Test 3 Flashcards
Where does carbon fixation ocurr?
Stroma
Where does the photosynthetic e transfer reaction occur?
Thylakoids membrane
chlorophyll absorbs photons from what portions of the visible light range?
Violet-blue
In the light reaction, movement of electrons through the electron transport chain transfers energy to what molecules?
ATP and NADPH
In the dark reaction, ATP and NADPH are used to drive the synthesis of sugars from CO2, this process is known as what?
Carbon fixation.
What do photo centers contain and where are they located?
Thylakoid membrane, chlorophyll.
Describe lesch-Nathan syndrome
X-link disorder
Due to absence of HPRT, which cause the formation of Uric acid.
How can amino acids be synthesized?
From intermediates of respiration.
Essential amino acids
Histidine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine
What are essential amino acids?
Amino acids that must be consumed from diets.
Non essential amino acids are?
Can be synthesized by humans.
What enzyme
Converts phenylalanine to tyrosine?
Phenyl alanine hydroxylase
When there are deficient amounts of phenylalanine hudroxylase, what happens?
Phenylalanine is converted to phenyl pyruvate (phenyl ketone).
Phenylketonuria (PKU)-development of intellectual disabilities.
Define peri nuclear space
The cavity between two membranes
The outer membrane if the nucleus is continuous with what organelle?
Endoplasmic reticulum
Lamina provide what?
- structural support for the nucleus
- attachment sites for chromatin –> may have a role in gene regulation.
Describe the function of nuclear pores:
-protein complexes that facilitate the transport of molecules through the nuclear envelope
What is the SV40 T-antigen?
Initiator of viral DNA replication
-NLS is a 7 amino acid stretch, typically + charged amino acids,
In the middle of a polypeptide
- cause formation of tumors
Protein complex
Nuclear protein ( cargo) and importin
What drives the nuclear import cycle?
Ran-GTP diffusion into the cytoplasm
If translation occurs in the free ribosome, where can the proteins be destined?
- nucleus
- chloroplast
- mitochondria
- free ribosome
If translation occurs in the ribosomes of the rough ER, where are proteins destined?
-transmembrane, lysosomal, or secreted product.
The smooth ER is the site of what?
Lipid synthesis and processing. Constructs membranes and membrane systems for the cell. P
What’s does the Golgi complex do?
Protein sorting
Requirements for cell to cell communication:
- a signal
- receptor
- signaling proteins
- modification of target proteins
What enzyme uses electrons from photo system 1 to synthesize NADPH?
Ferredoxin-NADP reductase
What happens in photosystem 1?
Photons are absorbed to generate high energy e-. e- are used to synthesize NADPH.
What happens in photosystem 2?
Photons are absorbed to generate high energy e-, which are transferred to Cyt b-f complex and then to photosystem 1. H2O is split.
How much CO2, ATP and NADPH are used in the Calvin cycle? What is produced?
- 3 CO2
- 9 ATP
- 6 NADPH
- 6 molecules of glyceraldehyde 3-phosphate are produce. Only one is store as starch.
What does the CO2 in the Calvin cycle react with and what catalyzes it?
Ribulose 1,5 bisphosphate and RuBP carboxylase
What is the most abundant enzyme on earth?
Ribisco
Describe dehydration synthesis?
Condensation reaction that consumes energy and yields water.
What is required in the formation of macromolecules?
Activated intermediates with a high energy bond that is broken in the final
Condensation step.
What two ways are nucleotides synthesized from nucleosides?
- de novo
- salvage
What is salvage? And example?
- recycling of nitrogenous bases
- single steps
- synthesis of purine nucleoside mono phosphates
What mutation of HPRT causes LNS ( lesch-nyjan syndrome)?
Xanthine oxidase
What does HPRT stand for? What pathway is it in? And what reaction does it catalyze?
- Hypoxanthine phosphoribosyltransferase in the purine salvage pathway
- Hypoxanthine to inosinate
Poly saccharides in animals? In plants?
- starch in plants
- glycogen in animals
What is the activated intermediate in the synthesis of polysaccharides?
UDP- glucose
-Glucose 1-P condenses with UTP
Bond that form proteins, nucleic acids, and polysaccharides?
- peptide bonds
- phosphodiester bonds
- glycosidic bonds p
What is the activate intermediate during the synthesis of peptide bonds?
Aminoacyl-TRNAs at the p site.
Describe nitrogen fixation:
- ATP is consumed
- atmospheric N2 is reduced to NH3
- nitrogen fixing bacteria
Describe Nitrate incorporation:
- NADH or NAPH consumed
- NO3- from soil is reduced to NH3
- bacteria, fungi, and plants
Describe the dimensions of a nuclear pore complex:
- 50 to 100 polypeptides long
- diameter of complex: 120nm
- diameter of opening:25nm
What are the steps of protein import through the nuclear pore?
1) formation of a protein complex
2) translocation of protein complex through the pore
3) binding of ran-GTP–> release of cargo
4) nuclear transport receptor/RAN-GTP complex returns to cytoplasm
5) RAN GAP hydrolyzes GTP
6) dissociation of transport receptor / RAN-GTP complex
Where is RAN-GTP more abundant?
Inside the nucleus.
What catalyzes the hydrolysis of Ran-GTP? Where?
Ran-GTPase-activating protein ( RAN GAP)
-cytoplasm
What catalyzes Ran-GDP to Ran-GTP? Where does this occur?
- Ran Guanine nucleotide exchange factor ( RanGEF)
- nucleus
What is NF-Kappa B?
A transcription factor that exists dormant in the cytoplasm in a complex with I Kappa B.
What’s happens to NF-Kappa B when IKP is phosphorylated?
- nuclear import binds to it and is transported to the nucleus
- required for an immune response
What is Pho4?
-A transcription factor that in the cytoplasm that is phosphorylated and therefore inactive.
- when dephosphorylated nuclear transporter binds
- activates genes that regulate cell cycle
What is required for a protein to be transported to the ER?
A signal sequence at the N-terminus consisting of 8 or more Hydrophobic AAs
Rough ER is the site of:
Protein synthesis or processing
-disulfide Bond formation, addition of cofactors, oligosaccharides to lipids and proteins
What does the Golgi complex do? And how to proteins enter and leave?
- protein sorting and packaging
- Protein vesicles from ER enter the Golgi at the Cis side and leave from the trans side
What is the ER-Golgi intermediate complex (ERGIC)? And where is it located?
- system of membrane stacks located between the ER and the GOLGI
- checkpoint that ensures that proteins that should stay in the ER don’t reach the Golgi complex
What is the retention signal of ER protein residents?
KDEL (Lys-asp-leu)
What are 3 types of transportation from the Golgi?
1) constitutive
2) regulated secretion
3) Transport of lysosomal proteins
What is constitutive secretion?
- operates in all cells continuously
- unregulated secretion
- includes secreted proteins, membrane proteins lipids, extra cellular matrix proteins
Examples of regulated secretion:
- endocrine cells
- pancreatic cells
- neurons
Describe transport of lysosomal proteins:
- hydrolytic enzymes are transported in Clathrin- coated vesicles from the Golgi or plasma membrane
What does Acetycholine (ach) released from motor nuerons cause?
Skeletal muscle contraction
Ach released by parasympathetic nuerons of the ANS causes what?
- a reduced frequency of cardiac muscle contraction and an increase in salivary secretions
What kind of receptor receives Ach in the skeletal muscle cells?
Ligand gated ion channel
What receptor receives Ach in the heart muscle cells and salivary glands?
G-protein coupled receptor
What are the requirements of a cell for cell to cell communication?
- Signal
- Receptor
- Intercellular signaling proteins
- Modification of target protons
What proteins can be targeted in cell-cell communication?
- metabolic enzyme
- gene regulatory protein
- cytoskeletal protein
What are the modes or signaling in cell to cell communication?
- Endocrine
- Direct cell to cell contact
- Paracrine
- Autocrine
- Synaptic
In axons, what molecule causes synaptic vesicles to fuse with the axon membrane?
Ca 2+ ions
Describe what happens during excitatory post-synaptic potential?
- excitatory neurotransmitters cause the depolarization the post synaptic membrane
- Na+ channels are opened.
Describe inhibitory post-synaptic potential (IPSP)
Inhibitory neurotransmitters cause the hyper polarization of the post synaptic membrane.
- Cl- channels are opened.
What are several ways neurotransmitters can be regulated?
1) enzymatic degradation
2) re-uptake by the ore synaptic membrane
3) modulation of post-synaptic receptors
4) balance inhibitory or excitatory neurotransmitters
Does Ach in the neuromuscular in junction cause EPSP or IPSP?
EPSP
Peripheral nervous system
What inhibits the activity of acetylcholinesterase? What happens?
- nerve gass
- severe paralysis
- death by paralysis of respiratory muscles
- muscles can’t relax
What is glutamate?
- an excitatory amino acid on the CNS
- glutamate receptors are Na+ and Ca2+ channels.
- excessive stimulation results on nurodegeneration
What is Gamma-aminobutyric acid (GABA)?
- inhibitory neurotransmitter on the CNS
- receptors are gates Cl- channels
- important for control of body movements and other brain functions
What does Valium do?
- Valium is a sedative drug that enhances the binding of GABA to it’s receptor
What is dopamine?
- excitatory neurotransmitter in the CNS
- controls body movements and pleasure sensations
What is Parkinson’s disease?
The degeneration of dopamine releasing neurons. Tremors
What does the consumption of cocaine cause?
- Heightening of pleasure sensations
- cocain resembles dopamine and prevents the removal of dopamine from the synapse which leaves the limbic system continually stimulated
How does the post-synaptic cell respond to the presence of cocaine?
- down regulation–> #of surface dopamine receptors are reduced.
- results in drug dependence –>synapse is less sensitive
What is serotonin?
- neurotransmitter in the CNS
- results in IPSP or EPSP
- regulates sleep, emotions, and appetite
- lack thereof cause depression
What is Prozac and how does it work?
- blocks the reabsorption of serotonin
- -> more serotonin is available for stimulation of the post synaptic cell
What is LSD and how does it work?
- a psychoactive drug that acts on excitatory serotonin receptors
What is ecstasy and how does it work?
A drug that releases massive amounts of serotonin
What is methamphetamine and how does it work?
Increase levels of dopamine and serotonin in the brain by reversing the direction of transporter action
What is substance p?
- 11 amino acids long peptide neurotransmitter
- released at the synapse by CNS
- result in EPSP: transmitting sensation of pain to brain
What are endogenous opiates?
- inhibitory número peptides that modulate the intensity of pain
- ekalphalins and endorphins
What is the function enkephalins?
- released by axons descending from the Brain into the spinal cord inhibit the passage of pain info to the brain
What are endorphins?
An endogenous opiate released by neurons in the brain stem to block the perception of pain.
What neurotransmitter stimulates the production of NO?
Ach
What is signal transduction?
The relay of an extracellular signal to its final targets through intercellular signaling molecules.
What is cortisol?
- a lipid soluble steroid hormone derived from cholesterol
- targets many organs
- produced by the adrenal cortex
What are the functions of cortisol?
- adaptions to long term stress
- raises blood glucose levels, blood pressure mobilizes fat
What activates target enzymes by exchanging GDP for GTP? And what inactivated it?
- GEF
- GTPase
What is the g-protein?
- trimeric GTP-binding protein
- activated by GTP
- consists of subunits:alpha,beta, gamma
Give an example of a target protein that is an enzyme? Which g-protein subunit activates it?
- epinephrine
- alpha subunit
What g-protein subunit activates Ach activity? And what kind of target enzyme is the receptor?
- Betagamma complex
- K+ channel in the plasma membrane if the heart muscles
What enzyme converts ATP to cAMP?
Adenyl Cyclase
What is PKA and what does if promote? what activates it?
- inactive as tetramer
- regulates glycogen metabolism
- cAMP activates it
What is epinephrine?
- hormone derived from tyrosine in the adrenal medulla
- stimulates break down of glycogen a in anticipation of muscular activity
- inhibits production of glycogen
- nuero transmitter in then SNS
What is cortisol?
A lipid soluble steroid hormone.
- produce by the adrenal cortex
- targets many organs
- adaption to long term stress–> raises blood glucose levels, blood pressure, mobilizes fat
What kind of receptor is the cortisol receptor?
-transcription factor
How does a G protein become activated?
-GEF exchanges GTP for GDP on the alpha subunit.
What does the alps subunit regulate?
The activity of membrane bound target proteins.
How does an epinephrine receptor become activated? What kind of receptor is it?
By an alpha protein
- membrane bound enzyme
How does an Ach receptor become activated? What kind of receptor?
- beta gamma complex
- K+ channel in the plasma membrane of a head cell
What enzyme converts ATP to cAMP?
Adenylate Cyclase
What does PKA promote?
Glycogen metabolism
How is PKA activated?
By cAMP
The catalytic subunits from PKA do what?
Phosphorylated effector proteins
Describe the break down of glucose:
-signal–> G protein activation –> adenylcyclase activation–> cAMP production–> PKA activation–> phosphorylase kinase activation–> glycogen phosphorylase–> conversion of glucose to glucose-1-p
What enzyme isomerizes glucose 1 p to glucose 6 p?
Phosphoglucomutase
Describe what happens adrenaline activates a G protein?
–> activated adenyl Cyclase–> cAMP production–> PKA activation–> entrance into nucleolus–> activated transcription regulator–> RNA production
Describe the calmodulin activation pathway:
Activate alpha protein–> activated phospholipase C (PLC)–> hydrolysis of PIP2 to DAG and IP3 –> IP3 opens Ca channels in ER–> Ca binds to calmodulin–> CaM kinase activation
What are Wnt proteins important for?
- embryonic development or cell proliferation
In the WNT signaling pathway, if there is no signal, what occurs?
- degradation complex forms on the cytoplasm
- APC containing complex targets beta-catenin for degredation
What happens when the WNT signal is present?
WNT binds frizzled (g-protein) and disheveled is activated
Disheveled inactivates the APC complex
Beta cannon enters the nucleus and activates a transcription factor
