Cell Structure &functions Lec 9 Flashcards
Energy in C-H bonds vs. C-O bonds
-Carbohydrates are used for structural support,protection and energy
-C-H bonds are stronger due to the bond length being shorter
-C-O bonds are longer due to the bond length being longer
Redox (Oxidation vs. Reduction)
Oxidation:Loss of electrons
-During glycolysis, Glyceraldehyde-3P losses electrons in hydrogen and gains oxygen as part of phosphate
Reduction:Gain of electrons
NAD+ vs. NADH
-Is a coenzyme that can transport electrons
-When an electron such as e- is transferred molecules pick up a hydrogen ion (H+ or proton)to balance the charge
-NAD is a nucleotide
-The coenzyme NAD+ is reduced which helps NADH gain 2 electrons
Coenzymes
-Are non protein cofactors for reactions
Describe the steps in the Glycosis
Step 1:Phosphorylation of glucose to glucose-6 phosphate. * This reaction requires energy, and so it is coupled to the hydrolysis of ATP to ADP and Pi.
Enzyme: hexokinase
-It has a low Km for glucose; thus, once glucose enters the cell, it gets phosphorylated.
* This step is irreversible. So, the glucose gets trapped inside the cell. (Glucose transporters transport only free glucose, not phosphorylated glucose.)
Step 2: Isomerization of glucose-6-phosphate to fructose 6- phosphate. The aldose sugar is converted into the keto isoform.
* Enzyme: phosphoglucomutase.
* This is a reversible reaction. The fructose-6-phosphate is quickly consumed, and the forward reaction is favored.
Step 3:Is another kinase reaction. Phosphorylation of the hydroxyl group on C1 forming fructose-1,6- bisphosphate.
* Enzyme: phosphofructokinase. This allosteric enzyme regulates the pace of glycolysis.
* Reaction is coupled to the hydrolysis of an ATP to ADP , and Pi.
* This is the second irreversible reaction of the glycolytic pathway.
Step 4: fructose-1,6-bisphosphate is split into 2 3-carbon molecules,
one aldehyde and one ketone: dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP).
* The enzyme is adolase.
What is Fermentation
-Occurs in the cytosol without oxygen
-Converts pyruvate into lactate
-Converts NADH back to NAD+
-Glycosis stops without NAD+
-Commonly used in Stressed tissues like overused muscles
-Converts pyruvate into ethanol
-Produces carbon dioxide
-Commonly used to make beer and wine
What is fermentation in yeast?
-Involvs metabolites in mutiple tissues
1)Dietary Glucose
2)Blood Glucaose -Liver Glucose-6P
3)Muscle Glucose-6P-Muscle Lactate
4)Muscle Glycogen
5)Liver Glycogen
6)Liver Glucose-6P
7)Liver Lactate-Blood lactate
What is the process of Replenish
-Happens in NAD+ for further rounds of glycosis
-Are used in coenzymes to describe how NAD needs this action for metabolic pathways to continue
Define Interconnected pathways
-A catalyization that happens in specific enzymes
of ATP produced by aerobic respiration
-Glycolysis and fermentation do not require oxygen to produce a little energy in the cytosol(2ATP)
Mitochondria
With oxygen there is :<32 ATP/Glucose
Without oxygen:There is 2ATP/Glucose
-Major energy source of eukaryotic cells
-Contains unique lipids called (Cardiolipin)
-Are derived from a symbotic prokaryote
-After the first organelles developed,a bacteria took up residence in a eukaryotic cell
-Some mitochondrial proteins are now encoded in the eukaryotic nuclear geonome
-Are more active
What is a mitochondrial genome(mtDNA vs.Nuclear genome(DNA)
mtDNA
-After the first organelles developed,a bacteria took up residence in a eukaryotic cell
Nuclear genome(DNA)
-Some mitochondrial proteins are now encoded in the eukaryotic nuclear geonome
Define Mitochondrial matrix
-Contains their own genome and ribosomes in the mitochondrial matrix
-Pyruvate travels through two transports to reach the mitochondrial matrix
-The matrix has a distinct chemical environment within mitochondria
Define Outer vs. Inner Mitochondrial Membrane
-On the outside of the mitochondrial matrix
-Specific pyruvate transports (MPC)imports pyruvate across the inner mitochondrial membrane
Define Intermembrane space
-Happens within the outer mitochondrial membrane of the porins and transfers into the intermembrane space
-The intermembrane space has similar ions to the cytosol
-The matrix has different ions than the intermembrane space
-The intermembrane space shares ions and molecules ithin the cytosol
Define Cristae
-Wrapped in two membranes, the inner membrane has internal folds
Define Symbiote
-An organism that is very closely associated with another,usually larger organisms
Define Mitochondrial Fission vs. Fusion
Mitochondrial Fission:
-Mitochondria use dynamic-related proteins(Drp) to squeeze the organelle to promote fission
Mitochondrial Fusion:of both mitochondrial membranes is needed to connect the cristae membranes and share a common matrix
-The outer membranes fuse with the help of mitofusins (Mfn) The inner membranes fuse with the help of Opa proteins
*Mitochondria can grow and divide to meet the metabolic needs of a cell *
Define Dynamin
Are large GTPases
Form of helix around membranes
Hydrolyze GTP to change conformation to thin membranes
Include membrane scission
Define the mitochondrial divide
-The ER helps mitochondria divide
-The endoplasmic recticulum marks future sites of mitochondrial fission
-Drpl is recruited and constricts the mitochondrion
-The mitochondrion divides into two mitochondria
Define Reactive Oxygen Species (ROS)
-Sperm mitochondria are damaged by ROS
-Damaged mitochondria are degraded via a processes called autophagy
-Only oocyte mitochondria are inherited by embryos
Define porin
-Are large channels that allow molecules to diffuse across the outer mitochondrial membrane into the inter-membrane space
Define a Beta-barrel
Are porins that are large with a large pore(<2nm) in the outer membrane
-Non-specific channel
Define Mitochondrial Pyruvate Carrier
-Are a heterodimer with transmembrane domains in the inner membrane
-Has a specific transporter(Facilitated)
· Specific vs. non-specific transport
Key Takeaways:Mitochondrial transport
-The mitochondrial outer membrane is generally permeable to small molecules via large porin channels
-The inter-membrane space has similar ions to the cytosol
-The mitochondrial inner membrane is a tightly controlled barrier with specific transporters fir each molecule
-The matrix has different ions than the inter-membrane space
Mitochondria:Key themes
-Redox reactions allow the exchange of energy in the form of electrons
-Mitochondria are key energetic organelles to a eukaryotic cell’s survival
-Mitochondria are subdivided into distinct compartments with different chemical compositions
