Notes, summaries, assignments, exams, and problems for Biology

Transgenic Vaccines

Transgenic vaccines are vaccines in which an extracted gene from an organism is introduced into a unicellular organism's genetic code (a bacteria or yeast). This is done to produce a certain protein (the one from the extracted gene) and to multiply that bacteria and the production of the protein in larger quantities. That protein is then able to produce the weakened protein of the membrane of the virus.

Steps of Production

The gene is extracted from the organism and introduced into the seed of the plant, meaning it's introduced inside the first genetic information of the plant. Then you need to plant the seed and allow for the production of the protein.

Advantage of Transgenic Vaccines by Yeasts Over Injured Viruses

They stimulate... Continue reading "Introduction to Biotechnology and Evolution" »

Real and Apparent Origins

Cranial nerves have a real origin, which is the nucleus of gray substance inside the brain, except for cranial nerves I, II, and VIII, whose real origin is outside the brain. The apparent origin is the attachment surface of the brainstem.

Specific Cranial Nerves

Olfactory Nerve (CN I)

Origin: Roof of the nasal cavity.

Optic Nerve (CN II)

Origin: Ganglionic cells of the retina.

Oculomotor Nerve (CN III)

Origin: Sulcus on the medial side of the cerebral peduncle.

• Superior division: Supplies the superior rectus and levator palpebrae superioris.
• Inferior division: Supplies the medial rectus, inferior rectus, and inferior oblique muscle.
• Function: Parasympathetic innervation, constricts the pupil via the ciliary ganglion.

Trochlear

Functions of the Blood

Transports nutrients and oxygen to all the cells and collects waste products produced by cell metabolism. Contributes to the regulation of body temperature. Plays a role in the fight against infections.

Cardiovascular System

Shares nutrients and oxygen between cells and collects waste products that cells produce during metabolism.

Puberty begins with the first ejaculation (spermache) and the first menstruation (menarche).

-Menopause (50), andropause (50)

Reproductive Tract

• Epididymis: Formed by the seminiferous tubes, where sperm mature.
• Ductus referens: Continuation of the epididymis and ascends up to the abdomen. It is used to store sperm.
• Urethra: Also part of the urinary tract connecting the bladder to the exterior.

Accessory Glands

• Seminal vesicles: Flow into ductus deferens, secrete spermatic fluid.
• Prostate: Secretes prostatic fluid which consists of substances to protect sperm from the acidity of the vagina.
• Cowper's glands: A pair of glands that secrete a lubricating fluid that facilitates sexual intercourse.

Reproductive Tract

• Fallopian tubes: Two small tubes located

1. Sensory Receptors

Sensory receptors are responsible for perceiving information, which they convert into a nerve impulse. The nerve impulse travels to the brain and produces feeling.

1.1. Types of Sensory Receptors

Sensory receptors can be classified according to the stimuli that they can receive, or by where they are located.

1.1.1. According to the Stimuli

• Photoreceptors: They detect light stimuli and are located in the eye.
• Mechanoreceptors: They are stimulated by mechanical changes such as pressure, contact, or sound waves.
• Chemoreceptors: They respond to chemical changes.
• Thermoreceptors: They detect temperature changes.

1.1.2. According to Their Location

• Internal receptors: They are located in the internal organs where they collect information

Muscle Fiber

Elongated cells that make up skeletal muscle tissue

Striation

Light and dark stripes in which skeletal muscle fibers are grouped

Fascicle

Dense bundles in which skeletal muscle fibers are grouped

Voluntary Muscle

Muscle that are consciously controlled

Involuntary Muscle

Smooth muscles that cannot be consciously controlled

Myofibril

Thread-like structures found in skeletal muscle fiber

Myosin

Thick filaments that make up myofibril

Actin

Thin filaments that make up myofibril

Z Line

Structure to which actin filaments are anchored

Sarcomere

The region from one Z line to the nerve

Tendon

Fibrous connective tissue that attaches muscles to bone

Flexor

Muscle that bends a joint

Extensor

Muscle that straightens a joint

Muscle Fatigue

Physiological inability of a

Porifera – sponges

Lymphatic System: Components and Functions

The lymphatic system is composed of lymph, lymphatic vessels, lymphatic organs, lymphatic tissues, and lymph nodes.

Key Components of the Lymphatic System

Lymph

Lymph is a transparent liquid composed of lymphocytes and interstitial plasma that is formed when blood plasma is filtered as it travels to the tissues.

Lymphatic Vessels

Lymphatic vessels are closed at one end. Lymphatic capillaries are found in tissues, and they join into bigger conduits known as lymphatic veins that eventually connect with blood veins.

Lymphatic Organs and Tissues

Lymphatic organs and tissues perform several functions, such as producing and maturing lymphocytes and purifying blood. The most important lymphatic organs are the spleen... Continue reading "Human Body Systems: Lymphatic, Excretory, and Urinary Functions" »

Endocrine Glands and Hormones

Endocrine glands respond to stimulations by producing hormones transported in blood through the body. Each hormone affects its target cell which contains specific receptors. Hormones are chemical messengers that activate or stop, accelerate or delay processes by organs. Hormone receptors cause chemical reactions inside the cell producing a response.

Hypothalamus produces nerve signals and hormones: releasing factors and inhibiting factors. These factors act on pituitary glands and control the release of hormones.

Pituitary (2 Lobes)

• Anterior: growth hormone/TSH-stimulates production of thyroid hormones/gonadotropes-follicle stimulating hormone (FSH) and (LH) act on ovaries and testes/ACTH-stimulates secretion of the

Transcription: From DNA to RNA

Steps of Transcription

Initiation

• Transcription begins when transcription factors bind to a specific nucleotide sequence of DNA known as the promoter region or the "TATAA box."
• These transcription factors signal RNA polymerase II to attach to the DNA at the promoter.

Elongation

• Once attached to the DNA, RNA polymerase synthesizes a single-stranded RNA molecule in a 5’ → 3’ direction.
• RNA nucleotides are added to the growing polymer, which are complementary to the DNA template.

Termination

• Eventually, RNA polymerase will reach a termination sequence in the DNA.
• This causes RNA polymerase to release the newly synthesized mRNA and to dislodge from the DNA.

Note: The template strand is also known as the antisense strand,