Eucaryotic cells and microorganisms

Eucaryotes Large Contains nucleus and other membrane-bound organelles Microbiological eukaryotes = protozoa, algae, fungi (yeasts + filamentous), parasitic helminths (larvae, eggs)

Endosymbiotic theory Mitochondria – have their own DNA – circular, like bacteria Chloroplasts – also have DNA – cyanobacteria-like Both are surrounded by double membrane

General eucaryotic structures

3 Eucaryotic cells Has every category

Flagella 10X thicker than procaryotic flagella function in motility appendages 10X thicker than procaryotic flagella function in motility Whips and thrashes; pushes or pulls (can be on anterior or posterior end) Vary in number and placement

appendages Cilia similar in overall structure to flagella, but shorter and more numerous found only on a single group of protozoa (ciliates) and certain animal cells function in motility, feeding & filtering Beat like oars (power stroke, recovery stroke)

Glycocalyx fungi and most algae: thick, rigid cell wall Cell envelope Glycocalyx Polysaccharides (usually) outermost boundary, direct contact with environment network of fibers, a slime layer or a capsule functions in: adherence, protection & signal reception beneath the glycocalyx: fungi and most algae: thick, rigid cell wall protozoa, a few algae, and all animal cells lack a cell wall & have only a membrane

Glycocalyx structure (fungus)

Cell wall rigid & provide structural support & shape Cell envelope rigid & provide structural support & shape Fungi: thick inner layer of polysaccharide fibers composed of chitin or sometimes cellulose & a thin layer of mixed glycans Algae: varies in chemical composition; substances commonly found include cellulose, pectin, mannans, silicon dioxide, & calcium carbonate

Cell membrane Typically a bilayer of phospholipids and proteins Cell envelope Typically a bilayer of phospholipids and proteins sterols may be present – give stability serve as porous barriers; transport substances into and out of cells eucaryotic cells also contain membrane-bound organelles that account for 60-80% of their volume

ORGANELLES The Nucleus compact sphere, most prominent organelle of eucaryotic cell nuclear envelope is composed of two parallel membranes separated by a narrow space & is perforated with pores contains chromosomes

organelles 1. nucleus

Organelles -Nucleus

2. Endoplasmic reticulum organelles Rough endoplasmic reticulum (RER)– Rough = ribosomes Protein synthesis (on ribosome) and packaging ER – protein then sent to Golgi apparatus Smooth endoplasmic reticulum (SER)– closed tubular network without ribosomes nutrient processing, synthesis & storage of lipids, etc.

2a. rough endoplasmic reticulum (RER)

2b. Smooth ER

organelles 3. Golgi apparatus consists of a stack of flattened sacs called cisternae closely associated with ER Transitional vesicles from the ER containing proteins go to the Golgi apparatus for modification and maturation Condensing vesicles transport proteins to organelles or secretory proteins to the outside receives, processes, packages, ships

Example (secretory protein): Transport process Assembly line Example (secretory protein): Protein made in ER (ribosomes) Leaves as TV  Golgi Modified, packaged, shipped (CV) Secreted (exocytosis) see movie link

4. Lysozomes vesicles containing enzymes organelles vesicles containing enzymes involved in intracellular digestion of food particles & in protection against invading microbes

has procaryotic ribosomes, DNA and metabolic enzymes 5. Mitochondria organelles consists of an outer membrane & an inner membrane with folds called cristae has procaryotic ribosomes, DNA and metabolic enzymes divides independently of cell function as powerplants of the cell

cytoskeleton

Ribosomes composed of rRNA and proteins Other cytoplasmic structures composed of rRNA and proteins 2 subunits (large, small) form functional ribosome larger than procaryotic ribosomes function in protein synthesis Free in cytoplasm or on RER