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

Applications of Modern Genetics

• Diagnosis and prevention of genetic diseases.
• Gene Therapy: Treatment of diseases by modifying genes.
• Design of more efficient medicines, enabling personalized treatment.
• New research into human genetics.

Genetic Engineering (GE)

Definition of Genetic Engineering

Techniques used to manipulate genetic material to change an organism's traits.

Stages of Genetic Engineering

1. The gene is located.
2. The gene is isolated. Enzymes are used to cut the DNA in specific places.
3. The gene is attached to a DNA molecule (vector) from a bacterium or a virus to transport it. Recombinant DNA (rDNA) is formed.
4. The rDNA is inserted into a cell so that it can be expressed and synthesize the corresponding protein.

Key Uses of Genetic Engineering

• Biological

The Endocrine System

The endocrine is made up of coordinated groups of glands called endocrine glands. They are called endocrine because they release hormones into the bloodstream.

Hormones

Hormones are chemical messengers that activate or stop, accelerate or delay many processes carried out by organs and tissues.

Health Diet (E.S)

Healthy diet, regulate moderate-intensity exercise, and don't consume drugs.

Health Diet

Healthy diet, exercise regularly, and practice correct postures.

The Control of Hormone Secretion

Feedback mechanisms in the endocrine system act similarly. When the amount of hormone in the blood reaches a specific level, a signal makes the gland stop releasing it.

How Hormones Work:

1. Stimulated endocrine glands respond by producing hormones

Stages of Cell Division

Prophase: The first stage of cell division, before metaphase, during which the chromosomes become visible as paired chromatids and the nuclear envelope disappears. The first prophase of meiosis includes the reduction division.

Metaphase: The second stage of cell division, between prophase and anaphase, during which the chromosomes become attached to the spindle fibers.

Anaphase: The stage of meiotic or mitotic cell division in which the chromosomes move away from one another to opposite poles of the spindle.

Telophase: The final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

Cytokinesis: The cytoplasmic division of... Continue reading "Cell Division, Reproduction, and Biological Processes" »

Genetics Terminology

Basic Concepts

• Trait: An inheritable characteristic of an organism.
• Gene: A DNA segment containing information that controls a specific trait.
• Allele: A variant form of a gene, often arising from mutations, contributing to hereditary variations.
• Locus (pl. Loci): The specific location of a gene on a chromosome.

Zygosity

• Homozygous Organism: Possesses identical alleles for a given gene (e.g., AA or aa).
• Heterozygous Organism: Possesses different alleles for a given gene (e.g., Aa).

Allele Interactions

• Dominant Allele: An allele that expresses its phenotype regardless of the paired allele.
• Recessive Allele: An allele that expresses its phenotype only when paired with an identical allele.

Genetic Inheritance Patterns

• Dominance (Dominant

Genome

Living vs. Non-Living Things

Both living and non-living things are made up of matter. All living things share certain common characteristics. These characteristics can help us identify a mineral as a non-living thing and a butterfly as a living one.

Composition of Non-Living Things

Non-living things are made up of inorganic matter. The most abundant chemical elements include:

• Oxygen
• Silicon
• Aluminum
• Iron

Composition of Living Things

Living things are made up of chemical elements called bioelements. The most abundant are:

• Oxygen
• Nitrogen
• Phosphorus
• Sulfur

Key Characteristics of Life

Nutrition

Autotrophic Nutrition

Organisms with autotrophic nutrition capture energy from their environment and use it to transform inorganic substances, such as water, carbon dioxide,... Continue reading "Key Differences Between Living and Non-Living Things" »

Autotrophs and Heterotrophs Defined

F.5.1 Define the terms photoautotroph, photoheterotroph, chemoautotroph, and chemoheterotroph

Photoautotroph: An organism that uses light energy to generate ATP and produce organic compounds from inorganic substances.

Photoheterotroph: An organism that uses light energy to generate ATP and obtains organic compounds from other organisms.

Chemoautotroph: An organism that uses energy from chemical reactions to generate ATP and produce organic compounds from inorganic substances.

Chemoheterotroph: An organism that uses energy from chemical reactions to generate ATP and obtains organic compounds from other organisms.

Examples of Autotrophs and Heterotrophs

F.5.2 State one example of a photoautotroph, photoheterotroph,

Animal Respiration

Breathing is essential for respiration. Animals breathe by inhaling oxygen and exhaling carbon dioxide. This gas exchange occurs via the respiratory system.

Respiratory Systems

Respiratory systems require thin, moist surfaces covered in blood vessels for efficient gas exchange. This facilitates oxygen uptake and carbon dioxide expulsion.

Cutaneous Respiration

Gas exchange through the skin (thin and moist). Examples include earthworms and adult amphibians.

Branchial Respiration

Gas exchange through gills (surrounded by blood vessels). Examples include fish and some crustaceans.

Tracheal Respiration

Gas exchange via internal tubes (tracheae) carrying air directly to cells. Examples include terrestrial arthropods.

Pulmonary Respiration

Gas... Continue reading "Animal Respiration, Circulation, and Excretion" »

Evidence of Evolution

1. Anatomical and Morphological Evidence:

• Homologous organs
• Analogous and vestigial organs

Fossils reveal that organisms in the Earth's past were different from nowadays.

Some embryos from different species are similar, indicating an evolutionary relationship between them.

Biogeographical patterns can be explained according to theories of evolution.

Molecular similarities reveal the degree of relatedness between two groups.

• Parasites: organisms that live off other species.
• Behavior: based on genetic inheritance.

Present-Day Theories of Evolution

Neo-Darwinism considers that natural selection does not act on the individual in isolation... Continue reading "Evidence of Evolution and Present-Day Theories" »

Origin of Life Hypotheses

The Oparin-Haldane hypothesis suggests that life arose gradually from inorganic molecules, with "building blocks" like amino acids forming first and then combining to make complex polymers.

The primitive atmosphere was reducing, containing water vapor and ammonia.

Both Oparin and Haldane proposed that the first life forms were heterotrophs.

Oparin's Work with Coacervates

Oparin's work with coacervates confirmed that enzymes fundamental for the biochemical reactions of metabolism functioned more efficiently when contained within membrane-bound spheres than when free in an aqueous solution.

Haldane's Primordial Soup Idea

Haldane's ideas about the origin of life were very similar to Oparin's. Haldane proposed that the primordial... Continue reading "Origin of Life: Oparin-Haldane & Miller-Urey" »