BIO 324 - The Cell - Biogenesis, Germ Theory, Membranes

The theory that mitochondria and chloroplasts arose from prokaryotic cells establishing a symbiotic relationship within a eukaryotic host

Endosymbiotic theory

Endosymbiotic Theory (4 Steps)

1. Eukaryotic ancestor engulfed oxygen using, non-photosynthetic prokaryotic cell

2. Engulfed cell forms a relationship with host cell

3. Host cell and engulfed cell merge into a new organism containing mitochondrion

4. One of the cells with mitochondrion must have engulfed a photosynthetic cell since ancestral past shows they contained chloroplasts

What is some evidence that supports the endosymbiotic theory? (5)

1. Mitochondrial DNA and chloroplast DNA are highly related to their bacterial counterparts

2. Mitochondria and chloroplasts are similar to bacterial ribosomes

3. Binary fission of these organelles resembles binary fission of bacteria

4. Bacterial symbionts observed in modern day eukaryotic cells

5. Examples found in guts of insects, and in organelles in protists

List Koch’s Postulates (4)

1. Microbe is found in ALL cases of the disease but ABSENT from healthy individuals

2. Microbe is isolated form diseased host and grown in PURE culture

3. When microbe is introduced to a healthy host, the host shows the SAME diseas

4. When the microbe is obtained from a newly diseased host, the strain shows the same characteristics as before

Structures common to prokaryotes and eukaryotes (4)

1. cytoplasma/cytosol

2. plasma membrane

3. chromosomes

4. ribosomes

List the functions of the plasma membrane on the basis behind its selective permeability

1. captures needed molecules and brings them into cell

2. waste removal

3. communication with other cells and environment

4. anchoring cell in place

Enables transport, communication with external environment, and attachment to surroundings

Membrane proteins

Hydrophobic or Hydrophilic

Phospholipid Head -

Phospholipid Tail -

Head - Hydrophilic

Tail - hydrophobic

Transport that occurs when molecules move from high concentration to low concentration - down a concentration gradient

Passive transport

Transport that moves molecules from low concentration to high concentration - against a concentration gradient

Active transport

Type of diffusion when molecules cross the membrane with the help of proteins

Facilitated diffusion

Type of diffusion when molecules cross the membrane without the help of proteins

Simple diffusion

Proteins that create a channel or hole for molecules to diffuse through

Channel proteins

Change shape as molecules diffuse through them

Passive carrier proteins

The diffusion of water molecules across selectively permeable membrane

Water moves from — solute to — solute

Osmosis

low solute to high solute

A solution that has the same solute concentration as another solution. There is no net movement of water particles and concentration on both sides of the cell membrane remains constant

Isotonic solution

A solution has a higher solute concentration than another solution. Water particles move out of the cell causing crenation

Hypertonic solution

A solution has a lower solution concentration than another solution. Water particles move into the cell causing the cell to expand and eventually lyse

Hypotonic solution

Components found in ALL bacteria (5)

1. Nucleoid

2. Ribosomes

3. Plasma Membrane

4. Cell wall

5. Bacterial chromosome

Components found in some bacteria (3)

1. Fimbriae - pili

2. Capsule

3. Flagella

Do prokaryotes have membrane-bound structures within their cell?

No

What type of membranes do prokaryotes have?

Plasma membranes that surround the entire cell

List the corresponding proteins that contain each component within cell membranes

Proteins with sugars attached —

Proteins with lipids attached —

On the outer leaf of the outer membrane of Gram-negative bacteria —

1. glycoproteins

2. lipoproteins

3. lipopolysaccharides

Prokaryotic ribosomes (?) are composed of two subunits.

List the subunits:

70s

30s - small subunit

50s - large subunit

The bacterial cell wall is composed of -

Its rigid structure allows it to resist -

Peptidoglycan

Allows to resist turgor pressure and determines cell shape

Gram-negative bacteria: thick cell wall or thin cell wall

Gram-positive bacteria: thick cell wall or thin cell wall

Gram-positive: thick

Gram-negative: thin

Species specific polymers covalently attached to the cell wall of gram-positive bacteria

Teichoic acids

Functions of teichoic acids (5)

1. shape molecular surface properties

2. mediate biofilm formation

3. serve as phage receptors

4. mediate interactions with host receptors

5. control susceptibility and/or resistance to antibiotics

The outer membrane of gram-negative cells contain

Lipopolysaccharide (LPS)

LPS is called — in infection settings

Endotoxin

Bacteria of the family mycobacteriaceae have an external layer of waxy — in their cell wall

Mycolic acid

Mycolic acid cell walls make mycobacteria resistant to (4)

1. antibiotics

2. disinfectants

3. detergents

4. host immune response

Dormant structures that form within vegetative bacterial cells in response to stress, to improve their chances of surviving that stress

Endospores

Endospores are tough and resistant to (6)

1. desiccation

2. UV radiation

3. extreme temperature

4. high pressure

5. disinfectants

6. antibiotics

A sugar coat on bacterial structures that has two important types. What is the structure and list the two types?

Glycocalyx

Capsules and Slime layers

Capsules are important virulence factors. List what they can prevent and help aid in (3)

1. prevent recognition and engulfment by phagocytic cells

2. protect cells from desiccation, bacteriophages and detergents

3. helps cells adhere to surfaces

Colonies of microbes that form in complex structures and layers on surfaces

What is their function?

Biofilms

Protect cells from predation and hinder the action of antibiotics and disinfectants in addition to helping bacteria stick to surfaces

Biofilms can form inside — that make infections difficult to eradicate

Host tissue

The process of endospore formation is called:

When does it begin? When conditions improve, what do they undergo?

Sporulation - Begins when nutrients become depleted or environmental conditions become unfavorable

Germination - now can carry out normal functions including growth and cell division

Very long “tail-like” structures that move cells via propeller like motion

Used primary for bacterial motility

Flagella

Used for motility, adherence, and conjugation

Pili

Term for a singular flagellum typically located at one end of the cell

Monotrichous

Term for flagellum or tufts of flagella at EACH end

Amphitrichous

Term for flagella tuft at ONE end of the cell

Lophotrichous

Flagella cover the entire surface of a bacterial cell

Peritrichous

Eukaryotic cells are defined by the presence of (2)

1. nucleus with a membrane

2. membrane bound organelles

The fluidity of membranes allows transport vesicles to — and —

pinch and fuse

Releasing contents to the extracellular environment

Exocytosis

Brings molecules from outside the cell into the cell

endocytosis

Cell engulfs a particle of food or bacteria to form a food vacuole

Phagocytosis

Cell gulps droplets of extracellular fluid into tiny vesicles

Pinocytosis

What can pathogens stimulate in host cells as part of their pathogenesis? What enables cells to acquire these specific substances?

Endocytosis

Receptor mediated endocytosis

Eukaryotes have an (?) ribosome

What is the large subunit

What is the small subunit

80s ribosome

60s large subunit

40s small subunit

Mechanism that allows cells to digest their own used or damaged macromolecules to build new macromolecules and structures

Autophagy

Extracellular matrix of animal cells are composed primarily of:

What is involved with and what do the components do?

Glycoproteins

Involve with cell-cell signaling and its components relay information about changes inside and outside of the cell to other cells

Cytoskeleton is unique to what type of cells?

Eukaryotes

Cilia are unique to

Pili are specific to

Eukaryotes

Prokaryotes (Bacteria)