Chapter 11 Reproduction and Embryonic Development Power Point

Chapter 11 Reproduction and Embryonic Development Power. Point Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Lecture by Richard L. Myers Copyright © 2009 Pearson Education, Inc.

Topics discussed in this chapter § Asexual reproduction Budding Fission Fragmentation/regeneration Hermaphroditism Sexual reproduction External fertilization Internal fertilization Human Reproduction Human male and female Reproductive anatomy Spermatogenesis and oogenesis Ovarian and menstrual cycles Hormones of the Ovarian and menstrual cycles Embryonic development Cleavage Gastrulation

ASEXUAL AND SEXUAL REPRODUCTION Copyright © 2009 Pearson Education, Inc.

Asexual reproduction results in the generation of genetically identical offspring § Asexual reproduction – One parent produces genetically identical offspring – – Very rapid reproduction – – Can proceed via – – Budding – Fission Asexual reproduction of an aggregating sea anemone (Anthopleura elegantissima) by fission – Fragmentation/regeneration

Sexual reproduction results in the generation of genetically unique offspring § Some animals exhibit hermaphroditism – One individual with male and female reproductive systems – Easier to find a mate for animals less mobile or solitary Hermaphroditic earthworms mating

Sexual reproduction results in the generation of genetically unique offspring § Sperm may be transferred to the female by – External fertilization – Many fish and amphibian species – Eggs and sperm are discharged near each other – Internal fertilization ﺍ – Some fish and amphibian species – Nearly all terrestrial animals – Sperm is deposited in or near the female reproductive tract Frogs in an embrace that triggers the release of eggs and sperm

Human Reproduction

Reproductive anatomy of the human female § Both sexes in humans have – A set of gonads where gametes (sperms & ovums) are produced – Ducts for gamete transport – Structures for copulation

Human Female Reproductive anatomy § Ovaries contain follicles that Nurture eggs and Produce sex hormones § Oviducts convey eggs to the uterus where embryos develop § The uterus opens into the vagina through the cervix § The vagina – Receives the penis during sexual intercourse – Forms the birth canal

Oviduct Ovaries Follicles Corpus luteum Wall of uterus Endometrium (lining of uterus) Uterus � Cervix (“neck” of uterus Vagina Front view of female reproductive anatomy (upper portion)

Human Male Reproductive anatomy § Testes (singular testis) produce Sperm and male hormones § Epididymis stores sperm as they develop further § Several glands contribute to semen – Seminal vesicles – Prostate – Bulbourethral

Urinary Bladder Prostate gland Seminal Vesicle (behind ) bladder) Bulbourethral gland Erectile tissue of penis Vas deferens Urethra Scrotum ﻛﻴﺲ ﺍﻟﺼﻔﻦ Epididymis Testis Glans of Penis Front view of male reproductive anatomy

Sperm production (Spermatogenesis) – Regulated by a negative feedback system of hormones – Involves the hypothalamus, pituitary, and testes

Midsagittal section through the human brain. Cerebrum Thalamus Hypothalamus Cerebellum Pituitary gland Medulla Spinal cord Fig. 41 -11 a, p. 876

Stimuli from other areas in the brain Releasing Hormone Anterior Pituitary Follicle stimulating hormone(FSH) Negative feedback Hypothalamus Luteinizing hormone(LH) Androgen production Testis Sperm production Hormonal control of the testis

Spermatogenesis (The formation of sperm) § Spermatogenesis – Occurs in seminiferous tubules – Primary spermatocytes – Formed by mitosis – Divide by meiosis I to produce secondary spermatocytes – Secondary spermatocytes divide by meiosis II to produce spermatids – Round spermatids differentiate into elongate sperm – Mature sperm released into seminiferous tubule and stored in the epididymis

Epididymis Testis Penis Scrotum Testis Seminiferous Tubule Cross section of seminiferous tubule

Diploid cell Primary spermatocyte (in prophase of Meiosis I) Secondary spermatocyte (haploid; double chromatids) spermatids Sperm cells (haploid) Center of seminiferous tubule

2 n Diploid cell Differentiation and onset of Meiosis I 2 n Primary spermatocyte (in prophase of Meiosis I) Meiosis I completed n Secondary spermatocyte n (haploid; double chromatids) Meiosis II n n Spermatids: Developing sperm cells Differentiation n n Sperm cells (haploid)

Oogenesis (The formation of egg) § Oogenesis – Begins before birth: diploid cells start meiosis and stop – Each month about one primary oocyte resumes meiosis – A secondary oocyte arrested at metaphase of meiosis II is ovulated – Meiosis of the ovum is completed after fertilization

2 n Diploid cell in embryo Differentiation and onset of Meiosis I Ovary ﺍ 2 n Completion of Meiosis I and onset of Meiosis II n Entry of sperm triggers completion of Meiosis II Primary oocyte (arrested in prophase of Meiosis I; present at birth) Corpus First n polar body luteum ﺓ Secondary oocyte (arrested at metaphase of Meiosis II; released from ovary) Growing Follicle n Second polar body n Ovum (haploid) Mature follicle Sperm Ovulation Ruptured follicle Oogenesis and the development of an ovarian follicle

Hormones synchronize cyclic changes in the ovary and uterus § Ovarian and menstrual cycles Occur about every 28 days Hypothalamus signals the anterior pituitary to secrete follicle-stimulating hormone (FSH) and leuteinizing hormone (LH), which trigger – Growth of a follicle – Ovulation

Hormones synchronize cyclic changes in the ovary and uterus § After ovulation, empty ovarian follicle becomes corpus luteum § Corpus luteum secretes estrogen and progesterone hormones , which 1) Stimulate the endometrium to thicken 2) Prepare the uterus for implantation of the embryo 3) Inhibit hypothalamus, reducing FSH and LH secretion

Hormones synchronize cyclic changes in the ovary and uterus § If egg is fertilized – Embryo releases hormones that maintain the uterine lining – Menstruation does not occur § If egg is not fertilized – Drop in LH shuts down corpus luteum and its hormones – Menstruation is triggered – Hypothalamus and pituitary stimulate development of a new follicle

Embryonic Development – Embryonic development begins with fertilization – Fertilization is the union of sperm and egg to form a diploid zygote – Results zygote triggers embryonic development

Fertilization Sperm adaptation Sperm are adapted to reach and fertilize an egg § Streamlined shape moves more easily through fluids § Many mitochondria provide ATP for tail movements § Head contains a haploid nucleus Tipped with an acrosome containing penetrating enzymes

Neck Plasma membrane Head Middle piece Tail Mitochondrion (spiral shape) Nucleus Acrosome The structure of a human sperm cell

Fertilization results in a zygote and triggers embryonic development § Fertilization events – Sperm squeeze past follicle cells – Acrosomal enzymes pierce egg’s coat – Sperm binds to vitelline layer – Sperm and egg plasma membranes fuse – Egg is stimulated to develop further – Egg and sperm nuclei fuse

1 The sperm squeezes through cells left over from the follicle 2 The sperm’s acrosomal enzymes digest the egg’s jelly coat 5 Acrosomal enzymes The sperm nucleus enters the egg cytoplasm 6 A fertilization envelope forms Sperm nucleus Cytoplasm Egg nucleus 7 The nuclei of sperm and egg fuse Egg cell Zygote nucleus

Embryonic development 1. Cleavage § Cleavage is a rapid series of cell divisions § Cleavage produces a ball of cells from the zygote – More cells – Embryo does not get larger – Thus new cells are smaller in size – A ball of cells called blastula is formed at the end of – cleavege

Cleavage Zygote 2 cells 8 cells Blastula (hollow ball) Many cells (solid ball) 4 cells Cross section of blastula Blastocoel

2. Gastrulation produces a three-layered embryo § Gastrulation § The blastula (ball of similar cells) resulted from cleavage go to gastrulation – Cells migrate – The basic body plan of three layers is established – Ectoderm outside—becomes skin and nervous systems – Endoderm inside—becomes digestive tract – Mesoderm in middle—muscle and bone Copyright © 2009 Pearson Education, Inc.

Blastula (end of cleavage) Gastrulation (cell migration) Gastrula (end of gastrulation) Simple digestive cavity Ectoderm Mesoderm Endoderm Development of the frog gastrula

You should now be able to 1. Explain how fertility drugs have affected multiple births in the United States 2. 3. 4. 5. Compare the types of asexual and sexual reproduction Describe the structures and functions of the male and female human reproductive tracts Describe and compare spermatogenesis and oogenesis Describe the events of the menstrual cycle 6. Describe the nature of the most common STDs 7. Describe the most common forms of birth control 8. Relate the structure of sperm to its roles in fertilization 9. Describe the processes of cleavage and gastrulation 10. Describe the functions of the four extraembryonic membranes 11 Describe the main changes that occur during each trimester of human development 12. Describe the most common reproductive technologies Copyright © 2009 Pearson Education, Inc.

Chapter 31 Reproduction in Flowering Plants

Topics discussed in this chapter Sexual reproduction in flowering plants The flower Angiosperm life cycle The development of pollen and ovules Pollination Pollen grain germination Seed germination Asexual reproduction Production of clones bulbs, root sprouts, runners and cuttings Test-tube cloning

The flower is the organ of sexual reproduction in angiosperms § Flowers typically contain four types of highly modified leaves called floral organs – Sepals—enclose and protect flower bud – Petals—showy; attract pollinators – Stamens—male reproductive structures – Carpels—female reproductive structures

Stigma Carpel Style Stamen Anther Ovary Filament The structure of a flower Petal Ovule Sepal

The flower is the organ of sexual reproduction in angiosperms § Angiosperm life cycle overview – Fertilization occurs in the ovule; the fertilized egg develops into an embryo encased in a seed – The ovary develops into a fruit, which protects the seed and aids in dispersal – The seed germinates under suitable conditions to produce a seedling, which grows into a mature plant

Ovary, containing Ovule Embryo ﺍ Fruit (mature ovary), containing seed Seed Mature plant with flowers, where fertilization occurs Seedling Germinating Seed Life cycle of a generalized angiosperm

The development of pollen and ovules culminates in fertilization § Pollination § Pollen grains are released from the anther – Transfer of pollen from anther to stigma – Pollen is carried by wind, water, and animals § Pollen grain germination – Pollen grain produces pollen tube, which grows down through the style to the ovary

The development of pollen and ovules culminates in fertilization – A cell in the ovule undergoes meiosis to produce four haploid spores – Three of the spores degenerate – The surviving spore undergoes a series of mitotic divisions to produce the embryo sac – One cell within the embryo sac is an egg ready for fertilization – One central cell within the embryo sac will produce endosperm

Pollen germinates Wall forms Pollen grain released From anther Pollination Two cells Embryo sac Two sperm in Pollen tube enters embryo sac Egg cell Two sperm Discharged Double Fertilization occurs Triploid (3 n) endosperm Nucleus Diploid (2 n) zygote (egg plus sperm)

The development of pollen and ovules culminates in fertilization § Double fertilization – One sperm fertilizes the egg to produce a zygote – One sperm fuses with the central cell nuclei to produce endosperm – Endosperm nourishes the developing embryo

The ovule develops into a seed § The zygote divides many times via mitosis to produce the embryo § The embryo consists of tiny root and shoot apical meristems and one or two cotyledons § A tough seed coat develops § Seed dormancy – Embryo growth and development are suspended – Allows delay of germination until conditions are favorable

Triploid cell Ovule mitosis Zygote ﺍ Two cells Endosperm Cotyledons Seed coat Shoot Development of a eudicot plant embryo Embryo Root Seed

The ovary develops into a fruit § Hormonal changes induced by fertilization trigger the ovary to develop into a fruit § Fruits protect the seed and aid in dispersal § Mature fruits may be fleshy or dry – Fleshy fruits —oranges, tomatoes, grapes – Dry fruits —beans, nuts, grains

Seed germination continues the life cycle § Germination breaks seed dormancy § Germination begins when water is taken up Copyright © 2009 Pearson Education, Inc.

Corn germination Foliage leaves Protective sheath enclosing shoot Embryonic root Cotyledon Corn germination (a monocot)

Asexual reproduction produces plant clones § Most plants are capable of asexual reproduction, producing genetically identical offspring (clones) – Production of clones via bulbs, root sprouts, and runners is common – Plants are often propagated by taking cuttings, which can produce roots – Plants can be cultured on specialized media in tubes § Asexual reproduction can be advantageous in very stable environments

Sprouts from the roots of coast redwood trees Sprout Cloves of a garlic bulb. each clove can give rise to separate plant as indicated by the green shoots emerging from some of them. The white sheaths are leaves attached to the stem. Dune grass. Propagate asexually by sprouting shoots and roots from runners. A ring of creosote bushes. All these bushes came from generations of asexual reproduction by roots.

Test-tube cloning