Micro Bio Exam 1

Eukaryote cells history

First appeared 1-2 billion years ago

Prokaryote cells history

first appeared 3-4 billion years ago

Bacteria

Mycobacterium tuberculosis, a rod-shaped cell (15,500x)

6 types of microbes- Fungi

Fungi: Rhizopus, the common fungus seen on bread, with lollipop-

like reproductive structures (1,000x)

6 types of microbes- Algae

Algae: Microsterias truncata (750x), one of the predecessors of

modern-day plants.

6 types of microbes- virus

Virus: SARS-CoV-2, the cause of COVID-19 (100,000x).

6 types of microbes- Protozoa

Protozoa: A protozoan, Oxytricha trifallax bearing tufts of cilia that

function like tiny legs (3,500x)

6 types of microbes: Helminths

Helminths: Roundworms of Trichinella spiralis coiled in the muscle

of a host (250x). This worm causes trichinellosis

Characteristics of cells and life

• All living things made of cells (single & multicellular)

• shape: spherical, cubical, cylindrical

• Internal content – cytoplasm, surrounded

by a membrane

• DNA chromosome(s), ribosomes,

  metabolic capabilities

Prokaryotic cell

• microscopic

• unicellular

• organisms

• lack nuclei and membrane-bound organelles

Eukaryotic cell

• unicellular (microscopic)

• multicellular

• nucleus and membrane-bound organelles

Cytoplasm

• Inside the cell

• dense gelatinous solution of sugars, amino acids, and salts

• 70 to 80% water

• Storehouse for nutrients & other

  essential cell components

• in prokaryotic cells it is the site of biochemical processes

Cytoplasmic (cell) membrane

• Surrounds the cytoplasm

• Phospholipid bilayer with embedded proteins

• Permeability barrier (selectively permeable)

• Anchor for embedded proteins

• Site for energy reactions and

  nutrient processing

External Structures: Locomotor Appendages- Flagella

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

• Covered by an extension of the cell membrane

• 10× thicker than prokaryotic flagella

• Whips back and forth, lashes, grabs the substrate and pulls

External Structures: Locomotor Appendages- Cillia

– Similar in overall structure to flagella, but shorter and more numerous

– Found only on a single group of protozoa and certain animal cells

– Function in motility, feeding, and filtering

External Structures: Glycocalyx

• An outermost boundary that comes into direct contact with environment

• Usually composed of polysaccharides

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

• Functions in adherence, protection, and signal reception

• Beneath the glycocalyx

• Fungi and most algae have a thick, rigid cell wall

• Protozoa, a few algae, and all animal cells lack a cell

wall and have only a membrane

Boundary of the Cell: Cell Wall

• Rigid, provides structural support and shape

• Fungi have thick inner layer of polysaccharide fibers composed of chitin or cellulose

and a thin layer of mixed glycans

• Algae – varies in chemical composition; substances commonly found include cellulose,

pectin, mannans, silicon dioxide, and calcium carbonate

Boundary of the Cell: Cell/Cytoplasmic Membrane

• Typical bilayer of phospholipids and proteins

• Sterols confer stability *more on this later

• Serves as selectively permeable barrier in transport

• Eukaryotic cells also contain membrane-bound organelles that

account for 60-80% of their volume

Organelles and Other Internal Structures: Nucleus

• “Brain/Control Center”

• 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

• Nucleolus – dark area for rRNA synthesis and ribosome assembly

Internal Structures: Rough Endoplasmic Reticulum

• originates from the outer membrane of the nuclear envelope and extends in a continuous network through cytoplasm;

• rough due to ribosomes; proteins synthesized and shunted into the ER for packaging and transport; first step in secretory pathway

• “Protein Highway”

Internal Structures: Smooth Endoplasmic Reticulum

• closed tubular network without ribosomes; functions in nutrient processing, synthesis, and storage of lipids

• “Detox center/fat factory”

Internal Structures: Golgi Apparatus

• ”Post office”

• Modifies, stores, and packages proteins

• Consists of a stack of flattened sacs called cisternae

Synthesis and Transport Machine

• The nucleolus provides ribosomes that travel to the RER

• Transport vesicles from the ER containing proteins go to the Golgi apparatus for modification and

maturation

• Condensing vesicles transport proteins to organelles or into secretory vesicles Synthesis and Transport Machineto be exported outside

Synthesis and Transport Machine

• Lysosomes Vesicles containing enzymes that originate from Golgi apparatus

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

• Vacuoles Membrane bound sacs containing particles to be digested, excreted, or stored

• Phagosomes Vacuoles merged with a lysosome

• ”Garbage disposals”

Internal Structures: Mitochondria

• “Power house”

• Function in energy production and storage (ATP)

• Spherical organelle with an outer membrane and an inner membrane with folds called cristae

• Cristae membranes hold the enzymes and electron carriers of aerobic respiration

• Divide independently of cell

• DNA and prokaryotic ribosomes are contained in the spaces around the cristae called matrix

Internal Structures: Chloroplasts

• “Plant Powe House”

• Convert the energy of sunlight into chemical energy through photosynthesis

• Found in algae and plant cells

• Outer membrane covers inner membrane folded into sacs called thylakoids, stacked into grana. They carry pigments (chlorophyll and others)

• Primary producers of organic nutrients for other organisms

Internal Structures: Ribosomes

• “Protein factories”

• Composed of rRNA and proteins

• Scattered in cytoplasm or associated with RER

• Larger than prokaryotic ribosomes

• Function in protein synthesis

Internal Structures: The Cytoskeleton

• “Scaffolding”

• Flexible framework of proteins, microfilaments (actin), intermediate filaments and microtubules form network throughout cytoplasm

• Involved in organelles anchoring, movement of cytoplasm, amoeboid motion, transport, and structural support

Macromolecules

large compounds assembled from smaller subunits

– Monomer: a repeating subunit

– Polymer: a chain of monomers

• 4 Biological Macromolecules: Carbohydrates, Lipids, Proteins,

Nucleic Acids

Lipids

Long or complex, hydrophobic, C—H chains attached to a glycerol

molecule

Triglycerides

• 3 fatty acids bound to a glycerol

• Most common type of fat in your body

• Used as energy storage

Saturated fatty acids

• no double bond

• straight structure

• solid at room temp

Unsaturated fats

• double bond

• liquid at room temp

Phospholipids

• Glycerol + Phosphate head with two fatty acid (lipid) tails.

• The head is hydrophilic, water-loving

• Faces the cytoplasm and environment in the membrane bilayer

• The tail is hydrophobic, water-hating

• Face each other in the membrane bilayer

Steroids

• Complex ringed compounds, commonly found in cell, membranes and animal

hormones

• Sterol = steroid with an OH group

– Ex. Cholesterol

• Maintains structural integrity and shape of the cell

Passive Transport- Diffusion

• Movement of particles from high concentration to low concentration

• Down a concentration gradient

Osmosis

• Diffusion of water

– In other words: water spreads out from where it is more concentrated to least

concentrated

Higher solutes in surrounding environment

water leaves cell

Lower solutes in surrounding environment

water enters cell

Hypertonic

Solutes in the environment are greater than solutes in the cell

Water exits the cell

Isotonic

Rates of diffusion are equal In both directions

Hypotonic

Solutes in the environment are less than solutes in the cell

Water enters the cell

Facilitated Diffusion

• Passive diffusion

• Requires carrier protein

• Carrier is specific for

• substance it is transporting

Active Transport

• Transport against concentration gradient

• Membrane proteins required

• Energy expended

Carrier Mediated

Steps of Carrier Mediated

Active Transport

1. A solute binds a specific membrane protein

2. ATP binds the membrane protein

3. Energy is released from ATP which pushes the solute through the membrane protein

Example: Bacteria pump sugars and amino acids into the cell, and some bacteria can pump antibiotics out of the cell causing antibiotic

Bulk Transport (Endocytosis)

• Phagocytosis ingests substances or cells (pseudopods)

• Pinocytosis ingests fluids and/or dissolved substances (microvilli)

Bulk Transport (Exocytosis)

an active transport process where a cell expels large molecules or waste by fusing an internal vesicle with the plasma membrane

Main themes

• Living organisms share several fundamental properties and are made of one of two types of cells: prokaryotic or eukaryotic.

• Prokaryotic and eukaryotic cells have several similarities & differences

• The cytoplasmic (cell) membrane is the gatekeeper of the cell

• Transport of particles across cells can occur with or without assistance from membrane proteins

• Water and solute concentration inside a cell must be balanced to ensure the life of the cell

Environmental factors that microbes must adapt to

• Nutrient and energy sources

• temperature

• gas content

• water

• salt

• ph radiation

Microbial Nutrition

Process by which chemical compounds (nutrients) are acquired from the environment to sustain life

Bioelements

basic requirements for life (carbon, hydrogen, oxygen, phosphorus, potassium, nitrogen, sulfur, calcium, iron, sodium, chlorine, magnesium)

Essential nutrients

substance (element or compound) an organism must get from a source outside its cells

Macronutrients

required in large quantities; play principal roles in cell structure and metabolism (proteins, carbohydrates)

Micronutrients or trace elements

required in small amounts; involved in enzyme function and maintenance of protein structure (manganese, zinc, nickel)

Organic nutrients

• contain carbon and hydrogen atoms and are usually the products of living things

• Methane (CH4), carbohydrates, lipids, proteins, and nucleic acids

Inorganic nutrients

• atom or molecule that contains a combination of atoms other than carbon and hydrogen

• Metals and their salts (magnesium sulfate, ferric nitrate, sodium phosphate), gases (oxygen,

  carbon dioxide), and water

Metabolism

Chemical processes in an organism that break down and build up energy sources

Catabolism

break down of large molecules to create energy

Anabolism

building of larger molecules to store energy

Enzymes

• Enzymes = catalysts

• Increase the rate of a chemical reaction by decreasing the activation energy

• Is not part of the product

• Is not used up during the reaction

Substrate

Starting material

Product

Ending material

Active site

location on enzyme where substrate binds to be modified

Hydrolysis reactions

• Catabolic reactions that break down large substrates into smaller molecules

• Requires the input of water to break bonds

Synthesis Reactions

• Condensation or dehydration reactions

• Anabolic reactions that synthesize large substrates from smaller molecules

• Release one water molecule per bond made

Energy

the capacity to do work or to cause change

Forms of energy

Thermal, radiant, electrical, mechanical, atomic, and chemical

Carbohydrates

• General formula: (CH2O)n

• Basic structure:

  • Backbone of carbon

  • aldehyde or ketone

• Monosaccharide

  • polyhydroxy aldehyde or ketone with 3 to 7 carbons

Disaccharide

two monosaccharides

Polysaccharide

five or more monosaccharides

Respiration

Supplies cells (plant and animal) with the energy for all processes that require energy

Reasons for respiration

• Growth and repair of cells

• Muscle contraction

• Protein synthesis

• Sending nerve impulses

• Active transport across the cell membrane

Aerobic respiration

Glucose + Carbon Dioxide = Carbon dioxide + water + energy

ATP

• Primary energy source for cells

• Energy cycle = use stored ATP create more ATP

• Molecular structure of ATP is such that when phosphates are removed energy is released

Processes that create ATP

• respiration

• fermentation

• photosynthesis

Processes that consume ATP

• chemical work

• Transport work

• mechanical work

3 types of ATP synthesis

• Substrate-level phosphorylation

• Oxidative phosphorylation

• photophosphorylation

Substrate-level phosphorylation

transfer of phosphate group from a phosphorylated compound (substrate) directly to ADP

Oxidative phosphorylation

series of reactions occurring during respiratory pathway

Photophosphorylation

in photosynthetic organisms, utilizing the energy of sunlight

How do high-energy electrons create usable cellular energy?

• Electrons are highly reactive, negatively charged particles which are transferred or shared between atoms during bond formation

• Electrons are captured and transported by carrier molecules

• Molecular oxygen—final electron acceptor in aerobic respiration

Where is energy generated in eukaryotic cells?

Cytoplasm & mitochondria

Where is energy generated in prokaryotic cells?

Cytoplasm and cell membrane

Glycolysis

• Breakdown of glucose into pyruvic acid (pyruvate)

• No oxygen required

• Starting substrate: glucose

• Product: 2 molecules of pyruvic acid

• ATP consumed = 2

• ATP made = 2

• NADH made = 2

Krebs Cycle (citric cycle)

• A carbon energy wheel

• *must have oxygen present

• Starting Substrate = pyruvic acid (pyruvate) converted to Acetyl CoA

• ATP consumed = 0

• ATP made = 2

• NADH made = 6

Electron Transport Chain (ETC)

• A relay system of electrons through electron carriers

  • Proton motive force

• Hydrogen ions (H+) captured by ATP synthase to make ATP = oxidative phosphorylation

• Chemiosmosis

• Eukaryotes in mitochondria

• Prokaryotes in cell membrane

Fermentation

• Breakdown of glucose in the absence of oxygen to generate energy

• Creates a small amount of energy = 2 ATP per glucose Advantages for bacteria:

• Survival in no or low oxygen environment

• Generates intermediates that can be used in other pathways or shared within the microbial population

Photosynthesis

• Process that uses sunlight to generate energy

• Occurs in plants and algae

• Chloroplast = location of photosynthesis

• Chlorophyll = green pigment in chloroplast

2 phases

• Light reactions = light to create ATP & NADH

• Calvin Cycle = carbon fixation, uses energy of light reactions to create stored glucose

Main Themes

• All organisms require energy to do work.

• That energy comes from breaking down “food” into smaller molecules that can be used by the cell or organism to do work or create other molecules essential to the cell or organism.

• The primary source of “food” in most organisms is glucose.

• The primary form of energy in organisms is ATP