LUCA L1 Flashcards
what is LUCA
Last Universal Common Ancestor
- Anaerobic, CO2-fixing, H2-dependent, N2-fixing thermophile, with FeS clusters (Redox), and free radical reduction mechanisms
where was LUCA produced
inhabited a geochemically active environment rich in H2, CO2, and Fe
what is the mitochondria
how many are there in a cell
Sub-compartments of eukaryotic cells (organelles) is 1-1000+ per cell
what do mitochondria do
- Generate energy
- Breakdown some waste products
- Produce chemicals the cell needs
- Part of apoptosis (in multicellular organisms)
what do mitochondria need
Require oxygen – site of respiration and oxidative phosphorylation
what is a plastid and where are they
sub-compartment of eukaryotic cells (organelles) particularly found in plants and algae
what do plastids contain
frequently contain pigments for photosynthesis (chlorophyll containing= chloroplasts) other specialized plastids exist
what are the 18S rRNA genes like in a eukaryote
18S rRNA genes for phylogeny of eukaryotes
18S rRNA genes is much weaker for eukaryotes than 16S rRNA genes are for prokaryotes
how have eukaryotic phylogenies been constructed
using other genes (e.g., tubulin, RNA polymerase, and ATPase)
how can you work out if things are related
Similarity in shape or form can be misleading, e.g. platypus has bird beak, is a mammal…
Better to compare similarity of molecular structure – compare conserved structures e.g. ribosomes and ribosomal RNA
difference in eukaryotes and prokaryotes
Eukaryotic cell much bigger than most prokaryotes
Prokaryotes usually much simpler
Limitation of how many molecules can move through eukaryotic cell as much larger
what does the nucleus contain
chromosomes
DNA wound round histones = chromatin
enclosed by two membranes
inside is nucleolus - rRNA synthesis site
what is the mitochondria structure
- Outer membrane - large numbers of integral porins, allow molecules of ≤ 5000daltons
freely diffuse across membrane - Folded internal membranes, cristae – has enzymes needed for respiration and ATP
production
what is used at the mitochondria for electron transport chain and ATP synthase
Electron transport chain (Utilizing the NADH, FADH2) ATP synthase (Utilizing the proton gradient created by the ETC)
what is in the inner most area of the mitochondria
matrix - has enzymes for oxidation of organic compounds
what happens in pyruvate decarboxylation
pyruvate –> CO2, acetyl-CoA, and NADH
what happens in citric acid cycle
acetyl-CoA –> CO2, NADH, FADH2, (GTP–>ATP)
what is hydrogenosome
Similar in size to, and probably evolved from mitochondria, but lacks TCA cycle enzymes and cristae
what occurs at hydrogenosome
Oxidation of pyruvate to H2, CO2, and acetate
does bacteria have endoplasmic reticulum and golgi
neither
what is the endoplasmic reticulum and function
- Rough contains attached ribosomes
- Rough is a major producer of glycoproteins
- Smooth part of the synthesis of lipids
what is the golgi and function
- Stacks of membrane distinct from, but functioning in concert with, the ER
- Modifies products of the ER destined for secretion
- Addition of carbohydrates (glycosylation) and phosphates (phosphorylation)
what are lysosomes and vacuoles and what do they contain
- Membrane-enclosed compartments
- Contain digestive enzymes used for hydrolysis including: proteins, nucleic acids, lipids, carbohydrates and cellular debris
what is the function of lysosomes and vacuoles
Allow hydrolytic activity to occur in cell without damaging other cellular components
what is the cytoskeleton for
- Helps maintain cell shape and internal organization
- Provides mechanical support so that cells can move and divide
- Bacterial cells don’t have a cytoskeleton as they have a high osmotic pressure to maintain shape
what is the cytoskeleton made of
three filamentous proteins, cells require protein filaments to hold their shape:
microfibrils
microtubules
intermediate filaments
what is the microtubule like and its function
largest 25 nm in diameter; composed of α- and β-tubulin
Function, maintain cell shape, in motility, in chromosome movement, and in movement of organelles
what is the microfilament like and its function
smallest 7 nm in diameter; polymers of actin
Function, maintain cell shape, motility by pseudopodia and in cell division
what is the intermediate filament like and its function
intermediate 8–12 nm in diameter; keratin proteins
Function, maintain cell shape and positioning of organelles in cell
what is the name of movement of transport vesicles, organelles, chromosomes, mRNA, rafts of proteins, and substances in the cell
where does this occur and why
intracellular transport
unique to eukaryotes as they possess membrane enclosed organelles and compartments - prokaryotes don’t have membraneous organelles and compartments
what is endocytosis role
transport of molecules into cell (invagination of plasma membrane)
what is the role for membrane bound transport vesicles
(e.g. movement of proteins from ER to Golgi apparatus)
flagella and cilia function
swimming
what are cilia
short flagella
structure of flagella
- Bundle of nine pairs of microtubules surrounding the central pair
- Dynein is attached to the microtubules and uses ATP
how does the cell move - flagella
propel the cell using a whip-like motion (as opposed to ‘whirling’ of a bacterial flagellum)
what is endosymbiosis
Suggested organelles descend from ancient, engulfed prokaryotic cells (primary endosymbiosis)
what evidence is there supporting endosymbiotic theory
- Mitochondria and chloroplasts contain DNA (an independent genome)
- Eukaryotic nuclei contain genes from bacteria (endosymbiotic gene transfer)
- Mitochondria and chloroplasts contain own ribosomes which are more similar to bacterial ribosomes (70S)
- Further development and divergence of Eukaryotic cells into different eukaryotic families resulted from further engulfment events (secondary endosymbiosis)
