Microbiology Ch.5

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The history of eukaryotes

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they first appeared approximately 2 billion years ago.

Evidence suggests evolution from prokaryotic organism by symbiosis.

Organelles originated from prokaryotic cells trapped inside them.

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Symbiosis

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Two or more organisms in mutual relationship

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Eukaryotic:

external

boundary of cell

internal

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External:

appendages

flagella

cilia

glycocalyx

capsules

slimes

Boundary of cell:

cell wall

cytoplasmic membrane

Internal:

cytoplasmic matrix

nucleus

organelles-[endoplasmic reticulum, Golgi complex-lysosomes, mitochondria, chloroplasts]

Ribosomes

cytoskeleton-[microtubules,microfilaments]

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External boundary structure:

Locomotor appendages:

Flagella

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Long, sheathed cylinder containing microtubules in a 9+2 arrangement

Covered by an extension of the cell membrane

Function in motility

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Cilia

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Similar in overall structure to flagella but shorter and more numerous

Found only on a single group of Protozoa and certain animals cells

Functions in motility, feeding and filtering

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Glycocalyx

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An outermost boundary that comes into direct contact with environment

Appears as a network of fibers, a slime layer or a capsule

Function in adherence, protection and signal reception

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Cell wall

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Rigid, provide structural support and shape

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Fungi

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Have thick layer mainly composed of chitin

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Algae

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Substances commonly found include cellulose

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Protozoa

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A few algae and all animal cells lack a cell wall and have only a cell membrane

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Cell membrane

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Typical bilayer of phospholipids and proteins

Sterols confer stability

Serves as selectively permeable barrier in transport

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Internal structures:

Nucleus

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Compact sphere, most prominent organelle of eukaryotic cell

Nuclear envelope composed of two parallel membranes separated by a narrow space and is perforated with pores

Contains chromosomes

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Nucleolus

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Dark area for rRNA synthesis and ribosomes assembly

Hint 13

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Endoplasmic Reticulum - Two Types:

Rough endoplasmic reticulum (RER)

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Rough endoplasmic reticulum (RER) - originates from the outer membrane of the nuclear envelope and extends through cytoplasm; rough due to ribosome; site for protein synthesis

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Smooth Endoplasmic Reticulum (SER)

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Closed tubular network without ribosomes; functions in nutrient processing, synthesis and storage of nonprotein molecules such as lipids

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Golgi Apparatus

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Consists of a stack of flattened sacs with spaces or cisternae

Transitinal vesicles from the er containing proteins go to the golgi apparatus for modification and maturation

Condensing vesicles transport proteins to organelles such as lysosome or transported outside the cell as secretory vesicles

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Lysosomes

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Vesicles containing enzymes (proteins) that originates from golgi apparatus

Involved in intracellular digestion of food particles and in protection against invading microbes

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Mitochondria

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(Energy generators/fuel house)

Consists of an outer membrane and an inner membrane with folds called cristae

Cristae - holds the enzymes and site for aerobic respiration

Divide independently of cell

Contain DNA and prokaryotic Ribosomes

Function in energy production

Hint 18

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Chloroplast

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Found in algae and plant cells

Outer membrane covers inner membrane folded into sacs, thylakoids, stacked into

Larger than mitochondria

Contain photosynthetic pigments - chlorophyll

Convert the energy of sunlight into chemical energy through photosynthesis

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Ribosomes

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Composed of rRNA and proteins

Larger than prokaryotic ribosomes

Function in protein synthesis

80s - two subunits, 60s and 40s

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Cytoskeleton

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Flexible framework of proteins, microfilaments and mircotubules from work throughout cytoplasm

Involved in movement of cytoplasm, amoeboid movement

-Transport

-Structural

-Anchors Organelles

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Survey of eukaryotic microbes

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Fungi

Algae

Protozoa

Parasitic worms

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Kingdom fungi

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100,000 species divided into 2 groups:

Macroscopic fungi - (mushrooms, puffballs, gill fungi)

Microscopic fungi - (molds, yeasts)

Fungal infections are known as mycoses

Who studies mycoses? mycologist

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Microscopic fungi

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Exist in two morphologies:

Yeast - single celled, round ovoid shape, a sexual reproduction

Molds - multi-cellular, contains multiple identical nuclei, have long filaments known as hyphae

Some exist in either form - dimorphic - characteristic of some pathogenic molds

An example is penicillium mameffei

At room temperature, it grows as a mold

At body temperature, it grows as a yeast

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Fungal organization:

Filaments fungi

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Mass of hyphae called mycelium, cottony, hairy, or velvety texture

Primarily through spores formed on reproductive hyphae

Spores helps to identify the fungi

Asexual Reproduction - spores are formed through budding or mitosis; conidia or sporangiospores

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Sexual Reproduction

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Spore are formed following fusion of male and female strains and formation of sexual structure

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Zygospore

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Is one types of sexual spores

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Kingdom Protista

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Algae

Protozoa

(Protista - algae & Protozoan)

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Algae

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Photosynthesis organisms

Contain chloroplasts with chlorophyll and other pigments

Cell wall - cellulose

Most are free - living in fresh and marine water

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Plankton:

Plankton

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Small and microscopic oraganisms drifting or floating in the sea or fresh water

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Dinoflagellates

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Coastal marine species which "bloom" during the warm months of summer. These species reproduce in such great numbers that the water may appear golden or red, producing a "RED TIDE"

They produce toxins, eating affected fish, clams, oysters, shellfish can cause neurological damage

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Protozoa

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Vary in shape, lack a cell wall

Some are animal parasites and can be spread by insect vectors

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Protozoa

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Most have locomotor structure - flagella, cilia, or pseudopods

Exist as trophozoite - motile feeding stage

Many can enter into a dormant resting stage when conditions are unfavorable for growth and feeding - cyst

(Latent stage & inactive stage)

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Important protozoan pathogens:

Pathogenic flagellates

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Trypanosomes - Trypanosoma

T.brucei - African sleeping sickness (vector is Testes fly)

T. Cruz - chaga's disease; south and Central America (vector is reduviid bug) *kissing bug*

Infective amoebas

Entamoeba histolytica - amoebic dysentery; worldwide

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Parasitic Helminths

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Multicellular animals, organs for reproduction, digestion, nervous, excretory and muscular system

Have mouths parts for attachments to or digestion of host tissues

Fertilized eggs go through larval period in or out of host body

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Helminths

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Acquired through ingestion of larvae or eggs in food; from soil or water; some are carried by insect vector