Development 1

Question 1

Multicellular life

Answer 1

cells, tissues, organs, systems, organisms

Question 2

Stages of Development

Answer 2

1. fertilization
2. cleavage
3. gastrulation
4. organogenesis

Question 3

Fertilization stage

Answer 3

Haploid egg + sperm fuse into a diploid zygote
1. Sperm contacts outer jelly coat
2. acrosomal reaction
3. bindins bond to receptors on egg
3b. sperm fuses with egg
4. cortical reaction

Question 4

polyspermy

Answer 4

when more than 1 sperm nucleus enters the egg.
If happens it leads to wrong # of chromosomes.

Question 5

Egg activation & Cleavage

Answer 5

Egg is activated & ready for cell division after fertilization.
Sperm & nucleus rapidly merges with the egg nucleus & the new zygote begins rapid cell division

Question 6

Blastomeres

Answer 6

new cells created by rapid divisions

Question 7

Blastula

Answer 7

resulting hollow ball of cells in cleavage

Question 8

Yolk

Answer 8

When eggs are fertilized externally they have yolk. A viscous fluid containing nutrients for the embryo

Question 9

blastocoel

Answer 9

hollow fluid filled space needed for gastrulation to occur

Question 10

Gastrulation

Answer 10

Formation of the gut tube that has 3 layers in the embryo called the embryonic germ layer (ectoderm, endoderm, mesoderm).

Question 11

Ectoderm

Answer 11

forms skin epithelium & nervous tissue. (Jaws, teeth epidermis of skin)

Question 12

Endoderm

Answer 12

forms the lining of the digestive tract & related organs (liver, pancreas), thymus, throid

Question 13

Mesoderm

Answer 13

a looser tissue that forms in the space between the endoderm & ectoderm (the coelom), skeletal & muscular systems

Question 14

Protostomes (molluscs, annelids)

Answer 14

Spiral & determinate cleavage patter.
Mouth develops from blastopore.

Question 15

Deuterostomes (echinoderms, chordates)

Answer 15

Radial & indeterminate cleavage patters.
Anus develops from blsatopore.

Question 16

Organogenesis

Answer 16

The process in which organ rudiments develop from the three germ layers after gastrulation.

Question 17

Cytoplasmic determinants

Answer 17

localized in the egg cytoplasm & end up in specific cells during cleavage

Question 18

Induction

Answer 18

A process in which a group of cells or tissues influences the development of another group through close-range interactions.
Example: Neural tissue signals surface ectoderm to thicken with signaling molecules

Question 19

notochord

Answer 19

axial mesoderm condensed into central strip of tissue (Chordates)

Question 20

Neurulation

Answer 20

First steps in the formation of the brain & spinal cord in vertebrates

Question 21

Somite

Answer 21

one of a series of blocks of mesoderm that exist in pairs just lateral to the notochord in a vertebrate embryo

Question 22

Neural crest cells

Answer 22

In vertebrates - a region along the sides of the neural tube where it pinches off from the ectoderm.
Neural crest cells migrate to various parts of the embryo & form pigment cells in the skin & parts of the skull, teeth, adrenal; glands, peripheral nervous system.

Question 23

Acrosomal reaction

Answer 23

discharge of hydrolytic enzymes from the acrosome, a vesicle in the tip of a sperm, when the sperm approaches or contacts an egg.

Question 24

determinate cleavage

Answer 24

type of embryonic development in protostomes that rigidly casts the development fate of each embryonic cell very early

Question 25

indeterminate cleavage

Answer 25

type of embryonic development in deuterostomes in which each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo. Humans = identical twins