Lesson 11

Question 1

what is day 0 of embryonic development (form and what is happening)

Answer 1

• zygote
• formed from sperm and egg nuclei fusion
• divides without growth to form small cells called blastocytes

Question 2

what is day 3 of embryonic development (form and what is happening)

Answer 2

• morula
• when zygotic division reaches 32 cells

Question 3

what is day 4-6 in embryonic development (form and what is happening)

Answer 3

• blastocyst
• hollowed-out morula
• has inner cell mass and outer trophoblast layer

Question 4

inner cell mass of blastocyst does what?

Answer 4

forms the embryonic body

Question 5

out trophoblast layer of blastocyst does what?

Answer 5

forms the chorion and fetal part of placenta

Question 6

implantation of embryonic development

Answer 6

blastocyst attaches to uterine wall

Question 7

what is day 7 of embryonic development (form and what happens)

Answer 7

• blastocyst implants with inner cell mass facing uterine wall
• trophoblast secretes enzyme to erode uterine mucosa to expose vascular network in submucosa
• chorionic villi from trophoblast and uterine tissue will form placenta
• as implanted blastocyst grows the three embryonic layers form

Question 8

what are the three embryonic layers

Answer 8

• amnion
• yolk sac
• allantois

Question 9

amnion

Answer 9

• encases embryo in fluid-filled chamber
• protects against trauma, temp, and adhesion from rapid embryonic growth

Question 10

yolk sac

Answer 10

forms embryo’s first blood cells and primordial germ cells here migrate to embryo body to form become germ cells in gonadal tissue

Question 11

allantois

Answer 11

helps form umbilical cord

Question 12

what is day 14 of embryonic development (form and what happens)

Answer 12

• uterine mucosa envelops embryo
• uterine wall beneath inner cell mass will form part of placenta
• embryo in gastrula stage

Question 13

decidua capsularis

Answer 13

uterine mucosa enveloping embryo

Question 14

decidua basalis

Answer 14

uterine wall beneath inner mass

Question 15

what is the gastrula stage of the embryo

Answer 15

three primary germ layers present and begin to differentiate for the next six weeks

Question 16

what are the three layers that form in the gastrula stage

Answer 16

• endoderm
• ectoderm
• mesoderm

Question 17

endoderm

Answer 17

forms mucosa of digestive and respiratory system and their associated glands

Question 18

ectoderm

Answer 18

forms skin and nervous system

Question 19

mesoderm

Answer 19

forms skeleton, skeletal muscles, walls of digestive organs, urinary, and circulatory system, etc.

Question 20

what happens in week 9 of embryonic development

Answer 20

• embryo is referred to as a fetus
• major focus of development at this point for fetal growth and tissue/organ specialization/growth

Question 21

all somatic cells contain

Answer 21

46 chromosomes (diploid 2n)

Question 22

egg and sperm contain

Answer 22

23 chromosomes (haploid n)

Question 23

how are the 46 chromosomes of the somatic cells obtained

Answer 23

the fusion of egg and sperm

Question 24

gene

Answer 24

unit/area on DNA (sometimes RNA) that contains hereditary information

Question 25

alleles

Answer 25

genetic information coding for the same traits found in each pair of homologous chromosomes

Question 26

homozygous trait

Answer 26

both alleles express the same information

Question 27

heterozygous trait

Answer 27

- one allele is dominant while the other allele is recessive - recessive allele is masked by the expression of dominant allele

Question 28

dominant gene

Answer 28

requires only 1 copy of the gene for expression

Question 29

recessive gene

Answer 29

requires both alleles to contain the gene for expression

Question 30

genotype

Answer 30

- individuals genetic makeup - whether he/she is homo/heterozygous for various alleles

Question 31

phenotype

Answer 31

the physical appearance of the genes

Question 32

what are the four main types of inheritance

Answer 32

- dominant/recessive inheritance - incomplete dominance - sex-linked inheritance - co-dominance

Question 33

dominant/recessive inheritance

Answer 33

- mendelian genetics - dominant alleles are expressed - recessive alleles are expressed only when homozygous - genotype and phenotype determined via punnett square

Question 34

albinism

Answer 34

inability to produce melanin

Question 35

incomplete dominance

Answer 35

heterozygous alleles yield phenotype different than from homozygous dominant phenotype

Question 36

a person with one recessive and dominant allele for sickle cell anemia can do what?

Answer 36

can make half normal and half sickle cell RBCs

Question 37

sex-linked inheritance

Answer 37

inheritance of genes from the X (23rd) chromosome

Question 38

what is determined by sex-linked inheritance

Answer 38

- color vision - blood clotting - baldness

Question 39

the 22 pairs of chromosomes other than the 23rd are called

Answer 39

autosomes

Question 40

if you just have X- in the 23rd chromosome what disease is presented?

Answer 40

turners syndrome

Question 41

if you have XXY in the 23rd chromosome what disease is presented?

Answer 41

Klinefelter's syndrome

Question 42

if there is -Y in the 23rd chromosome what happens?

Answer 42

the baby is miscarried

Question 43

if there is XXX or XYY in the 23rd chromosome what disease is present?

Answer 43

no disease (normal physiology)

Question 44

co-dominance

Answer 44

- all alleles are expressed in the phenotype - blood type

Question 45

in blood type what alleles are dominant

Answer 45

A and B over O

Question 46

in blood type which alleles are recessive

Answer 46

O

Question 47

in blood type what alleles are codominant

Answer 47

A and B

Question 48

Rh factor is controlled by ____ and has _____ inheritance

Answer 48

- another gene - dominant-recessive

Question 49

what are the steps for determining the genotype of the offspring? (5)

Answer 49

- determine genotype of the parents - draw square - place alleles on x and y axes - cross parents - determine offspring genotype/phenotype

Question 50

masking genes can do what?

Answer 50

alter the appearance if expected phenotype from genotype

Question 51

only a ____ can ever be used reliably to assign parentage

Answer 51

genetic paternity test