DNA, Mitosis and Meiosis

DNA and Genetics

• Adenine (A) pairs with Thymine (T)
• Cytosine (C) pairs with Guanine (G)
• DNA stores genetic information.
• Genes are specific segments of DNA coding for proteins.
• Chromosomes are coiled DNA and proteins in the nucleus containing many genes.
• DNA stores and transmits genetic information for development, functioning, and reproduction.
• Nucleotides consist of a sugar (deoxyribose), a phosphate group, and a nitrogenous base (A, T, C, G).
• DNA is a double helix with two strands held by base pairs.

Mitosis and Meiosis

• Mitosis is a cell division resulting in two genetically identical diploid cells.
• Mitosis facilitates growth, repair, and asexual reproduction.
• Meiosis is a cell division reducing chromosome number by half, producing four genetically diverse haploid cells (gametes).
• Meiosis facilitates sexual reproduction and genetic variation.

Stages of Mitosis (IPMAT)

• Interphase involves cell preparation for division, including DNA replication.
• Prophase involves chromosome condensation and spindle fiber formation.
• Metaphase involves chromosome alignment in the middle of the cell.
• Anaphase involves chromatid separation to opposite poles.
• Telophase involves nuclear membrane formation around each chromosome set.
• DNA replication occurs during interphase.
• Chromosome condensation occurs during prophase.
• Chromosome alignment occurs during metaphase.
• Chromatid separation occurs during anaphase.
• Nuclear membrane formation occurs during telophase.

Comparison of Mitosis and Meiosis

• Mitosis occurs in somatic cells.
• Meiosis occurs in germ cells (e.g., ovaries and testes).
• Mitosis produces genetically identical cells.
• Meiosis produces genetically diverse cells due to crossing over and independent assortment.
• Mitosis results in two daughter cells.
• Meiosis results in four daughter cells.

Sexual Health and Reproductive System

• Male and female condoms act as barrier methods to prevent sperm from entering the vagina.
• Abstinence is the choice to avoid sexual activity.
• Vaccinations, like the HPV vaccine, help prevent sexually transmitted infections (STIs).
• STI prevention includes regular testing, using condoms, and reducing the number of sexual partners.
• Viral STIs are treated with antiviral medications (e.g., for HIV, herpes).
• Bacterial STIs are treated with antibiotics (e.g., for chlamydia, gonorrhea).
• Animal parasite STIs are treated with medications (e.g., for pubic lice).
• Protist STIs are treated with antiprotozoal medications (e.g., for trichomoniasis).

Male Reproductive System

• Testes produce sperm and testosterone.
• The epididymis stores and matures sperm.
• The vas deferens transports sperm from the epididymis to the urethra.
• Seminal vesicles produce seminal fluid to nourish sperm.
• The prostate gland produces fluid that helps sperm motility.
• The bulbourethral gland secretes fluid that lubricates the urethra.
• The urethra transports semen and urine.
• The penis delivers semen into the female reproductive system.
• Male reproductive organs produce, store, and deliver sperm.
• Male reproductive organs secrete hormones (e.g., testosterone) that regulate reproductive function.
• LH stimulates testosterone production.
• FSH stimulates sperm production in the testes.
• Testosterone regulates sperm development and maturation.

Female Reproductive System

• Ovaries produce eggs (ova) and hormones (e.g., estrogen, progesterone).
• Fimbriae help capture the egg during ovulation.
• The fallopian tube is the site of fertilization.
• The uterus is where the fertilized egg implants and develops into a fetus.
• The endometrium is the lining of the uterus, thickens for embryo implantation.
• The vagina is the birth canal and passage for menstrual flow.
• The cervix is the opening to the uterus.
• Female reproductive organs produce eggs and hormones
• Female reproductive organs support fertilization, embryo development, and pregnancy.
• LH triggers ovulation.
• FSH stimulates the growth of ovarian follicles and egg maturation.
• Oestrogen promotes the thickening of the endometrium for implantation.
• Progesterone maintains the endometrium and prepares the uterus for pregnancy.

Fertilization and Pregnancy

• Fertilization is the fusion of an egg and sperm to form a zygote.
• A zygote is a fertilized egg, the first stage of development.
• Fertilization occurs in the fallopian tube when a sperm successfully penetrates an egg.
• The embryonic period is the first 8 weeks of development, when basic structures form.
• The foetal period is from 9 weeks to birth, characterized by growth and organ development.
• The placenta provides nutrients and oxygen to the developing fetus.
• The placenta removes waste products from the fetus.
• Chorionic villus sampling tests for genetic conditions.
• Amniocentesis tests for genetic disorders and abnormalities.
• Ultrasounds visualize the fetus and monitor development.