Lecture 5: Animal Development

Question 1

What is development:

Answer 1

Development is a series of progressive changes in form and function that occurs during an organisms life cycle

Question 2

How long does development last

Answer 2

Embryonic stages precede birth, and development continues until death

Question 3

The Key stages of development:

Answer 3

• Fertilisation
• cleavage
• Gastrulation
• organogenesis
• morphogenesis

Question 4

Fertilisation is the

Answer 4

fusion of eggs & sperm to give zygote

Question 5

Cleavage is the

Answer 5

division of cell stop form blastula

Question 6

Gastrulation is the

Answer 6

formation of tissue layers & axis

Question 7

organogenesis is the

Answer 7

formation of organs

Question 8

morphogenesis is the

Answer 8

mechanism of body shape formation

Question 9

development begins with

Answer 9

fertilisation.
- one sperm enters egg
- once inside, the paternal & maternal genetic material fuse to form a diploid cell
- fertilisation initiates the rapid divisions that produce the multicellular embryo

Question 10

the cytoplasm & mitochondria of the zygote comes from..

Answer 10

the egg

Question 11

The nucleus of the egg is in the

Answer 11

animal hemisphere

Question 12

nutrients accumulate in the

Answer 12

vegetal hemisphere

Question 13

in amphibians the vegetal hemisphere has a

Answer 13

ranslucent cortex

Question 14

in amphibians the animal hemisphere has an

Answer 14

opaque cortex

Question 15

in amphibians sperm enters at the

Answer 15

animal hemisphere; the context then rotates exposing the gray crescent

Question 16

Proteins in the gray crescent control

Answer 16

what form the cells will take.

Question 17

During cleavage cells typically

Answer 17

double at each stage of cleavage

Question 18

Cells divide during cleavage at

Answer 18

cleavage furrow

Question 19

cleavage results in a

Answer 19

blastula (hollow)

Question 20

3 patterns of cleavage depend on

Answer 20

1) complete
2) incomplete - discoidal
3) incomplete - superficial.

-Pattern depends on amount of yolk and orientation of spindles

Question 21

yolk is

Answer 21

nutrient filled material

Question 22

complete cleavage with no yolk

Answer 22

cells are equal in size.

Question 23

complete cleavage with yolk

Answer 23

yolk impedes the cleavage furrow, cells divide asymmetrically

Question 24

incomplete cleavage - discoidal

Answer 24

• With lots of yolk the cleavage furrows don’t penetrate the yolk; cleavage is incomplete.
• A blastodisc, forms on top of the yolk.

BIRDS

Question 25

blastodisc gives rise to

Answer 25

embryo and membranes

Question 26

Incomplete cleavage - superficial

Answer 26

• INSECTS
• yolk in middle, mitosis occurs but cytokinesis doesn’t. = multiple nuclei.
• The nuclei migrate to the edge and the membrane grows inward, partitioning the nuclei into individual cells