L4. The cell 3 Flashcards
(40 cards)
Describe LTPs in ERJS
- we can have LTP attached to both donor and acceptor membrane of the cell
- LTPs don’t diffuse between the membrane
- there is a flexible hinge enables LTP to move lipids by wining them between membranes
- highly efficient non-vesicular transport
Describe the mitochondria (functions)
- up to 10 um in length
- up to 1000/cell
- generates ATP by cellular respiration
- regulates cell death by apoptosis
- synthesizes phospholipids - cardiolipin
What are the mitochondrial compartments?
-outer membrane: porous allows passage of small molecules
intermembrane space: similar to cytosol
-inner membrane: folds called cristae; ATP Synthase complex;ETC complexes, ATP is generated through oxidative phosphorylation
-matrix: ~50% proteins, visocous contains cDNA, mitochondria rivosomes =, tRNA and mRNA
How many genes does mitochondrial cDNA have?
37 genes, others are imported from the nucleus
How are proteins encoded by the nucleus transported to the mitochondria?
- chaperone protein binds to the polypeptide and transports it to the mitochondria
- sequence in polypeptide directs to TOM complex
(TOM complex drives outer membrane insertion of the polypeptide) - small TIM complex binds the polypeptide and drives it towards the inner membrane
- large TIM complex inserts the polypeptide into the inner mitochondria membrane
- polypeptide is released into the membrane and folds into its structure
What is MELAS ( mitochondrial encephalopathy lactic acidosis and stroke like episodes)
- when you have cristae with no folds
- mutations in the mitochondria tRNA
- cannot produce energy
- weak posture
What are peroxisomes?
- beta oxidation
- self-replicating
- contains enzymes>40
- 1um
- proteins are obtained from
a. peroximal targeting signal sequence
b. vesicle fusion
What is Zellweger Syndrome?
defect in peroxisomal protein import
What are the functions for cytoskeletons?
- 3D protein filaments
- cell morphology
- intracellular motion
- whole cell migration
What are centrioles?
pairs of specialized micro-tubular structures within the centrosome, generate spindles
What makes thin filaments?
actin
What makes intermediate filaments?
nuclear lamins
What makes microtubules?
tubulin
Describe actin (filaments)
- F actin composed of 2 chains of G actin monomers
- Faster growing + end and a slower growing - end
- Capping proteins regulate length and speed of growth
- Different f actin bundles have different functions
- bundles are maintained by different actin binding /stabilizing proteins
- myosin motor proteins move cargo
What are focal adhesions
- where actin cytoskeleton comes into contact with ECM
- cells exerts tensile force on ECM
- needed for wound healing
- contractile bundles connect to ECM via integrins
- stabilized by Vanculin and Talin
Draw the focal adhesion complex
pg 67
Describe microtubules
- hollow tube consists of 13 parallel protofilaments of alpha beta tubulin heterdimer
- dynamic structure
- originates from centrosome from gamma tubulin ring complex
- plus end: addition of dimers
- minus end: shrinkage
What are the functions of microtubules
- chromosome segregation
- cillary and flagellar motion
- movement of organelles
What are the motor proteins for microtubules?
kinesins: + end directed motors
dyneins: - end directed motors
What is heterochromatin
Wound DNA, e- dense
What is euchromatin
unwound DNA
How large is a nuclear pore
9-11nm wide
What do the number of nuclear pores correlate to?
The amt of metabolic activity within the cell
What are the functions of the nuclear pore
- connected to each other by lamins
2. regulates the substances that enter and exit the nucleus
