Lecture 1 Flashcards
How many cell types does the body contain?
200 different cel types
What are the 3 major sub divisions of the cell ?
Plasma membrane
Nucleus
cytosol/plasm
Plasma membrane function
Acts as a barrier
separates intracellular and extracellular fluid
Plasma membrane structure
Lipid bilayer
Hydrophilic (polar) heads and lipophilic (nonpolar) tails
Many proteins that run completely/ partially through the membrane
Nucleus
Largest single cellular component and contains the genetic material of the cell DNA
Nuclear envelope
Surrounds the nucleus
= lipid bilayer
Contains any nuclear pores that allow for proteins, DNA & RNA to move between the cytosol and the nucleus
Cytosol
Complex gel like liquid surrounding the organelles
Occupies 55% of the total cell volume
Cytoplasm
Contains the membrane bound organs in the cytosol
Ie. Cytosol + organelles
6 main types of organelles
Nucleus ER Golgi Lysosomes Peroxisomes Mitochondria Vaults*
ER
Membrane system that is distributed throughout the cytoplasm
- mainly involved in protein and lipid synthesis
2 types : rough and smooth
Rough ER
Outer surface has lots of ribosomes
- ie. Ribosomal RNA protein complexes involved in the synthesis of protein
- interact with mRNA
There are also free ribosomes in the cytosol
All proteins made here have a sorting signal
What happens to proteins made in the ER?
After the ribosomes make the synthesized protein it is released into the ER lumen where it undoes folding and modifications
Then the folded protein is transported through the ER to the golgi
Smooth ER
No ribosomes
Ie. Not involved in protein synthesis
Serves primarily as a final packaging and discharge site for molecules transported to the golgi
Golgi
Stack of flattened, membrane- bound sacs called cisternae
Functions of golgi
Processing the raw molecules from the ER into finished products [ie. Accessorizing -adding groups]
Sorting and directing these molecules to their final destination [organelles or plasma membrane] - note that different parts of the golgi have parts specific to the location that the product is going. Ie. The plasma membrane products located differently from nucleus products.
Steps of protein transportation
- Synthesis in the rough ER
- Packaging and budding in the Smooth ER
- Fusion with the golgi complex
- Processing and sorting in golgi
- Budding from golgi and transport to plasma membrane
- Fusion with plasma membrane with exocytosis or membrane insertion
Exocytosis
The secretory vesicle blinds and fuses with the membrane, which then leads it to release the material outside
What proteins are involved in exocytosis?
NOTE: all proteins from the RER have a sorting signal - where in the golgi do i go to?
It involves the interaction of many proteins in the budding from the golgi complex such as [these are facing the cytosol):
Coat protein
Docking marker (v-snare)
Recognition marker
Then the fusion to the plasma membrane/ organelle involves :
Docking acceptor protein (t-snare)
Lysosomes
Membrane bound organelles that sever as the intercellular digestive system
- contain hydrolytic enzymes that break down the organic compounds ingested by the cell via a process called endocytosis
- so the nutrients can be used to make other things inside the cell
- can also degrade something bad
- also get rid of old organelles
Endocytosis types
- Pinocytosis
- Receptor-mediated endocytosis
- Phagocytosis
Pinocytosis
This is cell drinking
Non-selective uptake
Receptor mediated endocytosis
Highly selective uptake
Triggered by a ligands binding to its receptor
Phagocytosis
Internalization of large, multi molecular particles like bacteria or red blood cells
peroxisomes
Membrane bound organelles that contain oxidative enzymes and most of the cell”s catalase
Oxidation
Involved in the detoxification of various wastes produced in the cell and foreign toxins ingested by the cell
- oxidation causes the production of peroxide which is toxic to the cell
Mitochondria
Power plants of the cell as they supply the cell with 90% of its energy in the form of ATP
Double membrane
Membranes of mitochondria
Outer membrane: surrounds the organelle
Inner membrane: forms a series of infoldings called cristae
What does the mitochondria specifically do?
- It uses pyruvic acid molecules from glycolysis
- This is then taken up by the mitochondria and is converted to ATP via enzyme reactions in the matrix
- Excess hydrogen in the form of NADH is also produced
[NOTE: steps 2 and 3 called TCA] - Electron transport chain converts excess H+ into ATP via the movement of H+ across the inner mitochondrial membrane
Glycolysis location
Enzymes are located in the cytosol
Glycolysis function
Breaks down glucose into pyruvic acid
What occurs in the cytosol?
- Metabolic processes like glycolysis
- Ribosomal protein synthesis
- Storage of fat, carbs {glycogen}, and secretory vesicles
Cytoskeleton
Intracellular scaffolding to give cell shape and structure
- also intracellular highway for trafficking vesicles to and from the plasma membrane
What makes up cytoskeleton?
- Microfilaments [actin]
- Microtubules [tubulin]
- Intermediate filaments
Homeostasis
Maintenance of a stable environment
Essential for the survival of each cell and every cell contributes to the maintenance of the internal environment shared by the cells
Vaults
Classified as organelles
Don’t know exact functions yet
Specialized cell
Can have a larger smooth ER
Ex. Liver, Skeletal, steroid hormone secreting cells
Smooth ER in skeletal muscle
Called sarcoplasmic- reticulum
function is to store lots of calcium
Smooth ER in endocrine cells
Stores a lot of cholesterol
Smooth ER in liver
Detoxifying enzymes
Coat protein
cytosolic proteins
Bind the coat protein acceptor signals on the outside of the golgi membrane
When they bind, start to impart curvature to the outside of the golgi membrane and keep pulling until they get a full vesicle
General term for them is COP
Docking marker protein
How we get to the plasma membrane , outside of the secretory vesicles done budding
The specific docking marker is called the v-SNARE
V = Vesicle
Vesicle will go to target [in image = plasma membrane] - coat falls off after it makes vesicle
- green in image
T- snare
V snare’s target is t-snare
They bind together
Reactions occur, which allows ca to enter vesicle. Ca then triggers fusion of the 2 membranes
Catalase
2 H2o2 -> 2 H20 + O2
Breaks down peroxide
Glycolysis
Glycogen -> stored glucose
Glucose -> pyurvic acid - 2 ATP
Pyruvate
Kreb cycle - 2ATP
FADH and NADH - fuel oxphos
OXphos
28 - 32 ATP from single glucose
Total ATP generated from oxphos
32- 36
Actin
2 strands helically wrap around eachother
Microtubules
Hollow tube
Highway for vesicles - ie. In neuron
Kinesin - moves and carry vesicle out
Dynein - to move in
Intermediate filaments
Not made of a single protein
Middle in size
Kinesin
Uses ATP
Exocytosis
Dynein
Endocytosis
Has to go to cell body
Cleave ATP
