Cell Structure And Function Flashcards
___ Molecules need transporter to move from outside to inside of cell. Why?
Water soluble because the inner part of the phospholipid bilayer is hydrophobic
___ transport molecules across cell membrane; what do they look like
Integral proteins; span the entire phospholipid bilayer
What happens in the nucleus? (3 things)
Location of DNA and chromatin, DNA replication, and transcription to mRNA
What happens in nucleolus?
Synthesis of rRNA
Function of mitochondria?
Generates ATP and synthesizes steroids
Function of rough and smooth ER
Rough - translates mRNA to peptide (protein) on its ribosomes to be secreted or inserted into cell membrane
Smooth- detoxification and metabolizes lipids, steroids, and glycogen
Golgi body function? What is derived from golgi?
Packages translated proteins from rER
Secretory granules which are vesicles involved in secretion (exocytosis)
Lysosomes?
Degrade material
Centrioles synthesize ___?
Two main functions of this?
Microtubules
- Transport
- Modified cell shape (major part of cytoskeleton)
Nuclear envelope is continuous with?
Which has spaces called?
Which control?
RER
Nuclear pores
What goes into and out of the nucleus
Things travel through the nuclear pore complex to get into and out of the nucleus
- Types of things that go into the nucleus?
- Out of the nucleus?
- Enzymes and other proteins made in the cytoplasm
2. mRNA and ribosomes made in the nucleus
Function of the importin and exportin protein
Enables transport by a carrier protein (to get larger molecules into/out of nuclear pore)
After dna transcribes to mRNA, where is the mRNA exported?
Ribosomes in cytoplasm or on rough ER for translation into proteins
Job of nucleolus
Makes rRNA and then assembles rRNA and ribosomal proteins into ribosomes
What does “beads on a string” refer to?
(Slide 23 diagram)
Chromatin fibrils which occurs when dna is wound around histones (which are large proteins)
Euchromatin and heterochromatin similarity and difference
Both are formed when chromatin fibrils coil
Euchromatin = loosely coiled (state when cell is not dividing)
Heterochromatin = tightly coiled (preparing for cell division)
When heterochromatin is further tightly packaged, its name changes to ?
Chromosome
- DNA -> ___ -> mRNA
2. How does RNA splicing form mRNA?
- Heteronuclear RNA (hnRNA)
2. RNA splicing removes introns and splices together exons to form mRNA
- After mRNA is translated to protein at rough ER they enter ___ and then ___ for further processing
- The processing at the latter location is referred to as ____
- RER and golgi (via vesicles that bud off from rER)
2. Post translational modification
Constitutive secretory pathway vs. regulated secretory pathway
Both have to do with secretion at the golgi, but constitutive occurs constantly while regulated must be activated
Mitochondria
- Outer membrane allows for what kind of diffusion?
- Inner membrane?
- Has small pores so ions and small molecules can diffuse between cytoplasm and intermembrane space
- Lacks pores - contains ion channels and pumps and transporter proteins
3 phases of energy production:
- Glycolysis converts __ to __. Location?
- CAC: Product of glycolysis is transported to?
- ETC and ATP synthase: location?
- Glucose to pyruvate
- Mitochondrial matrix
- Inner membrane of the mitochondria
It is important for actin to be located in parts of cells that are?
Growing or changing in shape
Main function of intermediate filaments?
Structure?
Used as part structures that attach neighboring cells
Two monomer strands coiled together to for a dimer; dimer then linked into sheet like structure which could to form final rope like structure
Basic unit of microtubules is a dimer of 2 proteins: __ and __ which binds to form cylindrical structure
Function of microtubules?
Alpha and beta tubulin
Long extension of cells that form mitotic spindles and cilia and work with motor proteins to transport items
Out of the three components of the cytoskeleton, which have polarity?
Actin and microtubules (not intermediate filaments)
Name two motor proteins and which direction do they move?
Kinesin: moves towards plus end Dynein: move towards minus end
Two main types of receptors and brief function of each
- Ionotropic: ligand binds to receptor, opens channel so ions can move through
- Metabotropic: ligand binds to receptor to cause conformation change which activates an enzyme that is attached to the receptor
Very broad pathway of G-protein coupled receptors
Hormone binds to a receptor which activates protein attached to the receptor which then works on the enzyme (to either stimulate or inhibit it)
3 mechanisms of internalizing substances?
They do this by forming ___
- Pinocytosis, receptor mediated endocytosis (receptor becomes internalized as well), and phagocytosis
- Through formation of membrane vesicles
The 3 mechanisms for internalizing substances all involve formation of a vesicle. What is the fate of the vesicle after mechanism is complete?
Sometimes vesicle is recycled to the cell membrane
Sometimes they can fuse with endosomes which mature into lysosomes
Main function of peroxisomes and its enzymes
Peroxisome contain degradative enzymes (similar to lysosomes)
Peroxidases (specifically catalase) metabolize hydrogen peroxide (H2O2); beta-oxidase degrades lipids
What is an abnormal inclusion?
When the abnormal accumulation is in the lysosomes, what is this called? Give an example of a specific disease
Something that should have been broken down (degraded) from pathway that was not
Lysosomal storage disease (ex: Tay-Sachs); this happens when things aren’t being broken down in the pathway because of lysosome dysfunction (inherited usually)
- Autophagy would be used to degrade?
- For this to happen, materials are transported to where in the cell?
- What are the 3 modes
- Things inside of the cell (self eating)
- Lysosome
- Macroautophagy, microautophagy, and chaperone mediated autophagy
Proteosomal pathway is similar to autophagy except?
Broad pathway steps?
It is specifically for protein degradation
Proteins bind to ubiquitin (chaperone protein), which mediates translocation and entry into proteosomal vesicles which contain proteases.
What is the meaning of “fluid mosaic”?
Proteins and lipid rafts have horizontal mobility within the cell membrane (phospholipid bilayer doesn’t limit the movement)
Function of rRNA
Helps translate the information in mRNA to protein
Give brief overview of the Gs pathway
Hormone is stimulatory by binding to the Rs receptor which has a Gs protein attached. This protein will bind to the enzyme Adenylate Cyclase to convert ATP to cAMP which activates protein kinase A to phosphorylate other intracellular proteins that stimulate certain cell functions
Give brief overview of the Gi pathway
Hormone is inhibitory by binding to the Ri receptor which has a Gi protein attached. This protein binds to enzyme Adenylate Cyclase which blocks the conversion of ATP to cAMP, thus reducing protein kinase A activity and reducing its phosphorylation, thus inhibiting certain cell functions
Give brief overview of the Gp pathway
~more similar to Gs~
Hormone is stimulatory by activating R receptor that has a Gp protein attached. This protein binds to Phospholipase C and activates it, which cleaves a membrane phospholipid PIP2 into 2 products: DAG and IP3
DAG binds and activates protein kinase A which phosphorylates various proteins
IP3 levels are regulated through degradation by phosphatase enzymes; IP3 binds and opens calcium channels (that are embedded in ER); calcium flows from inside ER to cytoplasm where calcium can regulate protein and cell functions
Overview of lysosomal degradation pathway
Extra cellular substance binds transmembrane receptor
Clathrin proteins form coated pits and vesicles pinch off from membrane
Vesicle fuses with Endosome
Multivesicular bodies (MVB)(small vesicles) bud off the endosome
Endosomes become lysosomes (endosomes are more acidic than cytoplasm, lysosomes are even more acidic than endosomes)
