objective 8 pt 2

Question 1

consists of one stage
produces diploid cells
produces 2 idential daughter cells with the same number of chromosomes as parent cell
body cells

Answer 1

mitosis

Question 2

consists of two stages
produces haploid cells
produces 4 genetically different daughter cells
gamete formation
involves two consecutive cell divisions but only one round of DNA replication

Answer 2

meiosis

Question 3

what are the functions of meiosis?

Answer 3

• Number of chromosomes are cut in half (2n to n)
• Introduces genetic diversity, as all daughter cells are genetically different
  from original cell

Question 4

reduces chromosome number from 2n –> n

Answer 4

reduction division of meiosis

Question 5

what are the stages of meiosis?

Answer 5

prophase, metaphase, anaphase, telophase

Question 6

has events not seen in mitosis or meiosis 2

Answer 6

prophase 1

Question 7

each chromosome is split in two and homologous chromosomes pair up forming tetrads consisting of 4 chromatids

Answer 7

synapsis

Question 8

exchange of genetic material between chromatids
genetically called recombination

Answer 8

crossover (chiasmata)

Question 9

the pairs of chromosomes become arranged in homologous pairs connected b y centromeres

Answer 9

metaphase I

Question 10

the chromosomes are divided so that there are equal amounts on either side of the cell. as there are 46 chromosomes in a human cell, 23 end up on either side

Answer 10

anaphase I

Question 11

the two daughter cells are completely divided, a nucleic envelope forms and the chromosomes become less visible. there are 23 chromosomes in each of these cells with chromosomal combination different from those originally present in the parent

Answer 11

telophase I

Question 12

the two cells prepare to divide again

Answer 12

meiosis II

Question 13

the chromosomes become visible, the nuclear envelope disappears and the centrioles form the spindle fibers

Answer 13

prophase II

Question 14

the chromosomes line up along the middle

Answer 14

metaphase II

Question 15

the chromosomes get split into its two stands of DNA

Answer 15

anaphase II

Question 16

the cells are compleatly divided. the nucleic envelope reforms and four new cells with different DNA are created

Answer 16

telophase II

Question 17

production of sperm in seminiferous tubules; begins at puberty

Answer 17

spermatogenesis

Question 18

the diploid (2n) immature sperm cells
dividing by mitosis

Answer 18

spermatogonia

Question 19

give rise to sperm

Answer 19

spermatogenic cells

Question 20

what are the 3 steps of spermatogenesis

Answer 20

mitosis
meiosis
spermiogenesis

Question 21

spermatogonia (stem cell) forms spermatocytes
each mitotic division yields 2 daughter cells

Answer 21

mitosis (spermatogenesis)

Question 22

spermatocytes form spermatids (haploid male gamete)

Answer 22

meiosis (spermatogenesis)

Question 23

primary spermatocyte (2n) undergoes ___, forming 2 secondary spermatocytes

Answer 23

meiosis 1 (spermatogenesis)

Question 24

each secondary spermatocyte (n) rapidly undergoes _____ to become two spermatids (n)

Answer 24

meiosis II (spermatogenesis)

Question 25

spermatids become functional sperm

Answer 25

spermiogenesis

Question 26

spermatid elongates and forms a tail to become…

Answer 26

spermatozoon

Question 27

what are the major regions of sperm?

Answer 27

head
midpiece
tail

Question 28

genetic region that includes nucleus and helmetlike acrosome containing hydrolytic enzymes that enable sperm to penetrate egg

Answer 28

head

Question 29

metabolic region containing mitochondria that produce ATP to move tail

Answer 29

midpiece

Question 30

locomotor region that includes flagellum

Answer 30

tail

Question 31

• Extend through wall of tubule and surround
  developing cells
• Provide nutrients and signals to dividing cells
• Move spermatocytes and spermatids along to the
  lumen
• Secrete testicular fluid into lumen for sperm
  transport
• Phagocytize faulty germ cells and excess
  cytoplasm
• Produce chemical mediators to regulate
  spermatogenesis

Answer 31

sertoli cells (large supporting cells)

Question 32

tight junctions in sustenocytes form ____
* Prevents sperm antigens from escaping into
blood and causing activation of immune system
* Sperm is not formed until puberty, so it is
absent during immune system development
* Results in sperm not being recognized as
“self”
* Therefore, sperm needs to be kept separated
from rest of body to avoid being attacked by
immune system

Answer 32

blood testis barrier

Question 33

how long does spermatogenesis take?

Answer 33

64-72 days if conditions are hospitable

Question 34

• Production of gametes and sex
  hormones is regulated by
  sequence of hormonal events
  involving hypothalamus,
  anterior pituitary gland, and
  testes

Answer 34

hypothalamic-pituitary-gonadal axis (HPG)

Question 35

what hormones does HPG involve?

Answer 35

GnRH, FSH, LH, testosterone, and inhibin

Question 36

what are the sequence of events of hypothalamic-pituitary-gonadal axis?

Answer 36

1. Hypothalamus releases gonadotropin-releasing
   hormone (GnRH)
2. GnRH binds to receptors on anterior pituitary,
   causing them to secrete:
   * Follicle-stimulating hormone (FSH)
   * Lutenizing hormone (LH)
3. FSH stimulates spermatogenesis indirectly by
   stimulating sustentocytes to release androgen-
   binding protein (ABP)
   * ABP keeps concentration of testosterone high
   promoting spermatogenesis
4. LH binds to receptors prodding them to secrete
   testosterone
   * Rising testosterone levels trigger
   spermatogenesis
5. Testosterone entering blood stimulates sex
   organ maturation, development/maintenance
   of secondary sex characteristics, and libido
6. Rising testosterone levels inhibit GnRH release and
   gonadal hormone release
7. Inhibin: released by sustenocytes when sperm count
   high; inhibits GnRH and FSH release