Mirco test 2

T/F: Eukaryotic cells have both cilia and flagella.

True

The function of Flagella and Cilia in Eukaryotic cells is...

Motility

What motion does flagella make to move the eukaryotic cell?

Beats; motion starts at base, continues through tip

What motion does cilia make to move the eukaryotic cell?

Strokes FLUID like an oar

What powers the motility of Eukaryotic cells?

ATP

If you were to cut a transverse line in the flagella or cilia of a eukaryotic cell, what would you see?

Microtubules in a 9+2 array;
The doublets slide along one another creating motion.

What type of eukaryotic cells have cell walls?
Note: Many lack cell wall

Plant cells, algae, fungi

What is the difference between cell walls in (some) eukaryotic cell walls and bacterial cell walls?

-Cell walls in Euk. cell walls consist of carbohydrates
-Euk. cell walls are chemically simpler than peptidoglycan

What different types of carbohydrates do various eukaryotic cell walls consist of?

Plants - cellulose
Fungus - chitin
Yeasts - Glucan and Mannan

T/F: Eukaryotic Plasma membrane is similar to that of archaea. Why/Why not?

F. Euk. P.M. composition more closely resembles bacteria. Because they both have:
-lipid bilayer/fluid mosaic
-integral and peripheral proteins

What are three factors to the composition of the Eukaryotic Plasma Membrane?

1. Similar to bacteria PM
2. Contains sterols for stability (to resist osmotic pressure)
3. Contains carbs for recognition

Is the Eucaryotic PM the site of respiration?

NO.

T/F: Eukaryotic P.M. have very few protein pumps transporters and receptors.

False!
Euk PM have LOTS of protein pumps transporters and receptors.

What is another term for Plasma Membrane?

Cytoplasmic Membrane

How do eukaryotic and prokaryotic cytoplasmic membranes resemble one another?

-Selective Permeability
-Transport

How do Eukaryotic and Prokaryotic cells differ in function?

Euk. PM use endocytosis, phagocytosis, pinocytosis

What are endocytosis, phagocytosis, and pinocytosis?

Endocytosis: is the umbrella term for phagocytosis and pinocytosis
Phago- pseudopods extend and engulf particles
Pino- Membrane folds inward, bringing in fluid and dissolved substances

What are the various components of the cytoplasm of a eukaryotic cell?

Cyotsol (Liquid Component)
Cytoskeleton
Organelles

Of what is the cytoskeleton composted? What is its function?

Interconnected filaments:
-Microfilaments (protein: actin)
-Intermediate Filaments
Microtubules (tubulin - separates chromosomes in mitosis and meiosis)
FUNCTION: cell structure and movement

What is synthesized in the mitochondria of Euk cells and how?

ATP; TCA cycle and electron transport chain

Which of the mitochondria membranes has porins? What is significant about the other membrane?

Outer membrane has porins;
Inner membrane has infoldings (cristae) that increase surface area

What is significant about the DNA that mitochondria has?

1. its DNA is completely its own, apart from the cell.
2. The DNA is bacterial in nature: circular, haploid (single copy)

T/F: Both Mitochondria and chloroplasts multiply separately from the cell.

Truuuu

What is the site of photosynthesis in a euk. cell?

Chlorophyll of the chloroplasts

Fill in the blank:
Choloroplasts are ________________-bound organelles.

Membrane

According to evolution, eukaryotes evolved how many years ago?

2.5 billion

According to evolutionary theorists, mitochondria and chloroplasts are "thought to have evolved from bacterial cells that invaded or were ingested by early ancestors of eukaryotic cells." Why do they think this?

Evolutionists think this because they are similar to other types of bacteria:
mitchondria - exant bacteria
chloroplasts - cyanobacteria

What about the mitochondria and chloroplasts "support" the endocymbiotic theory?

- replication separate from the cell
- DNA is bacterial in nature (circular, haploid)
- have membrane

What are the main characteristics of the nucleus of a eukaryotic cell?

1. Double-membrane
2. Contains chromosomes and nucleolus (site of ribosome synthesis)

What is chromatin?

DNA and proteins [histones]
This condenses during cell division

Chromatin has two sub-types:
Euchromatin and heterochromatin
What are the differences between the two?

Euch. is loosely organized, genes are expressed
Hetero. is tightly coiled, genetically inactive

What is the endoplasmic reticulum (ER) of a eukaryotic cell?

Membranous tubules and flattened sacs (cisternae)

What are the two types of Endoplasmic reticulum?

Smooth - main site of lipid synthesis
Rough - main site of protein synthesis and packaging (studded with ribosomes)

What is the size of eukaryotic ribosomes as compared to bacterial/archaeal ribosomes?

Euk: 80S (60S+40S subunits)
May be attached to ER or free in cytoplasmic matrix
(the 60S is what is about to ER)

What is golgi, and what is its purpose?

Membranous organelle composed of cisternae (cis and trans face)
It's purpose is packaging and secretion of proteins for various purposes. Also, golgi bodies is where lysosomes are made.

What are lysosomes?

Membrane-bound vesicles found in MOST eukaryotes.
necessary for intracellular digestion (contains enzymes necessary to degrade the 4 macromolecules)
Found in protist, fungi, plants, and animals

What are some examples of macroelements (AKA macronutrients)?

C,H,O,N,S,P - organic molecules
K,Ca,MG,Fe - enzymes, biosynthesis
(Note: All are required in relatively large amounts)

What are some examples of microelements?

Mn,Zn,Co,Mo,Ni,Cu - enzymes and cofactors
(Note: small amounts required, typically supplied by water or media components)

T/F: Electrons play a role in energy production and reduction of CO2 to form organic molecules

True

T/F: Carbon sources often provide H, O, and electrons as well.

True

What is the difference between Heterotrophs and Autotrophs?

Heterotrophs: use organic molecules as carbon sources and energy sources
Autotrophs: Just use CO2 as sole/principal carbon source; obtain energy from other sources

What are three elements that are chemically required for microbial nutrition?

Nitrogen, Sulfur, Phosphorus

What is the role of Nitrogen in Microbial nutrition?

-in proteins, DNA, ATP
-Take sulfur from proteins
-some bact. use Ammonia and nitrate from organic material
-few bact. use N2 in nitrogen fixation

What is the use of Sulfur in microbial growth?

-in amino acids, thiamine, and biotin
-Bact. take sulfur from proteins
-Some bact. use Sulfate or Hydrogen Sulfide

What is the use of phosphorus in microbial growth?

-in DNA

List the main growth factor for microbes

organic compounds - necessary for essential cell components that the cell can't make itself

What are the classes of growth factors?

Amino Acids - protein synthesis
Purines/Pyrimidines - nucleic acid synthesis
Vitamins - enzyme cofactors
Heme

T/F: Microorganisms can synthesize many growth factors

True;
Think Vitamins B and K

What are the two types of chemical and physical types of culture media?

-Defined/synthetic
-Complex

What significant about defined/synthetic Media?

all components and their concentrations are unknown

What is significant about complex media?

Contain some ingredients of unknown composition and/or concentration

What are some media components?

Peptones
Extracts
Agar

What are peptones (i.e. media components)?

Protein hydrolysates prepared by partial digestion of various protein sources

What are extracts (i.e. media components)

Aqueous extracts, usually beef or yeast

What is agar (i.e. media components)?

Sulfated polysaccharide used to solidify liquid media; most microbes can't degrade it

What are the two functional types of media?

Selective and Differential

What is selective media?

It favors the growth of some microorganisms and inhibit growth of others
e.g. MacConkey agar; inhibits growth of G+; allows G- to grow

What is differential agar?

Distinguishes between different groups of microorganisms based on characteristics
e.g. MacConkey agar between lactose fermemnters and lactose nonfermenters

What are the reproductive strategies of eukaryotic microbes?

asexual - haploid
sexual - diploid

Explain Chromosome replication and partioning

single origin of replication - replication begins here
terminus - site at which replication is terminated (opposite side of circular chrom.)
Replisome - group of proteins needed for DNA synthesis
DNA replication proceeds in both directions from the origin
Origins move to opposite ends of the cell

What is microbial growth?

An increase in cellular constituents: increase in cell number and size
Growth refers to population--not individual cells

What are the stages of the growth curve?

Lag, exponential, stationary, senescence, and death

What occurs during the lag phase?

-Cell synthesizing new components (to replenish spent materials, adapt to new medium, etc.)
-Varies in length; could be short (even absent)

What occurs during the exponential phase (AKA Log phase)?

-rate of growth and division is constant and maximal
-population is uniform

What are Unbalanced and balanced growth? During which phase of microbial growth can they occur?

*They occur during log phase
Balanced Growth: cellular constituents produced relative to each other
Unbalanced Growth: cellular const. aren't produced at the same rate

What causes unbalanced growth during the exponential/log phase?

1. Change in nutritional levels
a. shift-up (poor medium to rich medium)
b. shift-up (rich medium to poor medium)

2. change in environmental conditions

What happens during the stationary phase?

Growth ceases and number of viable cells remains constant;
- active cells stop reproducing OR death rate balances production rate

What possible reasons cause the stationary phase?

1. Nutrient limitation
2. Limited Oxygen availability
3. toxic waste accumulation
4. Critical population density reached

What happens when Stationary Phase begins as a result of stressful conditions?

Survival Strategy is activated: morphological changes (endospores); decrease in size, protoplast shrinkage, nucleoid condensation;
RpoS protein assist RNA polymerase in transcribing genes for starvation proteins

What happens in the starvation response?

1. Production of starvation proteins
a. increase cross-linking in cell wall
b. Dps protein protects DNA
c. chaperone proteins prevent protein damage
2. Cells are called persister cells
a. long-term survival
b. Increased virulence

What are the Senescence and death phases?

Two alternative hypotheses:
1. Viable but not culturable (VBNC)
2. Programmed cell death

What can cause prolonged decline in growth?

1. Bacterial population adapts continually
2. Genetic distinct variants
3. Natural Selection

What is Generation time?

The time required for the population to double in size

What are two viable counting methods?

Spread and Pour plates;
Results expressed in cfu (colony forming units)

What is the turbidometric method of counting?

Measures the scattering of light
Quick, easy, sensitive
Not as accurate as spread/pour plates

What is metabolism? What are the two types?

All chemical reactions in cell;
1. Catabolism
2. Anabolism

What is catabolism?

1. Fueling reactions
2. energy-conserving reactions
3. Generate precursors for biosynthesis

What is anabolism?

1. simple --> complex
2. Requires energy from fueling reactions

What three types of "work" do microbes do?

Chemical Work, Transport Work, and Mechanical Work

What is Transport Work of microbes?

take up of nutrients, elimination of wastes, maintenance of ion balances

What is chemical work that microbial cells must do?

synthesis of complex molecules

What is the mechanical work that microbial cells must do?

cell motility and movement of structures WITHIN cells

What is chemical equilibrium?

when a rate of forward action = rate of reverse action

What is the equilibrium constant?

(Keq) expresses the equilibrium concentrations of products and reactants to one another

What are Exergonic and Endergonic reactions?

Exergonic reactions proceed spontaneously; Endergonic reactions with not do so

What is the relationship between product and substrates in exergonic reactions?

Keq = ([C][D]) / ([A][B]) > 1.0

What is the relationship between substrates and products in ENDERgonic reactions?

Keq = ([C][D]) / ([A][B]) < 1.0

Is it true that ATP is the "energy currency of the cell?"

yeS

Why is the exergonic breakdown of ATP coupled with endergonic reactions?

To make them more favorable

Other than ATP, what also provides energy?

GUANOSINE 5' - phosphate, CYTOSINE 5' - triphosphate, and URIDINE 5' - triphosphate

What is the main job carried out by enzymes?

They catalyze/quicken chemical reactions, but are not physically/chemically altered themselves

What are catalysts, substrates, and products?

Catalysts: something that increases the rate of a reaction without altering itself (e.g. enzymes)
Substrates: reacting molecules
Products: substances formed by reaction

What is the transition-state complex?

It's like in the middle of the process of the substrates becoming the products. It resembles both the substrates and products

What is activation energy?

The energy that it takes to form the transition-state complex.
The A.E. decreases greatly when enzymes are used in the reaction by lowering the "Ea"

By what 3 main factors is enzyme activity affected?

1. Substrate concentration
2. pH
3. temperature

T/F: The more electrons a molecule has, the more energy rich it is.

True

What does the Standard Redox Potential measure (E0*)?
*The 0 is a subscript

the tendency of the reducing agent to lost electrons

What does it mean if a molecule has a more negative Redox Potential? What about more positive?

Negative: better electron donor
Positive: better electron acceptor

What are examples of some electron carriers?

NAD, NADP, cytochromes, and others

What is the difference between sterilization and disinfectants?

Sterilization: Destruction/removal of all viable organisms
Disinfectants: killing/inhibition/removal of disease-causing organisms; typically used on inanimate objects