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Molecular Cell Biology > Test 3 > Flashcards

Test 3 Flashcards

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0
Q

Where does carbon fixation ocurr?

A

Stroma

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1
Q

Where does the photosynthetic e transfer reaction occur?

A

Thylakoids membrane

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2
Q

chlorophyll absorbs photons from what portions of the visible light range?

A

Violet-blue

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3
Q

In the light reaction, movement of electrons through the electron transport chain transfers energy to what molecules?

A

ATP and NADPH

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4
Q

In the dark reaction, ATP and NADPH are used to drive the synthesis of sugars from CO2, this process is known as what?

A

Carbon fixation.

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5
Q

What do photo centers contain and where are they located?

A

Thylakoid membrane, chlorophyll.

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6
Q

Describe lesch-Nathan syndrome

A

X-link disorder

Due to absence of HPRT, which cause the formation of Uric acid.

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7
Q

How can amino acids be synthesized?

A

From intermediates of respiration.

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8
Q

Essential amino acids

A

Histidine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine

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9
Q

What are essential amino acids?

A

Amino acids that must be consumed from diets.

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10
Q

Non essential amino acids are?

A

Can be synthesized by humans.

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11
Q

What enzyme

Converts phenylalanine to tyrosine?

A

Phenyl alanine hydroxylase

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12
Q

When there are deficient amounts of phenylalanine hudroxylase, what happens?

A

Phenylalanine is converted to phenyl pyruvate (phenyl ketone).

Phenylketonuria (PKU)-development of intellectual disabilities.

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13
Q

Define peri nuclear space

A

The cavity between two membranes

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14
Q

The outer membrane if the nucleus is continuous with what organelle?

A

Endoplasmic reticulum

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15
Q

Lamina provide what?

A
  • structural support for the nucleus

- attachment sites for chromatin –> may have a role in gene regulation.

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16
Q

Describe the function of nuclear pores:

A

-protein complexes that facilitate the transport of molecules through the nuclear envelope

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17
Q

What is the SV40 T-antigen?

A

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

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18
Q

Protein complex

A

Nuclear protein ( cargo) and importin

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19
Q

What drives the nuclear import cycle?

A

Ran-GTP diffusion into the cytoplasm

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20
Q

If translation occurs in the free ribosome, where can the proteins be destined?

A
  • nucleus
  • chloroplast
  • mitochondria
  • free ribosome
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21
Q

If translation occurs in the ribosomes of the rough ER, where are proteins destined?

A

-transmembrane, lysosomal, or secreted product.

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22
Q

The smooth ER is the site of what?

A

Lipid synthesis and processing. Constructs membranes and membrane systems for the cell. P

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23
Q

What’s does the Golgi complex do?

A

Protein sorting

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24
Q

Requirements for cell to cell communication:

A
  • a signal
  • receptor
  • signaling proteins
  • modification of target proteins
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25
Q

What enzyme uses electrons from photo system 1 to synthesize NADPH?

A

Ferredoxin-NADP reductase

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26
Q

What happens in photosystem 1?

A

Photons are absorbed to generate high energy e-. e- are used to synthesize NADPH.

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27
Q

What happens in photosystem 2?

A

Photons are absorbed to generate high energy e-, which are transferred to Cyt b-f complex and then to photosystem 1. H2O is split.

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28
Q

How much CO2, ATP and NADPH are used in the Calvin cycle? What is produced?

A
  • 3 CO2
  • 9 ATP
  • 6 NADPH
  • 6 molecules of glyceraldehyde 3-phosphate are produce. Only one is store as starch.
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29
Q

What does the CO2 in the Calvin cycle react with and what catalyzes it?

A

Ribulose 1,5 bisphosphate and RuBP carboxylase

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30
Q

What is the most abundant enzyme on earth?

A

Ribisco

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31
Q

Describe dehydration synthesis?

A

Condensation reaction that consumes energy and yields water.

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32
Q

What is required in the formation of macromolecules?

A

Activated intermediates with a high energy bond that is broken in the final
Condensation step.

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33
Q

What two ways are nucleotides synthesized from nucleosides?

A
  • de novo

- salvage

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34
Q

What is salvage? And example?

A
  • recycling of nitrogenous bases
  • single steps
  • synthesis of purine nucleoside mono phosphates
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35
Q

What mutation of HPRT causes LNS ( lesch-nyjan syndrome)?

A

Xanthine oxidase

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36
Q

What does HPRT stand for? What pathway is it in? And what reaction does it catalyze?

A
  • Hypoxanthine phosphoribosyltransferase in the purine salvage pathway
  • Hypoxanthine to inosinate
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37
Q

Poly saccharides in animals? In plants?

A
  • starch in plants

- glycogen in animals

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38
Q

What is the activated intermediate in the synthesis of polysaccharides?

A

UDP- glucose

-Glucose 1-P condenses with UTP

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39
Q

Bond that form proteins, nucleic acids, and polysaccharides?

A
  • peptide bonds
  • phosphodiester bonds
  • glycosidic bonds p
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40
Q

What is the activate intermediate during the synthesis of peptide bonds?

A

Aminoacyl-TRNAs at the p site.

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41
Q

Describe nitrogen fixation:

A
  • ATP is consumed
  • atmospheric N2 is reduced to NH3
  • nitrogen fixing bacteria
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42
Q

Describe Nitrate incorporation:

A
  • NADH or NAPH consumed
  • NO3- from soil is reduced to NH3
  • bacteria, fungi, and plants
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43
Q

Describe the dimensions of a nuclear pore complex:

A
  • 50 to 100 polypeptides long
  • diameter of complex: 120nm
  • diameter of opening:25nm
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44
Q

What are the steps of protein import through the nuclear pore?

A

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

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45
Q

Where is RAN-GTP more abundant?

A

Inside the nucleus.

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46
Q

What catalyzes the hydrolysis of Ran-GTP? Where?

A

Ran-GTPase-activating protein ( RAN GAP)

-cytoplasm

47
Q

What catalyzes Ran-GDP to Ran-GTP? Where does this occur?

A
  • Ran Guanine nucleotide exchange factor ( RanGEF)

- nucleus

48
Q

What is NF-Kappa B?

A

A transcription factor that exists dormant in the cytoplasm in a complex with I Kappa B.

49
Q

What’s happens to NF-Kappa B when IKP is phosphorylated?

A
  • nuclear import binds to it and is transported to the nucleus
  • required for an immune response
50
Q

What is Pho4?

A

-A transcription factor that in the cytoplasm that is phosphorylated and therefore inactive.

  • when dephosphorylated nuclear transporter binds
  • activates genes that regulate cell cycle
51
Q

What is required for a protein to be transported to the ER?

A

A signal sequence at the N-terminus consisting of 8 or more Hydrophobic AAs

52
Q

Rough ER is the site of:

A

Protein synthesis or processing

-disulfide Bond formation, addition of cofactors, oligosaccharides to lipids and proteins

53
Q

What does the Golgi complex do? And how to proteins enter and leave?

A
  • protein sorting and packaging

- Protein vesicles from ER enter the Golgi at the Cis side and leave from the trans side

54
Q

What is the ER-Golgi intermediate complex (ERGIC)? And where is it located?

A
  • 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
55
Q

What is the retention signal of ER protein residents?

A

KDEL (Lys-asp-leu)

56
Q

What are 3 types of transportation from the Golgi?

A

1) constitutive
2) regulated secretion
3) Transport of lysosomal proteins

57
Q

What is constitutive secretion?

A
  • operates in all cells continuously
  • unregulated secretion
  • includes secreted proteins, membrane proteins lipids, extra cellular matrix proteins
58
Q

Examples of regulated secretion:

A
  • endocrine cells
  • pancreatic cells
  • neurons
59
Q

Describe transport of lysosomal proteins:

A
  • hydrolytic enzymes are transported in Clathrin- coated vesicles from the Golgi or plasma membrane
60
Q

What does Acetycholine (ach) released from motor nuerons cause?

A

Skeletal muscle contraction

61
Q

Ach released by parasympathetic nuerons of the ANS causes what?

A
  • a reduced frequency of cardiac muscle contraction and an increase in salivary secretions
62
Q

What kind of receptor receives Ach in the skeletal muscle cells?

A

Ligand gated ion channel

63
Q

What receptor receives Ach in the heart muscle cells and salivary glands?

A

G-protein coupled receptor

64
Q

What are the requirements of a cell for cell to cell communication?

A
  1. Signal
  2. Receptor
  3. Intercellular signaling proteins
  4. Modification of target protons
65
Q

What proteins can be targeted in cell-cell communication?

A
  • metabolic enzyme
  • gene regulatory protein
  • cytoskeletal protein
66
Q

What are the modes or signaling in cell to cell communication?

A
  1. Endocrine
  2. Direct cell to cell contact
  3. Paracrine
  4. Autocrine
  5. Synaptic
67
Q

In axons, what molecule causes synaptic vesicles to fuse with the axon membrane?

A

Ca 2+ ions

68
Q

Describe what happens during excitatory post-synaptic potential?

A
  • excitatory neurotransmitters cause the depolarization the post synaptic membrane
  • Na+ channels are opened.
69
Q

Describe inhibitory post-synaptic potential (IPSP)

A

Inhibitory neurotransmitters cause the hyper polarization of the post synaptic membrane.

  • Cl- channels are opened.
70
Q

What are several ways neurotransmitters can be regulated?

A

1) enzymatic degradation
2) re-uptake by the ore synaptic membrane
3) modulation of post-synaptic receptors
4) balance inhibitory or excitatory neurotransmitters

71
Q

Does Ach in the neuromuscular in junction cause EPSP or IPSP?

A

EPSP

Peripheral nervous system

72
Q

What inhibits the activity of acetylcholinesterase? What happens?

A
  • nerve gass
  • severe paralysis
  • death by paralysis of respiratory muscles
  • muscles can’t relax
73
Q

What is glutamate?

A
  • an excitatory amino acid on the CNS
  • glutamate receptors are Na+ and Ca2+ channels.
  • excessive stimulation results on nurodegeneration
74
Q

What is Gamma-aminobutyric acid (GABA)?

A
  • inhibitory neurotransmitter on the CNS
  • receptors are gates Cl- channels
  • important for control of body movements and other brain functions
75
Q

What does Valium do?

A
  • Valium is a sedative drug that enhances the binding of GABA to it’s receptor
76
Q

What is dopamine?

A
  • excitatory neurotransmitter in the CNS

- controls body movements and pleasure sensations

77
Q

What is Parkinson’s disease?

A

The degeneration of dopamine releasing neurons. Tremors

78
Q

What does the consumption of cocaine cause?

A
  • Heightening of pleasure sensations
  • cocain resembles dopamine and prevents the removal of dopamine from the synapse which leaves the limbic system continually stimulated
79
Q

How does the post-synaptic cell respond to the presence of cocaine?

A
  • down regulation–> #of surface dopamine receptors are reduced.
  • results in drug dependence –>synapse is less sensitive
80
Q

What is serotonin?

A
  • neurotransmitter in the CNS
  • results in IPSP or EPSP
  • regulates sleep, emotions, and appetite
  • lack thereof cause depression
81
Q

What is Prozac and how does it work?

A
  • blocks the reabsorption of serotonin

- -> more serotonin is available for stimulation of the post synaptic cell

82
Q

What is LSD and how does it work?

A
  • a psychoactive drug that acts on excitatory serotonin receptors
83
Q

What is ecstasy and how does it work?

A

A drug that releases massive amounts of serotonin

84
Q

What is methamphetamine and how does it work?

A

Increase levels of dopamine and serotonin in the brain by reversing the direction of transporter action

85
Q

What is substance p?

A
  • 11 amino acids long peptide neurotransmitter
  • released at the synapse by CNS
  • result in EPSP: transmitting sensation of pain to brain
86
Q

What are endogenous opiates?

A
  • inhibitory número peptides that modulate the intensity of pain
  • ekalphalins and endorphins
87
Q

What is the function enkephalins?

A
  • released by axons descending from the Brain into the spinal cord inhibit the passage of pain info to the brain
88
Q

What are endorphins?

A

An endogenous opiate released by neurons in the brain stem to block the perception of pain.

89
Q

What neurotransmitter stimulates the production of NO?

A

Ach

90
Q

What is signal transduction?

A

The relay of an extracellular signal to its final targets through intercellular signaling molecules.

91
Q

What is cortisol?

A
  • a lipid soluble steroid hormone derived from cholesterol
  • targets many organs
  • produced by the adrenal cortex
92
Q

What are the functions of cortisol?

A
  • adaptions to long term stress

- raises blood glucose levels, blood pressure mobilizes fat

93
Q

What activates target enzymes by exchanging GDP for GTP? And what inactivated it?

A
  • GEF

- GTPase

94
Q

What is the g-protein?

A
  • trimeric GTP-binding protein
  • activated by GTP
  • consists of subunits:alpha,beta, gamma
95
Q

Give an example of a target protein that is an enzyme? Which g-protein subunit activates it?

A
  • epinephrine

- alpha subunit

96
Q

What g-protein subunit activates Ach activity? And what kind of target enzyme is the receptor?

A
  • Betagamma complex

- K+ channel in the plasma membrane if the heart muscles

97
Q

What enzyme converts ATP to cAMP?

A

Adenyl Cyclase

98
Q

What is PKA and what does if promote? what activates it?

A
  • inactive as tetramer
  • regulates glycogen metabolism
  • cAMP activates it
99
Q

What is epinephrine?

A
  • 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
100
Q

What is cortisol?

A

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
101
Q

What kind of receptor is the cortisol receptor?

A

-transcription factor

102
Q

How does a G protein become activated?

A

-GEF exchanges GTP for GDP on the alpha subunit.

103
Q

What does the alps subunit regulate?

A

The activity of membrane bound target proteins.

104
Q

How does an epinephrine receptor become activated? What kind of receptor is it?

A

By an alpha protein

- membrane bound enzyme

105
Q

How does an Ach receptor become activated? What kind of receptor?

A
  • beta gamma complex

- K+ channel in the plasma membrane of a head cell

106
Q

What enzyme converts ATP to cAMP?

A

Adenylate Cyclase

107
Q

What does PKA promote?

A

Glycogen metabolism

108
Q

How is PKA activated?

A

By cAMP

109
Q

The catalytic subunits from PKA do what?

A

Phosphorylated effector proteins

110
Q

Describe the break down of glucose:

A

-signal–> G protein activation –> adenylcyclase activation–> cAMP production–> PKA activation–> phosphorylase kinase activation–> glycogen phosphorylase–> conversion of glucose to glucose-1-p

111
Q

What enzyme isomerizes glucose 1 p to glucose 6 p?

A

Phosphoglucomutase

112
Q

Describe what happens adrenaline activates a G protein?

A

–> activated adenyl Cyclase–> cAMP production–> PKA activation–> entrance into nucleolus–> activated transcription regulator–> RNA production

113
Q

Describe the calmodulin activation pathway:

A

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

114
Q

What are Wnt proteins important for?

A
  • embryonic development or cell proliferation
115
Q

In the WNT signaling pathway, if there is no signal, what occurs?

A
  • degradation complex forms on the cytoplasm

- APC containing complex targets beta-catenin for degredation

116
Q

What happens when the WNT signal is present?

A

WNT binds frizzled (g-protein) and disheveled is activated

Disheveled inactivates the APC complex

Beta cannon enters the nucleus and activates a transcription factor

Molecular Cell Biology (2 decks)

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