Chap 29

Question 0

Homeoboxes

Answer 0

Genes that control expressions of other genes during development

Question 1

General Properties of Development

Answer 1

A. Proceeds from simple, undifferentiated style to more complex, differentiated condition
B. Based on regulation of gene activity

Question 2

Epigenetic

Answer 2

Gene effects only occur through interaction with the environment

Question 3

Exhibits equipotentiality

Answer 3

Gets some developmental outcome from a variety of different starting conditions

Question 4

Is Life Long

Answer 4

Ends in senescence = breakdown of the body in old age

Question 5

What is Senescence?

Answer 5

Due to accumulation of free radicals from metabolism

Question 6

What are Antioxidants?

Answer 6

Eliminates free radicals

Question 7

Human Embryonic Development: Embryonic Period (0-2 months)

Answer 7

. Fertilization
A. Usually occurs within 24 hrs of ovulation
B. Usually occurs in Fallopian tubes
C. Requires capacity
Removal of enzymes inhibitors on head of sperm (acrosome) to allow penetration of egg membrane

Question 8

Cleavage

Answer 8

Cell divisions with no overall increase in size
A. Occurs within Fallopian Tube, and within 24-30 hrs post-fertilization
B. Monozygotic (identical) twinning may occur here

Question 9

Dizygotic twins

Answer 9

Non-identical resting from fertilization of > 1 egg

A. Results in morula comprised of blastomeres

Question 10

Blastocyst Formation

Answer 10

A. Occurs approx. 5-7 days post-fertilization
B. Occurs in Fallopian tube, prior to entry into uterus
C. Morula enlarges and becomes hollow ball of cells

Question 11

Trophoblast

Answer 11

Outer layer of cells (eventually becomes placenta)

Question 12

Blastocoele

Answer 12

Hollow inner cavity of blastocyst

Question 13

Inner cell mess

Answer 13

Embryonic tissue

Question 14

Implantation

Answer 14

A. Occurs approx. 7 days post-fertilization
B. Blastocyst attaches to endometrium
* Trophoblast is site of attachment

Question 15

Gastrulation

Answer 15

A. Occurs during remaining portion of embryonic period

B. Inner cell mass folds in on itself (=blastophere), creating 3 germ layers

Question 16

Endometrium

Answer 16

Inner layer

Question 17

Mesoderm

Answer 17

Middle layer

* gives rise to all structures of the muscular, skeletal, and cardiovascular systems

Question 18

Ectoderm

Answer 18

Outer layer

• gives rise to all structures of the nervous system, plus skin and hair
• Coelom also forms

Question 19

Membrane lined body cavity

Answer 19

Peritoneum and pleura

Question 20

Formation of Embryonic Membranes:

What is a Yolk Sac?

Answer 20

Site of fetal blood formation, also provides some nourishment

Question 21

Amnion

Answer 21

Surrounds embryo, keeps amniotic fluid in place

Question 22

Amniotic fluid

Answer 22

Acts as a shock absorber

Question 23

Chorion

Answer 23

Formerly the trophoblast become the placenta

Question 24

Allantois

Answer 24

Becomes the umbilical cord

Question 25

What the the Embryonic Period end with?

Answer 25

Completion of the embryonic membranes

Question 26

Why is Progesterone secretion during the first 8 weeks of pregnancy necessary?

Answer 26

To maintain endometrium as primary source of nourishment until placenta is built

Question 27

Fetal Period (3rd to 9th month)

Answer 27

1. Functional placenta (embryo now referred to as fetus) | 2. Increase in size of structures created during gastrulation

Question 28

Parturition

Answer 28

Birth (9th month)

Question 29

What is dilation?

Answer 29

When the opening of the cervix expands

Question 30

What is expulsion?

Answer 30

Uterine contractions to expel fetus | * Controlled by oxytocin

Question 31

What does the term placental mean?

Answer 31

Afterbirth expelled (amnion and placenta)

Question 32

Stretch of DNA coding for a particular protein

Answer 32

Gene

Question 33

Particular version of a gene

Answer 33

Allele

Question 34

Genetic makeup of an individual (particular set of alleles possessed)

Answer 34

Genotype

Question 35

Physical appearance

Answer 35

Phenotype

Question 36

2 copies of the same allele (BB, bb)

Answer 36

Homozygous

Question 37

2 different alleles (Bb)

Answer 37

Heterozygous

Question 38

Allele expressed in heterozygote

Answer 38

Dominant

Question 39

Allele not expressed in heterozygote

Answer 39

Recessive

Question 40

Heterozygote is intermediate between 2 alleles

Answer 40

Incomplete Dominance

Question 41

Heterozygote expresses both alleles

Answer 41

Codominance

Question 42

Many genes that influence production of one trait (e.g., height)

Answer 42

Polygeny

Question 43

1 gene that influences production of more than 1 aspect of the phenotype

Answer 43

Pleiotropy

Question 44

Sex Determination: | Male=

Answer 44

XY

Question 45

Female=

Answer 45

XX

Question 46

Failure for homologs to separate during Meiosis 1 and 2

Answer 46

Non-Disjunction

Question 47

X (phenotypic female)

Answer 47

Turner's Syndrome

Question 48

XXY (phenotypic male) | Shows that Y (and not number of x) determines sex in humans

Answer 48

Klinefelter's Syndrome

Question 49

``` Traits carried on X chromosomes 1. More often expressed in males 2. Often expressed in males 3. Ex. Color Blindness A. X+ = normal, Xc = color blind B. Cross of X+ Y male with X+ Xc female: ```

Answer 49

Sex Linkage