Week 3 learning goals Flashcards
Where does the pathway begin for a molecule through the endomembrane system
Begins at the Hydrolase gene
What occurs in the nucleus for pathway of an endomembrane molecule
mRNA is moved out of the nucleus and translation begins
Signal Peptides
When the polypeptide begins to grow in the cytoplasm. peptides that belong in each part of the endomembrane system are relocated to their respective place as translation occurs
Describe the path of mRNA to the lumen of RER
mRNA approaches the RWR where the translocator allows it to bind to the RER
What happens at the RER?
Hydrolases fully synthesized Deposited in RER lumen Carbohydrate tag gets added - Mannose
Departure from RER
A vesicle containing hydrolase buds off the RER and fuses to Golgi
At the Cis Golgi Network?
As glycosylated hydrolase move through Golgi mannose tag’ is phosphorylated by golgi specific enzymes Result: Hydrolase w/ a Mannose - 6 Phosphate ‘tag’
What does the 6 of Mannose - 6 - Phosphate mean?
Phosphate is attached to the 6th C of Mannose - If a carb is missing the P will not add which will stop the formation of lysosomes
How did Ribosomes get on the RER?
When mRNA was begin transfer to the RER the Ribsosmes became attached for a short period but will eventually fall off
At the Trans Golgi Network?
Hydrolase w/ a M6P - tage serves as a recognition system Phosphate group binds to a receptor in Trans Golgi membrane Receptor specifically recognizes the M6P ‘tag’ b/c phosphate group Binding triggers packaging of hydrolase into a vesicle Vesicle fuses to acidified compartment endoscope
Endosome turns into
lysosome
Vacuoles
Cells may have more than 1 Function is cell specific Vary in Animals
Central Vacuoles - Structure
Mostly made of water in plants
Central vacuole - function
storage of inorganic compounds and water Maintain fluid balance Trugor pressure - to keep a plant upright
Food vacuoles
Formed by phagocytosis
Contractile vacuoles - Functon
to take up excess water
Mitochondria
multiple in a cell
Sites of Cellular respiration
In both plants and animals
Chloroplasts
Multiple in a cell
Sites of photosynthesis
Only in plants
Peroxisomes - structure
Similar in shape and size of lysosome, However is not apart of the endomembrane system
Peroxisomes - function
- Compartmentalize H2O2 producing rxns
- H2O2 breakdown
- Breakdown of long chain of fatty acid via B- oxidation
- Detoxification of oxidizable substances EX: alcohols
Explain the compartmentalizing of H2O2 producing rxns
Certain enzymes found in the peroxisome catalyze the breakdown of organic molecules
R to generate H202
RH2 +O2 –> R +H2O2
Explain why the breakdown of H2O2 occurs in Peroxisomes
H2O2 is too toxic for cells
H2O2 produced in peroxisome is then degraded into H2O +O2
- Degradation of H2O2 is catalyzed by other peroxisomal enzymes
EX: Catalase/ peroxidase
Cytoskeleton - structure
Network of protein fibers and associated proteins
- Network extends throughout the cytoplasm and underlie NE
Cytoskeleton - function
Organizes structures and activities in the cell
Cytoskeletal Associated Motor Proteins
Used to move vesicles from one place to another
Describe the possible origin og the endomembrane system
The possible origin could be the PM
In the early development of the cell infolding of the PM was done which allowed the endomembrane system to be connected
Symbiosis
“living together”
In biology = a close long term interaction btwn two diff. species
EX: ants and acacia trees/ bird + turtle
Occurs due to some type of necessary benefit
Explain the endosymbiotic theory for the origin of mitochondria and chloroplasts - originator + her ideas
Idea comes from Lynn Margulis in the late 1960’s
Hypothesis: Mito + Clr originated as free living prokaryotes
The idea is…
Smaller prokaryoteengulfed by larger prokaryotic organism
Symbiotic relationship developed
Dependency increased over time such that cells became one
Explain the endosymbiotic theory for the origin of mitochondria and chloroplasts.
The engulfment of the proteo bacteria came first
All eukaryotes gave mito then second rise to animals then the addition of the chloroplasts gave rise to the addition of plants
Evidence in support of the endosymbiotic theory
- Mito/ Clr similar size in prokaryotes
- Replicate by binary fission
- Double Membrane
- 70S ribosomes
- Circular genome
- Genoome sequence similarities to their respective bacterias
- Reduction of organellar genomes
Describe the Double membrane associated with the endosymbiotic theory
Inner membrane - similar to PM of prokaryotes
Outer membrane - may have been derived from host ‘phagosome’
Describe the reduction of organellar genomes in regards to the endosymbiont theory
Gene transfer between host and endosymbiont
Many genes need by mito/ clr are nuclear encoded
sequences similarity b/w genes in nucleus (of plants and people) and cyanobacteria/ proteobacteria
- Which suggest previous connection
What is horizontal gene transfer?
Occurs when genetic information is passed “sideways” to a relatively unrelated organism (as opposed to a direct descendent).
What is Neutrophil
able to detect bacteria using the receptors that are lined on it’s PM
Describe the movement of neutrophil
The microfilament polarize to go toward bacterium
- As bacterium move the strength of the receptors adjust according to the direction the receptor may have moved in
- E to conduct this movement is taken from the mitochondria
After - Neutrophil is engulded by phagosomes that are linked to lysosomes which lyzed the bacterium
List the 5 elements found in all living things
O
P
C
H
N
Compostion of Oxygen in the human body?
65%
Compostion of Carbon in the human body?
18.5%
Compostion of hydrogen in the human body?
9.5%
What is percent of Nitrogen in the human body?
3.3
Why is there so much Oxygen in the human body
Because the ,ajority of out body is made of H2O and O makes up most of the weight of the molecule. Also most cells have 70% water
Most cellular rxns take place in an aq enviroment
Cells in the human body are typically surrounded by aq fluids
Explain why certain elements are ‘reactive’. What makes them reactive? Explain the role played by valence electrons when determining reactivity.
Certain elements are more reactive because they have less valence electrons which will allow more electrons from other elements to fill in.
Define Electronegativity
The affinity(Wanting/ giving) of an atom/ molecule for electrons
Desribe the EN trend
Across a row - Increases
Down a column - Decreases
Covalent Bonds
Sharing of e-
Polar covalent
electrons are no shared equally
Why aren’t the electrons shared equally in a polar covalent bond?
Because atoms involved have unequal sharing due to EN difference btwn atoms
Inequality results in one part of a molecule being more negative than another part
Molecule thus has negative and positive poles like water
Are polar molecules hydrophilic or hydrophobic
hydrophilic = water loving
SO it is water soluble
Nonpolar molecules
electrons are equally shared
why are nonpolar molecules equally shared ?
atoms involved gave relatively same EN values
No one part of the molecule is distinctly postive or negative - no poles
are nonpolar molecules hydrophobic or hydrophilic?
hydrophobic = water fearing
SO IT IS NOT WATER SOLUBLE
Ionic bond
formed through electrostatic between oppositely charged ions
Electrons are NOT shared
What causes an ionic bond?
Due to attraction between…
an atom that has lost 1 or more e-
and an atom that has gained 1 or more e-
H bonds
define and what atoms can it bond w/?
Forces between polar molecules
Can form between H and N
Specifically involves H bound to a more EN atom such AS N, O, F of another molecule
Are the electrons shared in H bonds?
No H bonds are electrostatic interaction between dipoles
London Dispersion Forces
Temporary attractive force
- Found in all molecules
- Weakest of all forces
- Result when electrons in 2 adjacent atoms occupy positions that make the atoms form temporary dipoles b/c constant movements
Differentiate between a carboxylic acid and a carboxylate. Which one is protonated? Which one is charged?
Left is protanates
Right is unprotonated
Define an organic molecule
hydrocarbon based molecule
The presence of C alone DOES NOT constitute an organic molecule
Describe the properties of carbon that make it well suited to form the backbone of organic molecules.
Capable of forming 4 bonds
Relatively neutral EN
Covalent bonds
Forms stable molecules
Distinguish the various types of macromolecules found in living things.
Lipids
Carbs
Nucleic Acids
Proteins
Why are lipids not considered polymers?
Lipids are different from other macromolecules b/c
not formed by the same type of linear polymerizations as proteins, nucleic acids and polysaccharides
However they are still considered a macromolecule due to their high molecular weight and importance in cellular structures
*particularly membranes
Monomer units used to construct the polymeric macromolecules - Carbs
Monosaccharides
Monomer units used to construct the polymeric macromolecules - Nucleic Acids
nucleotides
Monomer units used to construct the polymeric macromolecules - proteins
amino acids
Breakdown of organic macromolecules occurs by
hydrolysis rxns.
Organic macromolecules are synthesized by
condensation rxns
Describe phosphorolysis
Using a P group to lyze a molecule
EX: Glycogen (storage polymer)
Polymer +Glycogen → Monomer w/ PO3 2- and Polymer w/ 1 less group
General properties of lipids
little affinity for water - Not soluble in water (hydrophobic molecules)
Readily soluble in non polar solvents.
Some lipids are amphipathic, havinf a polar + nonpolar regions
Functions of lipids
E storage
Membrane structure
Signal Transduction
Carbohydrate is ..
the most abundant organic molecule on Earth
- Cellulos - produced by photosynthetic organisms
- Chitin - fungal cell walls, exoskeletons of arthropods
Main functions of carbohydrates
Structural components & Storage = Major E source –> Glucose
Monosaccharides
simple sugars
generally have a molecular formula that is some multiple of CH2
Disacharides
join together monosaccharides via condesation to form a glycosidic bond
Glyscosidic bond
type of covalent bond that joins a carbohydrate molecule
*another group may or may not be another carbohydrate
→ when joined to lipid = glycolipid
→ when joined to protein = glycoprotein
Linkage identified by the carbon # of each monomer unit
EX: C1 of first monomer joined to C4 of second monomer = 1→ 4 glycosidic linkage
polysaccharide
a carbohydrate whose molecules consist of a number os sugar molecules bonded together
Monosaccharides can exists as…
linear chains or rings
Rings are more energitically favorable; more stable
Rings acan exists in alpha or beta form
Explain the difference between an alpha and a beta isomer.
Alpha - -OH on same side of ring
Beta- -OH on opposite side of ring
Alpha glucose
All glucose subunits are oriented in the same direction
Tends to form loose helical structures eg - starch/ glycogen
Beta glucose
Each glucose subunit is rotated 180 compared to its neighbor
OH on C6 alternated on each monomer in the polymer
Allows formation of linear rigid, rods
Can pack close together w/ other rods to form ‘rope’
