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Hand in Meiosis Pictures Lab

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Something to think about as your open up your notes

Humans have approx. 50-75 trillion cells and these cells are all different types (hair, skin, liver, stomach cells, etc.).

How can you explain all these types of cells if humans only start as a single cell?

AP Biology 2007-2008

Animal Reproduction&

Development

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Embryology The study of the Embryo

An organism in the

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IMPORTANT! RECOMBINATION Sperm = DNA (haploid) : one version of

each type of chromosome. Egg = DNA (haploid): same as above The combination of one sperm with one egg

will unite and make . If another sperm or another egg unite, a

human would result.

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Recombination: SO MANY OPTIONS!

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3 stages of embryo development

1.

2.

3.

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Oogenesis

Meiosis 1 completedduring egg maturation

Meiosis 2 completedtriggered by fertilization

ovulation

Unequal meiotic divisions unequal distribution

of cytoplasm egg polar bodies

What is theadvantage of

this development system?

Put all your eggin one basket!

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Fertilization

fertilization cleavage Gastrulation Differentiation

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Fertilization Joining of

(nucleus) enters

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1) Cleavage Repeated of zygote

1st step to becoming cellular unequal divisions establishes body plan

different cells receive different portions of egg cytoplasm & therefore different regulatory signals

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Cleavage zygote m b

establishes future development

zygote

blastulamorula

gastrulation

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Establish 3 cell layers E

outer body tissues skin, nails, teeth nerves, eyes, lining of mouth

M middle tissues

blood & lymph, bone & notochord, muscle

excretory & reproductive systems E

inner lining digestive system lining of respiratory, excretory &

reproductive systems

2) Gastrulation

ectoderm

mesoderm

endoderm

protostome vs. deuterostome

gastrulation inprimitive chordates

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Testing…In a study of the development of frogs, groups of cells in the germ layers of several embryos in the early gastrula stage were stained with five different dyes that do not harm living tissue. After organogenesis (organ formation), the location of the dyes was noted, as shown in the table below.

Tissue StainBrain RedNotochord YellowLiver GreenLens of the eye BlueLining of the digestive tract Purple

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Neurulation Formation of notochord & neural tube

develop into system

Notochord

Neural tube

develops intovertebral column

develops into CNS (brain & spinal cord)

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Growth and DifferentiationUmbilical blood vessels

Chorion

Amnion

Yolksac

AllantoisFetal blood vessels

Maternal blood vessels

Bird embryo

Mammalian embryo

Placenta

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AP Biology

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Testing…All of the following correctly describe the fate of the embryonic layers of a vertebrate EXCEPT

A. neural tube and epidermis develop from ectoderm

B. linings of digestive organs and lungs develop from

endoderm

C. notochord and kidneys develop from endoderm

D. skeletal muscles and heart develop from mesoderm

E. reproductive organs and blood vessels develop from

mesoderm

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A B C D E F

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3. Growth and Differentiation As embryo develops, the # of cells continues

to

Differentiation cells become

Different sections of DNA are , some are turned .

Certain cells act as organizers These cells influence other cells to become

certain cells, tissues

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STEM CELLS Omnipotent = have the potential to be

type of cell. If mitosis is done, all cells are

identical. FACT: all of your cells contain the

(because of mitosis)

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Differentiation: some DNA is turned off and only some directions are read, for example: Skin cells: all

DNA directions are turned off, except for how to make skin.

HOW DO WE GET DIFFERENT CELLS?

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Internal Development Development of the embryo , in the

of the body

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1. Placental Mammals Placenta - part of the wall of the uterus

Site of !!!!!!!!!!!!!!!!!!!!!!!!

Embryo’s and mother’s circulatory system are touching BUT NOT

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Umbilical cord Contains that the embryo will

get nourishment and oxygen from the mother’s blood to the

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Human fetal development

7 weeks4 weeks

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Human fetal development10 weeks

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Human fetal development

12 weeks 20 weeks

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Human fetal development The fetus just spends much of the 2nd & 3rd

trimesters just growing …and doing various flip-turns & kicks inside amniotic fluid

Week 20

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Human fetal development 24 weeks (6 months; 2nd trimester)

fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix

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Human fetal development 30 weeks (7.5 months)

umbilical cord

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Birthpositive feedback

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Getting crowded in there!! 32 weeks (8 months)

The fetus sleeps 90-95% of the day & sometimes experiences REM sleep, an indication of dreaming

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Birth (36 weeks)

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The end of the journey!

And you think 9 months of BioH is hard!

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2. Nonplacental Mammals mammals

Duckbilled platypus Anteaters

mammals Embryo begins to

develop in uterus Crawls into mother’s pouch Finishes developing in pouch Kangaroo, opossum

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A

1) Albumen –

A

2) Allantois –

A

3) Amnion –

Y

4) Yolk –

S

5) Shell – Calcium carbonate,

E

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August 08’

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June 08’

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August 07’