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TEST 1 Flashcards

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1
Q

Function of Flippase

A

Created by Golgi

flips phospholipids from exterior to interior of cell

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2
Q

Function of scramblase

A

keeps layers even by randomly switching lipids across layers

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3
Q

New phospholipids are made by what?

A

Enzymes on Endoplasmic reticulum, which are then dissipated in cytosol

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4
Q

Cholesterol functions as what in the bilayer

A

fills in space-stiffens plasma membrane

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5
Q

How do bacterial bilayers react to high and low temperatures?

A

Heat- add saturated long tails

Cold-add unsaturated short tails

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6
Q

Conditions of a liquid bilayer?

A

Unsaturated Short tails

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7
Q

Conditions of a solid bilayer?

A

Saturated long tails

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8
Q

How can lipids move in the bilayer?

A

Laterally-side to side
Rotationally
Flip flop across layers
Flexion

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9
Q

What lipid(s) are entirely hydrophobic?

A

Triacytglycerol

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10
Q

What lipids/horomones are amphiphatic?

A

phospholipids glycolipids cholesterol

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11
Q

Why do tryglycerols form into drops in water?

A

To limit its interactions with water

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12
Q

How do master transcription regulators direct formation of whole organs?

A

These regulators bind to multiple genes by binding to their DNA sequence which controls expression of other genes. So it activates genes, that activate other genes which signals to other cells to do the same, therefore creating organs.

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13
Q

How can transcription regulators be used to reprogram differentiated cells into stem cells/other types of cells?

A

By introducing certain regulators one can change the cells differentiation

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14
Q

Positive feedback & Cell memory

A

A cell receives a signal to create a regulator from that point on that regulator will activate transcription for production of more regulators like itself to reproduce identical cells, continued expression of the same genes to make the same regulator.

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15
Q

Cell memory

A

Patterns of gene expression responsible for that identity to be maintained when proliferating to daughter cells.

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16
Q

Epigenetic inheritance

A

Cell memory mechanisms that DONT change DNA sequence but maintain pattern of gene expression allowing cells to remember signals from environment

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17
Q

Post transcriptional Controls

A

Regulation after transcription to fine tune expression of genes
ex-alternative splicing untranslated regions of RNA regulatory RNA protein degredation

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18
Q

UTR’s untranslated regions control what of RNA?

A

Lifespan of RNA

How often RNA is translated

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19
Q

Regulatory RNA & examples

A

miRNA
Longnoncoding
SiRNA
All regulates gene expression

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20
Q

RNAi

A

Cells immune system
eliminates foreign mRNA from virus
Foreign mRNA is cut up by dicer which creates siRNA
siRNA joins with a RISC protein
complex then searches for complementary pair to destroy

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21
Q

siRNA

A

Created when foreign mRNA is cut up by dicer

needed for RNAi

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22
Q

Longnoncoding/lncRNA

A

Secondary X chromosome inactivator- binds to 2nd x chromosome signaling for enzymes to stop unpacking/transcription of chromosome

Can work as scaffolding to help repair damaged DNA after replication errors

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23
Q

How do transcription regulators recognize and bind to regulator DNA sequences in a DNA double helix?

A

Transcription regulators move up the DNA strands searching for regulatory sequences that serve as binding sites for gene regulatory proteins whose presence on DNA affects the rate of transcription

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24
Q

Regulatory DNA sequences

A

Sequences that switch on and off genes usually in bacteria

Very long in eukaryotes

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25
Transcription regulators
Binds to specific sequences on DNA- the regulatory DNA sequence
26
Thickness of plasma membrane
5nanometers or 50 atoms
27
How do eukaryotic repressor proteins decrease transcription?
Repressors bind and inactivate sections of DNA/genes which decreases transciption
28
Livers responce to cortisol
Create more glucose- creates tyrosine aminotransferase to convert tyrosine to glucose
29
Transcriptional Control
Step 1- How often gene is transcribed
30
mRNA transport
Step 3-choosing which mRNA is exported to cytosol from nucleas
31
mRNA degredation
Step 4- selecting how fast mRNA is degraded
32
Lac operon
Controlled by an activator and repressor | when lactose is in high supply and glucose is low the lac operon is activated which converts lactose to glucose
33
Fat cells response to cortisol
Tyrosine aminotransferase production is stopped
34
Transcriptional Regulators
Specific to 1 or groups of genes | can turn on genes from hundreds of base pairs away these make up combinatorial control
35
Combinatorial control definition | In bacteria and eukaryia
process of many transcription regulators working together to create 1 gene Bacteria-operon controlled by 1 promoter Eukaryia- Cell receives signal turns on several genes individually
36
Reporter gene
encodes/creates a protein-that proteins activity is easy to monitor
37
How are reporter genes used to studied regulatory DNA sequences?
One cuts out an area of DNA that has regulatory DNA sequence desired to study place them above reporter gene in DNA sequence if DNA sequence is regulatory DNA sequence reporter gene's expression will be driven when this is introduced to a cell the reporter gene will be expressed where the gene the regulatory DNA sequenced promotes is usually displayed
38
How does a regulatory sequence produce a striped in a fly embryo at a given location?
A DNA regulatory sequence is controlled by 2 repressors and 2 activators where the stripe is located the 2 activators are present and the 2 repressors are not present on the sides of the stripe the 2 repressors are present and the activators are not
39
In a fly what occurs when stripe 2 isn't present
Likely doesn't have 2 activators
40
In a fly what occurs when stripe 2 is extremely large/broad
likely 2 repressors aren't present
41
In a fly what occurs when Stripe 2 is narrow?
1 activator isnt present | THIS AFFECTS other repressors and activors
42
Ina fly what occurs when stripe 2 is fainter?
1 activator isn't present | this DOESNT affect other activators and repressors
43
What are 2 ways a limited number of regulators can direct differentiation?
Accumulation of many proteins over generations Regulator turning on and off groups of genes creating different cells such as cortisol
44
DNA methylation and Cell memory
Occurs on cytosine bases modification to cytosine blocks gene transcription by attracting proteins that block RNA polymerase this is passed onto daughter cells this stops a gene from expressing
45
Histone Modification
When DNA is replicated the daughter DNA contains half the parents cells histones which contains the parent histone modification enzymes bind to these past modifications then giving them to the new histones reestablishing parental structure of chromatin in daughter cells
46
miRNA
Regulates expression by base pairing with certain RNA by reducing stability/translation joins with RISC to bind to complementary mRNA to destroy/block translation with an extensive match this mRNA is completely and immediately destroyed with an limited match this mRNA is has reduced translation
47
noncoding RNA examples
tRNA-Structural/catalytic roles in protein synthesis rRNA-^ RNA of telomerase- needed for duplication of eukaryotic chromosomes
48
Bacteria do what with UTR's
Can use UTR's to only transcribe regions at certain temperatures
49
How do bacterial promoters interact with transcriptional activators and repressors in different ways in terms of how efficiently they bind and position RNA polymerase?
promotors can bind with activators and repressors RNA polymerase can bind to DNA without activator but poorly RNA polymerase doesn't like to transcribe areas with repressors
50
How are enhancers prevented from enhancing the wrong genes?
enhancers increase the rate of transcription to prevent the wrong gene being enhanced the chromosome loop forming clamp proteins section off DNA into loops so that only the correct gene gets enhanced
51
How do activators exploit chromatin packing to enhance transcription?
Activators on DNA found wound around histones try to get the DNA transcribe this can happen 2 ways Histone Acetyltransferase-this protein is attracted by the activator to enhance transcription this is done by leaving markers of acetyl groups on other histones to signal to other protein to transcribe that area Chromatin remodeling complex protein-This protein in is attracted by the activator to enhance transcription this is done by unwinding the DNA from histones
52
How do repressors exploit chromatin packing to repress transcription?
repressors on DNA wound in histone try to decrease transcription by Histone deacetylases- these remove acetyl groups from histones to decrease transcription
53
General transcription factors
every gene has these promoter TATA box to be transcribed
54
EX of housekeeping proteins
Ribosomal proteins enzymes for glycolysis RNA/DNA polymerase proteins in cytoskeleton
55
Tryglycerols do what in water
Form into fat droplets to limit its interactions with water
56
What lipids have hydrophobic tails and hydrophilic heads?
Phospholipids, glycolipids, cholesterol
57
Triacylglycerol is what to water
Hydrophobic
58
How can lipids move in a membrane
Laterally, rotationally flipflop and flexionally
59
How can a bilayer be liquid?
Unsaturated short tails
60
How can a biliayer be solid?
Saturated long tails
61
Cholesterol does what in a membrane?
Fills in spaces, stiffens bilayer,
62
Fluidiity of membrane allows what?
easier membrane fusion, distribution of molecules during proliferation, diffusion
63
As temperatures get lower the membrane does what?
Gains unsaturated short tails
64
As temperatures get higher the membrane does what?
Gains more saturated long tails
65
How do membranes keep orientation with fusing membranes?
1 layer only ever faces the cytosol
66
50% of the membrane is what
protiens
67
How many more phospholipids are in the membrane than proteins?
50x
68
Fucntions of membrane proteins
ion transports ion channels anchors structural support receptors enzymes
69
integral membrane portein
directly attached to membrane
70
peripheral membrane protein
atatached to membrane via 3rd party molecule can be taken off easily
71
how can transmembrane porteins cross the membrane with hydrophilic portions?
Alpha helixs form to bond to hydrophilic part of the helix to another hydrophilic part this allows the hydrophilic part of the helix to be inside and the hydrophobic part to be facing the membrane.
72
Single pass proteins
receptors and channels
73
multipass proteins
can be amphipathic to allow for small water soluble ions to pass
74
Beta sheet barrel
looks like a woven basket across membrane
75
Detergents are used for what
Extracting and studying membrane proteins These have 1 hydrophobic tail and 1 hydrophillic head These aggregate in micelles
76
What do detergents do to proteins and membrane
Separates phospholipids in groups woth the end of the groups covered in detergents Separates the protein surrounded by proteins
77
Bacterial rohodopsin
Hydrogen pump 7 alpha helixes Purple Retinal absorbes light
78
Plant/bacterial cells membrane is stabilized how
By a cell wall found on outside of membrane
79
Animal cells cell stabilization
Mechanically stabilizaed by cell cortex found on underside of membrane
80
RBC CORTEX is composed of what
Spectrin | Long thin flexible protein covering membrwne by attaching to proteins
81
What proteins stabilize all other animal cell types
Myosin and actin
82
The human/mouse hybrid experiment proved what
That proteins diffuse across membranes
83
Glycocalyx
Many proteins attached to carbs are on surface of membrane This is slimy Protects cell from damagw Cell to recognition
84
How is mobility if proteins on cells restricted
1 proteins connected to cell cortex beneath cell membrane 2 tethered to extracellular mateix 3 proteins on surface of another cell 4 diffusion barriers which restrict proteins to area of memebrwne
85
SPT microscopy
Tags proteins with gold nanoparticles The gold is easy to tract Tracks one protein
86
FRAP
Area of membrane is tagged with a fluorescent protein then a smaller area in there is bleached, then the amount of time it takes to diffuse shows how thin thr membrabe is

BIO 3090 (5 decks)

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