Sexual Reproduction

A. External Fertilization 2. Large number of eggs and sperm released 1. Egg fertilized outside female body I. Internal Vs. External Fertilization - Increase chance of fertilization - Many offspring because many die 3. Usually in Aquatic environments …why?

B. Internal Fertilization 2. Fewer eggs but many sperm needed …why? 1. Egg fertilized inside female body 3. Allows for terrestrial reproduction …how?

II. Male Reproductive System

A B C D E F G H I 1 2 3

c A B C D E F G H I 1 2

*Over 100 million sperm produced per day!

Made of semineferous tubules/Produce sperm & testosterone Holds testes outside of the body to keep them cooler than body Carries sperm from epididymis to urethra Passage for sperm (and urine) to exit the body Deposits sperm into female Produce/release seminal fluid Where sperm fully mature and are stored Testes (male gonads) Epididymis Scrotum Vas deferens Urethra Penis Seminal Vesicles Prostate Cowper’s Gland Produce/release seminal fluid

General Pathway of Sperm During Ejaculation Epididymis  Vas deferens  Urethra  Out of body

III. Female Reproductive System

A B C D E 1 2 3

A B C D E

Ovaries (female gonads) Produce eggs (stored in follicles), estrogen & progesterone Fallopian Tubes (oviducts) Carries egg from ovary to uterus /Usually the site of fertilization Uterus Thick, muscular organ where fertilized egg develops Cervix Opening of uterus Vagina Birth canal

Brief Review

The diagram below represents the human male reproductive system. Which pair of letters indicates a structure that produces gametes and a structure that makes possible the delivery of gametes for internal fertilization, respectively? (1) A and D (3) C and A (2) B and D (4) D and C

Meiosis (Gametogenesis in Sexual Reproduction) A. Meiosis:two-stage Reduction Division: 2n  n results in 4 haploid gametes/sex cells (half the chromosome number of the original cell) Haploid cells are expressed as “n” Diploid cells are expressed as “2n” Fertilization restores the diploid condition Sperm(n) + Egg(n) = Embryo(2n)

3. Overview: Non-functioning “Polar Bodies” are discarded Oogenesis Spermatogenesis Fertilization Zygote 46 (2n) 23 (n)(n) (n)(n) (n)(n) (n)(n) (n)(n) DaddyMommy 46 (2n) 46 (2n) 46 double chromosomes (2n) chromosomes 46 double Meiosis DNA Replication

B. The Process: Occurs in 2 consecutive divisions called Meiosis I and meiosis II.

B. The Process: Occurs in 2 consecutive divisions called Meiosis I and meiosis II.

Chromatin Duplication (during S-phase) Prophase I

Another way to think of it…

Synapsis Chiasma Recombination Metaphase I

Anaphase I

Telophase I

Cytokinesis

Prophase IIMetaphase IIAnaphase II Telophase IICytokinesis

1. Meiosis I a. Prophase I: Homologous pair tetrad Crossing over Crossing Over - Sections of chromosomes are exchanged to produce new combinations of alleles. * Increases genetic diversity within the species After chromosomal replication, pairs of homologous chromosomes join together to form a tetrad.

b. Metaphase I: Tetrads line up across the middle c. Anaphase I: Tetrads are split (disjunction) and the double chromosomes are pulled by centrioles to opposite sides of the cell. d. Telophase I: (and cytokinesis) : Two haploid cells are produced but chromosomes still consist of sister chromatids.

2. Meiosis II a. Follows the same steps as mitosis but deals with two haploid cells forming 4 haploid cells. b. Result: Four haploid (n) gametes * In females, only one large egg is produced. The other three cells are called polar bodies and are discarded.

A. Intro to theEndocrine System 2. Hormones: 1.Composed of glands that secrete hormones directly into bloodstream chemicals that travel through blood to send messages to cells throughout body -Affect activity of specific cells called “target cells” 3. Target Cell: has receptors for a particular hormone

4. Negative Feedback/Biofeedback: When the outcome of a process “builds up”, it causes the process to slow down. *Self-Regulating

B. Some Menstrual Cycle Info -Estrogen -Leutinizing Hormone (LH) 3. Hormones involved: day cycle 1. Begins at puberty and ends at menopause -Follicle Stimulating Hormone (FSH) -Progesterone ~Menopause: estrogen production declines

Follicular Phase Luteal PhaseMenstruation Ovulation The Menstrual Cycle Low levels of ________________ & _______________cause the pituitary to secrete ____________ FSH causes a __________to develop in the ovary The follicle secretes ___________which causes the uterine lining (_________________)to thicken Pituitary secretes a high level of _____ LH causes the follicle to burst and the mature egg is released into the ___________________________ Ruptured follicle turns yellow and becomes the _____________________ Corpus luteum secretes _____________ and __________________ These hormones maintain the endometrium and exert ___________ _____________on the pituitary which lowers secretion of FSH and LH If fertilization doesn’t occur, the corpus luteum disintegrates Low levels of ________________cause the endometrium to detach from the uterine wall. Endometrium, egg and blood are discharged through the _____________ *FSH = Follicle Stimulating Hormone*LH = Leutinizing Hormone estrogen progesterone FSH follicle estrogen endometrium LH Fallopian tube (oviduct) corpus luteum estrogen progesterone feedback negative progesterone vagina

Egg maturation in ovary