Developmental Bio 351 Exam 1| QUESTIONS WITH CORRECT ANSWERS| LATEST UPDATE
GUARANTEED SUCCESS
what happens is there is nondisjunction with homologous chromosomes in meiosis 1 all are
abnormal (aneuploid)
half have neither member of pair
half will contain both homologous chromosomes
n+1 n+1 n-1 n-1
what happens is there is nondisjunction with homologous chromosomes in meiosis II only
two of four gametes are aneuploid
one gamete will have extra one will have an absence
n+1 n-1 n n
trisomy 18 - edwards syndrome portruding intestines
Compare and contrast male and female meiosis in mammals. spermatogensis results in 4
spermatozoa
,oogenesis results in 1 egg
Describe the process of spermatogenesis
define all cell types and their ploidy and signals regulating these processes. starts w
spermatogonium 2N --> mitosis and differentiation
primary spermatocyte (2N) splits into two secondary spermatocytes
which then divide into N spermatids that eventually develop into mature sperm cells
sertoli cells nourish and protect developing sperm cells
are post mitotic after sexual maturity
necessary for both spermatogenesis and spermatogenesis
have N-cadherins and a carbohydrate receptor on surface that bind to galactosyltransferase
proteins on spermatogenic cell
Leydig cells secrete testosterone and other steroids estradiol
but can NOT make dihydrotestosterone
Develop from interstitial mesenchymal cells
,Look like little clusters of grapes in between the seminiferous tubules
what is the two cell hypothesis both leydig and sertoli cells needed for steroid production in
the testis
spermatogonia STEM CELLS in the testis, also called type AS spermatogonia or
spermatogonial stem cells
characteristics:
- Small cells with little
cytoplasm
- have ovoid nuclei
- found next to the basement membrane of the sex cords and seminiferous tubules
- quiescent until sexual maturity
Spermatogonia can divide asymmetrically by mitosis: which means 1) produce 2 more
spermatogonial stem cells- self- renewal
2) produce 2 type A1 spermatogonia, these cells will ultimately differentiate into spermatozoa
type B spermatogonia is committed or specified? its a precursor to ____. committed
• Precursor of the spermatocytes
, divide to form primary spermatocytes
• The primary spermatocytes complete meiosis I- are now secondary spermatocytes.
• Completion of meiosis II - known as round spermatids
• This is the end of spermatogenesis -next step is spermiogenesis
spermatogenesis vs spermiogenesis Production of haploid sperm from spermatogonial stem
cells is spermatogenesis.
Maturation of haploid spermatids into a fully motile spermatozoa is spermiogenesis. This
process begins at the end of meiosis.
sertoli cells secrete ___ and ____ SCF and GDNF
stem cell factor
Glial Cell Derived Neurotrophic Factor
GDNF expression is up-regulated by follicle stimulating hormone (FSH) from pituitary-
endocrine signaling
Describe the process of spermiogenesis. Maturation of haploid spermatids into a fully motile
spermatozoa is spermiogenesis. This process begins at the end of meiosis.
GUARANTEED SUCCESS
what happens is there is nondisjunction with homologous chromosomes in meiosis 1 all are
abnormal (aneuploid)
half have neither member of pair
half will contain both homologous chromosomes
n+1 n+1 n-1 n-1
what happens is there is nondisjunction with homologous chromosomes in meiosis II only
two of four gametes are aneuploid
one gamete will have extra one will have an absence
n+1 n-1 n n
trisomy 18 - edwards syndrome portruding intestines
Compare and contrast male and female meiosis in mammals. spermatogensis results in 4
spermatozoa
,oogenesis results in 1 egg
Describe the process of spermatogenesis
define all cell types and their ploidy and signals regulating these processes. starts w
spermatogonium 2N --> mitosis and differentiation
primary spermatocyte (2N) splits into two secondary spermatocytes
which then divide into N spermatids that eventually develop into mature sperm cells
sertoli cells nourish and protect developing sperm cells
are post mitotic after sexual maturity
necessary for both spermatogenesis and spermatogenesis
have N-cadherins and a carbohydrate receptor on surface that bind to galactosyltransferase
proteins on spermatogenic cell
Leydig cells secrete testosterone and other steroids estradiol
but can NOT make dihydrotestosterone
Develop from interstitial mesenchymal cells
,Look like little clusters of grapes in between the seminiferous tubules
what is the two cell hypothesis both leydig and sertoli cells needed for steroid production in
the testis
spermatogonia STEM CELLS in the testis, also called type AS spermatogonia or
spermatogonial stem cells
characteristics:
- Small cells with little
cytoplasm
- have ovoid nuclei
- found next to the basement membrane of the sex cords and seminiferous tubules
- quiescent until sexual maturity
Spermatogonia can divide asymmetrically by mitosis: which means 1) produce 2 more
spermatogonial stem cells- self- renewal
2) produce 2 type A1 spermatogonia, these cells will ultimately differentiate into spermatozoa
type B spermatogonia is committed or specified? its a precursor to ____. committed
• Precursor of the spermatocytes
, divide to form primary spermatocytes
• The primary spermatocytes complete meiosis I- are now secondary spermatocytes.
• Completion of meiosis II - known as round spermatids
• This is the end of spermatogenesis -next step is spermiogenesis
spermatogenesis vs spermiogenesis Production of haploid sperm from spermatogonial stem
cells is spermatogenesis.
Maturation of haploid spermatids into a fully motile spermatozoa is spermiogenesis. This
process begins at the end of meiosis.
sertoli cells secrete ___ and ____ SCF and GDNF
stem cell factor
Glial Cell Derived Neurotrophic Factor
GDNF expression is up-regulated by follicle stimulating hormone (FSH) from pituitary-
endocrine signaling
Describe the process of spermiogenesis. Maturation of haploid spermatids into a fully motile
spermatozoa is spermiogenesis. This process begins at the end of meiosis.
