Lecture 3

Question 1

Sex Determination

Answer 1

The factors that determine what the sex of an individual will be as a result of a fertilization event.

Humans have chromosomal sex determination.

Question 2

CHROMOSOMES are discrete units

of DNA

Answer 2

DNA is deoxyribonucleic acid.
DNA carries the genetic code, the blueprint for protein production in cells.
DNA and, hence, the genetic code consists of pairs of individual subunits called bases.

Question 3

Chromosomes continued…

Answer 3

Genes are specific sequences of bases that code for particular proteins.

Bases (chemical):
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)

Question 4

how many chromosomes do humans have?

Answer 4

Humans have two pairs of 23 chromosome types for a total of 46 chromosomes.

Question 5

Parental Contributions

Answer 5

Two gametes, one from each parent, must unite (fertilization) to form a new individual.

Each gamete (sperm & ovum) carries a copy of each chromosome type, i.e. 23 chromosomes.

When the two gametes combine, the new individual has two sets of 23 chromosomes for a total of 46 chromosomes.

One set is MATERNAL (from Mom) and one set is PATERNAL (from Pop).

Question 6

Each Chromosomes

Answer 6

Each pair of each chromosome, type 1 through 22, the autosomes, carry versions of the same genes. We’ll follow up on this in Lecture 12.

BUT, the remaining set of chromosomes are different than each other – do not carry the same genes. These are the sex chromosomes,

X and Y.

Question 7

Y-chromosome

Answer 7

approximately 80 genes

primarily related to male determining factors

Question 8

X-chromosome

Answer 8

approximately 2000 genes

diverse functions, most NOT related to sex determination

Question 9

xx

Answer 9

female

Question 10

xy

Answer 10

male

Question 11

Primary (Gonadal) Sex Determination is Chromosomal

Answer 11

Y chromosome carries SRY gene = ♂ = testes

No Y chromosome = no SRY gene = ♀ = ovaries

Question 12

SRY

Answer 12

SRY gene is the

testis determining factor (TDF)

Question 13

If no SRY?

Answer 13

So, if no SRY is present, an OVARY forms.If SRY is present, a TESTIS forms.

Note: sometimes SRY ends up on the X-chromosome…

Question 14

Hormone

Answer 14

A chemical substance produced by one cell and released, so that it acts on or regulates another cell. Hormones may also be called chemical messengers.

Question 15

Proteins

Answer 15

macromolecules that have lots of varied functions in cells:

 structural elements
 signaling molecules
 antibodies
 receptors
 transporters
 movement elements

Question 16

Enzymes

Answer 16

 CATALYZE CHEMICAL REACTIONS FOR MAKING ALL OTHER MOLECULES OF CELLS

Question 17

Classification of Hormones by Chemical Structure

Answer 17

Protein Hormones – soluble in water

Steroid Hormones – soluble in lipids (fats)

Question 18

Hormones Are Released From Glands:

Exocrine Gland & Endrocrine gland

Answer 18

Exocrine Glands: release substances (not always hormones) through a duct, directly to the target

Endocrine Glands: release hormones into the fluid-filled space around cells; fluids (especially blood) then transport them until reaching their target(s)

Question 19

Endocrine Hormone Delivery Classifications(5)

Answer 19

Paracrine  targets nearby cell
Autocrine  target is the same cell
Neurocrine/neuroendocrine  released by a nerve cell
Endocrine  carried a distance by fluid transport of the bloodstream
Pheromone  released by cells of one individual to act on cells of another individual

Question 20

Hormone Receptors

Answer 20

For any hormone to act on any cell, that cell must have a receptor for that hormone.

 Hormone receptors are specific to the hormone which they bind

No receptor? NO RESPONSE

Question 21

Classification of Hormones by Chemical Structure

Answer 21

Protein Hormones – soluble in water

Steroid Hormones – soluble in lipids (fats)

The chemical structures of these two groups determine their mechanism of action at the cell.

Question 22

Peptide Hormone Action at Cell

Answer 22

AMPLIFICATION!!

Question 23

Steroid Hormone Action at Cell

Answer 23

Steroids can induce repeated synthesis of the same protein!

Question 24

Endocrine Glands of Sex and Reproduction(5)

Answer 24

Hypothalamus, pituitary gland, adrenal glands, ovaries or testes

Question 25

Hypothalamus

Answer 25

The hypothalamus is the control center of autonomic regulatory activities. It relays information from lots of different parts of the brain to the body. Many of its messages are relayed through the pituitary gland.

Question 26

Releasing Hormones:

Answer 26

Hormones released by the hypothalamus that travel to the pituitary gland, where they induce the production and release of other hormones, which, in turn, act on target organs.

Question 27

Hypothalamic Releasing Hormones

Answer 27

``` GnRH = gonadotropin releasing hormone PRH = prolactin-releasing hormone CRH = corticotropin-releasing hormone ```

Question 28

Pituitary Hormones(2)

Answer 28

``` Anterior Pituitary Luteinizing Hormone (LH) Follicle Stimulating Hormone (FSH) Prolactin (PRO) Adrenocorticotropic Hormone (ACTH) Posterior Pituitary Oxytocin ```