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Flashcards in Reproductive Molecules Deck (45):
1

Name the 3 most important groups of molecules for human development

Glycoproteins, steroids and prostaglandins

2

Describe the structure of steroids

Lipids, 27C compound skeleton with four fused rings (different functional groups attached). Cholesterol is the core molecule.

3

Give examples of steroids

Oestradiol, oestrone, oestriol, progesterone and testosterone

4

What causes differences between steroid compounds?

Different functional groups

5

Describe the structure of the oestrogens

18 carbon steroids

6

Describe the structure of the progestagens

21 carbon steroids

7

Describe the structure of the androgens

19 carbon steroids

8

Explain the differences between oestradiol, oestrone and oestriol

Oestrone has 1 -OH group, oestradiol has 2 and oestriol has 3.

9

Generally, what does steroid synthesis involve cellularly?

Oxidative enzymes in the mitochondria and ER

10

What is the first step in steroid synthesis?

Conversion of cholesterol to pregnelolone

11

Describe steroid synthesis in males

GnRH released from hypothalamus --> anterior pituitary releases FSH and LH --> LH stimulates Leydig cells to produce testosterone --> testosterone and FSH act on Sertoli cells --> in Sertoli testerone converted to DHT by 5a reductase --> Sertoli cells then secrete ABP --> ABP binds testosterone and carries to seminiferous tubes --> spermatogenesis

12

Describe steroid synthesis in females

GnRH released from hypothalamus --> anterior pituitary releases FSH and LH --> LH stimulates testosterone production by theca cells in ovarian follicle --> testosterone enters granulosa cells (around oocyte) and is converted to oestrogen (17B-oestradiol) by aromatase --> oestradiol stimulates LH receptors on granulosa cells --> enables response to LH surge --> ovulation

13

What group of molecules are androgens, oestrogens and progestogens?

Steroids

14

Describe the role of androgens

Maintain male somatic tissue diffentiation, secondary male traits, support spermatogenesis, influence sexual and aggressive behaviour (both genders), promote protein anabolism, somatic growth and ossification, regulate anterior pituitary release, induce body hair (females) - pubic and underarm.

15

Describe the role of oestrogens

Growth of mammary gland and endometrium, female secondary traits, prepare uterus for sperm movement, increase vascular permeability, regulate gonadotrophin secretion

16

Describe the role of progestagens

Luteal form prepares endometrium for implantation (secretory phase of menstrual cycle), placental form maintains endometrium in pregnancy after ~10-12 weeks

17

Name 4 common androgens, and list them in terms of their potency

DHT, testosterone, androstenedione, DHEA

18

Name 3 common oestrogens, and list them in terms of their potency

17b oestradiol, oestriol, oestrone

19

How do steroids act on cells?

Small and lipophilic so can pass through by simple diffusion to bind to nuclear or cytoplasmic receptor

20

Describe the structure of glycoproteins

Oligosaccharide chain attached to protein side chains

21

Describe the synthesis of glycoproteins

Oligosaccharide chain is added in post-translational modification known as glycosylation

22

What group of molecules do gonadotrophins belong to?

Glycoproteins; they are hormones

23

Name 6 gonadotrophins

FSH, LH, hCG, inhibin, activing, relaxin

24

Where are what produces LH and FSH?

Anterior pituitary gland, by gonadotrophs

25

Where are what produces hCG?

Placenta - by syncytiotrophoblasts

26

Outline the role of FSH

Stimulates growth of immature follicles (female)
Enhances ABP production from Sertoli cells in men to help in spermatogenesis

27

Outline the role of LH

Surge triggers ovulation, and converts residual follicle --> corpus luteum (produces progesterone in fertilisation). LH needed to retain luteal function, and it supports thecal cells (these supply precursors for oestradiol production) and LH acts on Leydig cells to produce testosterone.

28

Outline the role of hCG

Maintains corpus luteum in pregnancy

29

Outline the role of inhibin

Males: produced by Sertoli cells to inhibit FSH and GnRH release when sperm count is high
Females: produced by Granulosa cells to give negative control of FSH production during menstrual cycle

30

Outline the role of activin

Part of transforming growth factor B family; increases FSH release and enhances response to LH in men and women

31

Outline the role of relaxin

Females: produced in menstrual cycle for follicle development and oocyte maturation, and in pregnancy for ligament relaxation and labour.
Men: in seminal fluid to enhance sperm motility

32

How do glycoproteins act on a cell?

Bind to a G-protein coupled receptor with large extracellular domains which bind to the hormone

33

Describe the structure of prostaglandins

Lipid compound (derived from FAs) with 20C (including 5C ring)

34

Where are prostaglandins present?

In almost all tissues and organs including the uterus and seminal fluid

35

What are the effects of prostaglandins?

muscle contraction, vasodilation, inflammation, hormone regulation, cell growth control and temperature regulation

36

Which prostaglandin is involved in labour?

PGF2a; activates contractions of myometrium and causes cervical ripening

37

Which prostaglandins are present in seminal fluid?

PGE1, PGE2, PGF1a, PGF2a

38

How do prostaglandins act on a cell?

Attach to a G-protein couple cell surface receptor

39

Where is growth hormone releasing hormone (GHRH) released?

Hypothalamus

40

Where is oxytocin released?

Hypothalamus

41

Where is prolactin released?

Anterior pituitary

42

How many subunits are there in a glycoprotein?

2; alpha and beta

43

In what glycoproteins is the alpha subunit identical?

FSH, LH, hCG and TSH (92 amino acids)

44

What is the significance of the beta subunit in glycoproteins?

Confers specific biological action

45

Which glycoproteins share similar beta subunits, and what does this mean?

LH and hCG, therefore they can bind to the same receptors as they both have the same sequence of amino acids in their beta subunit, only hCG has an extra 24.