Notes, abstracts, papers, exams and problems of Biology

DNA and RNA: The Nucleic Acids

What are DNA and RNA?

DNA and RNA belong to the group of molecules called nucleic acids.

Functions of DNA and RNA

DNA

• Stores genetic information
• Provides instructions for protein synthesis
• Passes genetic code to daughter cells

RNA

Carries out instructions from DNA for protein synthesis.

Types of RNA and Their Functions

• mRNA (messenger RNA): Makes a copy of DNA and carries this copy from the nucleus to the cytoplasm for protein synthesis.
• tRNA (transfer RNA): Transfers amino acids to ribosomes for protein synthesis.
• rRNA (ribosomal RNA): Controls ribosome formation in the cytoplasm.

Structure of Nucleic Acids

Monomers and Components

The monomer that makes up nucleic acids is called a nucleotide. Each nucleotide consists of:

• Phosphate

The Circulatory System

1. The circulatory system is responsible for transporting nutrients to and from the cells in the body. It is made up of the heart, blood vessels, and the blood.

2. The function of the internal environment is to give nutrients needed to cells. It is located in the interstitial fluid.

3. Blood carries nutrients that go from the blood vessels to the interstitial fluid. Cells found in tissues exchange substances with the interstitial fluid.

4. Cells get rid of waste products with the help of the interstitial fluid that collects this.

5. Cells would not obtain nutrients.

6.1. It transports nutrients and oxygen to the cells. 2. It removes waste: CO2, urea, salts. 3. Defends the organism against infections. 4. Helps to control body... Continue reading "Understanding the Circulatory System" »

The heart: double circulatory system

Vena cava - body to the heart (DO), pulmonary artery heart to lungs (DO), pulmonary vein - lungs to heart (O), aorta - heart to body (O). Arteries take blood away from the heart, veins take it towards the heart, Pulmonary means lungs. Valves make sure blood flows in a one way direction. Blood goes from heart to lungs to be oxygenated via the pulmonary artery. The now oxygenated blood goes back to the heart via the pulmonary vein to be pumped around the body via the aorta. Once the blood has been round the body, it is pumped to the heart via the vena cava to be sent to the lungs again for oxygenation then the cycle repeats.

Coronary heart disease

The coronary artery supplies blood to the heart (the heart is... Continue reading "Understanding the Human Heart and Immune System" »

3.3 The Nervous System

Receives information from the receptors, processes and coordinates it, and generates orders for the effectors. It is made up of the central nervous system or CNS, and the peripheral nervous system or PNS.

3.4 The Central Nervous System or CNS

Coordinates all the body's functions. It is formed by the encephalon and the spinal cord.

The Encephalon

Protected by the skull or cranium and by three membranes, the meninges, between which a liquid called the cerebrospinal fluid circulates. This liquid protects the encephalon from knocks and blows. Divided into three parts:

• The brain is divided into two hemispheres, which are separated by a fissure. Its surface, the cerebral cortex, is full of folds and furrows, known as circumvolutions.

Regulation of Enzyme Activity

Enzymes are the workhorses of cells, catalyzing the thousands of biochemical reactions that keep cells alive and functioning. The activity of enzymes is carefully controlled to ensure that the proper amount of product is produced at the right time.

Why Regulate Enzyme Activity?

There are several reasons why cells need to regulate enzyme activity. First, the concentration of substrates and products can vary widely within the cell. If enzyme activity were constant, the rate of the reaction would also vary wildly, depending on the availability of substrates. Regulation allows the cell to adjust the rate of the reaction to match the needs of the cell.

Second, the cell needs to coordinate the activities of different enzymes... Continue reading "Enzyme Regulation: Mechanisms and Examples" »

Chapter 5: Life Processes

Introduction

Life processes are the basic functions performed by living organisms for survival and body maintenance. These include nutrition, respiration, transportation, and excretion.

Nutrition

There are two modes of nutrition: autotrophic and heterotrophic.

Autotrophic Nutrition (Photosynthesis)

Photosynthesis is the process by which green plants synthesize their own food using carbon dioxide (CO₂) and water (H₂O) in the presence of chlorophyll and sunlight.

Raw Materials for Photosynthesis: Carbon dioxide and water.

Site of Photosynthesis: Chloroplasts in the leaves. Chloroplasts contain a green pigment called chlorophyll.

Main Events of Photosynthesis:

• Absorption of light energy by chlorophyll.
• Conversion of light energy

Valve Disorders

Valve disorders can be caused by congenital deformities or acquired diseases. Stenosis (narrowing) restricts blood flow. Structural malformations prevent the valve from closing properly, causing murmurs. These often present with other cardiac conditions/disorders. Athletes with electrical (arrhythmia) or structural changes (hypertrophy) may have limitations on their ability to play.

Mitral Valve Prolapse

Mitral valve prolapse prevents the valve from closing properly and is the most common valve disorder. Return to play (RTP) is often possible if there is no significant family history.

Systemic Hypertension

Systemic hypertension is common in athletes but is not the etiology of sudden cardiac death (SCD). The pathogenesis involves... Continue reading "Understanding Cardiovascular Conditions in Athletes" »

Human reproduction is sexual. Two individuals from different sexes are needed. Each produces a type of gamete (reproductive cell).

Embryo development: Zygote undergoes cell division until it becomes an embryo that continues development up to being a fetus.

Childbirth: Baby is born, alive and fully formed

Development: The baby grows until maturity is reached (adulthood)

Changes leading to sexual maturity

• Primary sex characteristics: The reproductive organs
• Puberty: Stage from the ages 10-16, when majority occurs
• Adolescence: From puberty to adulthood, physical maturity and physiological and social changes, sexual desire appears
• Sex