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Unit 2 > Unit 2 - Week 1 - Amack 1, Stein 1, Vossler, Moffat 1 > Flashcards

Unit 2 - Week 1 - Amack 1, Stein 1, Vossler, Moffat 1 Flashcards

1
Q

What percentage of liveborns will have a birth defect? What percentage of births will be premature?

A

3-6% will have a birth defect, 12% will be premature

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2
Q

What weeks of gestation are considered embryonic? What weeks of gestation are considered fetal?

A

Embryonic - Weeks 1 to 8
Fetal - Weeks 9 to 36
Full term - Weeks 36 to birth

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3
Q

What is another term for embyrogenesis?

A

Organogenesis

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4
Q

What are Carnegie stages?

A

Carnegie stages are a system used by embryologists to describe the apparent maturity of embryos. An embryo is assigned a Carnegie stage (1-23) based on its external appearance. These are not necessarily directly correlated with chronology.

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5
Q

What is postovulatory age?

A

Postovulatory age is used by clinicians to describe the maturity of an embryo. It refers to the length of time from the last ovulation before pregnancy. This term bypasses the need for terms like “conception” and “gestation” because conception is not universally agreed upon as the beginning of development.

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6
Q

Name the steps in the first week of embryogenesis.

A
  1. Fertilization
  2. Fusion of sperm and egg pronuclei
  3. Zygote
  4. Cleavage - begins at 2 cell stage (30h), 4 cell (40h), 8 cell
  5. Formation of morula (16 cells)
  6. Formation of blastocyst
  7. Implantation
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7
Q

Where is an oocyte typically fertilized?

A

In the ampullary region of the uterine tube

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8
Q

Cleavage divisions increase the number of cells without:

A

Increasing the size of the zygote

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9
Q

The process of compaction has what effect?

A

After the 3rd cleavage, at 8-cell stage the blastomeres maximize their contact with one another and form a compact ball of cells. The process of compaction segregates inner cells from outer cells.

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10
Q

About what day after fertilization is the morula formed?

A

3 days, with the late morula forming at about day 4.

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11
Q

In compaction, the tightly packed arrangement is stabilized by ___ that form between the outside cells of the ball, sealing off the inside of the sphere.

A

Tight junctions

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12
Q

Inner cells of the morula constitute the __1__. The __1__ gives rise to tissues in the embryo proper and the outer cells give rise to the __2__ that later contributes to the __3__.

A
  1. Inner cell mass (ICM)
  2. trophoblast
  3. placenta
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13
Q

What is cavitation?

A

Initially the morula does not have an internal cavity. However during the process of cavitation, the trophoblast cells secrete fluid into the morula to create a blastocoel.

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14
Q

Define a blastocyst.

A

A blastocyst is when the ICM segregates to one side of the embryo, leaving the other side occupied by the blastocoel (fluid-filled cavity), all surrounded by the trophoblast.

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15
Q

ICM are ____ cells that give rise to the embryo.

A

Pluripotent

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16
Q

Embryonic stem cells are derived from the ____.

A

ICM.

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17
Q

Define pluripotent.

A

Pluripotent means the cells can give rise to all of the cell types that make up the body.

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18
Q

Induced pluripotent stem cells are generated from:

A

Adult cells.

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19
Q

Define totipotent.

A

Totipotent means that the cells can give rise to ANY cell type, including extraembryonic tissues.

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20
Q

Recent studies have shown what kind of molecule on trophoblast cells mediates the attachment of the blastocyst to the endometrium?

A

L-selectins, which are carbohydrate binding proteins. The trophoblast also has integrins that can interact with the ECM of the endometrium, and penetrates it using proteases.

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21
Q

In the uterus, _____ immunoreactivity peaks during the window of receptivity of the blastocyst. It is thought this is what the L-selectins interact with during a “rolling and tethering” process.

A

MECA-79

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22
Q

On Day 8, the blastocyst is partially embedded in the endometrium and the trophoblast differentiates into two layers:

A
  1. cytotrophoblast, an inner layer of mononucleated cells

2. syncytiotrophoblast, an outer layer of multinucleated cells that lack distinct cell boundaries

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23
Q

What is the function of the synctiotrophoblast?

A

The syncytrophoblast tissue is thought to further the progression of the embryo into the uterine wall by digesting uterine tissue. The uterus, in turn, sends blood vessels to this area, where they eventually contact the syncytiotrophoblast.

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24
Q

On Day 9, the ICM differentiates into two layers: ___1___ and ___2___ which together form the ___3___. At this point, the trophoblast invades ___4___ to establish extraembryonic tissues and uteroplacental circulation.

A
  1. Hypoblast
  2. Epiblast
  3. Flat, bilaminar germ disc
  4. Maternal capillaries
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25
Q

If monozygotic twins each have their own chorion and amnion, when did the separation occur?

A

Occur in about 1/3 of identical twins, separation occured before the formation of the trophoblast (before day 5).

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26
Q

If monozygotic twins each have their own amnion, but share a chorion, when did the separation occur?

A

Between days 5 and 9, after the trophoblast formed, but before the amnions formed.

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27
Q

Monozygotic twins that share both a chorion and an amnion are at risk for:

A

being conjoined

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28
Q

The epiblast layer of what was once the ICM gives rise to:

A

All tissues in the embryo proper (endoderm, ectoderm, mesoderm).

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29
Q

About what day does implantation occur?

A

Day 7

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30
Q

What are the three goals of gastrulation?

A
  1. Bring inside the embryo areas destined to form endodermal organs
  2. Surround the embryo with cells capable of forming ectoderm.
  3. Place mesodermal cells in proper positions in between.
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31
Q

When does gastrulation occur?

A

About the 3rd week

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32
Q

The process of gastrulation transforms the __1__ into __2__ germ layers. It begins with the formation of the __3__ on the surface of the epiblast. This becomes a narrow groove with a structure called the __4__ surrounding a __5__ at the cephalic end.

A
  1. bilaminar disc
  2. three
  3. primitive streak
  4. primitive node
  5. primitive pit
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33
Q

What is embryonic invagination?

A

Epiblast cells migrate into the primitive streak, and then detach from the epiblast and move through the streak to slip beneath it.

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34
Q

The invaginating cells during gastrulation become the:

A

Endoderm and mesoderm.

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35
Q

What structure is referred to “the organizer” because it expresses genes that induce formation of the embryo?

A

Hensen’s node. Note that its transplantation from one species into another can still induce embryo formation!

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36
Q

What 3 main tissues are formed by the endoderm?

A

Digestive tract
Pharnyx
Respiratory tube, lungs

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37
Q

What 5 main tissues are formed by mesoderm?

A 
Notochord (dorsal)
Paraxial (bone)
Intermediate (kidney tubules)
Lateral (blood)
Head/facial muscle
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38
Q

What 3 main tissues are formed by the ectoderm?

A

CNS
Skin (epidermal)
Neural crest, ie pigment cell

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39
Q

When does the establishment of body axes occur?

A

Before and during gastrulation. The anterior-posterior axis is signaled by cells at the cranial margin of the embryonic disc, an area called the anterior visceral endoderm (AVE). The AVE expresses genes that direct head formation.

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40
Q

What is neurulation?

A

Neurulation is the process by which the neural plate forms the neural tube. Its formation is due to patterned crosstalk of signaling by BMP, FGF, retinoic acid, and other players.

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41
Q

What are the steps of neurulation?

A
  1. Formation and folding of neural plate
  2. Elevation of neural crest
  3. Convergence of neural folds
  4. Closure of tube when neural folds contact one another
    Day 25 to Day 28.
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42
Q

The events of neurulation divide the ectoderm into three distinct domains:

A
  1. Neural tube, internal –> brain and spinal cord
  2. Surface ectoderm –> skin
  3. Neural crest cells –> migrate to form lots of stuff
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43
Q

About when in gestation does neural tube closure occue?

A

4th to 5th week

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44
Q

What are two dietary factors that are important drivers of neural tube closure? What can occur if this process does not complete?

A
  • -Cholesterol and folic acid
  • -The most common condition caused by neural tube closure faiure is spina bifida - the bifurcation of the neural tube, leading to its extrusion out of the back
  • -If the neural tube does not close in the cranial region, a lethal condition known as anencephaly occurs where the brain remains in contact with amniotic fluid and degenerates.
  • -If the neural tube fails to close completely, it is called craniorachischisis.
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45
Q

Name some cell types that are the targets of neural tube cell migration.

A

Teeth, skin, head, face, heart, endocrine and GI systems.

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46
Q

Neural crest cells undergo a _______ transition.

A

Epithelial to mesenchymal. This allows them to the migrate to target tissue. Mesenchyme refers to loosely organized connective tissue of any origin.

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47
Q

Neural crest in different regions of the embryo fives rise to characteristic cell types. Explain the 4:

A
  1. Cranial (cephalic) neural crest
  2. Cardiac neural crest
  3. Trunk neural crest
  4. Enteric neural crest (vagal and sacral)
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48
Q

Cardiac neural crest cells enter the __1__ (cardiac outflow tract) to generate the __2__, thus separating the great arteries.

A
  1. truncus arteriosis

2. septum

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49
Q

What are the 5 neglected parasitic infections the CDC has targeted for public health action?

A
  1. Toxoplasmosis
  2. Chagas disease (trypanosoma cruzi)
  3. Tosocariasis
  4. Trichomoniasis
  5. Cystercerosis
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50
Q

Toxocariasis acquire the infection as __1__. The infection can cause __2__.

A
  1. accidental hosts

2. blindness

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51
Q

Trichomoniasis transmission occurs:

A

sexually

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52
Q

The most common cause of adult-onset siezures in most low-income countries is:

A

cysticerosis, eating wild pigs is the most common cause of the disease here, related to tapeworm

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53
Q

The main source of contracting toxoplasmosis is:

A

eating undercooked pork/meat.

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54
Q

What is a temporary parasite?

A

Visits the host only for feeding, ie bedbug

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55
Q

What is an accidental parasite?

A

A parasite that usually infects another animal, ie dog or cat, but accidentally infects a human host.

56
Q

What is an obligatory parasite?

A

A parasite that is completely dependent on the host, ie hookworm

57
Q

What is a facultative parasite?

A

It can change its lifestyle between free living in the environment and in the host, depending on the conditions

58
Q

What is a permanent parasite?

A

It lives on its host without ever leaving, ie head lice.

59
Q

What is an opportunistic parasite?

A

It is capable of producing disease in an immunodeficient host.

60
Q

A definitive host that harbors __1__ stages of the parasite. Transmission from host to host can occur __2__.

A
  1. adult/sexually mature

2. directly

61
Q

An ___1___ that harbors larval or sexually immature stages of the parasite (or in whom asexual reproduction occurs), for example, man is the __1__ of malarial parasites. The transmission to the definitive host requires a __2__.

A
  1. intermediate host

2. vector

62
Q

Host animals can be infected by several mechanisms, but not typically through:

A

Ingestion of the adult parasite.

63
Q

Name some common ectoparasites:

A

Fleas, ticks, mosquitos etc. They can either BE the parasite or be a vector.

64
Q

Name some common endoparasites:

A

Helminths, protozoa, larval stages of arthropods

65
Q

Unlike many bacterial or viral diseases, parasitic infections tend to be _____.

A

Chronic in nature

66
Q

Most of the pathology associated with a parasitic infection results from:

A

Immunologic response

67
Q

IgE can be ___1___ with parasitic infections.

A

Increased, especially with helminthic parasites and parasitic worms.

68
Q

Fun fact!

A

There is a hypothesis that eosinophils have evolved to defend against host infection by parasitic helminths and other large organisms.

69
Q

Epidemiologic studies have shown that people with parasitic infections have less:

A

immune-mediated or autoimmune disease

70
Q

Helminth parasites are regarded as:

A

Master manipulators of the immune system, ie schistosomiasis, filariasis

71
Q

Hook worms being researched showed promise in the treatment of:

A

Chrohn’s disease

72
Q

The most important survival strategy that parasites have is:

A

Their complicated lifecycle, thus making an immune response difficult to mount.

73
Q

Giardia is a:

A

Flagellate, parasitic protozoa

74
Q

Plasmodium and cryptosporidium are:

A

sporozoa, parasitic protozoa

75
Q

Pinworm is a type of:

A

nematode, parasitic helminth

76
Q

Tapeworms and flukes are type of:

A

parasitic helminths

77
Q

Parasitic survival strategies include:

A 
Antigenic shedding
Antigenic variation
Antigenic mimicry
Immunological subversion/suppression
Immunological diversion
78
Q

What are the four major categories of parasites:

A
  1. Protozoa
  2. Cestoda
  3. Trematoda
  4. Nematoda
79
Q

The most important protozoa in men are:

A

Intestinal, ie giardia lamblia (mastigophora)

80
Q

Infection of cestodes, the tapeworms, typically occurs:

A

through ingestion of a primary host

flat worms, up to 100 feet long

81
Q

Nematodes are also known as:

A

roundworms (pinworm, hook worm)

82
Q

Trematodes are also known as:

A

Flukes

83
Q

Entamoeba histolytica is the cause of the infection:

A

Amebiasis

84
Q

Name the 5 ways in which host animals can be infected by parasites:

A
  1. Direct ingestion of larva, eggs, cysts (entamoeba histolytica, giardia lamblia)
  2. Maternal transmission (toxoplasma gondii)
  3. Eating the intermediate host (diphyllobothrium latum)
  4. The parasite actively penetrating the principal host (hookworms acylostoma duodenale, necator americanus)
  5. Vector borne transmission, ie Malaria
85
Q

Malaria is caused by:

A

Plasmodium falciparum, and other plasmodiums

86
Q

Raising an innate/nonspecific immune response involves __1__ and may result in the destruction or removal of the parasite.

A

cytokines, activation of the complement system

87
Q

What is antigenic mimcry? Give 1 example.

A

The parasite expresses epitopes similar or identical host molecules, ie schistosoma

88
Q

What is antigenic shedding? Give 1 example.

A

Parasites can shed their antigens to create false leads in the immune system, ie entamoeba histolytica

89
Q

What is one example of antigenic variation?

A

Gene switching, thereby generating novel antigens, used by malaria parasite and others

90
Q

What is antigenic concealment? Give 1 example.

A

Hiding in a host cell w/o displaying its antigens, ie leishmania donovani and others

91
Q

Are viruses filterable agents?

A

No, the filter remains infectious

92
Q

Define a virus:

A

A capsid-encoding organism

93
Q

What is a capsid?

A

A protein shell that encapsulates the nucleic acid genome

94
Q

The particle encoded by a virus genome is a:

A

Virion

95
Q

All viruses encode genes for:

A
  1. capsid proteins
  2. the “replicon”
  3. multifunctinal proteins that interact with the host
96
Q

What is the term referring to the genes encoding the nucleic acid polymerase and accessory proteins to copy the genome?

A

Replicon

97
Q

What capsid structures do viruses have?

A
  1. Helical
  2. Icosahedral
  3. Complex
98
Q

Enveloped viruses obtain a __1__ from the host cell.

A

lipid bilayer

99
Q

Naked virions lack:

A

an envelope

100
Q

Virus classification is based on:

A
  1. Host cell (kingdom)
  2. Genome type (DNA/RNA)
  3. Virion structure (enveloped/naked, shape)
101
Q

Outside a host cell, virions are:

A

inert, and degrade over time

102
Q

Adenovirus structure:

A

Icosahedral, dsDNA, naked

103
Q

Influenza structure:

A

Helical, segmented RNA, enveloped

104
Q

Herpesvirus structure:

A

Icosahedral, dsDNA, enveloped

105
Q

HIV structure:

A

Circular, ssRNA, enveloped

106
Q

Poxvirus structure:

A

Complex, dsDNA, enveloped

107
Q

FISH involves using what kind of probes?

A

Site-specific

108
Q

True or False: You can use FISH to identify abnormalities of an entire genome.

A

False, you must make your probe for a specific site.

109
Q

What are the three basic classes of FISH probes?

A
  1. Repeat sequences
  2. Single copy DNA, ie subtelomere FISH
  3. Chromosome painting, ie multi-color
110
Q

Repeat sequence probes in FISH are usually isolated from:

A

telomere or centromere regions

111
Q

Centromere probes in FISH are best for:

A

detecting the gain or loss of a specific chromosome

112
Q

Repeat sequence probes in FISH are best for detecting:

A

aneuploidies, can use in interphase as well as metaphase

113
Q

A single copy DNA probe in FISH is also known as:

A

a unique sequence, such as a part of a particular gene

114
Q

Subtelomere FISH has become a very important diagnostic tool because it allows us to identify very small/cryptic deletions and rearrangements that cannot be seen by:

A

standard karyotype analysis

115
Q

3-5% of ______ is due to cryptic terminal deletions at the subtelomeres.

A

unexplained mental retardation

116
Q

WCP stands for:

A

whole chromosome paints

117
Q

When might WCP or chromosome painting be useful?

A

Because it causes a whole chromosome to fluoresce, it can be helpful in diagnosing large chromosome rearrangements, ie 3:1 nondisjunction, or when one piece of a chromosome attaches to the end of a different chromosome.

118
Q

VCFS is:

A

velocardiofacial syndrome

119
Q

FISH probes do not cover the entire deletion, only the:

A

critical region, BUT FISH is still 96-99% accurate!

120
Q

Most chromosomal deletions are about what size?

A

3 MB

121
Q

What is the critical region of a gene or chromosome?

A

The region that is always or almost always altered in a genetic anomaly/mutational process

122
Q

What kind of FISH analysis might you use if a patient comes in with very nondescript features and symptoms?

A

Subtelomere FISH

123
Q

What is a contiguous gene syndrome?

A

A contiguous gene syndrome is associated with a particular region in the genome where a group of adjacent genes are all related to a particular clinical outcome, even though individually, none of the normal functions of those genes are related. If one or more of those genes are lost or duplicated, it can result in multiple phenotype anomalies.

124
Q

Name the common contiguous gene syndromes:

A
  1. Prader Willi syndrome, Angelman syndrome
  2. WAGR syndrome
  3. Miller-Diecker syndrome/Lissencephaly
  4. Williams syndrome
  5. VCFS
  6. 1p syndrome
125
Q

Contiguous gene syndromes are also known as:

A

microdeletion or microduplication syndromes, because they cannot be identified by karyotype analysis

126
Q

Name some features of Williams syndrome.

A
  1. Suprvalvular aortic stenosis (no elastin gene)
  2. thickening of skin
  3. low IQ
  4. very outgoing
  5. autistic elements, such as terrible at math but great with music
  6. renal anomalies
  7. skeletal and joint limitations
    * *Must dx with FISH bc deletions are so small.
127
Q

____ is the 2nd most common syndrome, next to Down syndrome, known in humans.

A

VCFS

128
Q

What are the characteristics of VCFS?

A
  1. Weak immune system
  2. hypotonia
  3. short stature
  4. feeding difficult at birth
  5. cardiac anomalies
  6. facial anomalies
  7. learning disabilities
129
Q

VCFS is due to an __1__ microdeletion on chromosome __2__, including approximately 40 genes and 8 pseudogenes.

A
  1. interstitial

2. 22

130
Q

Fun fact!

A

In VCFS, 15% of the time, the parent carries the same deletion, but no clinical features.

131
Q

CGH, comparative genomic hybridization, is the intermediate step between:

A

FISH and microarray

132
Q

The three most common types of genetic microarrays are:

A
  1. Gene/DNA array
  2. Expression array (RNA)
  3. Chromosome array
133
Q

DNA arrays can identify genetic polymorphisms, specific mutations, and/or __1__. It cannot identify a balanced rearrangement because __2__.

A
  1. copy number variation, CNV

2. Structurally speaking, all the genes are there

134
Q

Micro-array analysis has become the go-to diagnostic tool in cases of:

A 
unexplained developmental delay
intellectual disability
autism spectrum disorders
multiple congenital anomalies
**but if testing for a known genetic syndrome, use FISH or karyotype analysis
135
Q

Balanced translocations may be detected by:

A

FISH and karyotype

molecular analysis

136
Q

What is a good method for detecting mosaicism?

A

FISH, if the correct probes are used.

Unit 2 (11 decks)

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