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

Protein Synthesis: From DNA to Protein

1. Transcription: Copying the Genetic Message

Transcription is the process of copying part of the genetic message from DNA to RNA so that it can be used to synthesize a specific protein.

Stages of Transcription:

• The double helix of DNA unwinds.
• Complementary nucleotides position themselves opposite one of the two strands.
• Only one of the DNA strands is copied.
• An RNA strand is produced with a sequence of bases that is complementary to the DNA bases.

2. Translation: Building the Protein

Stages of Translation:

• The message copied as RNA is identical to the message in the DNA (except it contains uracil instead of thymine).
• This RNA, known as messenger RNA (mRNA), is a single-chain molecule that can leave the nucleus.

The Pancreas

Long, greyish-white organ behind and underneath the stomach. Functions: Produces hormones (insulin & glucagon) that regulate the amount of glucose in the bloodstream. Secretes pancreatic juice which contains digestive enzymes & sodium bicarbonate.

How Digestion Works

Most digestive processes take place in the small intestine. Digestion produces nutrients that cells need:

• Monosaccharides (simple sugars): obtained from complex carbohydrates.
• Glycerol & fatty acids: obtained from fats.
• Amino acids: obtained from proteins.

Nutrient Absorption

Nutrients pass from the small intestine into the bloodstream through absorption and then are delivered to cells by the blood. The inside wall of the small intestine is covered in folds that... Continue reading "Understanding the Pancreas and Respiratory System" »

1. Sequence of Life's Emergence

What is the correct sequence of events representing how life may have emerged?

Answer: Monomers formed — Polymers formed — Membrane-bound "sacs" emerged — Metabolism and self-replication — RNA produced.

2. Identifying Extinct Species

Which species are extinct?

Answer: Species A and E.

3. Common Ancestor Location

In a phylogenetic tree, the common ancestor for both species C and E could be at position number:

Answer: 4.

4. Science of Classification

The area of science that classifies and names organisms is called:

Answer: Taxonomy.

5. Correct Binomial Nomenclature

Which of the following is correctly written using the binomial nomenclature system?

Answer: Canis lupus.

6. Definition of Binomial Nomenclature

Binomial nomenclature... Continue reading "Key Concepts in Biology: Life's Origins & Classification" »

The Nervous System: Communication Network

Neurons: The Building Blocks of the Nervous System

• Neurons: Specialized cells that conduct electrical impulses throughout the body. They are elongated cells with a cell body and a thin axon.
• Dendrites: Thin projections that extend from the cell body and connect with other neurons to allow electrical impulses to pass through.
• Myelin Sheath: An insulating lipid layer that surrounds some axons, speeding up impulse transmission.
• Nerve: A bundle of nerve fibers enclosed within a protective sheath.
• Nerve Fibers: Long axons of neurons together with any associated tissue.

Types of Neurons

The nervous system is comprised of three specialized types of neurons:

• Sensory Neurons: Transmit messages from receptors (e.g., eyes,

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

Fungi and Plant Kingdom Characteristics

Characteristics of Fungi (Four Points)

• Most fungi grow as tubular filaments called hyphae.
• The walls of hyphae are often strengthened with chitin.
• Fungi disperse themselves by releasing spores.
• Fungi are heterotrophic.

Characteristics of the Plant Kingdom (Four Points)

• Most plants are eukaryotic and chlorophyll-containing organisms.
• Cell walls of plant cells are comprised of cellulose.
• They have an ability to grow by cell division.
• In the life cycle of plants, interchanges occur from the embryos and are supported by other tissues for self-production.

Ecosystem Energy Flow and Cycles

Photosynthesis Equation and Components

The equation for photosynthesis is: 6CO₂ + 6H₂O + solar energy → 6O₂ + C₆H₁₂O₆

• CO₂: Carbon Dioxide
• H₂O:

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" »

Nervous Coordination and the Neuron System

Nervous coordination is carried out by the nervous system. This system is made up of nerve tissue whose cells, called neurons, are capable of transmitting information through nerve impulses.

Structure and Function of Neurons

Neurons are typically divided into three main parts:

• Cell Body (Soma): Contains the nucleus and other essential organelles.
• Dendrites: Short, branch-like projections that receive signals.
• Axon: A longer projection that transmits signals away from the cell body. It ends in a series of slender branches that widen slightly at the tip, called axon terminals.

In general, axons are protected by a white substance called myelin. The axons of various neurons sometimes group together to form nerve