- Количество слайдов: 48
Unit 13: Reproduction Ch. 18 300 How does reproduction illustrate “unity within diversity”? • Why do organisms reproduce? –to pass on genetic code & continue the species
What are the 2 Main Types of Reproduction? • asexual – How many parents? • 1 – In general, what happens to genetic material during asexual reproduction? • genetic material is copied & cell(s) divide(s) – How do offspring compare genetically to each other & parent? • identical
What are the 2 Main Types of Reproduction? • sexual – How many parents? • 2 – In general, what happens to genetic material during sexual reproduction? • genetic material combined when gametes (formed by meiosis) fuse during fertilization – How do offspring compare genetically to each other & parent? • different – How does sexual reproduction speed up evolution? – increases genetic variety b/c mixing genes
Examples of Asexual Reproduction • 1. What is binary fission? – DNA copied & organism divides in 2 • Ex. of organisms that reproduce by binary fission? – bacteria – protists • How is binary fission in protists different from in bacteria? Why? – protists undergo mitosis b/c eukaryotic (bacteria don’t… b/c prokaryotic) Describe the offspring in relation to the parent.
Examples of Asexual Reproduction • 2. What is budding? – Offspring (bud) begins to develop on the parent’s body & then breaks off • Ex. of organisms that reproduce by budding? – yeast – Hydra – sea anemone Describe the offspring in relation to the parent.
Examples of Asexual Reproduction • 3. What is vegetative propagation? – Essentially budding… in plants • Sends out runner/creeper… – once rooted, separates from original plant & grows independently (unlike regular stems) • Ex. of organisms that reproduce by vegetative propagation? tuber – strawberries – potatoes runners (creepers)
Examples of Asexual Reproduction • 4. What is fragmentation? – fragment (piece) grows into whole new organism • Ex. of organisms that reproduce by fragmentation? – sponges – sea stars • 1 leg new organism 1 leg growing whole new organism
Examples of Asexual Reproduction • 5. What is regeneration? – regrowth of missing body parts • Ex. of organisms that reproduce by regeneration? – Planaria (flat worm) – sea stars • leg cut off grows new leg – salamander • What process allows regeneration to occur? – mitosis 1 leg growing back
Examples of Asexual Reproduction • 6. What is sporulation? – reproduction through spores • which contain DNA, cytoplasm, & tough outer wall (coat) • Ex. of organisms that reproduce by spores? – mushrooms – mold – mosses – ferns fern sori What do you think the coat does? Why might some organisms produce a large number of spores?
Examples of Asexual Reproduction • 7. What is parthenogenesis? – unfertilized egg develops into adult (drone) • Examples of organisms that reproduce by parthenogenesis? – Daphnia – aphids – honey bees – lizards
Examples of Sexual Reproduction • 1. conjugation – genetic material exchanged thru conjugation tubes • bacteria • algae • fungi
Sexual Reproduction in Plants • 2. Sexual reproduction in plants… – What is alternation of generations? • Some plants switch between a diploid (2 n) sporophyte generation & a haploid (n) gametophyte generation • We’re just going to focus mostly on the sporophyte generation… flowers….
Sexual Reproduction in Flowering Plants • The flower is the plant’s reproductive organ. (pistil)
The flower is a plant’s reproductive organ. (pistil)
Sexual Reproduction in Flowering Plants • What are the female parts of a flower? – carpel (pistil) • stigma – sticky tip that traps pollen » & pollination occurs • style – connects stigma & ovary » sperm travels through • ovary – swollen base (fertilization occurs here… becomes fruit) » contains ovules (produce eggs &) matures into seeds
Sexual Reproduction in Flowering Plants • What are the male parts of a flower? – stamen • anther – produces pollen » contains sperm • filament – “stalk” that supports anther
Sexual Reproduction in Flowering Plants • What parts of the flower are neither female nor male? – sepals • protect young flower bud – leaf-like structures at flower’s base » usually green (can be same color as petals) – petals • attract pollinators – located in/above the sepals » can be large & colorful » can be scented » can produce nectar
Sexual Reproduction in Flowering Plants • Let’s see if you got that… What are 3&4 together called? 8 What are 5, 6, & 7 together called?
Sexual Reproduction in Flowering Plants • Most flowers have both male & female parts. – What type(s) of pollination can they undergo? • self- or cross-pollination • Some flowers are only male or female. – What type(s) of pollination can they undergo? • cross-pollination – Why is cross-pollination beneficial? • increases genetic variety • What is pollination? –transfer of pollen from anther to stigma
Sexual Reproduction in Flowering Plants • How many nuclei are in pollen? – 3 nuclei • 1 tube nucleus (forms pollen tube) • 2 sperm nuclei • How many nuclei are in an ovule? – 3 nuclei • 2 polar nuclei (become food/endosperm) • 1 egg (becomes embryo)
Sexual Reproduction in Flowering Plants • Recall… 1 st sperm (tube nucleus) formed pollen tube. • Other 2 nuclei carry out double fertilization in ovary… – 2 nd sperm nucleus fertilizes egg forms 2 n zygote (embryo) – 3 rd sperm nucleus fertilizes the 2 polar nuclei in central cell forms 3 n endosperm (food for embryo)
Path of pollen to egg • 1. Pollen from anther lands on the stigma. Tube nucleus moves through style forming a pollen tube to the ovule. • 2. Two sperm nuclei travel through the pollen tube made in the style to ovule. • 3. In ovule: • • One sperm nucleus fertilizes the egg to form a zygote that develops into the embryo. One sperm nucleus fertilizes 2 polar nuclei to form endosperm/food for the embryo.
Sexual Reproduction in Flowering Plants • What happens after fertilization in flowering plants? – ovule matures into seed • seed contains embryo & food embryo – ripened ovary becomes the fruit Seed coat
Sexual Reproduction in Animals • 3. Sexual reproduction in animals… – no alternation of generations – gametes produced in ovaries & testes – can have external fertilization (spawning) or internal fertilization – can have external development or internal development
Sexual Reproduction in Animals • What is external fertilization? Synchronized release of gametes ensured by mating behaviors – fertilization (& development) occurs in aquatic environment (not in mother) • Why in water? – so sperm can swim to egg – How many gametes are produced & released? • large #s – Why? » chances of fertilization & survival are generally low. . . lg #s increase chances Do animals that use external fertilization exhibit parental care?
Sexual Reproduction in Animals • What is internal fertilization? – fertilization takes place inside mother • How is internal fertilization an adaptation to life on land? – moist, protective environment – How many gametes are produced & released? • male many, female few – Why is it better than external fertilization? » chances of fertilization & survival are higher b/c sperm only exposed for short time
Sexual Reproduction in Animals • Sexual reproduction in humans…
Male Reproductive System Anatomy—Side View (Cowper’s Gland) *Accessory glands seminal vesicle, prostate, bulbourethral (Cowper’s) gland penis
Male Reproductive System Anatomy: What Path Does Sperm Follow from Production to Ejaculation? • 1. Sperm cells are produced by the testes (in the seminiferous tubules). – testes are house in scrotum to maintain cooler temperature • 2. Sperm are stored in the epididymis (& mature). • 3. Sperm pass through the vas deferens. • 4. Accessory glands along the vas deferens add seminal fluids (water, buffers, & nutrients) to sperm. – combo of sperm & fluid together is called semen • 5. Semen passes through the urethra – & out of the penis during ejaculation
Let’s Review B G F D A E C
Male Reproductive System Anatomy— Front View
Let’s Review F B C G A D E
Structure of Male Sperm
Female Reproductive System Anatomy— Side View (fallopian tube)
Female Reproductive System Anatomy: What Path Does Sperm Follow Until Fertilization Occurs? Where Does Fertilization Occur? Where Does the Development of the Embryo/Fetus Occur? • What path does sperm follow until fertilization occurs? 1. 2. 3. 4. sperm enters vagina passes through cervix enters uterus travels into oviduct (fallopian tube) • where fertilization normally occurs • What happens after egg is fertilized in oviduct (f. t. )? 1. fertilized egg (zygote) travels to uterus 2. implants in lining of uterine wall (endometrium) 3. development of embryo/fetus normally occurs in uterus
Let’s Review Female Reproductive System Anatomy—Side View D (oval object in back) E C B A
Female Reproductive System Anatomy—Front View (fallopian tube)
Female Reproductive System Anatomy— Front View D C E • What is the pathway that sperm follows prior to fertilization? B • Where does: • fertilization take place? • implantation take place? • the fetus develop? A
Formation of Eggs • Where do eggs form? – In follicles in the ovaries. • What is ovulation? – the release of an egg from follicle
Human Menstrual Cycle • What controls the menstrual cycle? – hormones • What is the role of the menstrual cycle? – prepares uterus for possible pregnancy • How often does the menstrual cycle occur? – usually monthly (~28 days)
Human Menstrual Cycle • What are the 4 phases of the menstrual cycle? 1. thickening of uterine lining (endometrium) 2. ovulation • egg matures & is released 3. passage of egg into uterus (if not fertilized) • ~day 14 4. loss of unfertilized egg & lining (menstruation)
Fertilization • What is the pathway that sperm follows prior to fertilization? The Miracle Begins
Fertilization & Development (below) Developmental Timeline Embryo & Fetal Development Animation
Labor & Delivery • The big day! – 3 stages 1. dilation of cervix 2. delivery of newborn – contractions of uterus push baby out head first 3. delivery of placenta – also by contractions of uterus
Comparing Asexual vs. Sexual Reproduction Asexual Sexual # of parents gametes produced? 1 2 No Yes genetic variety? No Yes time needed to produce offspring Short Long rate of population growth Fast Slow Domains/Kingdoms All
Asexual Reproduction • easy, fast • short generation times can produce large # of offspring & pop. grows quickly vs. Sexual Reproduction • requires little energy • no parental care of offspring high death rate • well adapted individuals spread quickly • poorly adapted individuals die easily • 2 parents increases genetic variation • more difficult, slow • long generation times small # of offspring & pop. grows slowly • offspring are genetically identical to parent no variation • long generation times small # of offspring & pop. grows slowly • parents often care for offspring low death rate • requires a lot of energy to find mate & carryout • survival of individuals “fit” for environment • parental care of offspring requires a lot of energy