Asexual vs Sexual Reproduction

• Reproduction is the process by which organisms create more of their kind.

Types of Reproduction

• Sexual reproduction involves two parents.
• Asexual reproduction involves only one parent.

Asexual Reproduction

• Asexual reproduction is a type of reproduction that produces genetically identical offspring from a single parent without gametes.
• Gametes are cells from a male and female that fuse together to form a zygote, which then divides to form a new organism.
• Sperm are male gametes.
• Ova are female gametes.

Types of Asexual Reproduction

• Binary fission
• Spores
• Budding
• Tubers

Binary Fission

• In binary fission, bacteria reproduce by cell division, where a bacterial cell divides into two, and each daughter cell becomes an independent bacterium.
• This cell division can occur rapidly, sometimes every 20 minutes, leading to a large colony of bacteria in a short time.

Reproduction by Spores in Fungi

• Fungi reproduce by spores and consist of aerial hyphae and rhizoids.
• Aerial hyphae have a sporangium and sporangiophore.
• Sporangium house the spores.
• Fungi produce spores in sporangia, which bursts and releases spores that spread by wind.
• The spores that land on food under favorable conditions such as temperature and humidity, germinate and form new fungi.

Budding in Yeast

• Budding is a type of asexual reproduction
• A new yeast cell forms from a bud on the parent cell
• The new cell can separate or form a chain

Asexual Reproduction in Potatoes

• Tubers are short underground stems or roots used for storage.
• Potato tubers have grooves called eyes, which each contain a bud with a scale leaf.
• Buds grow into new shoots and roots, using food stored in the tuber under favorable conditions.
• Roots grow down, and shoots form leaves.
• Underground side stems grow out to form new tubers and food is stored in these stems.
• The leaves, stems, and old tuber die, but the the new tubers remain dormant until the conditions become favorable.

Advantages and Disadvantages of Asexual Reproduction

• Asexual reproduction is rapid because no mating partner is needed.
• It produces identical strains, useful for parents with good traits.
• It can withstand unfavorable conditions using stored food.
• It maintains a good strain without variation.
• A rapid asexual process can be harmful if diseases are produced.
• Asexual reproduction causes no variety in offspring, so they may all die if they are unable to adapt to the environment.
• Harmful parental genes are transferred to the offspring.
• Overcrowding may occur, leading to food competition.
• Sexual reproduction produces new varieties.
• Sexual reproduction aids in the evolution of species.
• Harmful genes in parents aren't necessarily passed to offspring.
• Sexual reproduction is slower than asexual reproduction so it reduces overcrowding.
• Sexual reproduction does not allow excellent individuals to always give identical offspring.
• Sexual reproduction is a slow process that causes low offspring production, which makes it a disadvantae for organisms useful to humans, such as food producers.

Sexual Reproduction

• Sexual reproduction is a process that involves the fusion of haploid nuceli to form a diploid zygote that results in genetically different offspring.

Reproduction in Plants

• Parts of an insect-pollinated flower include: sepals, petals, stamens, filaments, anthers, carpels, style, stigma, ovary, and ovules.
• Self-pollination is when pollen grains are transferred from the anther of a flower to the stigma of either the same flower or a different flower on the same plant.
• Cross-pollination is when pollen grains are transferred from the anther of a flower to the stigma of a flower on a different plant of the same species.
• Self and cross-pollination affects variation, the ability to respond to changes in environment, and reliance on pollinators.

Flower Parts and Functions

• Receptacles are enlarged parts of the stem that carry the flower.
• Sepals are small, green structures that protect the flower when it is closed.
• Large, colored and sometimes scented petals attract insects for pollination and have guidelines to the nectary gland.
• Petals are used for insect landing, and they surround and protect the flower's reproductive organs.
• Stamens are the male part of the flower, consisting of an anther and a filament.
• Anthers contain pollen sacs which stores pollen grains that holds male gametes.
• Filaments carry the anther and expose the pollen grains to pollination.
• Carpels are the female organs, that consists of a stigma, style, and ovary.
• The stigma receives pollen and contains nutritive materials for germination.
• The style holds the stigma to expose pollination.
• The ovary produces ovules that contain female gametes.
• Nectary glands make a sugary solution called nectar used by insects for food.

Stages of Reproduction in Flowering Plants

• Pollination: the transfer of pollen grains from an anther to a stigma.
• Fertilization: fusion of the male and female gametes, producing a zygote.

Types of Pollination

• Self-pollination: the transfer of pollen from an anther to the stigma of the same flower or another flower on the same plant.
• Cross-pollination: the transfer of pollen from an anther of one flower to the stigma of another flower on another plant of the same species.

Characteristics of Self vs Cross-pollinated Flowers

• Self-pollinated flowers: hermaphrodite, mature at the same time, long stamens, and ripen before opening.
• Cross-pollinated flowers: unisexual, mature at different times, short stamens, ripen after opening, and secrete chemicals to kill pollen grains.

Understanding Self-Pollination Implications

• Plants with good strains are more likely to produce offspring of good strains because there is less variation than in cross-pollination.
• Self pollination is disadvantageous if there is an environmental change, because there isn't enough variation.
• Self pollination can be detrimental if a mutation develops in the pests, because such plants are unable to resist it.

Cross Pollination Implications

• Cross pollination produces variation for evolution.
• It can cause good strains to not be neccesary.

Agents/Means of Pollination

• Wind
• Animals
• Humans
• Insects

Insect Pollinated Flower Features

• Insect pollinated flower are usually large.
• They appear in warm weather.
• They attract insects with scent glands.
• The reproductive organs are enclosed in the flower, so the insect has to brush it to reach the nectar gland.

Pollen Grain Features in Insect-pollinated Flowers

• The pollen grains are sticky and cling to insects.
• They are small in number.
• They are large compared to wind pollinated flowers.

Wind Pollinated Flower Features

• Wind pollinated flowers are usually small.
• They appear in cold weather.
• The nectar is not scented.
• The reproductive organs are projected outside the flower.

Wind-dispersed Pollen Grains

• They are small, light, and dry to be carried by wind.
• They are large in number.
• The stigma is feathery to trap pollen grains from the air.

Fertilization

• When a pollen grain runs from the stigma, the stigma produces a sticky, nutritive fluid.
• The pollen grain absorbs this fluid, producing a pollen tube, and the nucleus of the pollen grain which is the male gamete then passes through the tube.
• The pollen tube grows towards the ovule until it reaches the micropyle, where the male nucleus passes to the ovule.
• The nucleus of the pollen grain fuses with the nucleus, which is the female gamete and produces a zygote.

Changes After Fertilization

• Sepals, petals, stamens, and the stigma and style will dry up and fall off.
• The ovule develops into seed.
• The integument becomes the testa of the stem.
• The ovary enlarges and becomes the fruit.
• The wall of the ovary becomes the pericarp

Fruit Functions

• Fruits protect the seeds and help the plant disperse them, and stores food

Non-Endospermic Seed Structure

• Testa: non-permeable, softens and ruptures during germination.
• Cotyledons: store food.
• Radical: produces roots.
• Plumule: produces shoots.
• Micropyle: pathway for water to enter

Seed and Fruit Dispersal

• Dispersal is the spreading out of seeds and fruits.
• Advantages of dispersal: avoids overcrowding, and competition for water and minerals, and allows species to spread.
• Disadvantages: spreading of bad properties, seeds/fruits fall on unsuitable soil, and undesirable plants may grow.

Types of Dispersal

• Wind dispersal
• Animal dispersal

Wind Dispersal

• Wind dispersal plants have winglike structures to allow it to be carried by wind.
• Examples include Sycamore and Burdock

Animal Dispersal

• Plants can use hooks to cling to animal fur.
• Fruits and seeds are often indigestible.
• Examples include Dandelions.
• Fruits and seeds of tomatoes, apples and strawberries are indigestible so they are evacuated through animal stool.

Germination

• Germination is the beginning of an embryo or spore's growth, where stored food is used to fuel the growth.
• Steps of germination:
  • The seed takes up water through the micropyle
  • The cotyledons swell causing the testa to burst.
  • Enzymes in the seed become active.
  • Enzymes are used to digest the stored food in the seed.
  • The digested food diffuses through the embryo.
  • The radicle emerges from the testa.
  • The testa falls off.
  • The plumule opens and shoots develop.

Germination Conditions

• Water: activates enzymes in the seeds, transports salts from the soil to the shoot, expands vacuoles to allow roots and shoots to grow, transports sugar.
• Oxygen: required for aerobic respirtation to provide the embryo with energy for metabolic reactions.
• Temperature: The best temperature is about 35–40°C.
• Dry-fresh mass at the beginning:
• Dry mass decreases and fresh mass increases to absorption.
• Dry mass increases because green leaves develop and photosynthesis may occur.

Human Reproduction

• Human reproduction is characterized by internal fertilization and development.
• Internal fertilization is the fusion of gametes inside the female's body.
• Internal development means that the embryo grows inside the female's body.
• Gonads are the organs responsible for producing gametes.
• Testes are male gonads.
• Ovaries are female gonads.

Female Reproductive System Parts and Functions

• Ovaries:
  • Produce ova (singular: ovum)
  • Produce female hormones (estrogen).
  • Produce one ovum every 2 months (56 days) from alternating ovaries.
• Oviduct (Fallopian Tubes):
  • The front part is a funnel-shaped structure used to get ova.
  • The funnel contains cilia to push the ova into the uterus
  • It is he site of fertilization.
• Uterus (Womb):
  • A muscular organ that consists of a muscular wall and a lining.
  • The uterus is the site where the embryo develops if the ovum is fertilized.
  • The lining is soft and spongy with a lot of blood vessels to supply the embryo with food and oxygen.
  • Implantation takes place in the lining.
  • No fertilization causes the broken lining to release blood (menstruation).
  • A new lining is formed every month unless you are pregnant.
  • It contracts during labor and birth and the lining supports the embryo during pregnancy.

Male Reproductive System and Properties

• Testes: responsible for the production of sperm and testosterone.
• Scrotum: holds testes outside the body at a temperature lower than body temperature; otherwise sperm production would be affected.
• Epididymis: a coiled tube that stores sperms and contracts to help in ejaculation of sperms
• Sperm duct: conducts sperm from the epididymis to the urethra and contracts by peristalsis to help in ejaculation
• Urethra: is a common passage for both urine and semen; semen contains fluid from the prostate gland and seminal vesicles.
• Seminal Vesicles: These have walls that contract in order to help in ejaculation; urination cannot take place during ejaculation because the sphincter muscle of the bladder contracts during ejaculation to prevent this.
• Prostate gland: secretes seminal fluid that it mixes with sperm
  • Mucus and nutrients are produced by the prostrate gland to help with copulation and swimming of sperm.
  • Sugars fructose provide energy for sperms.
  • Alkaline material neutralizes the acidity of the urethra and vagina (urethra is naturally acidic).
• Penis: the organ of copulation. Its erectile tissue has blood cavities that fill when the penis is stimulated.
• Erectile tissue enables copulation by filling with blood and causing erection; foreskin is a piece of skin that is removed with circumcision.

Sperm: Adaptive Features

• Contains a nucleus.
• Contains enzymes for breaking down the ovum wall (acrosome).
• Consists of mitochondria for movement.
• Uses flagellum for movement.

Ovum: Adaptive Features

• Ovum contains stored food for growth.
• It is surrounded by a jelly coat (made hard) to prevent sperm from entering after fertilization.

Male Gamete vs Female Gamete

• Male gametes are smaller, larger in numbers, have flagella/acrosome, and are motile.
• Female gametes are larger, smaller in numbers, have a jelly coat, and are nonmotile.

Fertilization Process

• Semen is deposited at the top of the vagina, near the cervix.
• Sperm use flagella to swim through the cervix.
• Sperm are naturally attracted to the ovum.
• Many sperm reach the egg but only one digests through it.
• After one sperm enters the egg, the tail is ejected.
• The nuclei then fuse, and create a zygote.
• Next, the surface of the egg immediately becomes impenetrable to prevent multiple fertilizations.

Important Terms

• Zygote: A cell resulting from male and female gamete fusion.
• Embryo: A ball of cells formed from division of the zygote by mitosis.
• Fetus: A mammalian embryo in an advanced development stage.
• Ovulation: The release of egg cells into the oviduct.

Menstruation

• Menstruation occurs in the absence of fertilization where the uterine lining sheds.
• It is caused by a drop when a hormone (progesterone) stops getting released by the ovaries

Stages of the Menstrual Cycle

• Pituitary glands release Follicle Stimulating Hormone (FSH) that stimulates the an ovum to develop into a larger structure (Graafian follicle)
• Estrogen is secreted by the Graafian follicle
  • Stimulates buildup of a uterine lining.
  • Inhibits FSH to prevent addition ova stimulation.
• Pituitary Glands then release Luteinizing Hormone (LH)
  • This causes the Graafian follicle to release the egg.
  • It forms the remaining follicle into the corpus luteum, or yellow body, which supports a thick uterine lining that fertilizes an egg.

Ovary and Pituitary Gland Conditions Based on Egg Fertilization

• The uterine lining stops growing and FSH/LH is not produced after fertilization.
• If the egg is fertilized:
  • The corpus luteum doesnt degenerate quickly.
  • It continuously secretes progesterone, which allows an embryo to be planted into the uterine wall, or for a placenta to develop.
• If the egg is not fertilized:.
  • The corpus luteum degenerates.
  • The progesterone is no longer secreted which results in the uterine wall breaking down.

Conditions When There is Fertilization

• No new follicle develops is there is another follicle present.
• The menstrual cycle stops (does not continue) during pregnancy because progesterone production continues.
• Implantation, where the embryo attaches to the lining.
• Amnion and placenta form.

Amnion (Amniotic Sac)

• Helps with absorbing shock and secretes amniotic fluid.
• Prevents adhesion of organs.
• Helps with fetus's movement.
• Maintains optimal temperature range.

Placenta

• Formation of placenta ensures connection between mother and the embryo.
• Embryo cells help fix it to the uterus.
• Uterus develops projections.
• Villi of both the mother and fetus combine to ensure close proximity.

Blood Composition

• Maternal blood comes from the uterine artery.
• Fetal blood comes from umbilical arteries and veins.

Placenta: Importance

• Gases are exchanged between mother and fetus.
• Oxygen is released from mother's blood, and diffused into the fetus's blood.
• Carbon dioxide diffuses into the mother's blood.
• Nutrition ensures food (amino acids and glucose) are brought for fetal uptake.
• Wasted products such as urea diffuse into the mother's blood
• Hormones: Estrogen and progesterone are released.
  • Prevents unreleased ova
  • Stimulates uterine lining growth
  • Supports tissues that will support milk creation
• The placenta ensures maternal and fetal blood is separate.
  • This protects the fetus from different blood pressures, bacteria, and/or viruses such as bacterial or HIV.
  • Ensures there is no blood agglutination (blood grouping is different).

Umbilical Cord

• Connects both the placenta and the fetus.
• Carries carbon dioxide and waste from the placenta.
• The umbilical vein carries food and oxygen from the placenta and diffuses into the fetus.

Sexually Transmitted Diseases (STDs)

• STDs are transmitted via body fluids when having sex with an infected person.
• (AIDS) Acquired Immune Deficiency Syndrome is caused by pathogens known as Human Immunodeficiency Virus (HIV).
• The virus is typically held in bodily fluids, and in lymphocytes weakening T-lymphocytes which causes a low immune defense, with long symptoms.
• Transmission occurs during sex, as well as during blood transfusions, sharing of hypodermic needles,or transplants when the person is infected

Avoiding STD Transmission

• Avoid sex with various partners
• Apply a Condom.
• Use non injected drugs.
• Never share razors or tooth brushes.

HIV Impact

• HIV affects immune cell lymphocytes.
• It then weakens our immune response, preventing us from attacking pathogens.

Fertility Drugs

• Fertility drugs stimulate ova production
• This increases LH and FSH.
• Multiple eggs may get released, and these Social Aspects of fertility drugs may cause issues, such as:
  • Premature/weak babies.
  • Defective or deformed babies.
  • Issues in regards to abortion .

Artificial Fertilization (Insemination)

• Artifical fertilization occurs within the human body, either inside the uterus itself or with glass tubes.

Social Aspects of Artifical Insemination

• In order to be a sperm donor the man has to forfeit his sperm and/or child.

Concerns For The Child

• Who is her mother / father?
• Concerns about the donor
• Ensure pregnancy

Why are Fertilized eggs left for an amount of time for Artificial Insemination?

• To allow succeed and embryo implant .
  • To allow implantation.

Aritificial Fertilization Advantages

• A woman can get pregnant from an egg implanted in their oviduct.
• Males who can't produce sperm can find a sperm donor to reproduce.
• To reduce the chance of spreading genetic disorders from both parents.

Artificial Fertilization Disadvantages

• The costs of money
• Puts a big strain on the parents.
• Many die or are used by researchers, which has ethical implications.
• Multiple Implantations are expensive.

Sex Hormones

• Male: Male sex hormone (Androgen), ex:Testosterone
  • Male sex hormones help with development, and other changes (Puberty). (Rough voice, deep)
• Female: Female sex hormones (Estrogen), ex: Testosterone
  • Female sex hormones help with sex characteristics. This involves hips, and breasts.
• Other examples: Fertility Drugs - Use of hormone treatment for fertility.
  • Such as: FSH/LH/Clomiphene. Which increases the fertility.
    • Progesterone causes endometrium to thicken .
    • Testoseterone can cause sperm production

Explore the differences between asexual and sexual reproduction in plants, fungi and bacteria. Learn about the advantages and disadvantages of each strategy and the conditions that favor them.