Reproduction Reproduction is the creation of new individuals from existing ones ASEXUAL AND SEXUAL REPRODUCTION Sexual and asexual reproduction are both common among animals

Asexual Reproduction Binary fission In asexual reproduction One parent produces genetically identical offspring Binary fission Is the simplest type of asexual reproduction Involves a single parent cell splitting through mitosis into two genetically identical offspring cells

Regeneration, is the re-growth of a whole animal from the pieces Budding Is the splitting off of new individuals from existing ones

Asexual reproduction has a number of advantages It allows a species to perpetuate itself if its individual members are sessile or isolated from one another It allows organisms to multiply quickly One potential disadvantage of asexual reproduction is that it produces genetically uniform populations

Sexual Reproduction Definition: Process in which two cells, termed gametes, come together to form one fertilized cell that contains genetic information from both parental cells. Production of offspring whose genetic constitution is a mixture of that of two potentially genetically different gametes.

Advantages of sexual reproduction Increases genetic variation Enhances reproductive success in changing environments Disadvantage of sexual reproduction Locating a mate

Meiosis 8

Quick Review - Meiosis - division of cells which results in the production of gametes Gametes - also known as sex cells, germ cells, or spores; cells of sexual reproduction, which contain only half the chromosomes of a normal cell Chromosomes - Threadlike bodies found in the nucleus, or center part, of a cell that carry the information of heredity.

What is the point of meiosis? To produce gametes The usual purpose of meiosis is to form gametes- the sex cells that will fuse together to form a new diploid individual.

A sperm cell consists of: a head, which contains the nucleus a midpiece, which contains energy-releasing mitochondria a tail, which propels the cell forward Head Nucleus Midpiece Mitochondria The sperm is the male gamete, or sex cell. Tail

Male gametes Male gametes, very large numbers 100 million sperm per ejaculation smallest cell in the human body Motile (if they can propel themselves, mobile if they can be easily moved)

Sperm Production (Spermatogenesis) Video

Female gametes (ova or eggs in animals, ovules in plants) Fairly small numbers. Human females for example release about 500 ova in a lifetime. Larger Stationary They often contain food reserves (lipids, proteins, carbohydrates) to nourish the embryo after fertilization Female gametes

Spermatogenesis Oogenesis Occurs in the testes Occurs in the ovaries Produces 4 hapoid cells Produces 4 viable spermatozoa Motile – swim with tail Production begins at puberty Production continues for entire life Occurs in the ovaries Produces 4 hapoid cells Produces 1 Ovum & 3 polar bodies Nonmotile – moved by currents All eggs present at birth Eggs mature from puberty to menopause Oogenesis

Fertilization Fusion of gametes to produce zygote In humans this takes place near the top of the oviduct. Hundreds of sperm reach the egg (shown in this photo). When a sperm reaches the ovum cell the two membranes fuse and the sperm nucleus enters the cytoplasm of the ovum. This triggers a series of reactions in the ovum that cause the jelly coat to thicken and harden, preventing any other sperm from entering the ovum. The sperm and egg nuclei then fuse, forming a diploid zygote. In plants fertilisation takes place in the ovary at the base of the carpel. The haploid male nuclei travel down the pollen tube from the pollen grain on the stigma to the ovules in the ovary. In the ovule two fusions between male and female nuclei take place: one forms the zygote (which will become the embryo) while the other forms the endosperm (which will become the food store in the seed). This double fertilisation is unique to flowering plants

http://www.doctoroz.com/videos/fertilization-animation fertilization

Basic lifecycle of sexually reproducing organisms All sexually-reproducing species have the basic life cycle shown on the right, alternating between diploid and haploid forms. In addition, they will also use mitosis to grow into adult organisms, the details vary with different organisms In the animal kingdom (including humans), and in flowering plants the dominant, long-lived adult form is diploid, and the haploid gamete cells are only formed briefly.

http://www.youtube.com/watch?v=SOllUTBYZtE Salmon spawning Look for some disadvantages of this means of fertilization when watching this video Types of fertilization: External

Types of fertilization: External

Human Reproduction 24

Are males & females all that different? Battle of the sexes!!! Are males & females all that different? Well…….…..YES and NO 25

Same embryonic tissues becomes male or female reproductive organs. 26

Male or Female??? All humans are female by default DNA determines baby’s gender XX = Female XY = Male All humans are female by default At ~ 7 weeks the baby’s body may be “told” by DNA to become male SRY gene located on the Y chromosome 27

Anatomy - similar Fetus begins with “starter parts” that could develop into either gender. Same tissue – Same function Testicles & Ovaries Glands responsible for the production of sex hormones and gametes Start inside body (Testicles “descend” before birth) Vas Deferens & Oviduct Passageway of gametes Penis & Clitoris Contain thousands of nerve ending to aid in sexual stimulation 28

Physiology – VERY different! Female Very Complicated! Born with ~ 400,000 eggs Uses ~500 Ovulation 1 egg “ripens” and is released once a month Careful coordination of hormones & body Support life Male Uncomplicated Produce sperm 2-4 MILLION every day 29

The Male Reproductive System

SPERM + SEMINAL FLUID = SEMAN Males Bladder Seminal vesicle Prostate gland Urethra Vas Deferens Penis Epididymis Testes Produce seminal fluid Provides a medium for the sperms to swim To activate and nourish the sperms SPERM + SEMINAL FLUID = SEMAN Prostate cancer – slow growing, surgical removal Erected during copulation for insertion into vagina Dilation of arterioles causes the erectile tissue of penis become turgid Semen is squeezed from the penis to the top of vagina Produces male sex hormone Produce 2-4 million sperm every day Outside body – why? Sperm like temps 1-2 cooler than body temp Tube taking both urine and semen outside the body Bulboureathral gland adds lubricant to aid travel of semen through the ureathra Temporary storage of sperm During copulation, muscle contract to release sperm Tube that carries sperm to the seminial vesicle and prostate 31

Sperm Why a pH buffer? Why so many sperm? Semen contains 300-500 million sperm – 5% Sperm food (fructose) – 30% Alkaline fluid (pH buffer) – 65% Why a pH buffer? Why so many sperm? 32

What is sperm? Head Mitochondria Flagellum Contains chemicals to dissolve egg goo Dad’s genetic information – one each of 44 autosomal chromosomes and 1 sex chromosome Mitochondria Energy Contains mitochondrial DNA from mother Flagellum “tail” used for locomotion 33

The Female Reproductive Cycle Human females have a reproductive cycle, a recurring series of events that produces gametes, makes them available for fertilization, and prepares the body for pregnancy

The Female Reproductive System Fallopian tube Ovary Uterus Cervix Urinary bladder Rectum Pubic bone The main function of the female reproductive system is to produce ova. The ovaries are the main organs of the female reproductive system. Egg Development  Each ovary contains about 400,000 primary follicles, which are clusters of cells surrounding a single egg. The follicle helps an egg mature for release into the reproductive tract, where it can be fertilized. Eggs develop within their follicles. When a follicle has matured, its egg is released in a process called ovulation. The follicle breaks open, and the egg is swept from the ovary into one of the two Fallopian tubes. While in the Fallopian tube, an egg can be fertilized. After a few days, the egg passes from the Fallopian tube into the uterus. If the egg is not fertilized it passes through the cervix, and finally out of the vagina. The vagina leads to the outside of the body. Vagina Urethra

Females Ovary Oviduct Uterus Cervix Vagina Allows for placenta to attachment During embryo development it protects the embryo and provides a constant environment for the embryo to develop During birth of baby it pushes the baby out by muscular contraction Carries the ovum forward by the beating action of the cilia on its inner surface and the contraction of muscles of oviduct For production of female gametes (ova/eggs) For production of female sex hormones Birth canal Opening between the uterus and vagina 38

Menstrual Cycle All about timing!!! Uterus must be ready when egg gets there in case it was fertilized If no fertilization, tear down lining of uterus and rebuild for next month 40

The Menstrual Cycle The Menstrual Cycle The menstrual cycle is controlled by internal feedback mechanisms between the reproductive system and the endocrine system. The cycle takes an average of 28 days.

http://www. abpischools. org. uk/page/modules/hormones/horm4. cfm http://www.abpischools.org.uk/page/modules/hormones/horm4.cfm?cositenavigation_alltopic=1 Menstrual cycle http://www.youtube.com/watch?v=9_tH8mLqXC8 Video (00:01:11)

The Menstrual Cycle Ovulation The menstrual cycle is divided into four phases. Notice the changes in hormone levels in the blood, the development of the follicle, and the changes in the uterine lining during the menstrual cycle.

FSH causes the follicle to grow Growing follicle releases estrogen Estrogen ↑ the lining of the uterus ↑ levels of estrogen ↑production of LH ↑ LH causes the follicle to rupture releasing the egg (ovulation)

6. Ruptured follicle (corpus luteum ) produces progesterone 7. Since follicle is gone: - ↓ in estrogen which causes - ↓ in LH which causes - corpus luteum to break down which causes - ↓ in progesterone

8. Progesterone keeps the lining of the uterus from shedding, therefore ↓in progesterone = menstruation **** if the egg does get fertilized, hormones will not drop and the uterine lining will be maintained for the entire pregnancy.

Hormones Estrogen Ovaries Drop in levels causes shedding of uterine lining Increase in levels causes uterine lining to thicken Progesterone Corpus litheum (ruptured follicle) LH (leuteinizing hormone) Pituitary gland & hypothalamus Stimulates release of mature egg from ovary FSH (follicle stimulating hormone) Pituitary gland Acts on ovaries to mature the egg HCG (Human Chorionic Gonadotropin) Corpus litheum (ruptured follicle) Produced if fertilization occurs Stimulates continued secretion of progesterone 49

Reproduction Hormones Produced by Function Testosterone Testicles Male sex traits FSH Pituitary Stimulates egg/sperm development Stimulate estrogen LH Stim. Testosterone Release of egg, corpus luteum, progesterone Estrogen Ovaries Female sex traits Progesterone Corpus luteum (Ovaries) Maintains Uterus lining

Q: How many of you have more than one parent? then, everyone in this room is a product of sexual reproduction

Characteristics of Sexual Reproduction Requires a female and male parent (i.e. it takes two to tango)

Q: Why do we need more than 1 parent? ½ + ½ = 1

Characteristics of Sexual Reproduction Requires a female and male parent (i.e. it takes two to tango) Each parent donates ½ of the Chromosomes/Genes/DNA

So, by what we’ve discussed, in sexual reproduction “mom” donates half, and “dad” donates half. How does this happen?

Characteristics of Sexual Reproduction Requires a female and male parent Each parent donates ½ of the Chromosomes/Genes/DNA Requires fertilization - the combining of gametes

Now, nine months later, you come out kicking and screaming (and dancing). To which parent do you look exactly alike? How about your siblings? Do you look exactly alike one another?

Characteristics of Sexual Reproduction Requires a female and male parent Each parent donates ½ of the Chromosomes/Genes/DNA Requires fertilization - the combining of gametes Produces genetic diversity - variation among and within species that is attributable to differences in hereditary material.

So what can we conclude about Sexual Reproduction? it produces diversity diversity ensures survival of a species in an environment that changes