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

Bone Formation Processes

Intramembranous Bone Formation

Bone forms via the direct secretion of bone matrix within connective tissue, without any intermediate formation of cartilage. There is no formation of cartilage in this process.

Key characteristics:

• Occurs in the periosteum (external part), endosteum, alveolar bone, and sutures.
• In the craniofacial vault complex, this type occurs specifically in the cranial vault and jaws.

Endochondral Bone Formation

In this process, cartilage is converted into bone.

Key characteristics:

• In early stages, cartilage is present from the nose to the cranial base and occipital bone.
• Prenatally, a series of synchondroses exist within and between the ethmoid, sphenoid, and occipital bones. These facilitate rapid increase

True or False Statements:

Characteristics of the Genetic Code

• Universality: The specificity of the genetic code has been conserved from very early stages of evolution.
• Degenerate: A particular codon always codes for the same amino acid.
• Specificity: Each codon corresponds to a single amino acid.
• Nonoverlapping and Commaless: The code is read from a fixed starting point as a continuous sequence of bases, taken 3 at a time.

Amino Acid Calculation:

The shortest gene discovered in human chromosome 19 consists of 1000 nucleotides, 666 nucleotides of which are introns. What is the maximum number of... Continue reading "Genetics: Transcription, Translation, and Genetic Code Principles" »

Cell Membrane Dynamics

Plasma membrane phospholipids are labeled with a fluorescent tag and then the phospholipids in one area are bleached with a laser beam to eliminate the fluorescent signal. What would one observe after the cell is incubated for a few minutes? The bleached molecules would diffuse laterally through the membrane and intermix with unbleached molecules. Cellular membranes are mosaic and fluid. Glycosylated proteins and lipids within the plasma membrane are important for cell recognition and protection.

Passive Diffusion

Passive diffusion is a spontaneous process. Water diffuses through certain organs such as the kidneys and bladder much faster than would occur by passive diffusion through a lipid bilayer alone. What accounts for... Continue reading "Cell Membrane Dynamics and Transport Mechanisms" »

Still the Eye

Homeostasis

Thermoregulation

Zika is a mosquito-borne disease transmitted by the same mosquito that carries the dengue virus. There have also been cases of transmission through sexual intercourse.

Transmission

Most people get Zika from a mosquito bite. Mosquitoes become infected when they feed on the blood of a person already infected with the virus, and when they bite others, they can transmit the virus. Other forms of transmission include:

• A pregnant woman can pass the Zika virus to her fetus during pregnancy or at the time of birth.
• Zika can also be transmitted through sexual intercourse and blood transfusion.

Symptoms

Zika can cause incomplete brain development in fetuses. Common symptoms include fever, rash, joint pain, and conjunctivitis.

Prevention

To reduce the risk of

SPERMATOZOA 

Receptors

Internal receptors perceive changes inside the body, such as a rise in blood pressure. External receptors perceive stimuli in the external environment.

Types of Receptors

• Mechanoreceptors: Perceive mechanical stimuli (pressure).
• Thermoreceptors: Perceive changes in temperature.
• Chemoreceptors: Detect chemical substances in the air, water, etc.
• Nociceptors: Perceive pain stimuli.
• Photoreceptors: Light sensitive.

Nervous System

The nervous system analyzes internal and external stimuli perceived by receptors, generating responses. It carries out this function through nerve impulses transmitted by cells called neurons. This system coordinates fast, short-lived responses (e.g., muscle contraction).

Endocrine System

The endocrine system is made up... Continue reading "Sensory Systems and Nervous Coordination" »

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

Antioxidants and Exercise

Key antioxidants include Vitamin C, Vitamin E, Carotenoids, Glutathione (GSH), and Coenzyme Q10 (Q10).

Enzymatic Antioxidant Systems

• Superoxide Dismutase (SOD)
• Catalase
• Glutathione Peroxidase

Functions of Antioxidants

• Neutralize free radicals by donating electrons (e-) and hydrogen ions (H+).
• Decrease lipid peroxidation both at rest and after exercise.
• Note: Supplementation may not necessarily decrease overall oxidative stress markers.
• Note: Vitamin E supplementation does not appear to decrease neutrophil count after exercise.

Benefits and Roles of Oxidative Species

• Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) are important for cellular development, function, and as stimuli (cellular messaging) – involved

Two Main Circuits of the Cardiovascular System

Pulmonary Circulation

Pulmonary circulation refers to the circulation of blood in which deoxygenated blood is pumped from the heart to the lungs and oxygenated blood is returned back to the heart. Pulmonary circulation only occurs between the heart and the lungs.

Systemic Circulation

Systemic circulation refers to the circulation of blood in which oxygenated blood is pumped from the heart to the body and deoxygenated blood is returned back to the heart. Systemic circulation occurs between the heart and the entire body.

Pericardial Sac

The pericardial sac is the outermost layer of the heart. It surrounds the heart and protects it.

Heart Valves

Atrioventricular (AV) Valves

The AV valves prevent backflow into... Continue reading "The Cardiovascular System: Pulmonary and Systemic Circulation" »