow tubes; large; made of tubulin; roadways of the cell–proteins (kinesin and dynein) move cargo along microtubules; form spindle during cell division (helps separate chromosomes; usually arise from centrosome
Intermediate filaments
rope-like fibers about 10nm in diameter; different proteins make up intermediate filaments; contribute tensile strength
Microfilaments
fine fibers; smallest; made of actin; tend to assocaite with myosin; functions in muscle contraction, pinches cell apart, faciliates movement of pseudopodia
Nucleus
DNA is loosely organized as chromatin; DNA floats in nucleoplasm; enclosed by nuclear envelope; has nuclear pores that control things in/out of nucleus
Nucleolus
dense area in the nucleus; enriched with RNA; site where ribosomal subunits begin their development
Endoplasmic Reticulum
continous with nuclear envelope at some points; essentiaal roles in protein and lipid production; many of the products made in the ER are destined for exportation to other organelles or for secretion; series of interconnected membranes that originate from the nuclear envelope ; smooth or rough
Rough ER
millions of ribosomes on outer surface; proteins are directly inserted into the ER membrane or transported into the lumen; modifies proteins (clips, folds, addition organic/inorganix factors)
Smooth ER
not associated with ribosomes; interlaced tubular appearance; involved in lipid production; important role in detoxifying substances
Golgi Apparatus
vesicles that bud off the ER are often shuttled to golgi; series of cisternae (disc-like flattened sacs); coordinates with ER; modifies cellular proteins, build lipids, sorts and distributes finsihed products
Transport Vesicles
move substances are the cell
Secretory Vesicles
shuttle materials to the cell surface for discharge from the cell
Lysosomes
contain hydrolytic enzymes that break down substances engulfed by the cell
Peroxisomes
contain enzymes that break down fats and amino acids by oxidation, protect cells from toxic oxygen intermediates
Vacuoles
conglomerate of many vesicles that merged to make a large membranous sac; contain mainly water and various organic and inorganic substances; vary in size and shape; common in plants and fungi
Contractile Vacuoles
in some protists; regulates the osmotic pressure to avoid lysing when in a hypotonic environment
Mitochondria
make ATP; make amino acids and vitamins; regulate cell division; carry out programmed cell death (apoptosis); impact a number of disease states; play a role in cancer and aging; smooth outer membrane; inner membrane contain critae; matrix
Chlrorplasts
allow the cell to harvest energy from sunlight using light collecting pigments; inner and outer membrane; thylakoids stacked in grana; stroma
