Reproduction I

Question 1

asexual reproduction

Answer 1

• single parent -> 2+ offspring
• identical
• clones
• no meiosis
• no gamete fusion

Question 2

list the types of asexual reproduction

Answer 2

• budding
• fission
• fragmentation and regeneration
• parthogenesis

Question 3

what are the advantages to asexual reproduction?

Answer 3

• rapid - many offspring in a short time
• all of organism’s genes passed on
• don’t need to find a mate (great if sessile, low population density)

Question 4

sexual reproduction

Answer 4

• reproduction involving production and fusion of gametes
• sperm: small, motile, flagellated
• egg (ovum): large, non-motile, contains nutrients for embryo
• involves fertilization: fusion of sperm and egg = zygote (2n)

Question 5

what are the disadvantages of sexual reproduction

Answer 5

• “reproductive handicap” - only 1/2 of population can actually reproduce
• only 1/2 of organism’s genes passed on

Question 6

what are the advantages of sexual reproduction

Answer 6

• promotes genetic diversity
• new combinations of alleles
  (1) get rid of harmful alleles or combinations of alleles
  (2) offspring may be more fit than parents
  (3) more likely that some of population can survive environmental changes

Question 7

what are the functions of the male reproductive system

Answer 7

1. make sperm (spermatogenesis)

2. deliver sperm to female reproductive tract

Question 8

pathway of sperm

Answer 8

Seminiferous tubules
Epididymis
Vas deferens
Ejaculatory duct
n(othing)

Urethra
Penis

Question 9

testes

Answer 9

• male gonads
• endocrine gland
• seminiferous tubules
• ley dig cells

Question 10

seminiferous tubules

Answer 10

• site of spermatogenesis

- long hollow tube, very small diameter

Question 11

ley dig cells

Answer 11

• produce testosterone and other sex hormones

- scattered between seminiferous tubules

Question 12

epididymis

Answer 12

• coiled tube above testes ~ 6m long
• transport sperm - takes ~ 3 weeks
• maturation of sperm
• storage of sperm

Question 13

scrotum

Answer 13

• skin-covered sac - contains testes and epididymis

- external in most mammals - suspended from body -> cooler than body -> temp improves sperm production and longevity

Question 14

ducts

Answer 14

• Vas deferens
• extend from scrotum to behind the bladder
• ejaculatory duct

Question 15

penis

Answer 15

• copulatory organ
• delivers sperm into female reproductive trait
• urethra

Question 16

Vas deferens

Answer 16

sperm ducts - one from each epididymis

Question 17

ejaculatory duct

Answer 17

passes through prostate gland, joins urethra

Question 18

urethra

Answer 18

carries urine and semen through penis

Question 19

what are the parts to the penis anatomy?

Answer 19

erectile tissue, glans, and prepuce

Question 20

erectile tissue

Answer 20

3 parallel columns of tissue

during sexual stimulation:

• NO released from endothelial cells
• arterial smooth muscles relax
• dilate arteries/compress veins -> blood enters faster than it leaves

Question 21

glans

Answer 21

tip of penis, contains most sensory nerves

-homologous with clitoris in females

Question 22

prepuce (foreskin)

Answer 22

cuff of loose fitting skin, removed in circumcision

Question 23

semen

Answer 23

sperm and fluids from accessory glands

Question 24

accessory glands

Answer 24

• secrete fluids into vas deferens
• ~ 60% of semen volume -> fluoresces - forensically important
• produce fluids rich in:
  (1) fructose - E for sperm after ejaculation
  (2) Prostaglandins - stimulate contractions of uterus - help more sperm up female reproductive tract

Question 25

prostate gland

Answer 25

- contains anticoagulant enzymes and citrate (nutrient) - secretes into urethra - common site of cancer in men > 50 - >1/2 of men > 40 have enlarged prostate - ~ 3% of men die of prostate cancer`

Question 26

bulbourethral gland

Answer 26

- 2 smalls round glands on either side of urethra - BEFORE ejaculation: secrete bulbourethral fluid into urethra-clear mucus to neutralize only acidic urine (contains some sperm as well - "pulling out" is ineffective)

Question 27

describe the sperm path

Answer 27

- produced in seminiferous tubules in testes - travels through/stored in epididymis - during ejaculation, travels from epididymis through vas deferens

Question 28

describe the process of spermatogenesis

Answer 28

- Spermatogenesis = production of mature sperm cells, ~ 7 weeks in humans, continuous after puberty - in embryonic testes (before male is born) - primordial germ cells divide, differentiate into spermatogonial stem cells

Question 29

what happens in the mature testes at/after puberty

Answer 29

- spermatogonial stem cells divide via mitosis -> spermatogonia (2n) - undifferentiated cells in walls of seminiferous tubules - maintained via mitotic divisions - some become 1° spermatocytes (~ 3 million/day)

Question 30

1° spermatocyte (2n)

Answer 30

divides via meiosis

Question 31

SEQ spermatogenesis

Answer 31

1° Spermatocyte (2n) -> meiosis I -> 2° Spermatocyte (n) -> meiosis II -> spermatids (n) -> differentiation -> mature sperm cells

Question 32

what are the parts to a mature sperm cell?

Answer 32

head, midpiece, tail

Question 33

androgens

Answer 33

principle sex hormones in males

Question 34

testosterone

Answer 34

- needed for spermatogenesis - growth of primary male sex characteristics - sex organs - stimulates puberty -> secondary sex characterisitics (1) physical, behavioral differences between males and females, not directly related to production (2) facial/body hair, deep voice, muscle development - 10x more testosterone in males than females

Question 35

Signaling Pathway

Answer 35

- hypothalamus: gonodotropin - releasing hormone (GnRH) - anterior pituitary: luteinizing hormone or follicle stimulating hormone - leydig cells: testosterone - sertolic cells: androgen binding protein and inhibin

Question 36

follicle stimulating hormone (FSH)

Answer 36

- stimulates development of seminiferous tubules - stimulates sertoli cells to produce, secrete androgen binding protein (ABP) - FSH secretion inhibited by inhibin

Question 37

androgen binding protein (ABP)

Answer 37

- binds testosterone | - helps maintain high testosterone levels in testes

Question 38

inhibin

Answer 38

peptide hormone secreted by sertoli cells