chapter 42: animal development and aging

Question 1

when does an oocyte complete meiosis II

Answer 1

after fertilization

Question 2

what is cleavage

Answer 2

results in a multicellular embryo & is cell division without growth

Question 3

what is morula

Answer 3

Formation of a solid ball of cells

Question 4

what are blastula

Answer 4

dividing morula - hollow ball of cells

Question 5

what is a blastocoel

Answer 5

a fluid-filled cavity in blastula

Question 6

what is gas truly

Answer 6

germ layers form in part by invagination

Question 7

what is the archenteron

Answer 7

primitive gut

Question 8

what is the blastopore

Answer 8

opening into the primitive gut

Question 9

what is the ectoderm

Answer 9

Nervous system; epidermis of skin and derivatives of the epidermis (hair, nails, glands); tooth enamel, dentin, and pulp; epithelial lining of oral cavity and rectum

Question 10

what is the mesoderm

Answer 10

Musculoskeletal system; dermis of skin; cardiovascular system; urinary system; lymphatic system; reproductive system—including most epithelial linings; outer layers of respiratory and digestive systems

Question 11

what is the endoderm

Answer 11

Epithelial lining of digestive tract and respiratory tract, associated glands of these systems; epithelial lining of urinary bladder; thyroid and parathyroid glands

Question 12

what is the neural tube

Answer 12

: Tube formed by closure of neural groove. In vertebrates develops into spinal cord & brain

Question 13

what is the somite

Answer 13

mass of mesoderm lateral to notochord in vertebrates; muscles associated with axial skeleton & vertebrae

Question 14

what is the notochord

Answer 14

Cartilage-like supportive dorsal rod; replaced by vertebrae in vertebrates

Question 15

what is the gut

Answer 15

formed by endoderm as body folds into tube

Question 16

what is the coelom

Answer 16

body cavity lined with mesoderm; between digestive tract & body wall

Question 17

what is cellular differentiation

Answer 17

Process & developmental stages by which cell becomes specialized for particular function

Question 18

what is morphogenesis

Answer 18

Emergence of shape & patterns in tissues, organs, or entire embryo during development

Question 19

what is pattern formation

Answer 19

positioning of cells during development determines final shape of organism

Question 20

characteristics of cellular differentiation

Answer 20

Zygote is totipotent
Cells specialize lose their totipotency
Cellular specialization caused differential gene expression
Transcription factors: segregation & induction

Question 21

what is totipotent

Answer 21

cell that has full genetic potential of the organism, including potential to develop into a complete organism

Question 22

what are maternal determinants

Answer 22

substances present in egg that influences course of development

Question 23

what is cytoplasmic segregation

Answer 23

is parceling of maternal determinants during mitosis

Question 24

what is induction

Answer 24

-Specialization influenced by both maternal determinates but also by signals of neighboring cells
-Induction: ability of one embryonic tissue to influence the development of another tissue

Question 25

what is morphogenesis

Answer 25

-Requires cells associate to form tissues & tissues give rise to organs -Most animals share common sets of genes that direct pattern formation -Highly conserved among animals with segmented body morphologies, including humans

Question 26

characteristics of anterior/posterior axis

Answer 26

-Establishment of anteroposterior polarity -Polarity present in egg before fertilized -Results from maternal determinates -Proteins products (morphogens) diffuse away from area of highest concentration -Forms gradients that influence patterns of tissue development

Question 27

what is segmentation pattern

Answer 27

-Gap genes come into play -Divide anteroposterior axis into broad regions -Temporarily activated by gradients anterior & posterior morphogens -In turn activate pair-rules genes -Influence segment-polarity genes

Question 28

what are homeotic genes

Answer 28

genes that control overall body plan by controlling fate of groups of cells during development

Question 29

what are homeoboxes

Answer 29

Developmental genes, shared by all animals, that orchestrate development of body plan

Question 30

what is the homeodomain

Answer 30

Conserved DNA-binding region of transcription factors encoded by homeobox of homeotic genes

Question 31

what is chorion

Answer 31

functioning for respiratory exchange in birds & reptiles; contributes to placenta formation in mammals

Question 32

what is amnion

Answer 32

forms an enclosing fluid-filled sac

Question 33

what is the yolk sac

Answer 33

extraembryonic membrane in shelled vertebrates contains yolk for nourishment of the embryo & in placental mammals is first site for blood cell formation

Question 34

what is the allantois

Answer 34

accumulates nitrogenous wastes in the eggs of reptiles, including birds; contributes to the formation of umbilical blood vessels in mammals

Question 35

emrbyonic development stages

Answer 35

-fertilization, blastocyte -implantation in wall of uterus, gastrulation -nervous system and heart, form umbilical cord -head enlarges, eyes ears nose, nervous system developed -cervix dilates, baby born, placenta delivered

Question 36

characteristics of the placenta

Answer 36

Functions in gas, nutrient, & waste exchange Tenth week fully developed & producing progesterone & estrogen Exchange of molecules between fetal & maternal blood take place across walls of chorionic villi

Question 37

how does the aging process work

Answer 37

as the cell divides over time the telomeres shorten, eventually signaling the cell to stop dividing (senescence)

Question 38

characteristics of damage accumulation

Answer 38

-May involve the accumulation of damage over time -First accumulation of harmful DNA mutations or the buildup of harmful metabolites -Second is proteins may become increasingly cross-linked with age -Inability of organs such as blood vessels, heart, & lungs to function as they once did -Glucose has the tendency to attach to any type of protein -First step in a cross-linking process