Chloroplasts, Apoptosis, Endomembranes (Lecture 18) Flashcards
Ligand-Receptor interaction is the first step in what?
What provides structural support in multicellular organisms
What does the Endosymbiont Theory suggest?
Mitochondria have membranes and compartments that carry out what?
-
Ligand-Receptor interaction is the first step in transducing signals from outside the cell to the inside.
- Conformation change ~~G-proteins~~ Signal Cascade
- The Extracellular Matrix and Cell Walls provide structural support in multicellular organisms.
3. The Endosymbiont Theory suggests mitochondria and chloroplasts are derived from ancestral bacteria.
4. Mitochondria have membranes and compartments that carry out oxidative phosphorylation to provide energy for the cell (ATP).- electrochemical gradient ~~~ proton-motive force
The Big Leap in Evolution: Energy Supply
Explain the aerobic respiration and what is the equation?
Aerobic respiration: converts energy stored in food molecules (e.g. glucose) into chemical energy stored in ATP. This process consumes oxygen and produces carbon dioxide as a by-product (waste).
(CH2O) + O2 → CO2 + H2O + ATP
The Big Leap in Evolution: Energy Supply
Explain photosynthesis and what is the equation?
Photosynthesis: building carbohydrates using energy from sunlight and CO2.
CO2 + H2O → sunlight → (CH2O) + O2
Chloroplasts: Structure and Function
Name the structure of the chloroplast…
Explain light-dependent reactions
Light-dependent Reactions
- occur in Thylakoid membrane
- chlorophyll in Light-Harvesting Complex
- SUN + H2O → O2 + e- + H+
- e- enters ETC (also in Thylakoid membrane)
- H+ pumped into Thylakoid lumen
Explain light-independent reactions
(Dark Reactions)
(Calvin cycle)
Light-independent Reactions
(Dark Reactions)
(Calvin cycle)
- occur in Stroma
- ATP (and NADPH) made in Light Reaction used to make (CH2O)
What do mitochondria play an important role in?
Mitochondria Play an Important Role in Programmed Cell Death (Apoptosis)
What is PCD?
What is the Madagascar Lace Plant?
How does PCD affect the Madagascar Lace Plant?
- Programmed Cell Death (PCD) also occurs in plants.
- The Madagascar Lace Plant is an aquatic plant that makes fenestrated leaves.
- In the course of normal development, PCD generates leaves with holes in them.
Explain oxidation and reduction
Oxidation of water, with O2 produced as a by-product
Reduction of CO2 to form carbohydrates
Comparison of normal and apoptotic cells
What is Apoptosis characterized by?
Apoptosis is characterized by:
- Shrinkage of cell
- Blebbing of the plasma membrane
- Fragmentation of DNA and nucleus
- Loss of attachment to other cells
- Engulfment by phagocytosis
What happens to a cell when there is a kill signal?
- Breakup of the nuclear envelope
- Nuclear fragmentation
- Blebbing
- Cell fragmentation
then. ..
* Phagocytosis
What does Intrinsic Pathway of Apoptosis mean?
The Intrinsic Pathway of Apoptosis:
- initiated by intracellular* stimuli
- (e.g.,*genetic damage, hypoxia, virus)
- “killer” proteins cause changes in mitochondria membrane such that they leak protein (i.e. Cytochrome c)
- Release of apoptotic mitochondrial proteins commits the cell to apoptosis
What is The Intrinsic Pathway of Apoptosis?
- Bax assembles on OMM to form pore
- Cytochrome c assembles Apoptosome in the cytoplasm
- Cytoplasmic factors (e.g. Apaf-1)
- Procaspase-9
- Activated initiator caspase-9 complex (Apoptosome
- Apoptosome activates executioner caspases
What releases during apoptosis?
What do Caspases do?
Release of Cytochrome c and nuclear fragmentation during apoptosis
Caspases
- Disrupts cell adhesion
- Destroys Lamins
- Breaks down cytoskeleton
- Activates DNase (genome breakdown)
Apoptosis and Disease
Too little apoptosis can lead to what?
Too much apoptosis can lead to what?
Apoptosis and Disease
- Some diseases are directly associated with aberrant apoptosis. In some cases, the problem is due to too little apoptosis; e.g., cancer where malignant cells will not die
- In other cases, too much apoptosis can lead to neurodegenerative diseases like Alzheimer’s and Parkinson’s disease.
Cytoplasmic Endomembrane System
What did early EM work reveal (within the cytoplasm)?
- Early EM work revealed (within the cytoplasm):
- membrane-bound organelles and vesicles
- an extensive network of membranous canals and stacks of “sacs” (= cisternae)
Label the Cytoplasmic Endomembrane System
Origin of Cytoplasmic Membrane Systems
What are the 4 steps?
Anaerobic
Prokaryotic
- Ancestral Prokaryote
- Infolding of plasma membrane
- Endosymbiosis
- Ancestral Eukaryotte
The endomembrane system
“inside” and “outside”
Overview of the biosynthetic/secretory endomembrane system
What are the 9 steps of the biosynthetic/secretory endomembrane system?
Label the diagram
- Protein synthesis on bound ribosomes; co-translational transport of proteins into or across ER membrane
- Budding and fusion of ER-to-Golgi vesicles to from cis-Golgi
- Retrograde Golgi-to-ER transport
- Cisternal Maturation
- Retrograde transport from later to earlier Golgi cisternae
- Consecutive secretion
- Regulated secretion
- Sorting to lysosomes
- Endocytosis
Technique: Using GFP to track cell components
What is GFP?
✦ The Green Fluorescent Protein from jellyfish (Aequorea victoria) can be fused with a
cellular protein.
✦ The fusion protein can be expressed in cells.
✦ The cellular: GFP fusion protein fluoresces and can be visualized under a
microscope.
✦ Observation of the fusion protein provides information about the endogenous protein
(e.g. where it is localized in a cell or organism).
Vesicular Transport / Trafficking
What is the order of compartments these proteins travel through?
ER → Golgi → Plasma membrane
How is the transmembrane protein maintained during its travel?
Which end of the protein sticks out? Which end faces in?
The orientation of a transmembrane protein with respect to the cytoplasm and the interior of membrane-bound compartments is maintained during its travel through the endomembrane system.
Where does GFP appear in a cell?
In the endoplasmic reticulum, GFP is inside the compartment. It then moves through to the Golgi complex still inside, as it moves through the cell and exits the GFP is on the exterior of the cell as shown.
