Mircobiology Exam #2

Chapters 5, 9 & 10

First Eukaryotic Cell

Appeared 4 billion years ago

Bacteria and Eukaryotes evolved from

a precursor called the Last Common Ancestor (LCA). which was not a prokaryotic or eukaryotic.

Organelles

originated from more primitive cells that became trapped in eukaryotic cells

Endosymbiotic Organelles

bacterial or archaeal cells infesting another descendant cell of the Last Common Ancestor and it becoming a permeant part of the cell.

Ex. Mitochondria snd Chloroplasts

Endosymbiosis

one of the symbiotic organisms lives inside the other.

Dr. Lynn Margulis is credited form providing evidence to support endosymbiosis

Primitive Eukaryotes

Were single celled and independent

Eukaryotes became…

specialized to perform particular functions

complex, multicellular organisms

Always Unicellular

Protozoa

May be Unicellular or Multicellular

Fungi and Algae

Always Multicellular

Helminths (have unicellular eggs/larva)

Features of All Eukaryotic Cells:

• Cytoplasmic Membrane (what goes in/out)

• Nucleus (genetic info)

• Mitochondria (powerhouse)

• Endoplasmic Reticulum (ribosome - protein production)

• Golgi apparatus (prepares, modifies, and sorts proteins)

• Vacuoles (get rid of waste products)

• Cytoskeleton (maintains their shape and internal organization)

• Glycocalyx (protection against phagocytosis and can also serve for attachment in biofilms)

Found in SOME eukaryotic groups:

• cell wall (provides shape, support, and protection to the cell and its organelles)

• locomotor appendages (capture or collect food)

• chloroplast (site of photosynthesis)

Generalized Eukaryotic Cell:

• More Complex

• Larger in Size

• Contains a Nucleus

• Division of Labor

• Organelles

Microtubules in Flagella

Composed of Tubulin ( 9 pairs + 2 arrangements)

Move in a whip like fashion

Cilia:

• structure is similar to flagella

• shorter and more numerous

• found only in a single group of protozoa and certain animals cells

• function as feeding and filtering structures on some cell

• rowing motion (power and recovery strokes)

Glycocalyx

• outermost boundary

• also called extracellular matrix

• made of polysaccharides

• Look like a network of fibers (slime layer & Capsule)

Functions of Glycocalyx

• protection

• adhesion

• reception of signals

Cell Wall

• found in fungi and algae

• Rigid and provides structural support

• Different chemical composition than bacterial cell wall

• Chitin or Cellulose in Fungi

Chitin

allows for flexibility from external pressure

Ex. mushrooms

Cytoplasmic Membrane

• Typical Bilayer of Phospholipids embedded with protein molecules

• Contains sterol (cholesterol)

• Selective permeable barriers

Nucleus

Most prominent organelle

• Stains more intensely due to the RNA

• Site for ribosomal RNA synthesis

Mitosis vs. Meiosis

Mitosis: The process by which a single parent cell divides to make two new daughter cells

Meiosis: cell division in sexually reproducing, production of sex cells (eggs and sperm)

Chromatin

the material of eukaryotic Chromosomes

Histone proteins

are bound to long, linear DNA molecules

Rough Endoplasmic Reticulum

• Ribosomes are attached to its surface

• proteins held for packaging and transport

Smooth Endoplasmic Reticulum

• Does NOT contain ribosomes

• Synthesis and storage of Nonprotein molecules

• Detoxification of metabolic by products

• Calcium ion storage

Golgi apparatus

Site of Protein modification and transport

• consists of a stack of flattened, disc-shaped sacs

• closely connected (not physically) to Endoplasmic Reticulum

• Adds polysaccharides and lipids to proteins

Transitional Vesicles

transfer of membrane materials to the Golgi apparatus from endoplasmic reticulum.

Condensing Vesicles

conveyed to lysosomes or transported as secretory vesicles

Nature’s Assembly Line

Genetic info: form nucleus

➡

Proteins are Synthesized on Ribosomes and deposited into the Rough ER

➡

Proteins are then transported to the Golgi to be chemically modified and packaged into vesicles

Cellular Vesicles:

Lysosomes & Vacuoles

Lysosomes

• come from the Golgi and contain a variety of enzymes

• involved in intracellular digestion of food

• involved in protection against invading microorganisms

  *Package of toxic material

Vacuoles

• Membrane-bound sacs

• Contains fluids or solid particles to be digested, excreted, or store

• like a sump pump

Mitochondria

Energy Generator of the cell

• divides independently of the cell

• contain circular strands of DNA

• Contain prokaryotic sized 70S Ribosome’s

Mitochondria Structure

Cristae: folds on the inner membrane that hold the enzymes and electron carriers of aerobic respiration

Matrix: holds ribosomes, DNA, and enzymes and other compounds used in metabolism

Chloroplasts

Photosynthesis Machines

• Converts energy of sunlight into chemical energy

• Primary producers of food web and oxygen

  • Double lipid bilayer

  • own genetic material

  • reproduce autonomously

Cytoskeleton Functions

• Anchoring organelles

• moving RNA and vesicles

• permitting shape changes and movement

Three Main Types of Cytoskeletons:

1. Microtubules

   • long hollow tubes are the largest of the cytoskeletal elements

   • function during mitosis

   • components of flagella and cilia

2. Actin

   • Cytoskeletal components are responsible for Cell movement (crawling)

   • Thinnest of all cytoskeletal proteins

3. Intermediate Filaments

   • Rope-like

     between the other 2 cytoskeletal proteins in size

   • provide structural reinforcement of the cell and organelles

The Kingdom of Fungi

approximately 3-4 million species of fungi

The two groups of Fungi:

1. Macroscopic Fungi

2. Microscopic Fungi

Macroscopic Fungi

Mushrooms, puffballs, and gill fungi

see with the naked eye

Microscopic Fungi

Molds and yeasts

cannot see with the naked eye

Microscopic Morphology:

Yeast Cells: round to oval shape & uses asexual reproduction

Hyphae: long, thread-like cells found in filamentous fungi or mold. Pseudohypha- chain of yeast

Dimorphic: some fungi can take either form dependent on growth conditions

Yeast

• Single-cell fungi

• Budding (sexual and asexual)

  Blastospores- asexual fungal spore produced by budding

Useful Yeasts:

• Saccharmoyces

Pathogens

• cryptococcus - bird droppings (CNS and Lungs)

• Candida-infections like thrush

Microscopic Morphology of Yeast

Looks like clusters of Grapes

Fungal Nutrition:

Heterotrophic

Saprobes

Parasites

Heterotrophic:

organisms that can't make their own food and so must get energy by eating plants and animals to survive

Saprobes:

obtain nutrients from dead plants and animals

Parasites:

Live on the bodies of living animals and plants

Organization of Microscopic Fungi

Mycelium: the woven, intertwining mass of hyphae that makes up the body or colony of mold. ex. rootball

Septa: cross walls dividing hyphae into segments

Spores: fungal reproductive bodies

Fungi Structures and How it spreads:

Structures: Mycelium (intertwining mass of hyphae), Septa (cross walls), and Spores (reproductive bodies)

Reproductive Strategies: Fragmentation (separated piece of mycelium generates new colony), Spore Formation (primary)

Sexual vs Asexual reproduction

Sexual: Provides a bunch of genetic diversity, but uses an expenditure of energy to mate

Asexual: Doesn’t expend energy on mate, but lacks genetic diversity