Term
| How are animals classified? |
|
Definition
| According to how they develop |
|
|
Term
|
Definition
| The idea that humans existed fully formed in sperm and mature in the womb |
|
|
Term
|
Definition
| Form developing over time |
|
|
Term
| Why is development studied in frogs? |
|
Definition
| They have many offspring, large eggs, are free swimming, and cell division occurs every 30 mins |
|
|
Term
| Are early divisions symmetrical? |
|
Definition
| No, the dorsal side is slightly smaller |
|
|
Term
| What are cells in the cleaving embryo called? |
|
Definition
|
|
Term
|
Definition
| Dyeing an area in an embryo and seeing where that area ends up during development |
|
|
Term
What is the standard vertebrate life cycle?
Focused on embryos obviously |
|
Definition
Fertilisation includes:
Oocyte
Cleavagte includes:
Morula, Blastula
In gasstrulation: The blastocoel develops, followed by the blastopore, and seperation of ecto, endo and mesoderm
Then organogenesis occurs |
|
|
Term
|
Definition
| multicellular animals that pass through embryonic stages of development |
|
|
Term
| What is a portion of an embryo in early cleavage called? |
|
Definition
|
|
Term
| Where are pluripotent cells found in an embryo? |
|
Definition
|
|
Term
| What are the decreasing levels of developmental potential? |
|
Definition
| totipotent, pluripotent, multipotent, oligopotent, unipotent |
|
|
Term
| How could maternal molecules influence cell fate? |
|
Definition
| They could act as morphogenetic determinants, and there are also RNAs that direct early embryonic development |
|
|
Term
| What is a morphogenetic determinant? |
|
Definition
| Molecules that diffuse away from where they start to form a diffusion gradient, with differend daughter cells inheriting different concentrations |
|
|
Term
|
Definition
|
|
Term
| When does RNA synthesis begin, and what directs development before this? |
|
Definition
| mid blastula stage, maternal molecules |
|
|
Term
|
Definition
| A process in which tissue is internalized into the emrbyo to produce the three primary somatic germ layers - meso, ecto and endoderm |
|
|
Term
| What does the ectoderm give rise to? |
|
Definition
| Epidermis and nervous system |
|
|
Term
| What does the mesoderm give rise to? |
|
Definition
| Muscles, skeleton and internal organs |
|
|
Term
| What does the endoderm give rise to? |
|
Definition
| guts tube, and internal organs |
|
|
Term
| What is neurulation, and what basic path does it follow? |
|
Definition
| Formation of the CNS, and neural folds form, followed by neural groove, followed by an open neural tube |
|
|
Term
| Which direction is neural? |
|
Definition
|
|
Term
| Which direction is the gut/ |
|
Definition
|
|
Term
| What is the pahryngula bottleneck? |
|
Definition
| All animals pass through a phylotypic stage where the embryos look similar |
|
|
Term
| What is the difference between homologous and analogous characteristics? |
|
Definition
Homologous - evolved from the same features and ancestor
Analogous - does the same job |
|
|
Term
| Which was the last germ layer to evolve? |
|
Definition
|
|
Term
|
Definition
| A master regulator of mesoderm development, it regulates it in all creatures |
|
|
Term
| What two major groups are bilaterians divided into, and when does this occur? |
|
Definition
Deuterostomes (vertebrates) - blastopore forms anus, then mouth, blastopore is dorsal
and Protostomes (insects and others)- blastopore forms mouth, then anus, blastopore is ventral
This occurs during gastrulation |
|
|
Term
| What does BMP4 induce, and how? |
|
Definition
| BMP4 induces ventral fate - it binds ectoderm, which then becomes epidermis |
|
|
Term
| What does chordin inhibit, and what effect does this have? |
|
Definition
| Chordin inhibits BMP4 by forming inactive complexes with it - BMP cannot bind the ectoderm, so the ectoderm takes the default path and becomes the CNS |
|
|
Term
| Which axis determines the polarit of the emrbyo? |
|
Definition
|
|
Term
| What does noggin do and what does it inhibit? |
|
Definition
| Noggin - molecule that helps develop head, if enough is injected can just end up with a head - it also inhibits BMP |
|
|
Term
| In what creatures is the Chordin.BMP system founD? |
|
Definition
|
|
Term
| What does overexpression of BMP cause? |
|
Definition
|
|
Term
| What do protostome body plans look like compared to deuterostome? |
|
Definition
|
|
Term
| What does BMP induce in protostomes? |
|
Definition
|
|
Term
| Which body plan was original? |
|
Definition
|
|
Term
| What does pax6 code for, and where is it conserved? |
|
Definition
| Eyes, protostomes and deuterostomes |
|
|
Term
| What does the dorsal lip of the blastopore signify? |
|
Definition
| The start of gastrulation |
|
|
Term
| What is the dorsal lip caused by and when does it dissapear? |
|
Definition
| Cells migrating back into the embryo, when all cells have moved in? |
|
|
Term
| When does neurulation occur, and what (simply) occurs? |
|
Definition
Neurulation occurs after gastrulation, neural folds, neural groove and open neural tube form, cells migrate up to form neural tube - which will become nervous system
After neurulation, embryo will begin to take form, can identify rudimentary structures |
|
|
Term
| What occurs during neurulation? |
|
Definition
Notochord formed from mesoderm
Notochord induces ectoderm to become neuroectoderm
Strip of neuronal stem cells runs along back of fetus - known as the neural plate - this is the origin of the entire nervous system
Neural plate folds outwards to form neural groove
Neural folds close around groove to create neural tube (known as primary neurulation)
The anterior part of the neural tube is called the basal plate, the posterior is known as the alar plate, and the interior is known as the neural canal
By the fourth week of gestation, the ends of the neural tube (known as the neuropores) close off.
Secondary neurulation then occurs
Neural plate forms a cord-like structure that migrates inside the embryo and hollows to form a tube |
|
|
Term
| Do cells change sides during cleavage? |
|
Definition
|
|
Term
| Where did the genetic machinery to make the mesoderm come from? |
|
Definition
|
|
Term
| What is the common ancestor of protostomes and deuterostomes? |
|
Definition
| The urbilaterian ancestor |
|
|
Term
| What is special about the hemichordates and echinoderms? |
|
Definition
| They are deuterostomes with similar features to the protostomes |
|
|
Term
| When did the nervous system move from ventral to dorsal? |
|
Definition
|
|
Term
| How do morphogenetic determinant concentrations determine fate/ |
|
Definition
| They induce expression of different genes |
|
|
Term
| What is autonomous specification? |
|
Definition
| A system in which each cell gets a different set of morphogenetic determinants and knows very early on what it will become. The development of each cell is independent. Traditionally, such embryos have been called mosaic embryos. |
|
|
Term
| What occurs when the blastomeres are seperated? |
|
Definition
each of them will still give rise to its normal derivatives - the vegetal posterior blastomeres form muscle
there is no compensation, i.e. none of the other cells will compensate for the loss of the muscle producing cells
cell potency and cell fate are identical
the fate of every cell is specified autonomously |
|
|
Term
|
Definition
| In the cytoplasm of muscle forming cells |
|
|
Term
| Where are all nuclear determinants retained? |
|
Definition
|
|
Term
| What is chromosome dimunition? |
|
Definition
| Some chromosomes are not fully maintained in differentiated tissues |
|
|
Term
| What suggests regulative development in sea urchins? |
|
Definition
| All cells retain nuclear determinants |
|
|
Term
| How does conditional specification occur? |
|
Definition
| Cells reach their respective fates by interaction with other cells |
|
|
Term
| How can a cells fate be changed? |
|
Definition
Stochastic(random) intrinsic events.
If the fate is conditional, external signalling |
|
|
Term
| What occurs during germlines specification in model organisms for PGCs? |
|
Definition
| Maternal molecules block transcription and translation to prevent them becoming part of the soma |
|
|
Term
| How is mRNA presence detected? |
|
Definition
mRNA in situ hybridisation.
Holes are made in the cell by a detergent, then a RNA probe with a dioxigenin label is inserted. Next, an alkaline phosphatase-conjugated antibody is inserted. Add a chemical that becomes purple when phosphate is removed, if mRNA is present, it will be dyed purple. |
|
|
Term
| What is immunohistochemsitry? |
|
Definition
| Protein detection with an antibody that has an enzyme attached to it. The antibody binds where the protein is and the presence of the conjugated enzyme is detected with a colour-forming (chromogenic) substrate. |
|
|
Term
| How is differential gene expression acheived? |
|
Definition
| Chromosome dimunition, or epigenetic regulation at the level of gene transcription |
|
|
Term
| What to histones do to DNA? |
|
Definition
| Consense it, and bind it and each other to build nucleosomes |
|
|
Term
| What packages and stabilizes nucleosomes? |
|
Definition
|
|
Term
| How do transcription factors normally work? |
|
Definition
1. by helping RNA polymerase - bind to the promoter - elongate the transcript
2. by making DNA more accessible - recruiting chromatin remodellers and modifiers |
|
|
Term
| How do transcriptional activators make DNA more accesible? |
|
Definition
by:
recruit enzymes that demethylate DNA
recruit enzymes that remove negative histone marks
recruit enzymes that place positive histone marks |
|
|
Term
| How do trancriptional repressors work? |
|
Definition
Transcriptional repressors bind to silencers and help to
recruit enzymes that methylate DNA
recruit enzymes that add negative histone marks
recruit enzymes that remove positive histone marks |
|
|
Term
| What does CTCF do, and how> |
|
Definition
| Restricts the influence of enhancers and form a barrier for heterochromatin, by binding insulator elements, and interacting with cohesins to form chromatin loops |
|
|
Term
| Which four transcription factors can remake pluripotent cells? |
|
Definition
|
|
Term
| What experiments reveal sites of open chromatin? |
|
Definition
DNase I hypersensitive sites-chip or DNase I HS-Seq experiments reveal sites of open chromatin
Digest with DNase I and blunt end DNase I hypersensitive site
Ligate biotinylated linkers
Sonicate to shear DNA
Enrich on streptavidin column |
|
|
Term
| Which experiments find protein binding sites? |
|
Definition
|
|
Term
| How do CHIP-chip experiments work? |
|
Definition
| Take cells from a culture and tissue samples. The protein of interest is cross linked with the DNA site it binds to, before the cells are lysed and the DNA is sheared by sonnication. The DNA linked to the protein forms a protein-DNA complex. These are filtered out using an antibody specific to the protein. The complex is then reversed and purified so only DNA is left. The DNA are labelled with a fluorescent tag. The DNA is pored over a microarray, and hybridizes to complementary strand. |
|
|
Term
| How do CHIP-seq experiments work? |
|
Definition
| Take cells from a culture and tissue samples. The protein of interest is cross linked with the DNA site it binds to, before the cells are lysed and the DNA is sheared by sonnication. The DNA linked to the protein forms a protein-DNA complex. These are filtered out using an antibody specific to the protein. The complex is then reversed and purified so only DNA is left. It is then sequenced and mapped to a reference genome, and the coverage is read by extended sequence tags. |
|
|
Term
|
Definition
| Chromatin immunoprecipitation |
|
|
Term
|
Definition
| Blocks translation of mRNA prior to fertilisation |
|
|
Term
| What is bicoid and what can it do> |
|
Definition
Proteins like Bicoid can bind to an mRNA and block translation initiation
Bicoid is a homeobox transcription factor that can bind DNA and RNA |
|
|
Term
|
Definition
| block translation, initiation or cause mRNA degredation |
|
|
Term
| How can protein activity be modified after production? |
|
Definition
If it:
needs to be released from precursors
needs to be addressed to the correct compartment within the cell
has to be assembled with other proteins to be able to fulfil their role
requires ions, e.g. Ca2+
has to be modified covalently - acetylated, phosphorylated etc..... |
|
|
Term
| When are Otx2, Pax6, Sox2, and L-MAF expressed? |
|
Definition
| In presumptive lens ectoderm in early neurula stage, and Sox2 and L-MAF are added in late stage |
|
|
Term
| Where do permissive signals often come from? |
|
Definition
|
|
Term
| How does FGF signal through the RTK-MAPK signal transduction pathway? |
|
Definition
Ligand binding causes autophosphorylation of the receptor tyrosine kinase (RTK)
activation of the guanine exchange factor (GEF) via an adapter protein
GEF exchanges the GDP on G-protein Ras for a GTP
Ras recruits the MAPKKK Raf to the membrane and activates it
Raf phosphorylates the MAPKK Mek
Mek phosphorylates the Mitogen-activated kinase (MAPK) ERK
ERK goes into the nucleus and phosphorylates a TF GAP: GTPase-activating protein |
|
|
Term
| Which cascade is used by receptors for epidermal growth factors, platelet-derived growth factor, stem cell factor, and vascular endothelial growth factor and what do these things all have in common? |
|
Definition
| The RTK-MAPK signal transduction pathway, and they are all RTKs |
|
|
Term
| What occurs to reciprocal transplants between different regions of different organisms? |
|
Definition
| The transplanted cells differentiate according to their new position (regional specificity of induction) but they retain their identity of origin (genetic specificity of induction) |
|
|
Term
| What three types of cell specification are there? |
|
Definition
| Autonmous, conditional, syncytial |
|
|
Term
| What is characteristic of autonomous specification? |
|
Definition
Predominant in invertebrates
Specification by differential acquisition of cytoplasmic molecules
Blastomere fates are invariant, cannot change cell fate
cell specification precedes migration
"Mosaic development" |
|
|
Term
| What are the characteristics of conditional specification? |
|
Definition
Predominant in vertebrates
Specification by interactions between cells
Massive rearrangemnts before and during specification
regulative development, cells can acquire different functions |
|
|
Term
| What are the characteristics of syncytial specification? |
|
Definition
predominant in insects
specialisation of body regions by interactions between cytoplasmic regions prior to cellularization of the blastoderm
No rigid cell fates
Both autonomous and conditional specification can be seen after cellularization |
|
|
Term
| In what arrangement do cells arrange themselves? |
|
Definition
| the most thermodynamically stable |
|
|
Term
|
Definition
Cadherins play major roles in boundary formation
are calcium-dependent adhesion molecules
transmembrane proteins
interact with cadherins on the other cells
anchored to the actin cytoskeleton via catenins
the cadherin-catenin complex forms the adherens junction |
|
|
Term
| What is the extracellular matrix? |
|
Definition
| The extracellular matrix (ECM) is an insoluble network of macromolecules secreted by cells into their immediate environment - it is made up of collagen, proteoglycans and specialised glycoproteins like fibronectin and laminin. It plays important roles in cell signalling, cell migration, cell adhesion, formation of epithelial sheets or tubes. |
|
|
Term
| What do basal laminas do? |
|
Definition
Basal laminas support epithelial sheets and tubes
epithelial tissues like the epidermis (sheet), the intestine (tube) and the endothelium of blood vessels (tube) are supported by basal laminas |
|
|
Term
|
Definition
are receptors for extracellular matrix
bind to RGD (Arg-Gly-Asp) sequences in adhesive proteins in the ECM
connect via Talin and α- Actinin to the actin microfilaments inside the cell
integrate the inner and the outer scaffold (i.e. the actin cytoskeleton to the ECM)
- interact with collagens and fibronectin in the ECM - inside they interact with the actin microfilaments |
|
|
Term
| What occurs when mesenchymal cells move? |
|
Definition
When mesenchymal cells move, they
1. first become polarised
• often directed by diffusing or EMC signals
• these signals reorganise the cytoskeleton
• defining a front and a back |
|
|
Term
| What protrusions do cells form? |
|
Definition
- filopodia (finger-like) & lamellipodia (sheet-like)
- the mechanical force for protrusion formation comes from the polymerisation of actin microfilaments
• creating long parallel bundles (filopodia)
• creating sheets (lamellipodia) |
|
|
Term
| How are morphogenetic movements of epithelial sheets controlled? |
|
Definition
| By changes in the actin cytoskeleton |
|
|
Term
| What is the epithelial mesenchymal transition |
|
Definition
polarised epithelial cell
interacts with the basement membrane
connects with neighbouring cells via adherens junctions and the apical polarity complex
the cell becomes mesenchymal
loses connection to the basement membrane
down-regulates Cadherins
rearranges cytoskeleton and secretes new ECM molecules |
|
|
Term
| What is the ability to respond to a specific inductive signal? |
|
Definition
| Competence - and it must be aquired |
|
|
Term
| What is reciprocal induction? |
|
Definition
| An organ induces fate in another cell, only to be induced by the other cell secreting something after formation. occurs with the lens and optic vesicle |
|
|
Term
| What are the three proposed general principles characteristic of most instructive interactions? |
|
Definition
1. In the presence of tissue A, responding tissue B develops in a certain way.
2. In the absence of tissue A, responding tissue B does not develop in that way.
3. In the absence of tissue A, but in the presence of tissue C, tissue B does not develop in that way. |
|
|
Term
| What is permissive instruction? |
|
Definition
| Here, the responding tissue contains all the potentials that are to be expressed, and needs only an environment that allows the expression of these traits. For instance, many tissues need a solid substrate containing fibronectin or laminin in order to develop. The fibronectin or laminin does not alter the type of cell that is to be produced, but only enables what has been determined to be expressed. |
|
|
Term
| What is responsible for regional specificity of induction in the competent epidermal epithelium? |
|
Definition
|
|
Term
| Which four major families are important in paracrine signalling? |
|
Definition
| he fibroblast growth factor (FGF) family, the Hedgehog family, the Wingless (Wnt) family, and the TGF-β superfamily. |
|
|
Term
|
Definition
| FGFs can activate a set of receptor tyrosine kinases called the fibroblast growth factor receptors (FGFRs). Receptor tyrosine kinases are proteins that extend through the cell membrane (Figure 6.10A). On the extracellular side is the portion of the protein that binds the paracrine factor. On the intracellular side is a dormant tyrosine kinase (i.e., a protein that can phosphorylate another protein by splitting ATP). When the FGF receptor binds an FGF (and only when it binds an FGF), the dormant kinase is activated, and it phosphorylates certain proteins within the responding cell. The proteins are now activated and can perform new functions. |
|
|
Term
|
Definition
|
|
Term
| What is Shh responsible for? |
|
Definition
This peptide is responsible for patterning the neural tube such that motor neurons are formed from the ventral neurons and sensory neurons are formed from the dorsal neurons.
Sonic hedgehog is also responsible for patterning the somites so that the portion of the somite closest to the notochord becomes the cartilage of the spine. Sonic hedgehog has been shown to mediate the formation of the left-right axis in chicks, to initiate the anterior posterior axis in limbs, to induce the regionally specific differentiation of the digestive tube, and to induce feather formation. |
|
|
Term
| What are BMPs involved in, and how are they different from other members of the TGF superfamily? |
|
Definition
| They have been found to regulate cell division, apoptosis (programmed cell death), cell migration, and differentiation, as well as bone formation. BMPs can be distinguished from other members of the TGF-β superfamily by their having seven, rather than nine, conserved cysteines in the mature polypeptide. |
|
|
Term
| What are pathways between the cell membrane and genome called? |
|
Definition
| signal transduction pathways |
|
|
Term
| How do ligand-receptors effect the genome? |
|
Definition
| Each receptor spans the cell membrane and has an extracellular region, a transmembrane region, and a cytoplasmic region. When a ligand (the paracrine factor) binds its receptor in the extracellular region, the ligand induces a conformational change in the receptor's structure. This shape change is transmitted through the membrane and changes the shape of the cytoplasmic domains. The conformational change in the cytoplasmic domains gives them enzymatic activity usually a kinase activity that can use ATP to phosphorylate proteins, including the receptor molecule itself. The active receptor can now catalyze reactions that phosphorylate other proteins, and this phosphorylation activates their latent activities in turn. Eventually, the cascade of phosphorylation activates a dormant transcription factor, which activates (or represses) a particular set of genes. |
|
|
Term
| Which transcription factors to TGFs activate? |
|
Definition
|
|
Term
|
Definition
| The TGF-β ligand binds to a type II TGF-β receptor, which allows that receptor to bind to a type I TGF-β receptor. Once the two receptors are in close contact, the type II receptor phosphorylates a serine or threonine on the type I receptor, thereby activating it. The activated type I receptor can now phosphorylate the Smad proteins.These phosphorylated Smads bind to Smad 4 and form the transcription factor complex that will enter the nucleus. |
|
|
Term
| How does is maskin inactivated? |
|
Definition
Kinase phosphorylates CPEB
phosphorylated CPEB can bind CPSF
CPSF binds Maskin
translation is initiated |
|
|
Term
| What does premature activation of the FGFR3-STAT1 pathway cause? |
|
Definition
| thanatophoric dwarfism - cartilage growth is stopped before birth |
|
|
Term
| How do cells sort themselves? |
|
Definition
| Via surface cohesion, greater = inside |
|
|
Term
| How do adhesions to the extracellular matrix be released? |
|
Definition
Stretch-responsive Ca2+-channels open
The Ca2+ ions activate proteases that destroy focal adhesions |
|
|
Term
| Where are germinal granules found? |
|
Definition
|
|
Term
| How does germ plasm repress transcription |
|
Definition
| It represses the phosphorylation of RNA polII |
|
|
Term
| Which ways are PGCs formed |
|
Definition
| Maternal molecule induction, induction from pluripotent cells |
|
|
Term
| Where are PGCs formed and where do they migrate to? |
|
Definition
| The posterior regions, the gonad |
|
|
Term
| Where do the genital ridges form? |
|
Definition
| The coelom, they are derived from the mesonephros (embryonic kidney) |
|
|
Term
| What happens after female PGCs reach the genital ridge? |
|
Definition
They almost immediately enter the meiotic cell cycle and differentiate into oocytes
Females are born with all of the oocytes she will ever have |
|
|
Term
| What happens when male PGCs reach the genitral ridge? |
|
Definition
| Male PGCs multiply after reaching the GR. They do not enter meiosis. They are arrested as PGCs until released at puberty. At puberty PGCs differentiate into spermatogonia, and enter the cell cycle. Spermatogonia are stem cells that can differentiate into sperm. |
|
|
Term
| What is development of PGCs into sperm or egg determined by> |
|
Definition
The decision to of PGC to become sperm or egg is determined by Retinoic Acid (RA) Signalling RA is produced by the mesonephros In females RA induces transcription factor Stra8, which induces DNA synthesis and Entry into meiosis. This leads to oocyte Development. In males Cyp26 is an enzyme that degrades RA blocking entry. Cyp26 is expressed only in male genital ridge
In females RA induces transcription factor
Stra8, which induces DNA synthesis and
Entry into meiosis. This leads to oocyte
Development. |
|
|
Term
| How do PGCs form in drosophila? |
|
Definition
| In Drosophila, PGCs form as a group of cells (pole cells) at the posterior pole of the cellularizing blastoderm. These nuclei migrate into the posterior region at the ninth nuclear division, and they become surrounded by the pole plasm, a complex collection of mitochondria, fibrils, and polar granules. If the pole cell nuclei are prevented from reaching the pole plasm, no germ cells will be made. |
|
|
Term
| On the other page is some information, it didnt really seem to fit anywhere. I love how helpful and informative this module is. |
|
Definition
OOGENESIS -Oocytes closely associated with follicle cells in follicle.
-Oocyte and Follicle cells Produce Glycoprotein membrane called Zona Pellucida (analogous to egg shell)
-Follicle cells multiply, produce cavity called antrum
-At ovulation egg bursts from follicle on surface of ovary |
|
|
Term
| Where does early development of mammals take place? |
|
Definition
|
|
Term
|
Definition
Resact is a Chemoattractant Protein secreted by Sea urchin eggs
Sperm aggregates around chemoattractant
Resact Binding Triggers opening of Calcium Channels
Calcium Signal concentrates on one side of sperm membrane
Binding to Polysaccharides in Egg Jelly Triggers the Acrosomal Reaction
Acrosome reaction in sea urchin sperm
Polysaccharides in Egg Jelly bind to Receptors on Acrosomal Vesicle Binding of Sperm to Molecules on Egg Jelly is species Specific |
|
|
Term
|
Definition
|
|
Term
| What does a mature spermatid have at the tip? |
|
Definition
|
|
Term
| What prevents polyspermy? |
|
Definition
The addition of sperm causes
membrane depolarization
Na+ from sea water rushes in and
Charge is reversed from negative to
Positive. Sperm can no longer bind. |
|
|
Term
|
Definition
| Egg agglutination? Honestly I cant tell. possibly sperm attractant |
|
|
Term
| What is the receptor for Bindin? |
|
Definition
|
|
Term
| What is egg activation triggered by? |
|
Definition
| Phospholipase C splits PIP2 into IP3 and DAG, which lead to increased Ca++ intake. This causes Ca2+ to form intracellular calcium pools triggering corticle granule breakdown. |
|
|
Term
| Why does fertilisation troigger an increase in cytoplasmic pH? |
|
Definition
| The calcium released activates sodium hydrogen pumps. |
|
|
Term
| What does the increase in pH at fertilisation cause? |
|
Definition
Mobilizes inactive maternal
RNAs into polysomes to
increase Translation Rate
Causes in crease in protein
synthesis
Translation of maternal RNA
is repressed prior to
fertilization |
|
|
Term
|
Definition
-Mammalian Sperm is capacitated by uterine fluids.
-Capacitation is partial breakdown of acrosome. If not capacitated,
then sperm can not fertilize.
-If sperm meets ovulated egg in ampulla, then fertilization.
It weakens the acrosomal membrane, without which acrosome reaction will not occur |
|
|
Term
| What causes capacitation? |
|
Definition
ZP3 is a Sperm receptor on the Surface of the Zona Pellucida
Binding to ZP3 causes breakdown of acrosome. Enzymes from
acrosome breakdown ZP, sperm reaches egg membrane.
-Sperm fuses with egg, and enters egg.
-Sperm fusion with membrane causes cortical granule breakdown |
|
|
Term
| Which histone modifications are associated with active genes? |
|
Definition
Promoters: H3K4me3
Enhancers: H3K27Ac, H3K9Ac, H3Kme1 |
|
|
Term
| Which histone modifications are associated with inactive genes? |
|
Definition
Promoters: H3K27me3
Enhancers: H3K9me3 |
|
|
Term
| Which chromatin is active? |
|
Definition
|
|
Term
| What enzyme represses chromatin? |
|
Definition
| Deacetylase methyltransferase |
|
|
Term
| What enzyme activates chromatin? |
|
Definition
|
|
Term
|
Definition
Mammalian Sperm DNA is packaged by
Sperm specific proteins called protamines
Protamines are exchanged with histones
Stored in the egg to make them compatible |
|
|
Term
| How is demethylation of the parental genomes different? |
|
Definition
Demethylation of the Maternal Genome is passive
Demethylation of the Paternal Genome is active |
|
|
Term
| Which family of enzymes oxidise 5-methylcytosine and to what? |
|
Definition
The Tet Family of Enzymes Oxidize 5-methylcytosine
To 5-Hydroxymethylcytosine |
|
|
Term
|
Definition
|
|
Term
|
Definition
| Genomic imprinting is the epigenetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner. If the allele inherited from the father is imprinted, it is thereby silenced, and only the allele from the mother is expressed. |
|
|
Term
| Where is the imprinting pattern wiped out? |
|
Definition
|
|
Term
| What is karyokinesis and cytokinesis? |
|
Definition
Karyokinesis: Nuclear Division
Cytokinesis: Cytoplasmic Division |
|
|
Term
| What are the animal and vegetal poles? |
|
Definition
Animal pole contains nucleus and is the top of an embryo
Vegetal pole contains yolk and is the bottom of an embryo |
|
|
Term
|
Definition
|
|
Term
| What is the Wnt signalling pathway? |
|
Definition
| Wnt -> Frizzled -> disheveled -/ GSK3 -/ Beta-catenin - > transcription |
|
|
Term
| How is asymmetry generated in c. elegans? |
|
Definition
Egg cytoplasm is symmetric.
Cytoplasm contains Mex-5 protein,
Cortex contains Par-3.
Cytoplasm contains Par-2
Sperm enters opposite female
Pronucleus.
Par-2 enters posterior Cortex
and replaces Par-3.
Mex-5 is displaced towards anterior
Along with Par-3
At pronuclear fusion AB blastomere
Is surrounded by Par-3 and contains
Mex-5. P1 blastomere cortex
contains Par-2 |
|
|
Term
|
Definition
|
|
Term
| How is the expression of Par2 different in anterior and posterior cells? |
|
Definition
Par3 represses Par2 in Anterior Cell
Par2 Represses Mex
So Mex is Expressed
Mex represses Pie-1
Par2 represses Mex in Posterior Cell
Pie-1 is Expressed
Pie-1 is Master regulator of PGCs |
|
|
Term
| How is snail coiling controlled? |
|
Definition
|
|
Term
| Where does division occur in syncytial blastoderm? |
|
Definition
|
|
Term
| What occurs to the ventral tube in gastrulation? |
|
Definition
|
|
Term
| How is anterior-posterior polarity induced in drosophila? |
|
Definition
Gurken RNA is produced by the oocyte nucleus
Nucleus moves to posterior of egg
Gurken Protein activates Torpedo receptor
in follicle cells
Activation of Torpedo Posteriorizes follicle cells
Causes Par1 localization to posterior
Par1 orients microtubules
Nanos RNA is translocated to the Posterior Pole by microtubules and Kinesin (which moves towards Positive end)
Bicoid RNA is translocated to the Anterior Pole by microtubules and Dynein (which moves towards Negative end)
Nucleus is pushed by microtubules of expanding oocyte into anterior dorsal Periphery and expresses zygotic Gurken gene |
|
|
Term
| How is a dorsal ventral gradient established in drosophila? |
|
Definition
Oocyte nucleus travels to anterior dorsal side of oocyte where i localizes gurken mRNA.
gurken messages are translated, gurken is received by torpedo signals during mid oogenesis. Torpedo signal causes follicle cells to differentiate to a dorsal morphology.
Synthesis of pipe is inhibited in dorsal follicle cells.
Gurken does not diffuse to ventral side.
Ventral follicle cells synthesize Pipe. |
|
|
Term
|
Definition
|
|
Term
|
Definition
Pipe Induces Sulfation of Vitelline Membrane Proteins
Gastrulation defective (GD) Binds Sulfated
Proteins, establishes Protease Complex
GD Cleaves snake
Snake, Easter are proteases that are activated by cleavage. They Cleave Spaetzle
Cleaved Spatzle Binds to Toll Receptor
Active Toll Receptor Activates Pelle
Pelle is a kinase that phosphorylates Cactus
Phosphorylation of Cactus destoys it,
releasing Dorsal to enter the nucleus
Dorsal is a transcription factor that activates ventral gene expression
Pipe Expression in
Ventral Follicles Activates Dorsal |
|
|
Term
| What are the dorsal/ventral layers, descending from dorsal? |
|
Definition
Dorsal
Amnioserosa
Dorsal ectoderm
Lateral ectoderm
neurogenic ectoderm
Mesoderm
ventral |
|
|
Term
| How does dorsal induce mesoderm? |
|
Definition
Mesoderm is induced by expression of Dorsal protein in ventral cells.
Targets of Dorsal include: Twist , Snail, FGF8, the FGF8 receptor and rhomboid.
Dorsal binds to enhancers of Twist and Snail with low affinity; therefore, only high levels of Dorsal can activate expression of these genes.
Twist activates mesodermal genes; Snail represses non-mesodermal genes
Lower levels of Dorsal can activate FGF8 and rhomboid
Snail represses expression of FGF8 and Rhomboid,
so they are only expressed in the neurogenic ectoderm |
|
|
Term
|
Definition
Dpp is the Drosophila
Homolog of BMP
Sog (Short Gastrulation)
is Homolog of
Chordin |
|
|
Term
|
Definition
Sog (short gastrulation) inhibits DPP
Sog is activated by Dorsal
Sog inhibits DPP
Short Gastrulation is activated by Dorsal |
|
|
Term
|
Definition
The bicoid gene encodes the morphogen
responsible for head structures
Anterior
bicoid is a transcription factor
It activates hunchback expression
bicoid also is a translational regulator
It inhibits translation of caudal RNA |
|
|
Term
| Where is bicoid tethered? |
|
Definition
|
|
Term
| What does nanos and caudal do? |
|
Definition
Posterior
nanos is a translational inhibitor
It inhibits hunchback RNA translation
Caudal is a transcription factor
It activates genes responsible for development of the abdomen |
|
|
Term
|
Definition
Segmentation genes divide early embryo into
repeating series of segment primordia along
the anterior/posterior axis
They were defined by mutants
Gap gene mutants lack large regions of the
body (several contiguous segments)
Pair Rule mutants lack portions of every other segment
Segment Polarity mutants show defects
(deletions, duplications, polarity reversals) in every segment |
|
|
Term
| Which are the gap genes and how are they regulated? |
|
Definition
The Gap genes hunchback, Kruppel, knirps and giant
Span the entire segmented region of the embryo.
They are transcription factors that regulate
Each other expression by mutual repression
This establishes the boundaries between
segments |
|
|
Term
| What do segment polarity genes do? |
|
Definition
establish cell fate within a segment
They determine positional identity within the segment as well as the Anterior/Posterior polarity within an individual segment |
|
|
Term
| What cell-cell comunication is there between segment identity genes? |
|
Definition
engrailed activates expression of
frizzled, the receptor for wg,
and activates expression hedgehog
Hedgehog signalling maintains
Wg expression. Wg maintains
Hedgehog expression
Reciprocal interaction maintains
Cell identity in the absence of
Maternal Factors that established
segment identity |
|
|
Term
| What occurs after segmental boundaries are set in drosophila? |
|
Definition
After segmental boundaries are set, the pair-rule genes and gap genes interact
To regulate expression of the homeotic selector genes, which specify the
Characteristic structures of each segment |
|
|
Term
| What are morpholino oligos? |
|
Definition
Advanced tools for blocking sites on RNA to obstruct cellular processes. A Morpholino oligo specifically binds to its selected target site to block access of cell components to that target site. This property can be exploited to block
translation, block splicing, block miRNAs or their targets, and block ribozyme
activity. |
|
|
Term
|
Definition
| immature, actively dividing cells |
|
|
Term
| How can cells undergoing cell death be visuallised? |
|
Definition
| A tunel assay that detects broken DNA, or detecting proteins only expressed during apoptosis |
|
|
Term
| What is Proliferating Cell Nuclear Antigen (PCNA)? |
|
Definition
| An antigen expressed in S phase |
|
|
Term
| What three options are there for generation of new cells? |
|
Definition
(a) mature cells retain/regain ability to divide - mammalian liver, zebrafish heart
(b) mature cells dedifferentiate, divide and redifferentiate - axolotl limb
(c) immature cells divide and differentiate
high cell turnover tissues (blood, intestine, epidermis)
mammalian liver after severe injury (oval cells) |
|
|
Term
| What are adult stem cells? |
|
Definition
Are immature cells that divide to give rise to daughters that
– are stem cells ( self-renew )
– are progenitor cells that differentiate (become distinct cell types) |
|
|
Term
| What are more common than true stem cells? |
|
Definition
| Semi-committed progenitors |
|
|
Term
| Where are long term replicating haemopoetic stem cells found? |
|
Definition
|
|
Term
| What are macroscopic spleen colonies? |
|
Definition
They are derived from proliferative
cells, are clonal, i.e. are derived from a single progenitor, a CFU-S (colony-forming unitspleen)
– donor BM cells were injected into an irradiated host
– the host was then irradiated again causing genomic abnormalities in the injected donor cells
– donor cells formed spleen
colonies
– all cells of one spleen colony had the same abnormality
• Contain differentiated cells
from several lineages:
– Erythrocyte
– Megakaryocyte
– Granulocyte |
|
|
Term
| When are LTR-HSCs used medically? |
|
Definition
used mainly in cases of red blood cell deficiency and leukaemia
– cells are isolated directly from the bone marrow or mobilised into the blood stream and isolated from it |
|
|
Term
| What is the stem cell niche? |
|
Definition
The niche is the regulatory microenvironment that stem cells sit in
Roles of the niche -
– provides anchorage
– controls stem cell biology
• maintenance of stem cells
• formation of progenitors
➡ controls self-renewal vs differentiation
• paracrine factors, cell-cell adhesion and cell-ECM
interactions maintain the cells in an uncommitted state
– once outside the niche, the cells do not receive these anymore and differentiate
• the niche needs to respond to local and systemic cues
➡ its a flexible and changing environment |
|
|
Term
| How is the fate of HSCs determined? |
|
Definition
- prior programming of the cell
- stochastic (random) intrinsic events
- signals from environment (conditional) |
|
|
Term
| What paths can HSCs take? |
|
Definition
With GATA-1 -> lymphoid progenitor, then B cells or T cells.
With GATA-1 and Pu.1 -> Myeloid progenitor
From myeloid progenitor - GATA-1 leads to megakaryocytes and red cells, and Pu-1 leads to granulocytes and macrophages |
|
|
Term
| What are the issues with stem cells and how could they be circumvented? |
|
Definition
problems:
1. ES cells used in cell
transplantation will not be
genetically identical to the patient
➡ risk of rejection
2. "ethical issues" as cells need to be
removed from an embryo
• these could be circumvented by
reprogramming somatic patient
cells
– forced expression of TFs
reprograms somatic cells
– induced pluripotent stem cells
(iPS cells) |
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