Eukaryotic vs Prokaryotic cell anatomy

L3

Name 7 components of eukaryotic anatomy?

• nucleus

• endoplasmic reticulum

• golgi complex

• lysosomes

• mitochondria

• chloroplasts

• flagella/clila

What are 3 major differences between eukaryotic and prokaryotic cells?

size, nucleus/no nucleus, compartmentalisation

What are 4 components of prokaryotic anatomy?

• nucleoid

• cytoplasm

• envelope

• appendages

What is contained in the eukaryotic nucleus?

• chromatin = DNA with histones

• site of mRNA, tRNA, rRNA (nucleolus) synthesis

• euchromatin/heterochromatin

What are the 2 types of ER?

• rough: network of ribosomes, site of protein synthesis, sorting signals

• smooth: no protein synthesis but lipid and steroid synthesis

• toxin breakdown

What is the role of the golgi complex?

→ Carbohydrate synthesis (cell walls, extracellular matrix)

→ Modification of proteins for specific targeting (secretion / incorporation in membranes)

What ribosomes are in eukaryotes vs prokaryotes?

80S ribosomes vs 70S ribosomes

What is the origin of lysosomes? What do they contain?

from golgi can fuse with other vesicles

digestive enzymes to hydrolyse macromolecules

What is the origin of peroxisomes? What’s their role?

from ER

incorporate lipids and proteins from cytoplasm + oxidise alcohols and fatty acids

What is the role of mitochondria?

"power station of the cell"

(respiration, oxidative phosphorylations, Krebs cycle => ATP + reducing power)

What are original properties of mitochondria?

organelle with its own genome (~15kbp; 37 genes!)

mitochondria multiply by division

What are structures of the mitochondria?

matrix, cristae, inner and outer membranes

What are chloroplasts made from?

thylakoids (forming grana) found in stroma (matrix)

What metabolic activity occurs in chloroplasts?

Converts light into organic compounds via the Calvin cycle

6 CO₂ + 12 H₂O  → C₆H₁₂O₆ + 6O₂ + 6H₂O

What are original properties of chloroplasts?

organelle with its own circular DNA (~150kbp)  / translation machinery 

chloroplasts multiply by division

What are flagella/cilia made up of?

Consist of a bundle of 9 pairs of microtubules surrounding central pair (axoneme). Microtubules are connected to adjacent ones via nexin molecules

What drives motion in flagella/cilia?

ATP hydrolysis carried out by dynein molecules

What produces the whiplike movement of eukaryotic flagella/cilia?

Microtubules slide against one another

What is contained in the prokaryotic nucleoid?

→ Usually a single, circular chromosome (ds DNA <10Mbp)

→ DNA complexed with histone-like proteins 

→ Genetic material also includes plasmids

What are specificities of prokaryotic DNA?

small, self-replicating DNA that can be transferred from cell to cell

What are some types of organelles that can be contained in prokaryotic cytoplasm?

• magnetosomes

• photosynthetic membranes

• internal membranes (planctomycetes)

Define an organelle

compartment enclosed by a membrane with a dedicated physiological function

What is a magnetosome?

lipid vesicle stuffed with magnetic iron minerals that allows alignment with a magnetic field

What is a planctomycete?

play a considerable role in global carbon and nitrogen cycles

What types of inclusion bodies are contained in prokaryotic cytoplasm?

• carboxysomes (CO₂ reduction in photosynthetic bacteria)

• storage granules (sulfur/phosphate/nitrogen)

• gas vesicles

What different structures are in prokaryotic cytoplasm?

• organelles

• proteins, tRNAs, mRNAs and ribosomes

• inclusion bodies like storage granules

What is a prokaryotic envelope made up of?

• cytoplasmic membrane

• peptidoglycan

• polymers covalently bound to peptidoglycan

• outer membrane

What are different prokaryotic appendages?

• pilus

• fimbriae

• flagella

What is the role of a prokaryotic pilus?

hollow sex pilus, appendage dedicated to conjugation (plasmid exchange) that allows exchange of large sized plasmids between bacteria

What is the role of a prokaryotic fimbriae or pili?

involved in adherence to host cells/surfaces; antigenic structures made of 1 major protein

retractable so allows mvt

What is the role of flagella?

supramolecular assembly involved in bacterial motility

What are different types of prokaryotes depending on the number of flagella they have?

• monotrichous is one flagella

• lophotrichous is multiple flagella

• amphitrichous is a flagella each side so 2 total

• peritrichous is lots of flagella everywhere

How is the flagella anchored into the CM in both gram + and - bacteria?

through bilayer of two layers, thanks to an ATP-dependent hook - changing the conformation of proteins associated to the flagella = rotation of the structure = mvt

What resulted in the formation of mitochondria and chloroplasts?

Stable incorporation of endosymbiotic bacteria

At what stage relative to the acquisition of mitochondria and chloroplasts by endosymbiosis did the nucleus appear in cells?

before the acquisition, eukarya and archaea share nucleus, only eukarya have mitochondria and chloroplasts

What are properties in favour of the endosymbiotic theory for the origin of mitochondria and chloroplasts? (what’s the most striking?)

• Both have an inner and outer membrane with distinct compositions and functional properties; some signatures of prokaryotes (cardiolipin, peptidoglycan)

• contain specific Mitoribosomes and chlororibosomes (not identical to bacterial ribosomes!)

• Semi-autonomous organelles capable of binary fission

What does the theory of endosymbiosis not account for?

fact that both eukaryotes and prokaryotes have similar lipid composition!! 

Describe the hydrogen hypothesis?

no primitively mitochondrion-lacking eukaryotes ever existed!

Mitochondria originated from engulfment of a 

H₂-producing bacterium by an H₂-consuming Archae