Mitosis, Meiosis and Reproduction

• Reproduction is either asexual, involving one parent and producing identical offspring, or sexual, involving two parents and resulting in diverse offspring.

Mitosis and Meiosis

• Mitosis, occurring in eukaryotes, involves a single cell dividing into two diploid daughter cells with a full set of chromosomes.
• Mitosis is involved in asexual reproduction, growth, and repair.
• Meiosis involves a cell dividing twice to produce four haploid cells, each with half the original number of chromosomes and occurs only in sexual reproduction.
• Haploid cells have 23 chromosomes from each parent.
• Diploid cells result from the combination of 23 chromosomes from each parent, forming 23 pairs (46 total) in a zygote.

Methods of Asexual Reproduction

• Binary fission: one cell splits into two (e.g., bacteria).
• Budding: an organism grows on another and breaks off (e.g., hydra, yeast).
• Fragmentation: a part of an organism breaks off and becomes a new organism (e.g., starfish).
• Sporing: example includes mushrooms
• Vegetative propagation: a plant part grows into a new plant (similar to fragmentation).

Advantages and Disadvantages of Sexual and Asexual Reproduction

• Asexual reproduction is time and energy efficient, as it doesn't require a mate.
• Asexual reproduction lacks genetic variation, so mutations are rare, but genetic diseases are easily transferred.
• Sexual reproduction allows for genetic variation, making individuals unique and more resistant to diseases.
• Sexual reproduction is more time and energy intensive, requiring two organisms.

Parts of the Male Reproductive System

• Scrotum: protects testes and maintains temperature.
• Testes: produce sperm and testosterone (most active during puberty).
• Epididymis: stores and transports sperm.
• Urethra/Urinary Duct: transports urine and semen.
• Vas Deferens/Sperm Duct: carries sperm out of testes.
• Prostate Gland/Seminal Vesicles: produces seminal fluid for nourishing, protecting, and transporting sperm.
• Seminal Vesicle: Small gland that produces semen
• Penis: used for sexual intercourse and urination.

Parts of the Female Reproductive System

• Vagina: passageway for blood, mucosal tissue and sperm during intercourse, and the birth canal.
• Cervix: allows fluids to flow in and out of uterus.
• Uterus: where a fertilized egg implants, is nourished, and develops into a baby.
• Oviduct: transports eggs from the ovary to the uterus using cilia.
• Fimbriae: captures eggs released from the ovary during ovulation.
• Ovary: produces eggs, estrogen, and progesterone.
• Endometrium: prepares for embryo implantation.

Fertilization

• Fertilization is the fusion of sperm and egg, forming a zygote in the oviduct/fallopian tubes.
• The zygote undergoes cell division, through mitosis and differentiation, to develop into an embryo, fetus, and baby.

Hormones

• Hormones are produced in endocrine glands and released in the bloodstream, influencing bodily characteristics.
• Hormones act as chemical messengers, affecting target organs/tissues with appropriate receptors.
• Hormones regulate metabolism, energy levels, puberty, reproduction, growth, responses to injury, sickness, stress, and environmental factors.

Hormones Controlling the Menstrual Cycle

• Follicle Stimulating Hormone (FSH): matures eggs in the ovaries.
• Luteinising Hormones (LH): triggers egg release from the follicle (ovulation) and signals ovaries to produce estrogen.
• Estrogen: thickens the uterine lining (endometrium).
• Progesterone: maintains the endometrium, sustaining pregnancy.
• The endometrium is the part that goes through changes, during the menstrual cycle.

Secondary Sexual Characteristics

• In males: deeper voice, facial/pubic hair, increased muscle mass, widening shoulders, sperm production, and growth of testes and penis (due to testosterone).
• In females: breast development, hip widening, armpit hair growth, and start of egg production.

The Menstrual Cycle (Approximately 28 Days)

• Day 1: menstruation begins.
• Day 5: menstruation ends.
• Days 5-13: the uterine wall thickens, and one egg matures.
• Day 14: ovulation occurs.
• Days 14-16: the egg moves down the fallopian tube.
• Days 14-21: the uterine wall remains thick and becomes spongy.
• Days 22-28: if the egg isn’t fertilized, the uterine lining breaks down.

Assisted Reproductive Technologies (ART)

• Artificial Insemination (AI): direct insertion of prepared sperm into the uterus.
• In Vitro Fertilisation (IVF): egg and sperm are combined outside the body, and the resulting embryo is implanted in the uterus/fallopian tubes.
• Intracytoplasmic Sperm Injection: a single sperm is directly injected into an egg.
• Frozen Embryo Transfer (FET): embryos are frozen for later use.
• Surrogacy: a gestational carrier carries an embryo formed from another woman's egg and sperm.