Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cell Biology > Exam V > Flashcards

Exam V Flashcards

1
Q

ACh: Muscarinic vs. Nicotinic Receptors

A

Shows the versatility of signaling molecules
Muscarinic: decreases heart rate and force of contraction as well as increases saliva production
Nicotinic: contraction of skeletal muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Example of Autocrine Signaling

A

T cells that produce and react to its own secretions of IL-2; no IL-2 means that the T cell will undergo apoptosis since there is a lack of signal; signal = proliferation of T cells due to infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Paracrine Signaling- specific example

A

Synaptic signaling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Glucocorticoid Receptor (GR)

A

The receptors in the cell within the nucleus
Glucocorticoid receptor and is usually found within the cytoplasm and the hormone cortisol enters the cell via diffusion because it is hydrophobic and it will find the receptor that is inactive by binding three molecules bound to the receptor (2 are heat shock proteins and the other is immuophilin) and together they produce an inactive receptor
When cortisol comes along these three proteins separate so the receptor can be activated and it will enter the nucleus and bind to DNA and activate the genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Estrogen Receptor

A

The estrogen receptor, in this case it is found in the nucleus and the estrogen enters the cell and finds the receptor in the inactive form because Hsp90 is bound, but when estrogen binds to the receptor the Hsp goes away; two estrogens is bound to the receptor creating a dimer and the function only occurs in the form of the dimer; the dimer binds to HAT = coactivator; the molecule is now activated so it can now bind the DNA and active the transcription in the downstream direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Thyroid Hormone Receptor (THR)

A

THR is always bound to proteins and it remain bound to proteins in absence or presence of the thyroid hormone
In response to a ligand, there will be 2 THR and they are bound to the molecule that acts as a corepressor, HDAC, because they are already bound to the DNA so acting as a repressor
Once the thyroid ligand binds the repressor and HDAC will be removed and then replaced with HAT as an activator and binds to the DNA and transcription proceeds and produces the molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Pleiotropic Growth Factors

A

Different effects on same target cell type
Same effect on many different cell types
Inhibition or growth may be dependent on the cell environment- availability or lack of nutrients as example

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

GH Positive Feedback

A

Positive feedback: tells the hypothalamus to release more GHRH to increase GH
If fuels (food and nutrients) are scarce, then GH is not necessary; GH and insulin like growth factor, they both will send negative signals (feedback) that signal to the hypothalamus and inhibits the release of GHRH and therefore inhibit GH release from the pituitary
If you have plenty of food, the signals are positive so you can grow, and vice versa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Fibroblast Growth Factor

A

fibroblasts make bone, collagen, etc. their regulation is important
4 types of receptors for the fibroblastic growth factor; these are connected with Tyr kinase receptor
Tyr kinase is important for phosphorylation to activate cascades inside the cells
This receptor interacts with heparin sulfate found in the extracellular matrix, and the way it binds the FGF/FGFR/HS in 2:2:2 creating dimers
Induction of transphosphorylation via Tyr kinase which leads to activation to effect the nucleus by activating transcription to produce products that change the cell behavior

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

3 Ways of Signal Transduction

A
  1. Directed towards cytoskeletal organization – important for cell during growth because the cytoskeleton is responsible for movement
  2. Anti-apoptosis – increase the survival signals
  3. Activation of kinase AMPK that ultimately works at gene level where it creates these TF that will activate transcription or stops the genes from being transcribed (most important part of signaling)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Basophils (circulation) & Mast Cells (resident)

A

Granules contain mediators:
Heparin
Histamine
SRS-A (slow-reacting substance of anaphylaxis)
ECF-A (eosinophil chemotactic factor A)
they produce eosinophil chemotactic factor (ECF), which causes eosinophils to enter area of parasite or allergen

when Ab (IgE) is bound to the something ex. Muscle and on the membrane there is a molecule that is called the FC receptor that binds the Ab FC part of it (stem of the “Y”) and once it is bound the cells will be coated with Ab; the cells involved in allergy (type I hypersensity or immediate hypersensitivy) against bee sting for example; sometimes so severe that one bee sting will cause liver death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Mediators of Type I hypersensitivity

A

Preformed: Histamine, Heparin, Eosinophil chemotactic factor of anaphylaxis (ECF-A), Neutrophil chemotactic factor, Serotonin

Newly Synthesized: Prostaglandins, Thromboxanes, Leukotrienes (Slow reacting substance of anaphylaxis (SRS-A))

For vasodilation: histamine binds to H1
For extravasation: histamine binds to H4 to cause eosinophils to go through the blood vessel and fight infections/allergies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Mast Cell Degranulation and Histamine Signaling

A

Histamine release
Histamine binds endothelial and smooth muscles H1 receptors  Induction of vasodilation
Higher histamine conc.  acting on eosinophil H4 receptors  induction of migration/ extravasation into affected area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

NO mediated vascular relaxation

A

Some intercellular signaling molecules (ACh, histamine, ATP, etc) that bind to specific receptors on the endothelial cells leading to activation of enzymes that changes that brings down Arg AA to citrulline so NO can be released which will diffuse through the cell and go to the neighboring cells (paracrine signaling) smooth muscle of blood vessel and bind to Hb to activate the gunaylyl cylase to make cGMP from GTP; cGMP will diffuse and activate other kinases leading to relaxation of vascular muscle cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

ErbB2,3, & 4 Receptors

A

Structure is intracellular, extracellular, and intracellular
2 Cys rich (lots of disulfide bridges) domains, transmembrane protein (hydrophobic) and the Tyr kinase within the cell = three domains of each molecules
ErbB2, 3, and 4 work in dimers; when two different ones are together = heterodimers, but if same = homodimer = basic structures
These have connection with molecules inside the cells and communicate with NRG, a neural regulator, and they can be connected to the EGF and to other molecules
For example: heterodimers are involved in neural crest or heart development, so Erb2 and 3 are found in neural crest and involved in developed where Erb2 and 4 are associated with heart function development

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Neuregulin -1

A

present: trabeculation and normal heart develop; absent is vice versa
Two layers: endocardium and myocardium and are connected / communicate with each other via NRG1 signal coming from the endocardium to the receptor heterodimers ErbB2 and 4 in the myocardium so the communication to the myocardium is transmitted and the result is the trabeculation occurs, but if the signal is defected (knocked out for example) then trabeculation of the ventricles of the heart will not be normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

TGF-Beta

A

signaling molecules involved in development and differentiation
serine-threonine kinase receptors, so phosphorylation occurs on Thr and Ser AA
There are two types of receptors: TGF beta R1 and R2; these two receptors, none of them can bind TGF beta by itself (all or none binding) both must cooperate to transduce the signal via a complex
Examples of TBF beta: BMP, Nodal and Lefty, heart valve development, NOTCH signaling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

BMP Signal Transduction Pathway

A

BMP has a receptor that have two components: dimer of I and II; and from that there will be TGF beta activated kinase (it will phosphorylate) and act on TAK which activates MKK (mitogen kinase kinase) to phosphorylate other kinases, and these will phosphorylate the molecules like JNK (controls cell cycle) and MAPK/p38
Another pathway that goes above a molecule, Smads, that get phosphorylated and they can go into the nucleus and participate in activation of genes there

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Development of left and right; nodal protein and lefty

A

Nodal will bind the receptor and will send a signal through Smads and this will activate the transcription in the nucleus; for example, when nodal cannot bind the receptor and the lefty does (in competition with each other) and no signal is tranduced; aka lefty will stop the signaling through this receptor complex, but nodal will transmit the signal
Nodal is on the left and will have the effects on lefty and on itself and pushes lefty1 to middle between the left and right to prevent things from moving to the side they aren’t supposed to be on
TGF beta like molecule = nodal and lefty; nodal and lefty 2 are in competition, so when nodal is on left side, lefty2 cannot do anything on that side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Physiologic and Pathological Cardiac Hypertrophy

A

Physiologic – when child is born, the heart must grow in size in response to positive signals (with nutrients and exercise/movement)
Pathologic response – occurs in response to signals like stress, high BP, etc. so that the muscle must work much harder to push the blood leading to hypertrophy and can happen after MI
Difference between growth: response to positive/healthy signals = adaptive; and the other is sluggish and like getting fat or something like that = maladaptive
Situations are interchangeable; for example, you can exercise with healthy lifestyle to change from pathologic to physiological response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

4 Phases of the Cell Cycle

A

G1 or GAP 1 (only growth)
S stage- DNA replication occurs
G2 or GAP 2 (prep for M)
M or mitosis- nuclear (chromosomes separate) and cytoplasmic (cytokinesis) division
G0: no cell division or growth; Response to a lack of growth factors or nutrients; Parenchymal cells of the liver and kidney enter G0 almost permanently; alternative to apoptosis if cell is damaged; nerve cells that are highly differentiated spend most time in G0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Cyclins

A

work with CDKs to form holoenzymes (depend on each other)
allow the cell cycle to proceed via phosphorylation or dephosphorylation of proteins at the checkpoints; kinases can only phosphorylate; only phosphatases can dephosphorylate
regulated by p21, p27, etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

p27

A

binds to cyclin and CDK blocking entry into S phase
Breast cancer prognosis is determined by p27 levels
Reduced levels of p27 predict a poor outcome for breast cancer patients and vice versa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

G1 CDK/Cyclin Association

A

CyclinD-Cdk4 & CyclinD-Cdk6 and CyclinE-Cdk2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

S CDK/Cyclin Association

A

CyclinE-Cdk2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

G2 CDK/Cyclin Association

A

CyclinA-Cdk2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

M CDK/Cyclin Association

A

CyclinB-Cdk1 (called Cdc2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

p53

A

Regulates G1/S and G2/M checkpoints
Blocks cell cycle if DNA is damaged
Severe damage leads to apoptosis (programmed cell death)
p53 levels are increased in damaged cells, allowing time for DNA repair by blocking the cell cycle
p53 mutation is the most frequent mutation leading to cancer
Mutated p53 found in >50% of cancers
*employs Bcl-2 family to induce apoptosis at mitochondrial level (via Bax)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Li Fraumeni syndrome:

A

extreme case of p53 mutation; genetic defect in p53 leads to a high frequency of cancer in affected individuals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

pRb

A

The protein can be found in two states:
1. hypophosphorylated where the protein is not phosphorylated much
2. hyperphosphorylated – a lot of phosphorylation
Hypophosphorylation: pRb is bound to E2F and this will keep the E2F from acting as a TF; and cyclins will phosphorylate the Rb, becoming hyperphosphorylated and loses the E2F and can work as a TF; G2 will then occur because the necessary enzymes for it are now able to be synthesized; these kinases work in response to extracellular agents ex. Damage through carcinogenic substance, etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Cdc25C phosphatase

A

dephosphorylates CDK and allows progress from G2/  M

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

MPF (Maturation Promoting Factor)

A

Triggers progression through the cell cycle i.e. moves the cell from G1  S  G2  M; includes CDKs and cyclins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

c-Jun & c-Myc

A

referred to oncogenes, but originally are proto-oncogenes that control the cell cycle activate at G0 and G1, and they keep the cells that are in G0 within G0, but when mutated then they cannot keep them in G0 and the cells go into G1 and start the cycle
Some of the cancer that are proven to have involvement of c-Jun and c-Myc are the Tcell lymphomas and leukemias

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Prophase

A

Chromatin condensation
Chromosomes become visible in the light microscope
Nucleolus disappears
Centrioles move to opposite poles of the cell
Centrioles originate from the centrosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Prometaphase

A 
Nuclear membrane dissolves
Creation of kinetochores 
Proteins attachment to the chromosomal centromeres 
Microtubules attach at the kinetochores 
Chromosomes movement begin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Metaphase

A

Spindle fibers align the chromosomes along the middle of the cell nucleus- Metaphase plate
Ensure correct separation of chromosomes and equal distribution between the daughter nuclei
Each new nucleus will receive one copy of each chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Anaphase

A

Separation of paired chromosomes at the kinetochore
Move to opposite poles of the cell
Motion results from a combination of
Kinetochore movement along the spindle microtubules
Physical interaction of polar microtubules
MT push at the poles of the cell causing pulling of chromosomes and elongation of the cell itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Telophase

A

Chromosomes arrive at opposite poles of cell
Formation of new membranes around daughter nuclei
Chromosomes disperse into chromatin
Not visible under the light microscope anymore
Spindle fibers and associated MT degraded
Cytokinesis may begin - Partitioning of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

G Banding

A

During mitosis, the 23 pairs of human chromosomes condense and are visible with a light microscope.
A karyotype analysis usually involves blocking cells in mitosis and staining the condensed chromosomes with Giemsa dye.
Giemsa dye stains regions of chromosomes that are rich in the base pairs Adenine (A) and Thymine (T) producing a dark band.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Karyotypes:

  1. 46 XY or 46 XX
  2. 47, XX, +21
  3. 47, XY, +21/ 46, XY
  4. 47, XY, +24
  5. 46, XY, del (4) of p14
  6. 46, XX, dup(5p)
A

46 chromosomes with XY = normal male; 46 XX is a normal female
47 XX with +21 = trisomy 21 female/abnormal
47 XY with +21/ 46 XY = the male has a mix of normal and abnormal cells = mosaic; therefore they have less symptoms than regular trisomy 21 because the normal cells can compensate for abnormal ones
47, XY, +24 = there is no 24th chromosome!
46 XY, del (4) of p14= male has normal chromosome number, but has a deletion in chromosome 4 on short arm (p) band number 14
46 XX dup(5p) = normal number of chromosomes with a duplication of short arm on chromosome 5

41
Q

Robertsonian Translocation Karyotype

A

Chromosomes 13 has one half missing and the other one has something added to it
Chromosome 14 – part of this chromosome came to the chromosome 13
Written: 46, XX -13,-14
Normal phenotype
This is abnormal organization; sometimes leads to normal phenotype or sometimes has some defects; it depends on how mitosis reacts to it
risks: spontaneous abortion or abnormal child

42
Q

FISH: Chromosomal Disorders Test

A

Fluorescence in situ Hybridization
Used to determine additions or deletions
If no hybridization = know something is missing
Labelled probe hybridized to chromosomes from metaphase, prophase, or interphase
Sometimes have chromosome that has an addition and you see large chromosome
This can be done at any stage of mitosis

43
Q

Asexual/Vegetative Reproduction

A

Reproduction by mitosis only; there is no change genes
Trees keep the type of fruits the same because the same genes, so if we had sexual reproduction, then the fruits would change
Offspring called clones meaning that each is an exact copy of the original organism
This method of reproduction is rapid and effective allowing the spread of an organism
Since the offspring are identical, there is no mechanism for introducing diversity

44
Q

Meiosis

A

is a process to convert a diploid cell to a haploid gamete, and cause a change in the genetic information to increase diversity in the offspring

45
Q

Bivalent Chromosomes

A

has 2 chromosomes (dyads) and 4 chromatids:

one chromosome coming from each parent

46
Q

Down Syndrome

A

Trisomy 21- Autosomal aneuploidy
Most common surviving trisomy
Extra chromosome- Maternal contribution (95%)
Significant problems: Mental retardation, Respiratory infections, Leukemia, Congenital heart defects, GI tract obstruction
Increased risk for trisomy 21 is maternal age of 35 or greater

47
Q

Mosaicism

A

Condition in which an individual has two or more genetically distinct cell lines derived from a single zygote, but differing because of mutation or nondisjunction

48
Q

Turner Syndrome

A

45, X
rarely born alive; one of the survivable monosomies
1. Characteristically broad “webbed” neck.
2. Reduced stature
3. Poorly developed sexual secondary characteristics
4. Usually infertile because of gonadal dysgenesis
5. Rarely undergo menarche
6. Estrogen treatment
7. Around 30-40% mosaic, mostly 45,X/46,XX

49
Q

Necrosis

A

due to mechanical, chemical, or viral infection damages
premature death
causes inflammation - can be chronic
Cellular swelling
Membranes are broken
ATP is depleted
Cell lyses, eliciting an inflammatory reaction
DNA fragmentation is random, or smeared
In vivo, whole areas of the tissue are affected

50
Q

Apoptosis

A

due to signals internally or externally to prevent threats of disease/cancer as well as aids in the developmental process (tadpole tails, fingers/toes, and nerve cells)
Cellular condensation
Membranes remain intact (blebbing and shrinkage)
Requires ATP
Cell is phagocytosed, no tissue reaction
Ladder-like DNA fragmentation
In vivo, individual cells appear affected
apoptotic body formation = engulfed
no inflammation
mitochondrial leakage
*no nucleus is required for apoptosis because the proteins are always expressed, but not active all the time due to inhibitory mechanisms
*decision to enter PCD is final - all or nothing

51
Q

Caspases

A

central executioners of apoptosis
they are substrates for each other; one caspase will break down another caspases to amplify the proteolytic cascade
Asp is the target and where it is cleaved, whereas Cys is the active site that helps the one caspases cleave the other caspases

52
Q

Initiator Caspases

A

8, 9, 10, & 12

53
Q

Effector Caspases

A

3, 6, & 7

54
Q

3 Mechanisms of Caspase Activation

A
  1. Proteolytic Cleavage- pro-caspase is cleaved and the ends attach to each other to activate the caspase (ex. caspase 3)
  2. Induced Proximity- two molecules come close together causing the removal of the unnecessary parts leaving the rest to combine and form the active caspase (ex. caspase 8)
    3 Oligomerization- Apaf-1, cytochrome c, and pro-caspase 9 come together to form a complex and this activates caspase 9
55
Q

Extrinsic Apoptosis Pathway

A

death ligands (Apo2L/TRAIL) bind to death receptors (DR4 or DR5) in order to recruit FADD to activate initiator caspase 8 or 10, which forms a complex, DISC, to activate effector caspase 3, 6, or 7 to cause apoptosis via CAD, Lamin, actin, adhesion molecules, etc.
*the extrinsic and intrinsic pathways both lead to the activation of effector caspases
*independent of p53
*mostly occurs through induced proximity mechanism
Inhibits of this pathway: AKT and FLIP

56
Q

Intrinsic Apoptosis Pathway

A

DNA damage is detected by p53, which then signals the mitochondria/cytochrome c to leak out (also caused by ROS), which then activates initiator caspase 9, which then activates effector caspase 3, 6, or 7 to cause apoptosis
*forms an apoptosome, which is a oligomerization mechanism complex

57
Q

Bcl-2 Family

A

regulate apoptosis at the mitochondrial level by influencing the permeability of the mitochondrial membrane
can be anti or pro-apoptosis
Anti: Bcl-2 and Bcl xl
Pro: bak, bad, etc.
Only affect the intrinsic pathway because employed by p53

58
Q

Apoptosis > Proliferation

A

1.AIDS
2. Neurodegenerative disorders
Alzheimer disease
Parkinson disease
Retinitis pigmentosa
Cerebellar degeneration
3. Ischemic injury
Myocardial infarction
Stroke
Reperfusion injury: blood returns to the tissue after ischemia (O2 deficiency) –> Tissue injury
4. Toxin-induced liver disease – more liver cells dying than produced ex. Alcohol

59
Q

Proliferation > Apoptosis

A 
1. Cancer
     Follicular lymphomas 
     Leukemia
     Breast cancer
     Prostate cancer
     Ovarian cancer
2. Autoimmune disorders
   	 Systemic lupus erythematosus 
3. Viral infections
     Herpesviruses, Poxviruses, Adenoviruses
60
Q

Mitotic Catastrophe

A

includes events around the cell cycle checkpoints and the spindle assembly, which will control mitosis in cases of cell damage
Mitosis and cell cycle are controlled by different checkpoints and proteins that will allow it to proceed in accordance to need, but if the cycle cannot stop before mitosis, their can be issues like aneuploidy ex. Spindle fibers are not released at appropriate time so they don’t pull the chromosomes appropriately causing a big problem in mitosis
need it to abort the processes because you don’t want these cells to accumulate (with less or more chromosomes than needed creating chromosome instability or cancer)
If occurs during metaphase/anaphase transition: caspase 2 is activated in response to DNA damage, mitochondrial membrane permeabilization, and release of cell death effectors

61
Q

Control of Mitotic Castrophe

A 
Cell-cycle-specific kinases 
*cyclin B1-dependent kinase Cdk1 – M- cyclin
polo-like kinases 
Aurora kinases
Cell-cycle checkpoint proteins, 
Survivin
*P53
caspases 
Bcl-2 family members
62
Q

Pro-Caspase to Caspase

A

2 prodomains from amino-termini are cleaved- discarded
2 small subunits from COOH termini cleaved and unite with 2 large subunits to active caspase
Tightly regulated by Bcl2 family

63
Q

Bcl-2 Member: Bax

A

Bax binds to outer mitochondrial membrane
Facilitates the release of cytochrome c into cytosol
Cyt. C binds adaptor protein- activation
Adaptor-Cyt-c complex (7:7)
A-Cc recruits procaspase 9 to the complex  Apoptosome
Procaspase-9 activation leading to cascade of activating caspases which then induce apoptosis

64
Q

Bcl-2

A

itself acts antiapoptotic by inhibiting apoptosis by inactivating other members of “his” family: Bak, Bax & Bad
Bad sequesters cell death inhibitory proteins such as Bcl2, but Serine/threonine protein kinase (Akt) inactivates Bad by phosphorylation leading to release of active Bcl2
Result: Apoptosis inhibited

65
Q

Survival Factors

A

Survival factors can bind to receptors on the cell surface
An activation cascade includes activation of regulators of transcription to ctivate Bcl2 gene (nucleus) so the mRNA travels to cytoplasm where translation of Bcl-2 occurs, which inhibits apoptosis

Nerve Cell Apoptosis: target cells secrete survival factor, and the nerve cells that do not have the factor undergo apoptosis to get rid of the extra nerve cells to make the processes more efficient

66
Q

Heart Valve Development

A

Myocardium
Endothelium
Extracellular matrix- cardiac jell in between
First step in valve development- specification of cells that delaminate and move into cardiac jelly
Endothelial-to-mesenchymal transformation
Swelling of cardiac jelly and mesenchymal cells forming cushion
Tapering, thinning to make the valve

67
Q

NOTCH signaling

A

NOTCH1-NOTCH4
Signaling pathway increases TGF-β, which increases the transcription factor “snail or Slug” activity, in turn causing down-regulation of VE-cadherin to decrease cell-cell adhesion causing the delamination of endothelial cells so cells can loosen from each other and growth via getting rid of contact inhibition
Example of endocardial autocrine signaling

68
Q

Restriction Endonucleases
DNA ligase
DNA polymerase
Reverse Transcription

A

Restriction Endonucleases: cut at specific and they leave either sticky ends or blunt ends; the recognize these sites via a palindrome
DNA ligase: anneals DNA together
DNA polymerase: produces reverse complement DNA from a template; use Taq polymerase from hot springs so heat doesn’t denature it
Reverse Transcription- cDNA made from RNA

69
Q

Probes

A

Single-stranded DNA or RNA: cDNA, genomic fragments, synthetic oligonucleotides, RNA
Identifies complementary sequence on larger single-stranded DNA or RNA
Base-pairs with complementary sequence
Annealing or hybridization

70
Q

DNA Gel Electrophoresis

A

DNA fragments move toward anode (+)
Separate based on size of DNA and percentage of gel
Size determined relative to molecular markers
Visualized with stain or by autoradiography
DNA, RNA, or protein transferred to nitrocellulose sheets for blotting technique testing (S, N, or W)

71
Q

cDNA vs. Genomic Library

A

Collections of DNA fragments
Bacterial host or phage

Genomic library is fragments of an entire genome
Phage (20 kb inserts), BACs (150 kb) and YACs (1,000 kb)

cDNA library contains just the expressed portion of the genome of a specific cell type under specific conditions
Made from RNA using RT
Plasmids (~2 kb inserts)

72
Q

Blotting Technique with Associated Probe Type

A

Southern: DNA bound by DNA probe
Northern: RNA bound by DNA probe
Western: proteins bound by Ab probe

No alkali treatment for RNA or protein
Western blot probed with antibody, not nucleic acid probe

73
Q

Sanger Sequencing

A 
Reaction contains
- DNA template
- dNTPS
- One ddNTP
DNA polymerase
primer
5’ to 3’
Run on gel to separate by size
Read bottom to top
If you have the ddNTP, it terminates where it base pairs ex. ddATP will bind where A is supposed to be and the sequence will be terminated
74
Q

Automated DNA Sequencing

A

Same principle as Sanger sequencing
Different fluorolabel attached to each ddNTP (4 different colors)
All 4 reactions performed in one tube
electrophoresis performed in 1 lane of the gel (or column)
Sequence read as bands pass the detector

75
Q

Sanger vs. Automated

A

Sanger: 4 tubes, 4 lanes on gel, radioactive, visualized by autoradiography

Automated: 1 tube, 1 lane on gel (or column), nonrad!, visualized by fluorescent reader

76
Q

DNA Polymorphisms

A 
Any change in the DNA sequence 
mutations
variations between individuals
SNP = single nucleotide polymorphism (point mutation)
Deletions or insertions
Expanded repeat sequences
Can occur in genes or in noncoding regions of genome
Majority are in non-coding regions
77
Q

PCR

A

Denaturing, annealing, and extending
Need: Primers (short oligonucleotides), dNTPs, Taq polymerase
rapid amplification of DNA

78
Q

Cystic Fibrosis

A

mutation in CFTR gene that codes for the Cl- channel

70% of cases = 3 base pair deletion coding for Phe

79
Q

Restriction Fragment Length Polymorphisms (RFLPs)

A

Repetitive sequences in tandem of variable length
Highly variable regions of genome
Variable number tandem repeats (VNTRs)
aka, microsatellite DNA
Unique to individual (or identical twins)
Used for DNA fingerprinting and diagnosis
Digest DNA at flanking sites
Gel electrophoresis and specific probe
Unique pattern and length of repeats
DNA Fingerprinting: can show familial relationship; most done with PCR instead of restriction enzymes
Diagnostic: Screen by digesting DNA with MstII and Southern blotting with a probe for the b-globin gene. example: sickle cell anemia normal vs. abnormal or both

80
Q

Allele-Specific Oligonucleotides (ASOs)

A

Need to know EXACT mutation to test
Depends on the sequence difference
Prepare 2 oligonucleotides, one with normal and one with mutant sequence
Easier with insertion/deletion than base-pair
Label oligos, hybridize to spots of DNA on substrate under stringent conditions
Should bind only if match exactly
Normal sequence on top and abnormal on the bottom

81
Q

Shotgun Cloning

A

Sequences the entire genome quickly
Individual clones from a genomic library in YACs are broken up into smaller fragments by subcloning, which are then sequenced
The results are fed into a computer that, by sequence comparison, aligns the fragments to reconstruct the entire genomic sequence

82
Q

Lyon Hypothesis

A

states that in cells with multiple X chromosomes, all but one are inactivated during mammalian embryogenesis.
This happens early in embryonic development at random in mammals.

83
Q

Nomenclature of Chromosomes

A

p or q arm, regions, bands, sub-bands

84
Q

FISH

A

Chromosomal DNA is denatured and fixed, but the chromosomes retain their structure and remain visible under the microscope.
A fluorescent DNA probe of the gene to be tested is then annealed to the fixed chromosomes.

FISH analysis is used to test for deletions, the copy number of a gene, and of course its chromosomal location. Can only see large changes, not SNPs.

FISH can be used with probes that hybridize with specific genes, or chromosome regions, or even repetitive sequences like Alu (forms own banding pattern)

FISH can only test up to 12 chromosome pairs whereas CGH can test the full 23 pairs

85
Q

Spectral Karyotyping (SKY)

A

allows scientists to visualize all of the human chromosomes at one time by “painting” each pair of chromosomes in a different fluorescent color.

Combine probes that are specific to each chromosome to make it easier to sort them
If you see red on a yellow chromosome, you can see a translocation
Visualize large changes only

86
Q

Structural vs. Numerical Abnormalities

A

Structural: breakage or unequal crossing over during meiosis
Numerical: nondisjunction

87
Q

Comparative genomic hybridization (CGH)

A

developed to survey DNA copy-number variations across a whole genome.
With CGH, differentially labeled test (i.e. tumor) and reference (i.e. normal individual) genomic DNAs are co-hybridized to normal metaphase chromosomes, and fluorescence ratios along the length of chromosomes provide a cytogenetic representation of the relative DNA copy-number variation.
Chromosomal CGH resolution is limited to 10-20 Mb -therefore, anything smaller than that will not be detected.

A main disadvantage of conventional CGH is its inability to detect structural chromosomal aberrations, without copy number changes, such as mosaicism, balanced chromosomal translocations, and inversions.

88
Q

array CGH

A

arrays of genomic BAC, P1, cosmid or cDNA clones are used for hybridization instead of metaphase chromosomes in conventional CGH technique.

Fluorescence ratios at arrayed DNA elements provide a locus-by-locus measure of DNA copy-number variation, represents a means of achieving increased mapping resolution.

Basic assumption: ratio of binding of test and control DNA is proportional to the ratio of the concentrations of sequences in the two samples.

89
Q

Screening Newborns

A

Newborn Screening
Allows early detection and treatment
PKU, galactosemia, hypothyroidism
Hemoglobin disorders (HbS), muscular dystrophy
Can be used to inform future reproductive decisions
Heterozygote screening
Find carriers in populations at risk
Aid in reproductive decisions, prenatal diagnosis
Pre-symptomatic diagnosis- for those at risk for certain disorders

90
Q

Linkage Anaylsis

A 
Works when gene is not known, but has been localized
Indirect method, follows linked markers
Need to test multiple family members
Must determine linkage phase
Not all matings are informative
Recombination events can interfere
Highly polymorphic short tandem repeats (STRs) are improving utility
Pedigree example/diagram
91
Q

Direct Mutation Analysis

A

Need to know molecular basis for mutation
Trio sequencing
Much data now available about many genes
Many genes have many mutated forms
May be simple or difficult to analyze
Various techniques can be applied
if a restriction site mutated, can use RFLP
Direct genetic diagnosis requires typing the disease-causing mutation itself (specific mutation must be known). It is potentially more accurate than indirect diagnosis and does not require family information.

92
Q

Aminocentesis

A 
Samples amniotic fluid 
Usually done at 15 to 17 weeks
Visualize fetus with ultrasound
Sample taken with syringe and needle
Cells grown for karyotyping and other tests
Cytogenetic tests take 10 to 12 days
Pregnancy loss ~0.5% above background

Drawbacks: Cannot be done early in pregnancy
Long wait for cytogenetic results delays decision-making
Cytogenetic changes may occur during culture

93
Q

Chronic Villus Sampling

A

Can be done earlier, at 10 – 11 weeks
Transcervical approach possible
Samples placental tissues

94
Q

Fetal Blood Sampling

A

Cordocentesis or percutaneous umbilical blood sampling (PUBS)
Obtain blood from umbilical cord
Can test hematologic disorders directly
Hemoglobinopathies, etc.

95
Q

Fetal DNA in Maternal Circulation

A 
Fetal cells can cross placenta
Isolated in first trimester
FISH/PCR 
NIPS – noninvasive prenatal screening
Cell-free fetal DNA
96
Q

Gene Therapy

A

Somatic cell therapy: treat certain tissues, get gene expression, not passed on in germline, even partial expression can alleviate symptoms

Gene replacement therapy: insert functional copy of defective gene, may need to be tissue specific, may require proliferating tissue, usually uses viral vectors

97
Q

Gene Therapy Vectors

A

Adenovirus: well-studied, no need for proliferating cells, does not integrate into chromosomes, limited expression time, immune response, can target liver, get good systemic response

Retroviruses: insert into DNA of dividing cells, can maintain long-term expression, can interrupt genes, need targeting

Adeno-Associated Virus (AAV): Little immune response seen, small insert capability so far, expression level limited
Lentivirus (HIV family), SV40, other viruses under investigation
Human artificial chromosomes
Naked DNA
Liposomes

98
Q

Gene Blocking Therapy

A

Antisense therapy
Ribozymes
RNA interference (RNAi)
Much effort is directed at cancer and AIDS

Cell Biology (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions