AP biology: 21/47 evodevo

Question 1

embryos have been studied since…

Answer 1

In 1901 Hans Spemann used baby hair ligature to induce twins in early frog embryos

Question 2

Ross Harrison

Answer 2

1918- self regulation

Early embryonic tissue has “morphogenetic fields” that regulate their own differentiation

Question 3

The Organizer Experiment

Answer 3

1924 Speman and Mangold

Discovered embryonic induction and received the Nobel Prize in 1935

Question 4

Homeotic transformations

Answer 4

Carl Lewis 1946
Bithorax = patterned gene discovered by Morgan
determined the pattern of thorax and abdomen of fruit flies

Mutations caused transformations of one body region/ segment into another

Proceed in order from anterior to posterior (front to back)

Question 5

Homeobox

Answer 5

1983- Garber and Gehring – Anntennapedia
Gene that can transform an antenna into a leg

Homeobox- short sequence in all sequence genes – 180 bases long or 60 amino acids
Shortened to HOX genes
Connect all bilateral animals – genes have duplicated and changed with time

Question 6

Human embryo takes how long to show distinctive features

Answer 6

6-8 weeks

Question 7

Zygote to embryo (5)

Answer 7

Zygote formation due to sperm and egg fusion
Cortical reaction- increase in Ca++ ions block polyspermy and increases cellular respiration
Cleavage- zygote divides into smaller cells ( blastomeres)
16- 32 cell stage- the morula
Hollow ball= blastula( at least 120 cells)

Question 8

Gastrulation

Answer 8

Gastrulation rearranges the cells of a blastula into a three-layered embryo, called a gastrula, which has a primitive gut

Question 9

ectoderm

Answer 9

germ layer

forms the outer layer: becomes nervous system, outer epidermis, cornea and lens of eye, and pituitary glands

Question 10

endoderm

Answer 10

lines the digestive tract along with skeletal, muscular, excretory, ciculatory, lymphatic, and reproductive systems

Question 11

mesoderm

Answer 11

partly fills the space between the endoderm and ectoderm and becomes the epithelial lining of respiratory and excretory systems, the liver, pancreas, thyroid and parathyroid glands

Question 12

cell divisions

Answer 12

The zygote gives rise to a large number of cells

Question 13

cell differentiation

Answer 13

Cells become specialized in structure and function

Question 14

morphogenesis

Answer 14

encompasses the processes

That give shape to the organism and its various parts

Question 15

Genomic equivalence

Answer 15

All nucleated cells in an organism have the exact same genome or same DNA.
Differences between cells in a multicellular organism
Due almost entirely from differences in gene expression.

Question 16

Stem cell is a relatively unspecialized cell because

Answer 16

Can reproduce itself indefinitely

Can differentiate into specialized cells of one or more types, given appropriate conditions

Question 17

totipotent cell

Answer 17

Is one capable of generating a complete new organism

Question 18

pluripotent cell

Answer 18

can become many different types but not all

Question 19

cloning

Answer 19

Is using one or more somatic/ body cells from a multicellular organism to make another genetically identical individual

Question 20

Experiments with frog embryos…

Answer 20

Have shown that a transplanted nucleus can often support normal development of the egg

Question 21

John Gurdon

Answer 21

Differentiation
1962: repeated experiment BUT
Removed frog egg nucleus and replaced with diploid nucleus of mature intestinal cell
Fully mature tadpole/ frog resulted

Question 22

Reproductive cloning of mammals

Answer 22

In 1997, Scottish researchers
Cloned a lamb from an adult sheep by nuclear transplantation
In nuclear transplantation
The nucleus of an unfertilized egg cell or zygote is replaced with the nucleus of a differentiated cell

Question 23

first cat ever cloned

Answer 23

“Copy cat”

Question 24

Problems associated with animal cloning

Answer 24

In most nuclear transplantation studies performed thus far
Only a small percentage of cloned embryos develop normally to birth
Defects may result ( heart disease etc)
Over methylation of “donor DNA” which may interfere with normal development if genes are turned off

Question 25

Transcriptional Regulation of Gene Expression During Development

Answer 25

Cell determination precedes differentiation and involves expression of genes for tissue-specific proteins
Tissue-specific proteins enable differentiated cells to carry out their specific tasks

Question 26

Stem cells can be isolated

Answer 26

From early embryos at the blastocyst stage

Question 27

Shinya Yamanaka 2006

Answer 27

Created iPSC ( induced pluripotent stem cells)
Introduced 4 genes to reprogram adult skin cell into neurons and intestinal cells
Since then:  created egg cells which are totipotent

Question 28

Cytoplasmic Determinants and Cell-Cell Signals in Cell Differentiation

Answer 28

Maternal substances that influence early development are called cytoplasmic determinants
These substances regulate expression of genes that affect the cell’s developmental fate

Question 29

Induction

Answer 29

The other important source of developmental information is the environment around the cell, especially signals from nearby embryonic cells
In the process called induction, signal molecules from embryonic cells cause transcriptional changes in nearby target cells

Question 30

Pattern formation in animals and plants results from similar genetic and cellular mechanisms

Answer 30

Pattern formation is the development of a spatial organization of tissues and organs
It occurs continually in plants, but it is mostly limited to embryos and juveniles in animals
HOX genes early on determine

Question 31

Role of Apoptosis in vertebrates

Answer 31

part of normal development of the nervous system, operation of the immune system, and morphogenesis of hands and feet in humans and paws in other mammals

Question 32

Apoptosis process

Answer 32

During apoptosis, a cell shrinks and becomes lobed (called “blebbing”); the nucleus condenses; and the DNA is fragmented

The timely activation of apoptosis proteins in some cells functions during normal development and growth in both embryos and adult