BIOC19H3 Lecture Notes - Lecture 2: Secretion, Polarity In Embryogenesis, Ecdysone

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pucemarten532

13 Nov 2014

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The 8 cell- stage is called a morula. The morula undergoes cell division which forms the blastula which is the hollow ball structure. The blastula envaginates on itself to form gastrula. It"s the nucleus where we have differential gene expression. The cytoplasm also affects the nucleus. Also, different cell types arise due to differential gene expression in different cell types. This theory suggests that different cells contain different genes. Slide 7 (1930s) hans worked with fertilized egg of newts because they have large eggs. He tied a loop around the newt egg, and tightened it so it squeezed the egg into 2 parts. In one of the parts there was cytoplasm that had the zygote nucleus. In the other part there was no nucleus. He let the embryonic division proceed. He saw that the part that contained nucleus underwent cellular division and cells formed on that side by dividing normally. The other side didn"t do anything.

Related Questions

Hello can you help me with the following questions:

1. Which part of an udder was transferred to an empty oocyte to clone the sheep Dolly?

a. blastocyst (I think its this one)

b. meiotic spindle

c. intact udder cell

d. nucleus

2. What is the principle of nuclear equivalence?

a. Differentiated cells have lost DNA that codes for other cell types.

b. All nuclei are the same shape.

c. Only nuclei of germ cells contain DNA capable of producing an entire organism.

d. The genome of every somatic cell contains information capable of generating any other cell type in the body.

3. A gene contains 6 exons, numbered 1-6. Which of the following mRNA isoforms is not a possible transcriptional product of this gene?

a. 1-2-3-4-5-6

b. 2-5-3-4

c. 2-4-5-6

d. 5-6

4. Which of the following is a mechanism used to alter gene expression using mRNA transcripts?

a. Different stability (longevity) of mRNA transcripts

b. Inhibition of translation of certain mRNAs

c. Production of small RNA molecules (microRNAs) that block translation

d. All of the above

e. None of the above

5. You have recently started working in an embryology lab and have obtained a large number of unfertilized zebrafish oocytes. You decide to treat the oocytes with RNAse (a protein that will degrade RNAs, but leave DNA proteins intact) prior to fertilizing them. Will the resulting embryos develop into normal fish?

a. Yes, because RNAs from sperm cells can replace those lost from the egg.

b. Yes, because intact DNA is the only factor required for development to proceed.

c. No, because RNAse treatment will damage the structure of the oocyte.

d. No, because maternal mRNAs are required for the early stages of development.

When Sheila and Tyrone's daughter Mallory was born, on June 12. Anika was pregnant.
after she missed her period. Anika and her husband. Jeremy, were thrilled at the news,
Anika's last menstrual period began on April 3, and she's taken a pregnancy test a week
because a few months earlier she'd also thought she was pregnant. At that time, she had
started cramping and bleeding, and an ultrasound scan showed an empty sac- there was
no embryo. Anika knew from her biology classes that this probably meant that a sperm
had entered a polar body, which is a product of meiosis in the female that has very little
cytoplasm and is not the functional equivalent of an oocyte. The hormonal changes
typical of pregnancy had ensued anyway, which was why her pregnancy test had been
positive.
For the current pregnancy, at her first prenatal visit to an obstetrician, an
ultrasound scan confirms that Anika is in her fifth week. This time, instead of an empty
sac, the embryo looks like a lima bean with a pulsating blip in the center- beating
heart.
As Anika gazes at the ultrasound screen in wonder. a nurse looks over her chart
and asks about an acne drug, Accutane, that Anika had taken for several years. The drug.
a derivative of vitamin A. interferes with prenatal development at the fourth week.
disrupting formation of facial features, causing structural defects of the heart, and leading
to low IO and learning disabilities. Fortunately, Anika knew all about these effects and
had long since stopped taking the drug. However, the nurse frowns when she sees a
notation for another drug that Anika is currently taking for a skin condition- the
antibiotic doxycycline. This drug can cause tooth discoloration in childhood following
exposure as a fetus.

1. A polar body cannot sustain development becase

a) it lacks sufficient cytoplasm and organelles

b) it lacks a nucleus

c)its nucleus is diplod

d)it secretes a substance that prevents sperm from swimming

e)it cannot divide

2. The barries that the sperm had to pass to enter the oocyte are

a)the blastocyst and gastrula

b) Anika's parents

c)a layer of follice cells surrounding a layer of glycoprotein

d)the chorionic villi and placenta

e) the seminiferous tubules and the epididymis

3. At the time of Mallory's birth, Anika and Jeremy's child-to-be is

a) a blastocyst

b) a morula

c) a gastrula that has just folded into three layers

d) a primordial embryo

e) on the boundary of the embryonic and fetal periods

4. The approximate date of the conception of Anika and Jeremy's child-to-be is

a)mid october

b) late january

c) mid april

d) late may

e) early september

5. When Anika learns that she is pregnant for the second time, which of the following has already happened?

a) fertilization only

b) ovulation only

c) inner cell mass formation, but not blastocyst formation

d) gastrulation, but not blastocyst formation

e) formation of three primordial germ layers

6. When Mallory is born, her future second cousin already has

a) a placenta

b) eyebrows

c) nipples

d) nails

e) a neural tube

7. The time whena drug affects a prenatal human is called its ___ period

a) menstrual

b) genetic

c) obstetric

d) critical

e) chronological

8. A drug such as Accutane likely causes likely causes more severe birth defects than a drug such as doxycycline because

a)it acts earlier in development

b) it acts later in development

c) it causes dominant mutations

d) it causes recessive mutations

e) it kills sperm

cyanmole529

1. When does differentiation begin in fruit fly (insects)?

a. Prior to fertilization

b. Just after fertilization, but before any cell divisions takeplace

c. Just after the first cell division

d. At the blastula stage

e. At the globular embryo stage

2. When does differentiation begin in frog (vertebrates)?

a. Prior to fertilization

b. Just after fertilization, but before any cell divisions takeplace

c. Just after the first cell division

d. At the blastula stage

e. At the globular embryo stage

3. When does differentiation begin in flowering plants?

a. Prior to fertilization

b. Just after fertilization, but before any cell divisions takeplace

c. Just after the first cell division

d. At the blastula stage

e. At the globular embryo stage

4. Which axis develops first in animals, anterior-posterior(A-P) or dorsal-ventral (D-V)?

a. A-P

b. D-V

c. They develop at the same time.

d. They are controlled by the same transcription factors at thesame time.

5. Which axis develops first in plants, anterior-posterior ordorsal-ventral?

a. A-P

b. D-V

c. They develop at the same time.

d. Plants only develop A-P, and with respect to gravity andlight.

6. Focusing in on A-P development in Drosophila, maternaltranscription factors produce

proteins that control axis development in what order?

a. bicoid and nanos proteins; caudal and hunchback proteins; gapand pair-rule

proteins

b. caudal and hunchback proteins; bicoid and nanos proteins; gapand pair-rule

proteins

c. gap and pair-rule proteins; bicoid and nanos proteins; caudaland hunchback

proteins

d. gap and pair-rule proteins; caudal and hunchback proteins;bicoid and nanos

proteins

7. What ultimately controls pattern formation in Drosophila?

a. Morphogen gradients and signaling molecules under maternalcontrol

b. Morphogen gradients and signaling molecules under embryoniccontrol

c. De-repressors and signaling molecules under maternalcontrol

d. De-repressors and signaling molecules under embryoniccontrol

PLANT STRUCTURE, CELLS, CELL WALLS, PLASMODESMATA

8. Which of the following cannot be found in leaves?

a. Xylem

b. Phloem

c. Mesophyll

d. Parenchyma

e. Apical meristem

9. What are intercalary meristems?

a. Meristems that develop between internodes in some plants

b. Meristems that develop primary meristematic tissues

c. Meristems that are responsible for secondary growth in woodyplants

d. Root meristems

10. Roots, shoots, and leaves all contain three basic tissuesystems. What are they?

a. Ground, structural, conductive

b. Ground, vascular, dermal

c. Vascular, dermal, structural

d. Conductive, transmissive, supportive

11. All growth in plants is due to

a. Cell division in the three basic tissue systems andsubsequent cell elongation

b. Cell division at meristems and subsequent cell elongation

c. Cell division as needed throughout the plant body, followedby cell elongation

d. Hormone-induced cell division throughout the plant body

12. Which plant cells are dead at maturity, although stillproviding some useful function?

a. Dermal

b. Ground

c. Xylem

d. Phloem

e. Lateral meristems

13. Which meristems are responsible for lateral growth (increasein girth)?

a. Apical meristem

b. Root meristem

c. Vascular and bark cambium

d. Intercalary meristem

14. Where are most guard cells generally located in vascularplants?

a. Stem dermal tissue

b. Root dermal tissue

c. Petiole dermal tissue

d. Undersides of leaves

e. Uppersides of leaves

15. How can you distinguish guard cells from non-guardcells?

a. They contain mitochondria

b. They contain chloroplasts

c. They do not have plasmodesmata

d. They have plasmodesmata

e. B and C

PINs, IAA, ACID GROWTH

16. What are PINs?

a. Plasma membrane transport inhibitors

b. Auxin efflux transporters for active transport across plasmamembranes

c. Growth regulators

d. Hormones

e. Membrane transport proteins for embryogenesis

17. What is IAA?

a. Cytokinen

b. Gibberellic acid

c. Florigen

d. Auxin

e. Abscissic acid

18. Which hormone can trigger cell wall expansion?

a. Cytokinen

b. Gibberellic acid

c. Florigen

d. Auxin

e. Abscissic acid

19. Which ion is used by plants to decrease pH and activateenzymes that break cress-bridges

between cellulose fibers for cell wall expansion?

a. Na

b. K

c. Cl

d. H

e. Mg

20. Where do the ions come from to cause acidification of thecell wall?

a. Apoplast

b. Cytoplasm

c. Chloroplasts

d. Mitochondria

e. Vacuole

PLANT EMBRYOGENESIS, SHOOT APICAL MERISTEM (SAM), ROOT APICALMERISTEM

(RAM)

21. The first cell division in a plant zygote isasymmetrical.

a. True

b. False

22. At what stage of embryogenesis do PIN proteins firstinfluence orientation of the root-shoot

axis?

a. First cell division

b. Second cell division

c. 8-cell stage

d. Globular stage

e. Heart-shaped stage

23. Which hormone most strongly affects cell division inembryos?

a. IAA

b. GA

c. Ethylene

d. AA

e. CK

24. How do the major tissue systems in plants become establishedin developing embryo?

a. Anticlinal cell divisions

b. Periclinal cell divisions

c. All of the above

d. None of the above

STEM/ROOT PRIMARY, SECONDARY GROWTH

25. Fifteen years ago, your parent hung a swing from the lowerbranch of a tree in your yard. It is at the exact same height as itwas then. Why isn

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BIOC19H3 Lecture Notes - Lecture 2: Secretion, Polarity In Embryogenesis, Ecdysone

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