Lecture 18: Chloroplasts, Apoptosis, Endomembranes Flashcards
Photosynthesis happens in the…?
Chloroplast
What are the two different reactions that photosynthesis can be divided into?
Light-dependent reactions
Light-independent reactions
Chloroplast have…
Double membrane
Stroma of the chloroplast is the
inter membrane space
Thylakoid membrane inside the thylakoids has..
All of the necessary things to allow photosynthesis to take place
Light dependent reactions occur..
In the thylakoid membrane
Function of the light-dependent reactions is to
Excite electrons that are used to generate a proton gradient
Light-dependent reactions steps
Electron enters ETC, and H+ is pumped into the thylakoid membrane
Co-enzyme in light-dependent reactions is
NADP+ and NADPH
Light-independent reactions occur in
Stroma of the chloroplast
Light-independent reactions are also known as..
Dark reactions/calvin cycle
What happens in the light-independent reactions?
CO2 is reduced to carbohydrates by ATP and NADPH
Programmed cell death (Apoptosis) is…
A normal process that involves the death of cells in a coordinated sequence of events, it is part of an organisms growth and development
Programmed cell death genes…
Are sequenced in every single cell, however they are just not activated if a cell isn’t undergoing apoptosis
How does apoptosis happen?
Bone morphogenetic protein (bmp) is a secreted protein that binds to bmp receptors which activates apoptosis
Apoptosis is characterized by
- shrinkage of the cell
- fragmentation of DNA and nucleus
- blebbing (bulge or protrusion) of the plasma membrane
- loss of attachment to other cells
- engulfment by phagocytosis
What stimuli can cause apoptosis?
- genetic damage, hypoxia, virus infection
- proteins such as Bax cause change in mitochondria membrane potential and to the leak of cytochrome c
- release of apoptosis mitochondria proteins commits cell to apoptosis
Bax proteins function like…
- bind to mitochondria
- forms pores in membrane and cytochrome c spills out into cytosol
- apoptosome is formed by cytochrome c and Bax
- this forms other structures which trigger apoptosis
What are the functions of Caspases?
- disrupts cell adhesion
- destroys laminate
- breaks down cytoskeleton
- activates DNase
Too little apoptosis…
Leads to cancer
Too much apoptosis leads to…
Alzheimer’s
Function of the cytosol
Protein synthesis, many metabolic pathways
Endoplasmic reticulum function
Synthesis of lipids, synthesis of proteins
Golgi apparatus function
Protein modification, packaging of proteins and lipids
Lysosomes function
Degradation of cellular material
Endosomes function
Sorting, recycling
What is the endo membrane system?
Extensive network inside the cell that consists of: ER, Endosomal transport vesicles, golgi complex, lysosomes, vacuoles
GFP is?
Fluorescent protein that can be fused with cellular proteins, and can be expressed in cells to track proteins
Vesicular transport destinations
Organelle to PM and vice versa
Organelle to Organelle and vice versa
During vesicular transport…
The vesicle buds off donor compartment and makes its way to recipient compartment via motor protein
What is being transported during vesicular transport?
Certain proteins must stay in donar compartment and certain proteins will be transported to recipient compartment. These proteins are sensed by receptors present in the cytosol of the compartment
Key elements of vesicular trafficking:
- Movement of vesicle - uses cytoskeleton and motor proteins, can be anterograde or retrograde
- Tethering vesicle to target compartment - via proteins from Rab family
- Docking of vesicle to target compartment - uses proteins called SNAREs
- Fusion of vesicle and target membrane
Anterograde vs retrograde
Anterograde - forward (from ER to Golgi)
Retrograde - backward (Golgi to ER)
