exam 2- embryo development

Question 1

in embryo development, name the 5 common developmental steps

Answer 1

1- fertilization
2- cell division (cleavage)
3- gastrulation (animals)
4- polarity formation
5- organogenesis

Question 2

stage of development: ___ union of parental gametes to form a zygote

Answer 2

fertilization

Question 3

stage of development: ___ the zygote divides by mitosis to form a multicellular structure called a blastocyst

Answer 3

cleavage

Question 4

stage of development: ___ the 3 primary germ layers arrange themselves in ways that give rise to all organs in the body

Answer 4

organogenesis

Question 5

stage of development: ___ the blastocyst cells form 3 primary germ layers, which are the basic cellular structures from which all body tissues develop

Answer 5

gastrulation

Question 6

plants have a little diff development

Answer 6

one reason is the lack of cell movement/cell walls

• still fertilization, still cell divisions that can be called cleavage, then form tissue layers (not called same thing, but roughly same thing), last step totally diff

Question 7

what is the first step of development of a new individual

Answer 7

fertilization

Question 8

3 characteristics of fertilization

Answer 8

• the union of a tiny sperm and a large egg to form a zygote
• sex determination of offspring in many animals
• stimulates changes in the egg initiating development

Question 9

fertilization may be divided into 4 steps:

Answer 9

1- sperm contacts egg
2- sperm of its nucleus enters egg
3- egg becomes activated and developmental changes begin
4- sperm and egg nuclei fuse

Question 10

describe calcium signals in fertilization

Answer 10

this sets up the polarity
- initial binding, increased calcium signals, cell division and fusion happen later

Question 11

name 3 things that happen when fertilization activates the egg

Answer 11

• aerobic respiration increases
• enzyme systems become activated
• a burst of protein synthesis begins

Question 12

it is possible to physically stimulate some eggs to undergo activation, and even division without ___

Answer 12

fertilization

• such parthogenetic and haploid eggs usually go through limited division series
• naturally pathogenetic species have special mechanisms to retain the 2N state of their genes

Question 13

___ is the development of an individual from an egg without fertilization

Answer 13

parthenogenesis

Question 14

brief overview of cleavage

Answer 14

shortly after fertilization, the zygote begins to undergo a series of cell division, that gives rise to a rapid increase in cell number (lots of cell division, not a lot of growth)

Question 15

does the egg or the sperm contribute most of the zygote cytoplasm?

Answer 15

egg

Question 16

in cleavage…the zygote forms a two-celled embryo and continues division to form a ball of __ cells called the ___

this continues division to form the hollow ___ with up to several hundred cells

Answer 16

32 cells called morula
blastula

Question 17

name the 2 types of divisions (cleavage)

Answer 17

karyokinesis = mitotic division of the cell nucleus
cytokinesis - division of the cell/cytoplasm

• these processes are coordinated, but karyokinesis can occur without cytokinesis resulting in multinucleated cells

Question 18

division patterns during cleavage are influenced by both the presence and location of the ___

Answer 18

yolk

Question 19

describe yolk

Answer 19

provides energy for egg development

• the more metabolically active end of the cell is the animal pole, which contains less yolk
• vegetal pole opposite the animal is the yolk-rich region of the egg

Question 20

cleavage pattern: ___, egg contains little or no yolk, and cleavage occurs evenly throughout

Answer 20

holoblastic cleavage

Question 21

cleavage pattern: ___, eggs composed almost entirely of yolk
- cleavage is incomplete or occurring in only part of the embryo

Answer 21

meroblastic cleavage

Question 22

cleavage patterns: ___, superficial cleavage (not rlly any cleavage), instead of splitting in half, split the nucleus (the egg has dozens of nuclei)- one enormous cell with lots of nuclei
- we will see in Drosophilia

Answer 22

centrolecithal