Zoo 470 Exam 1

Front 1

Epigenesis

Back 1

Complexity arises through the interaction of simpler parts

Front 2

Preformation

Back 2

Idea that the head of the sperm had all the information to provide embryo

Front 3

Differentiation

Back 3

The process by which differing properties are conferred on parts of the embryo at different times and inspecific locations, such that specific structures arise in the mature organism in a reliable fashion.(How parts become different)

Front 4

Morphogenesis

Back 4

The study of the mechanisms by which the shape of the embryo arises

Dynamic movements of tissues and cells

Front 5

Pattern Formation

Back 5

The process by which different regions of an embryo become spatially organized to produce different structures

Front 6

Germ Layers

Back 6

Primary tissue layers that ultimately generate all of the major differentiated tissues of the bodyThe three germ layers are ectoderm, mesoderm, and endoderm

Front 7

Induction

Back 7

The process by which one cell or tissue (the inducer) sends a signal to a second cell or tissue (the induced cells), resulting in a specific and reproducible change in their differentiation

Front 8

Sufficiency

Back 8

When a group of cells (or molecule), when added to a cell, embryo, or tissue, confers the ability to differentiate in a particular way

(Does NOT mean a molecule or group of cells is necessary)

If a cell or molecule is sufficient but not necessary, this often indicates functional redundacy

Front 9

Necessity

Back 9

When a group of cells (or molecule), is removed from a cell, embryo, or tissue, the ability to differentiate in a particular way is lost

(Does NOT mean a molecule or group of cells is sufficient)

If something is necessary but not sufficient, it indicates it acts together w/ other essential cells/molecules

Front 10

Specification

Back 10

The extent to which a cell or tissue will differentiate normally placed in new surroundings

Front 11

Autonomous Specification

Back 11

Early decisions (know what they will be->develop correctly with their function); reproducible divisions

Often associated with localized determinants-> can be necessary, sufficient or both

Front 12

Conditional Specification

Back 12

Late decisions (in sea urchins: when isolated, made small proportionate larva) ; variable decisions

Often associated with "regulative development"

Front 13

Fate Mapping

Back 13

Process by which cells in an early embryo are followed to see what progeny they make later in development.

Fate mapping can involve applying bits of color to the exterior of the embryo, simply watching embryos carefully, or injection of a tracer into the cytoplasm of individual cells.

Front 14

The "Lineage" Plan

Back 14

A cell has become polarized; molecules are found in one region but not another

- If the cell divides in one way, both cells receive some of the molecule

Front 15

Why Do Clones Die?

Back 15

-Defects in chemical status of chromatin (DNA & associated proteins, called histones)

- Chemical status of DNA is established separately from simple transfer of chromosomes to offspring

Front 16

"Therapeutic" Cloning

Back 16

Deriving embryonic stem cells from blastocysts' inner cell mass; purposefully destroying embryo

Goal: genetically matched cells to replace or repair damaged cells

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Clone

Back 17

From Greek "twig"

Clones are genetically identical to a preexisting organism

Front 18

Totipotency

Back 18

Able to make any cell in the embryo/body

Front 19

Pluripotency

Back 19

Able to make almost all of the different cell types in the embryo/body

Front 20

Stem Cells

Back 20

Can divide to form more stem cells or cells that go on to differentiate

Front 21

Teratomas

Back 21

Are tumors formed from ICM or ES cells. If cells can make teratomas, this is evidence they are pluripotent

Front 22

Transdifferentiation

Back 22

Direct reprogramming of cells without going through a pluripotent stem cell step; can be accomplished using specific transcription factors involved in forcing cells to differentiate

Front 23

Cell Surface "Sorting Out"

Back 23

Front 24

Intercellular Junctions

Back 24

Adhesion molecules assemble at specific locations into elaborate structures in sheets of cells (epithelia)

- Adherens junctions: contain cadherins & confer adhesion

- Tight junctions: form a permeability barrier/seal cells

- Gap junctions: allow passage of small molecules between cells

-Demosomes: form mechanically strong "spot welds" between cells

Front 25

The Extracellular Matrix

Back 25

Collagen: is a scaffold for adhesion proteins, such as fibronectin & laminin

Integrins: allow cells to bind to ECM proteins & to the cytoskeleton

Proteoglycans & Glycosaminoglycans (GAGs): are space-filling molecules that swell in contact w/ water

Front 26

Epithelia & the ECM

Back 26

The ECM associated w/ the inner side of epithelia often contains laminin & it is often called a basal lamina

Hemidesmosomes allow cells in epithelia to attach to the ECM

- contain specialized integrins

Front 27

Cytoskeleton

Back 27

Allows cells to move & to move internal components

3 main types of cytoskeletal filaments: polymers that form from subunits

- Microtubules: tubulin polymers

- Microfilaments: actin polymers

- Intermediate: IF subunits

Front 28

Drugs that Perturb the Cytoskeleton

Back 28

Front 29

Molecular Motors

Back 29

Molecular motor proteins attach to actin (myosins) or MTs(dyneins & kinesins). They couple ATP hydrolysis tomovement along cytoskeletal filaments.

Front 30

Dyneins & Kinesins

Back 30

Kinesins move towards the plus ends of MTs

Dyneins move towards the minus ends of MTs

Front 31

Actin & Cell Crawling

Back 31

Actin polymerizes at the leading edge as cells crawl to help form protrusions

- thin protrusions: filopodia

- broad, flat protrusions: lamellipodia

Front 32

The Extracellular Matrix: Integrins

Back 32

Integrins attach to the ECM (e.g. fibronectin)

- their cytoplasmic tails bind to F-actin via linker proteins

Clusters of integrins are focal adhesions

Front 33

Cadherins and the Cytoskeleton

Back 33

Cadherins are transmembraneproteins. In the cytoplasm, they connect to actin via b- and a-catenin

Front 34

Receptors & Phosphorylation

Back 34

Receptors often act as kinases, i.e. they catalyze addition of phosphates to themselves or other proteins

Front 35

Ca2+ & IP3

Back 35

Ca2+ & IP3 are second messengers (first messengers=ligand binding to surface)

- IP3 binds to proteins on the wall of the endoplasmic reticulum (ER)

- opens channel for Ca2+ to pass through

Different receptors can use the same messenger

Front 36

Spermatogenesis

Back 36

Meiosis separates cytoplasm equally

- Mitochondria are needed to produce ATP for flagellar dyein

- The acrosomal vesicle contains enzymes released during fertilization

Front 37

Acrosomal Vesicle

Back 37

Vesicle in sperm head containing digestive enzymes and othercomponents. The AV fuses with the sperm plasma membrane following the acrosomereaction.

Front 38

Oogenesis

Back 38

Meiosis separates cytoplasm unequally

Front 39

Polar bodies

Back 39

Small products of meiosis

Small product of each of the two female meiotic divisions. The oocyteretains virtually all of the cytoplasm, whereas the polar bodies have very little cytoplasm

Front 40

Testis Organization

Back 40

Sperm maturation occurs in the epididymis; in order to fertilize efficiently, capacitation must occur in the female reproductive tract

Sertoli cells are connected to & provide nutrients for developing spermatids

Leydig cells make testosterone

Front 41

Sperm Structure

Back 41

The sperm's flagellum uses microtubule sliding within the axoneme to accomplish bending

- the axoneme has a "9+2" arrangement of microtubules

Flagellar dyneins are positioned so that outer doublets can interact

Front 42

Flagellar bending

Back 42

Dyneins are positioned to slide adjacent doublets, which are locked together into an integrated network

Front 43

Broadcast Spawning

Back 43

Release of large numbers of gametes into an aquatic environment

Front 44

Oocyte Structure

Back 44

Oocytes in meiosis I have a large nucleus (germinal vesicle). Many oocytes contain localized determinants, typically mRNAs.

- the less yolky end=animal pole

- the opposite=vegetal pole

Front 45

Ovary

Back 45

One follicle per ovulatory cycle matures in humans (follicular dominance)

Dominance may involve local production of growth factors by the follicle that "wins"

Front 46

Oogenesis in Mammals

Back 46

The mature follicle must rupture to release the oocyte, which normally is swept into the Fallopian tube

Front 47

Female Reproductive System

Back 47

Fimbriae sweep the oocyte/cumulus complex into the open end of the Fallopian Tube

Front 48

Hormone Regulation in the Ovary (Control of Ovulation)

Back 48

A surge of LH (luteinizing hormone) & FSH (follicle-stimulating hormones) stimulates ovulation

Front 49

Hormonal Regulation of the Uterus (Control of Ovulation)

Back 49

A surge of estrogen contributes the FSH/LH surge; progesterone stimulates uterine lining thickening

Front 50

Estrogen & Progesterone

Back 50

Estrogen is made by connective tissue cells in the ovary.Progesterone is made by the follicle, but especially by the remnant of the follicle (corpus luteum).

Estrogen and progesterone inhibit hormone production by the hypothalamus and pituitary

Front 51

Ovulation: Hormonal Feedback Control

Back 51

The hypothalamus stimulates the anterior pituitary via the release of gonadotropin releasing hormones (GnRHs) specific for particular gonadotropins, e.g., LH or FSH

Gonadotropins positively regulate cells in the ovary.

Front 52

Human Chorionic Gonadotropin & Progesterone

Back 52

hCG is made by the embryo & stimulates the corpus luteum to maintain progesterone production

Front 53

RU486 & Progesterone

Back 53

RU486/mifepristone binds the progesterone receptor but does not activate signaling, thereby competing with progesterone

Front 54

Sea Urchin Egg Structure

Back 54

Egg jelly produces molecules that attract sperm

Egg jelly triggers acrosome reaction

Front 55

Sea Urchin Egg Structure: Vitelline Envelope

Back 55

The vitelline envelope (attached to the egg plasma membrane) will be remodeled after fertilization to form the fertilization envelope

Front 56

Mammalian Oocyte Structure

Back 56

Sperm bind to & digest through the zona pellucida

The cumulus complex contains proteoglycans.

Front 57

Zona Pellucida

Back 57

Front 58

Stages of Oocyte Meiotic Arrest

Back 58

Oocytes have not completed meiosis when they are fertilized

Eggs have completed meiosis

Most mammalian & amphibian oocytes are arrested in metaphase II

Front 59

MPF & CSF: Yoshio Masui

Back 59

Maturation promoting factor (MPF) causes oocyte maturation; cytostatic factor causes arrest at metaphase II by preventing destruction of MPF

Front 60

Meiotic Maturation: MPF

Back 60

Cytoplasm is extracted from a mature egg cell

Extracted cytoplasm is injected into an oocyte

- both via micropipette

Meiosis is triggered

Mature egg cell results

Conclusion: MPF promotes maturation but results in arrest at metaphase II

Front 61

MPF Activation

Back 61

MPF consists of a cyclin & a cyclin-dependent kinase (Cdk)

MPF is active when the Cdk is appropriately phosphorylated

Front 62

CSF causes Metaphase Arrest

Back 62

One blastomere injected at 2-cell stage -> no division

Spindle arrested at metaphase

Conclusion: CSF must prevent inactivation of MPF, since the injected cell arrests at the next metaphase

Front 63

What Does Fertilization Accomplish

Back 63

Sexual reproduction allows meiotic recombination (increasing genetic variation)

Restores the diploid genome

Sperm brings in the paternal centrosome (organizes microtubules for pronuclear migration & first mitosis)

Species-specific sperm/egg union

Leads to blocks to polyspermy

Egg activation (includes completion of meiosis in many species)

Front 64

Sea Urchin Sperm Undergo Chemotaxis toward RESACT

Back 64

Chemotaxis: moving toward higher concentrations of a molecule (the chemoattractant)

RESACT is a peptide released from egg jelly

Front 65

Sea Urchin Fertilization

Back 65

1. Sperm contacts jelly layer

2. Acrosomal reaction

3. Digestion of jelly layer

4. Binding to vitelline envelope

5. Fusion of acrosomal process membrane and egg membrane

Front 66

Calcium ionophores

Back 66

Drugs that trigger release of calcium in the absence ofnormal signals

Front 67

Sea Urchin Fertilization Prevention

Back 67

Fast block- involves membrane depolarization (occurs within milliseconds to a few seconds)

Slow block- cortical granules release proteases that release the envelope

- also release enzymes that result in hardening of the envelope & proteoglycans that swell, aiding in lifting the envelope

Front 68

Sea Urchin Sperm/Egg Fusions

Back 68

The "fertilization cone" draws sperm in

Front 69

Mammalian Fertilization Steps

Back 69

1. Sperm activated by female reproductive tract

2. Sperm binds zona pellucida

3. Acrosomal reaction

4. Sperm lyses hole in zona

5. Sperm and egg membrane fuse

Front 70

Mammalian Fertilization

Back 70

The cumulus layer partially activates sperm; the zona triggers the full acrosome reaction

Mammalian sperm do not make an acrosomal process

The zona pellucida contains 3 main proteins: ZP3 (glycosylated), ZP2 & ZP1

Front 71

Zona Remodeling & Slow Block

Back 71

The zona is enzymatically remodeled after fertilization. This contributes to the slow block to polyspermy, in mammals

Front 72

Calcium indicators

Back 72

Allow us to visualizecalcium concentration