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Embryology Test 1 > Entire Study Guide > Flashcards

Entire Study Guide Flashcards

2
Q

What is epigenesis?

A

Epigenesis is the idea that the embryo builds itself one step at a time, which is contrasted to preformation

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2
Q

What are the three hypotheses for cell differentiation? How can we test these hypotheses?

A
  1. Differential gene loss2. Selective gene amplification3. Genetic equivalence with differential gene expression. # can test with cloning!
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2
Q

PCR

A

Amplify a specific gene of interest

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2
Q

Describe the findings and hypotheses behind the “sorting out” (differential adhesion) experiments?

A
  1. Took neural plate cells and epidermal cells, jumbled them and then they were able to sort out by cell type. 2. Repeated with many different types of cells and found similar results3. *Differential Adhesion hypothesis* = cells sort to be nearer to cells with similar adhesion properties4. Altered Cadherin levels within cells and observed how the cells sorted - those with similar levels were conjugated, higher quantity = centered.
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2
Q

What does meiosis accomplish?

A
  1. 4 daughter haploid germ cells, recombination occurs (genetic variation), 2. Each cell has of 1 copy of each chromosome
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3
Q

Contrast epigenesis with preformation

A

Preformation is the idea that a miniature human is contained within the sperm or the egg. Epigenesis is the idea that the embryo builds itself one step at at time.

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3
Q

Describe differential gene loss hypothesis?

A

First cell has all of the genes for the organism, daughter cells only have a subset.

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3
Q

DNA Microarrays

A

Can analyze differential expression of genes throughout the entire genome at once

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3
Q

What are cadherins? catenins?

A
  1. Cadherins are intermembrane proteins that interact with cadherins of other cells for adhesion2. Catenins - small proteins with 3 subunits that anchor cadherins to the cytoskeleton
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3
Q

What are the differences between meiosis in sperm and eggs?

A

Sperm - symmetry of meiotic separations. Metaphase plate is always in the center of the cell. Eggs - Asymmetric divisions. Creates 3 polar bodies and one egg. Metaphase plate is located on one side of the cell.

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4
Q

What are the two “big ideas” of embryology?

A

Differentiation and Morphogenesis

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4
Q

Describe selective gene amplification hypothesis

A

Certain genes are preferentially amplified within cells, which affects the cell fate.

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4
Q

Western Blotting

A

Quantify protein abundance of a single protein

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4
Q

What evidence suggests that cadherins are involved in sorting out?

A
  1. Mixing cells with p and e cadherins, quantity seems to be the most important factor. When cells have equal quantities of cadherins, proper sorting does not occur. 2. Also, if we delete catenins, the cadherins can be “ripped out” of the cell membrane and will not sort properly.
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4
Q

What is a polar body?

A

Result of meiotic divisions, are barren cells that contain a haploid genome.

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5
Q

What is differentiation?

A

Differentiation is the idea that different parts of the body are conferred from different parts of the embryo an at different times

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5
Q

Describe the genetic equivalence with differential gene expression hypothesis

A

(what actually happens) - Each cell has every gene. Each cell can express the genes differently to achieve different functions

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5
Q

Northern Blotting

A

Quantify RNA abundance

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5
Q

What major cytoskeletal systems are there in cells, what are they made of, and what are their functions?

A
  1. Microtubules (tubulin dimers) – a. important for transportation of cargo throughout the cell, via molecular motors, dynein and kinesin.b.they important in cell division and structure.c. They are also important in molecular motors such as in flagella and form the mitotic spindle. 2. Microfilaments (actin monomers) – Important in cell crawling3. Intermediate Filaments (intermediate filament proteins) – give rigidity to tissues
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5
Q

What is the basic structure of the seminiferous tubule in mammals?

A

Spermatogonium are around the exterior of the tube. The developing spermatids align adjacent to sertoli cells and have their tails facing the lumen of the tubule.

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6
Q

What is morphogenesis?

A

The dynamic movement of tissues and cells. Also, the study of the mechanisms by which shapes of the embryo arises.

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6
Q

What experiments in amphibians indicate genomic equivalence of nuclei?

A
  1. A somatic cell was enucleated and the nucleus and meiotic spindle was implanted into an activated egg. Clone was created, which indicates genomic equivalence because the somatic cell contained all of the information necessary for a full frog to develop. 2. Albino frog cloning. Albino nucleus donors grown in WT frogs resulted in all albino offspring.
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6
Q

Southern Blotting

A

Quantify DNA abundance

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6
Q

What is the major cytoskeletal system involved in cell migration?

A

Microfilaments

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6
Q

What is the function of the Sertoli cells?

A

Provide nutrients and “nurse” the sperm

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7
Q

What are the two types of specification?

A

Autonomous and conditional

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7
Q

How does the nucleus exert its effects on differentiated cells?

A

By expressing different genes at required levels to achieve desired cell function.

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7
Q

Immunostaining

A

Localization of proteins within cells/organisms

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7
Q

How do integrins function in promoting cell migration?

A

Integrins link the cytoskeleton to other extracellular stuff and provide traction for the cell. They do not link to other cells, as do cadherins.

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7
Q

Why are Type A1 spermatogonia considered stem cells?

A

Type A1 spermatogonia are non-differentiated and are constantly producing new Type A1 cells which will be made to make more A1 cells. They are also used to make type A2 cells, which are then further differentiated.

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8
Q

What is autonomous specification? + example?

A

cell fate is determined at a very early age. Mollusks

8
Q

Describe experiments that resulted in Dolly

A

Udder cells were removed (original dolly), and entire cell as implanted into the egg of a Scottish Blackface surrogate. The egg and cell were fused in a petri dish, and the embryo was cultured for 7 days. The embryo was then implanted into the surrogate mother.

8
Q

in situ hybridization

A

measures RNA expression of specific mRNAs

8
Q

What is the extracellular matrix (ECM)?

A

The ECM is a complex of proteins on the outside of the cell that has roles in cell adhesion, cell migration, and epithelial sheet formation

8
Q

What specializations are present in sperm that relate to their function? (For example, what is the acrosome? How does the flagella work?)

A
  1. Centriole organizes in center, which grows microtubules2. Acrosome is made from GA and carries enzymes that degrade egg outer membrane3. Flagella have abundant mitochondria and are made of microtubules that propel the cell forward by a spinning or undulating motion.
9
Q

What is conditional specification? + example?

A

cell fate is determined late. Divisions are variable. For example, 1/4 of the sea urchin larva can grow a full sea urchin.

9
Q

(1) What is “large offspring syndrome”, and (2) what is it thought to be caused by?

A
  1. Large offspring syndrome is when the clones are born much larger than normal2. Possible explanation is imprinting, in which parental methylation patterns lack maternal and paternal patterns and thus cause LOS through (3).3. Father contributes Insulin-like growth factor 2 (Igf2) which enhances growth, mother contributes active H19 and igf2r, which serve to reduce growth for an easier pregnancy. In LOS, the clone may lack the mother’s expression patterns and thus be dominated by the father’s ifg2 expression.
9
Q

RNAi

A

degrade target mRNA

9
Q

What are the major ECM molecules?

A
  1. Collagen2. Proteoglycans3. Specialized Glycoproteins4. Fibronectin5. Laminin 6. Integrins7. Basil Lamina
9
Q

What is the structure of the ovary?

A

The ovaries contain eggs used for reproduction. The eggs are maintained within follicles. The follicles grow and mature and become grafian follicles. This mature follicle eventually binds to the outer membrane and ruptures releasing the secondary oocyte. Old follicles mature into a corpus luteum, which produces fats and progesterone as it heals and then is eventually degenerated.

10
Q

(1) What are the two types of cloning? (2) Describe the difference between the two.

A
  1. Reproductive & Therapeutic cloning2a. Reproductive = cloning to the point of full offspring development.2b. Therapeutic = cloning embryo, but removing blastocysts inner cell mass for embryonic stem cells. Aka, no functional offspring results.
10
Q

Morpholinos

A

Small oligonucleotide prevents specific mRNA from attaching to ribosome - prevents translation

10
Q

Collagen

A

Provides strength

10
Q

What is the corpus luteum, and what is its function?

A
  1. Develops from the follicular cells surrounding an ovarian follicle 2. The corpus luteum produces progesterone, which serves as a sort of master regulator of the pregnancy and serves to inhibit the release of hormones from the hypothalamus and AP gland and induce the Uterine Lining to prepare for implantation.
11
Q

What is the state of legislation in the US regarding human cloning?

A

Currently, no federal law prohibits cloning. 7 states ban all forms of cloning, 8 ban only reproductive cloning. Some don’t ban any cloning

11
Q

Genetic Mutagenesis

A

Forward genetics - increase (cause) random mutations

11
Q

Proteoglycans

A

absorb water and fill space

11
Q

GnRH

A
  1. Gonadotropin releasing hormone2. From Hypothalamus, to AP3. Causes release of FSH & LH
12
Q

Genetic KO

A

Reverse genetics - remove one specific gene

12
Q

Fibronectin

A

cross linker, and can form structures

12
Q

FSH & LH (Female)

A

released from AP & act on ovary to induce ovulation

13
Q

Transgenics

A

Adding a new copy of a gene

13
Q

laminin

A

structural support, part of the basil lamina

13
Q

Estrogen

A

released from ovary, causes increase in GnRH from hypothalamus, and resulting LH and FSH release from AP. Positive feedback loop alone, negative with progesterone.

14
Q

Integrins

A

transmembrane, link the actin cytoskeleton to the extracellular matrix

14
Q

Progesterone

A

Acts with estrogen to cause a negative feedback loop which slows the release of GnRH from HT, and FSH and LH release from AP, and prevents induction of ovulation from ovary.

15
Q

Basal Lamina

A
  1. laminal layer that can separate two types of cells to serve as a filter, such as in kidneys. 2. Layer of the ECM3. Can surround entire cell or be made into a layer under a layer of epithelial cells 4. Made of integrins
15
Q

FSH (male)

A

causes spermatogenesis

16
Q

Three major types of cell signals?

A
  1. Endocrine – secreted factors/hormones (act distant)2. Paracrine – secreted diffusible factors (act locally)3. Juxtacrine – ECM membrane proteins interact between cells (cells must be touching)
16
Q

LH (male)

A

causes production of testosterone which serves as a negative feedback loop on GnRH release

17
Q

How do signals at the cell surface get transferred from a transmembrane receptor via signal transduction to the interior of the cell?

A
  1. Receptor-ligand binds2. Signal transduction (via secondary messengers) 3. Cellular responses (in the cytosol)4. Changes in gene expression (in the nucleus)
17
Q

Testosterone

A

released from testes after LH stimulation and serves as a negative feedback loop on GnRH in the hypothalamus. Also has roles in primary and secondary sex characteristics

18
Q

What are growth factors?

A
  1. Compared and contrasted to hormones, growth factor = short-range ligands (juxtacrine and paracrine), contact driven or short range. 2. In contrast to hormones that travel through the blood stream.
18
Q

What is the role of human chorionic gonadotropin in maintaining pregnancy?

A

hCG causes a positive feedback loop that helps maintain the pregnancy. It helps by increasing progesterone production of the corpus luteum and supports endometrium, inhibits contractions, and firms the cervix.

19
Q

What are the major pathways of cell signaling during development?

A

5 Major Paracrine Signals2 Major Juxtacrine Pathways

19
Q

What is the molecular mode of action of the standard birth control pill?

A

estrogen and progestin (synthetic progesterone) – works to prevent ovulation, increase cervical mucus to prevent sperm travel, and alters the uterine lining to prevent implantation

20
Q

5 Major Paracrine Signals

A
  1. Fibroblast Growth Factor (FGF) family2. Hedgehog family3. Wnt family (aka wingless)4. TGF-Beta superfamily5. Jak/STAT
20
Q

Plan B

A

high levels of progestin (synthetic Progesterone) – causes same effects as standard birth control an induces menses

21
Q

2 Major Juxtacrine Pathways Used Throughout development

A
  1. Notch Signaling 2. Eph/ephrin signaling
21
Q

RU486

A

Binds to progesterone receptor and has inhibitory action – induces menses, contractions and dilation of the cervix

22
Q

What effects does inositol triphosphate (IP3) have on the endoplasmic reticulum?

A
  1. PIP2 cleaved into DAG and IP32. IP3 binds to calcium receptors in the ER membrane and cause Ca+ efflux which causes activation of various proteins in the cell 3. Calcium stimulates Na+/H+ exchange pumps which increase alkalinity and causes stimulation of cell division, DNA synthesis, and RNA translation which causes egg activation
22
Q

How do we trigger superovulation for in vitro fertilization?

A

By Increasing LH and FSH, we cause superovulation which causes multiple follicles to mature an increases the likelihood of pregnancy

23
Q

At what stage(s) of meiosis are mammalian oocytes/eggs arrested?

A

Second Metaphase

24
Q

How do cdks and cyclins regulate the cell cycle?

A

CDKs act to active Maturation Promoting Factor (MPF), which initiates 1st meiotic metaphase. CDK levels are constant, but the levels of active CDK vary with the amount of cyclins that are present. CDK activation causes cyclin degredation to prevent constant CDK activation.

25
Q

Describe the meiotic cycle of the egg with respect to the control of MPF.

A

MPF activation serves to activate the 1st meiotic metaphase to allow for egg maturation to occur. LH triggers MPF activation after puberty.

Embryology Test 1 (6 decks)

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