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

Translation

• mRNA (Messenger RNA): Conveys genetic information from DNA to the ribosome.
• tRNA (Transfer RNA): Helps decode the mRNA sequence into a protein.
• rRNA (Ribosomal RNA): The RNA component of the ribosome, essential for protein synthesis.
• Ribosome: Protein builders that connect one amino acid at a time to build long chains.
• Codon: A sequence of three DNA or RNA nucleotides in mRNA.
• Anticodon: Binds with the codon in the ribosome.
• Amino Acid: A simple organic compound.
• Start Codon: The first codon of an mRNA transcript translated by a ribosome.
• Stop Codon: A nucleotide triplet within mRNA that signals the termination of translation.
• Peptide Bond: A covalent chemical bond formed between two amino acid molecules.
• Polypeptide: An organic polymer consisting

Fundamentals of Genetics

In the nucleus of every cell, there are a number of long threads called chromosomes. Each chromosome is made up of a large number of genes coding for the formation of different proteins, which ultimately determine our characteristics or traits.

Defining Key Genetic Components

DNA (Deoxyribonucleic Acid)

A molecule that carries most of the genetic instructions used in the development of living organisms. It serves as the blueprint for all living things.

Chromosome

A very long DNA molecule that carries a large amount of genetic information.

Gene

A section of a DNA molecule that codes for a specific protein or characteristic (e.g., hair color). A part of a DNA molecule coding for one protein is called a gene.

Trait

A notable feature

Trophic Levels in Ecosystems

Producers

Producers are organisms that use photosynthesis to capture energy from sunlight, water, and carbon dioxide to create organic matter (carbohydrates). They also synthesize complex biomolecules such as proteins and lipids. They perform autotrophic nutrition.

Consumers

Consumers are organisms incapable of producing their own basic molecules, requiring them to consume other organisms for nutrition. They perform heterotrophic nutrition and are categorized as follows:

• Primary: Herbivores that consume producers.
• Secondary: Carnivores that consume herbivores.
• Tertiary: Carnivores that consume other carnivores.

Decomposers

Decomposers consume dead plant and animal material, converting it into energy and nutrients for producers.... Continue reading "Ecosystem Energy Flow and Biogeochemical Cycles" »

Main Reasons Why Cell Divides

• Larger cell demands more place for the DNA.
• Larger cells result in less moving nutrients and waste materials across the cell membrane.

Information Overload

Cell grows, information is used to build the molecules needed for cell growth. DNA doesn't increase.

Exchanging Materials

Food, oxygen, water enter by the cell membrane, waste products also go out like that.

Division of the Cell

Forms 2 daughter cells. Cell division: process in which a cell divides into 2 daughter cells.

Asexual Reproduction

1 parent, cell divides by fission, little chances of genetic variation, found in bacteria, 2 offspring.

Sexual Reproduction

2 parents, cell divides by meiosis, genetic variation, found in mammals, 1 offspring.

Both

Forms of reproduction,... Continue reading "Cell Division, Chromosomes, and Cell Differentiation" »

Endocrine System

The endocrine system coordinates body processes using chemical messengers called hormones.

Functions of Hormones:

• Control cell metabolism
• Maintain the body's internal stability (homeostasis)
• Regulate growth, sexual development, and reproduction

Endocrine Glands

Endocrine glands produce and release hormones, which the bloodstream distributes throughout the body to all cells.

Hormone Regulation

The endocrine glands and circulatory system work together to regulate hormones. For example, the pancreas secretes insulin when it detects excess glucose in the blood. Insulin causes muscle cells and liver cells to absorb glucose from the bloodstream.

Nervous System Coordination

The nervous system coordinates the activity of endocrine glands through... Continue reading "Endocrine System and Hormone Regulation: A Comprehensive Guide" »

Nature of Science

Science attempts to study and gain information about nature. Science poses hypotheses (usually based on observations) and attempts to explain these hypotheses by observations, inferences, and experimentation.

Hypothesis vs. Theory

A theory is the basis of facts and how they work together. A hypothesis is a question or an educated guess.

Properties of Water

Water is polar. Water is most dense at 4 degrees Celsius.

Cell Organelles and Their Functions

Chromosomes

• Usually in the form of chromatin
• Contains genetic information
• Composed of DNA
• Thicken for cellular division
• Set number per species (e.g., 23 pairs for humans)

Nuclear Membrane

• Surrounds nucleus
• Composed of two layers
• Numerous openings for nuclear traffic

Nucleolus

• Spherical shape
• Visible

The Electron Transport Chain: ATP Production

Inside the inner membrane of the mitochondria, there is a chain of electron carriers known as the electron transport chain (ETC). Electrons generated from oxidative reactions in earlier stages of cellular respiration pass along this chain.

NADH donates two electrons to the first carrier. As these electrons pass along the chain, they release energy from one carrier to the next. At three specific locations along the chain, sufficient energy is released to synthesize ATP via ATP synthase, an enzyme also located in the inner mitochondrial membrane.

FADH₂ also donates electrons, but at a later stage than NADH. Electrons from FADH₂ release enough energy at only two locations along the chain. This ATP production,... Continue reading "Electron Transport Chain: ATP Synthesis & Oxygen's Role" »

Human Digestive System Processes

Digestion involves two main types of processes:

• Mechanical Digestion: Food is ground, cut, and mixed with juices.
• Chemical Digestion: Food is broken down by hydrolytic enzymes.

1. Digestion in the Mouth

Mastication

This is the mechanical process involving the teeth and tongue. Food is torn and ground into small pieces.

Insalivation

Food is mixed with saliva. Pieces of food are moistened to form a bolus. Saliva is produced by the salivary glands and contains:

• Salivary Amylase: Responsible for the digestion of starch.
• Mucin: Gives viscosity to the saliva.
• Lysozyme: Attacks bacteria.

2. Deglutition (Swallowing)

The food bolus moves from the mouth towards the pharynx and passes the epiglottis. The bolus then enters the oesophagus,... Continue reading "Human Digestive System: Stages and Processes" »

1. An example of an organic compound would be: CH4.

2. Which of the following would not be an organic molecule? WATER

3. The measurement of the concentration of hydrogen ions compared to the concentration of hydroxide ions in a solution is called: pH.

4. The waste products of cellular respiration include: WATER AND CARBON DIOXIDE.

5. Matter is anything that: HAS MASS AND TAKES UP SPACE.

6. When an overwhelming body of observations and measurements supports a scientific hypothesis or group of related hypotheses, it becomes a: SCIENTIFIC THEORY.

7. Which of the following statements is a correct distinction between autotrophs and heterotrophs? ONLY AUTOTROPHS CAN LIVE ON NUTRIENTS THAT ARE ENTIRELY INORGANIC.

8. What happens to all the energy you expend?... Continue reading "Understanding Organic Compounds and Cellular Processes" »