L4 - Eukaryotes

Eukaryotic cells are different from prokaryotic cells. How? (3)

Usually bigger, more complex, more organelles

How is DNA packaged in eukaryotic cells?

Into linear chromosomes & kept in double membrane bound nucleus

Eukaryotc cells have membrane-bound organelles including?

Mitochondria (most eukaryotic microorganisms), and sometimes both mitochondria & chloroplasts (e.g. algae)

Secretory pathways/ What are they made up of? (2)p

Series of multiple organelles that directs newly made proteins to their new destinations.

• endoplasmic reticulum (ER; rough & smooth)

• golgi apparatus

Morphology of typical eukaryotes

Morphology of typical eukaryotes (4)

1. membrane bound nucleus

2. larger than bacterial or archaeal cells

3. contain organelles

4. possess a cell wall & complex internal cytoskeleton

Internal organelles of eukarya (9)

1. Nucleus

2. mitochondrion

3. chloroplast

4. rough endoplasmic reticulum (ER)

5. Golgi apparatus

6. vacuole

7. lysosome

8. peroxisome

9. hydrogenosome

Internal organelles of eukarya  -  nucleus function

Contains most of cell’s DNA, site of transcription

Internal organelles of eukarya  -  nucleus interesting features (2)

1. double membrane containing pores

2. outer membrane continuous w/ endoplasmic reticulum

Internal organelles of eukarya  -  mitochondrion function

energy production

Internal organelles of eukarya  -  mitochondrion interesting features (4)

1. double membrane

2. contains DNA

3. Independent replication

4. not present in amitochondriates

Internal organelles of eukarya  -  chloroplast function

photosynthesis

Internal organelles of eukarya  -  mitochondrion interesting features (4)

1. Double membrane

2. contains DNA

3. Independent replication

4. unique to photosynthetic organisms

Internal organelles of eukarya  -  Rough endoplsamic reticulum (ER) function

Site of translation & protein folding

Internal organelles of eukarya  -  Rough endoplsamic reticulum (ER) interesting features

Rough ER has protein-synthesizing ribosomes attached to it

Internal organelles of eukarya  -  golgi apparatus main function

Modifies, sorts, and transports proteins

Internal organelles of eukarya  -  golgi apparatus interesting features

Connected to ER thru a series of vesicles

Internal organelles of eukarya  -  vacuole main function

Storage & structure

Internal organelles of eukarya  -  vacuole interesting features (2)

1. Food vacuoles serve as sites of digestion

2. Contractile vacuoles help maintain water balance

Internal organelles of eukarya  -  lysosome main function

Digestion of macromolecules

Internal organelles of eukarya  -  lysosome interesting features

Contains digestive enzymes

Internal organelles of eukarya  -  peroxisome main function

Breakdown of fatty acids

Internal organelles of eukarya  -  peroxisome interesting features

Contains various oxidative enzymes, like catalase and oxidase

Internal organelles of eukarya  -  hydrogenosome main function

Production of H2 & ATP

Internal organelles of eukarya  -  hydrogenosome interesting features (3)

1. double membrane

2. found in some amitochondriates

3. may be remnant of mitochondrion

Nucleus

• what does it do?

• what kind of structure?

• contains…?

• what exists within nucleus?

• Plays a role in the storage & expression of info.

• Double membrane structure.

• Contains linear chromosomes of cell

• Non-membrane bound nucleus exists within nucleus (ribosome synthesis)

In the nucleus, there is ___ separation. Discuss (2)

Spatial

• transcription occurs in nucleus

• translation occurs in cytoplasm

Secretory pathway

• what does it use?

• what happens to proteins here?

Uses ER/Golgi apparatus. Proteins are often extensively modified in these structures prior to reaching their destinations

Mitochondria

• what does it do?

• what does it use to produce ___?

Play a role in cell metabolism - TCA cycle. Use electron transport chains to produce ATP (chemiosmosis via the proton motive force).

Chloroplasts

• what do they do?

• what do they leverage

• What do they do with ATP?

• Play a role in cell metabolism

• leverage electron transport chains to produce ATP (chemiosmosis via proton motive force)

• Use ATP they produce to fix carbon into organic compounds (e.g., glucose)

Both mitochondria & chloroplasts are ____?

Semi-autonomous

Both mitochondria & chloroplasts are semi-autonomous.

1. what do they each have?

2. can they replicate?

3. where do most of their proteins come from?

1. each has a DNA genome, ribosomes, and transcription machinery

2. can replicate independently of the rest of the cell

3. most of their proteins originate from the DNA in the nucleus of the cell.

Plasma membrane - layer

Phospholipid bilayer with embedded proteins that allow molecule transport. Facilitated diffusion (no energy required from cell). Active transport (cell expends energy)

Plasma membrane plays a role in?

Homeostasis - maintaining a constant internal environment

Plasma membrane characteristics (4)

1. membrane structure

2. lipid structure

3. sterols

4. proteins

Plasma membrane characteristic - membrane structure

function (3)

1. membrane assembly

2. hydrophilic surface

3. hydrophobic core

Plasma membrane characteristic - lipid structure

function

Membrane fluidity

Plasma membrane characteristic - strerols

function

membrane stability

Plasma membrane characteristic - proteins

function

structural

Plasma membrane characteristic - membrane structure

bacteria

phospholipid bilayer

Plasma membrane characteristic - membrane structure

archaeons

bilayer or monolayer

diverse lipid composition (sulfo, glyco, isoprenoid)

Plasma membrane characteristic - membrane structure

eukarya

phospholipid bilayer

Plasma membrane characteristic - lipid structure

bacteria

ester linkage

straight fatty acid chains

Plasma membrane characteristic - lipid structure

archaeons

ether linkage

branched isoprenoid chains

Plasma membrane characteristic - lipid structure

eukarya

ester linkage

straight fatty acid chains

Plasma membrane characteristic - sterols

bacteria

No

Plasma membrane characteristic - sterols

archaeons

No

Plasma membrane characteristic - sterols

eukarya

yes

Plasma membrane characteristic - proteins

eukarya

low abundance

Plasma membrane characteristic - sterols

archaeons

high abundance

Plasma membrane characteristic - sterols

bacteria

high abundance

Cell wall

Plays a role in cell support. Broad separation btwn those w/ & those w/o cell walls. Vary widely btwn domains

Cytoskeleton

Role in cell structure. Each major piece differs in structure/fxn; all contribute to cell shape.

Cytoskeleton is compromised of ___ major pieces. What are they?

3

• microtubules (tubulin)

• microfilaments (actin)

• intermediate filaments (various proteins)

Cytoskeleton is also involved in ____, ___, and ____. Can be observed via ?

Cytoskeleton is also involved in intracellular trafficking, motion, and cell division. Can be observed via fluorescent microscopy 

Cell division is assisted by?

Spindle fibers

Motion of eukarya is achieved by?

Cilia/flagella. Very different structure than for bacteria or archaea.

Cellulose and chitin

• use…?

• provides?

• specific b-1,4-glycosidic bonds btwn sugars

• provides strength & rigidity

How many microtube doublets are there? What do they form?

9, form a tube around a core pair of microtubules (axoneme)

When does motion occur? (microtubules)

When ATP is burned, helping microtubules in the axoneme slide past each other.

What can pathogens do here? E.g. (2)

Exploit cytoskeleton. E.g., HSV, listeria

Basic structural components for bacteria - gram-positive (2)

1. thick peptidoglycan layer (~40nm) compromises 40-80% of cell wall dry weight

2. surface of peptidoglycan layer decorated by teichoic acid.

Basic structural components for bacteria - gram-negative (2)

1. thin peptidoglycan layer (~2nm) compromises 5% of cell wall dry weight

2. Outer membrane has phospholipid inner leaflet & lipopolysaccharide outer leaflet

Basic structural components for archaea

Varied

Basic structural components for archaea - methanogens

glycopeptides or pseudopeptidoglycan

Basic structural components for archaea - Halogens & hyperthermophilic

glycopeptides

Basic structural components for eukarya -  fungi

chitin

Basic structural components for eukarya -  algae

cellulose

Basic structural components for eukarya -  protozoa

none

Cytoskeleton structure & proteins in eukarya (3)

Microtubules, microfilaments, intermediate filaments

Cytoskeleton structure & proteins in eukarya - microtubules

functions (3)

1. intracellular transport

2. separation of chromosomes in mitosis & meiosis

3. cell movement (e.g., cillia & flagella)

Cytoskeleton structure & proteins in eukarya - microtubules

structure (2)

1. 25 nm

2. 13 protofilaments that form a hollow tube

Cytoskeleton structure & proteins in eukarya - microtubules

building blocks

Cytoskeleton structure & proteins in eukarya - microtubules

motors (2)

Dyneins, kinesns

Cytoskeleton structure & proteins in eukarya - microfilaments

motors

myosins

Cytoskeleton structure & proteins in eukarya - microfilaments

building blocks

actin

Cytoskeleton structure & proteins in eukarya - microfilaments

structure (2)

1. 7nm diameter

2. 2 protofilaments twisted around each other in helix

Cytoskeleton structure & proteins in eukarya - microfilaments

functions (3)

1. maintain cell shape

2. cerate division furrow in cytokinesis

3. cell movement (e.g., pseudopods)

Cytoskeleton structure & proteins in eukarya - intermediate filaments

building blocks

varied: lamin, keratin, vimentin

Cytoskeleton structure & proteins in eukarya - intermediate filaments

motors

none

Cytoskeleton structure & proteins in eukarya - intermediate filaments

structure

8-11 nm diameter

Cytoskeleton structure & proteins in eukarya - intermediate filaments

functions (2)

nuclear structure, cell-cell interactions

Flagella structure in bacteria (3)

• nonflexible hollow helical filament

• extends outside of cell membrane & cell wall

• composed of flagellin subunits

Flagella assembly in bacteria (2)

1. at distal tip

2. flagellin monomers are transported out inside of hollow flagella

Flagella arrangement in bacteria (2)

1. polar (1 or multiple)

2. peritrichous (multiple)

Flagella motion in bacteria (2)

1. motor in membrane turns flagella in a screw-like motion

2. energy from a proton motive force

Flagella structure in eukarya (3)

1. flexible

2. covered by cell membrane

3. composed of a 9+2 array of microtubules termed the axoneme

Flagella assembly in eukarya (2)

1. at distal tip

2. microtubule segments are transported out along the outside of the axoneme via intraflagellar transport system

Flagella arrangement in eukarya

varies by cell type

Flagella motion in eukarya (2)

1. fynein spokes slide microtubules along each other within axoneme. This bends axoneme & gives a whip-like motion to flagella

2. energy from hydrolysis of ATP

2 organelles that help with cellular metabolism?

mitochondria, chloroplasts

Mitochondria & chloroplasts contain what to generate ____ through ___ thanks to?

internal membranes, ATP, chemiosmosis, proton motive force

Main structural categories in eukaryotic protein-filament cytoskeletons (3)

1. microtubules (tubulin)

2. microfilaments (actin)

3. intermediate filaments (different proteins)

Phylogeny of eukaryotic microorganisms is typically determined by?

Comparing small subunit (SSU) rRNA genes & other highly conserve genetic sequences

4 general categories of eukaryotic microorganisms

1. fungi

2. protozoa (“protists”)

3. slime moulds

4. algae

Fungi

Heterotrophic microorganisms with chitin-based cell walls. 

Example of fungi, incl scientific name

Saccharomyces cerevisiae (yeast)