Notes, summaries, assignments, exams, and exercises for Biology for Baccalaureate

Understanding Genetic Mutations

Mutations are heritable changes in the genotype (DNA) that may or may not manifest in the phenotype. They are responsible for the variability of characters and drive species evolution.

Classification by Affected Cells

• Somatic mutations: Affect somatic cells and are not transmitted to offspring; they can cause cancer.
• Germline mutations: Affect germ cells and are transmitted to offspring, holding great evolutionary significance.

Classification by Genetic Material Involved

• Gene mutation: Affects the nucleotide sequence of a gene, often occurring due to DNA polymerase errors.
• Chromosomal mutations: Affect the sequence of genes on a chromosome, often caused by errors during meiotic recombination.
• Genomic mutations: Affect

Photosynthesis

It is a unique process of plants containing chlorophyll, transforming simple substances such as water and carbon dioxide into more complex substances like carbohydrates.

Chlorophyll

It is a green pigment that absorbs radiation reflected in colors like blue, purple, and red. There are four types of chlorophyll (a, b, c, and d), with slight chemical variations in their formulas.

Chloroplasts

These are cytoplasmic organelles formed by polymembranous structures containing areas called grana, where light-phase reactions occur. There are other areas called stroma, where enzymatic reactions take place.

Factors Affecting Photosynthesis

1. Light: A decisive factor in this process because it can accelerate or retard the reaction. This energy is

Glycolysis: The Anaerobic Breakdown of Glucose

Glycolysis is a set of reactions that degrade glucose (6C) into two molecules of pyruvic acid (3C). Performed in the hyaloplasm, it is an anaerobic process. From each molecule of glucose, the cell obtains 2 ATP and 2 NADH + H⁺.

Ten Steps of the Glycolytic Pathway

1. Step 1: Phosphorylation of glucose into glucose-6-phosphate by ATP, catalyzed by hexokinase.
2. Step 2: Glucose-6-phosphate is isomerized to fructose-6-phosphate by isomerase.
3. Step 3: Phosphorylation by ATP to form fructose-1,6-diphosphate (6C), catalyzed by kinase.
4. Step 4: The molecule is divided to form two molecules: glyceraldehyde-3-phosphate and dihydroxyacetone phosphate.
5. Step 5: Dihydroxyacetone phosphate is an isomer of the aldose glyceraldehyde-

DNA Replication

DNA replication begins with the double helix unwinding, separating like a zipper. Each strand serves as a template for creating a new complementary strand. DNA polymerase enzymes add nucleotides one by one, matching adenine with thymine and guanine with cytosine. This process creates two identical DNA molecules, each with one original and one new strand. Errors during replication can lead to mutations, which can be harmless, cause diseases, or contribute to evolution.

The Importance of Base Complementarity

Base complementarity is crucial for accurate DNA replication, ensuring that genetic information is passed correctly from parent to daughter cells. It also forms the basis of many molecular biology techniques.

Gene Expression:

The Cell Wall

The cell wall is an outer covering found in bacteria, plants, algae, and fungi.

Chemical Composition

In fungi, the wall is composed of chitin (a polymer). In most algae and higher plants, it consists of cellulose. Cellulose is a linear polymer made of thousands of glucose monomers that form long, strong, associated microfibrils of great length. These microfibrils are embedded in two other polysaccharides: hemicellulose and pectin.

Structure

The cell wall consists of two layers: the middle lamella and the primary wall. When the cell matures, it produces a third layer called the secondary wall, located between the plasma membrane and the primary wall.

• Middle Lamella: Located between the primary walls of neighboring cells, except in places

Understanding Stem Cells and Pandemic Phases

Post-Pandemic Period Assessment

Following the pandemic, flu cases have become comparable to the usual seasonal flu patterns.

Stem Cells: Definition, Function, and Application

What Are Stem Cells?

Stem cells are progenitor cells that are self-renewing.

How Do Stem Cells Work?

Within the bone marrow, stem cells are found that reproduce identical cells through mitosis.

Where Are Stem Cells Located?

1. Cells in the blastocyst embryo state.
2. Organ-specific cells (e.g., bone marrow).

Stem Cell Capabilities

They are able to generate any cell type of the body.

Therapeutic Effect of Stem Cells

They function as restorative medicine for damaged tissues.

When Are Stem Cells Applied?

They are used in treatments, often alongside...

Stages of Human Embryonic Development

1. If a sperm finds an egg in a fallopian tube, it tries to get through its membrane. The egg then produces a hard coating that prevents the penetration of a second spermatozoon. Fertilization ends when the nuclei of the sperm and egg fuse. From this moment, embryonic development begins.
2. The zygote, formed by a single cell, continues to move down the tube on its way to the uterus and begins to divide.
3. The cells continue to divide until they form an embryo of 32 cells, called a morula.
4. A cavity forms inside the morula, which takes the form of a hollow ball, and is called an early blastocyst.
5. A condensed group of cells inside the blastocyst forms a compact mass at one end, ready to become the late blastocyst. The

The Small Intestine: Structure and Function

Structure

It is divided into three parts: the Duodenum, Jejunum, and Ileum. The small intestine represents the largest portion of the digestive tube. Its length varies with the type of feed: it is longer in herbivores and shorter in carnivores.

Function

Its primary function is to perform most of the chemical digestion and absorption of nutrients. For this, it requires that the secretions discharged by the pancreas, liver, and intestinal glands are mixed with chyme through sawing motions and peristaltic waves. After this mixture, chyme becomes chyle, consisting of H₂O, mineral salts, monosaccharides, and amino acids, which are absorbed by the intestinal mucosa to be incorporated into the circulatory...

Invertebrate Excretory Organs: Structure and Function

Invertebrates utilize various specialized organs to manage waste and maintain osmotic balance:

• Protonephridia

  Found in small animals like Platyhelminths (flatworms) and Nematodes. These consist of a series of closed, branched tubes. The inner ends terminate in ciliated cells (flame cells or solenocytes) that capture waste products. Excretory fluid circulates inside the tube, and once excess water is reabsorbed, the final product is eliminated through excretory pores.

• Metanephridia

  Found in Annelids and Mollusks. These are tubes open at both ends. The internal opening, called the nephrostome, is funnel-shaped, ciliated, and opens into the coelom (general body cavity). The other end opens to the

Methods for Introducing Cloning Vectors

The next step is to introduce the cloning vector containing your target gene into a host cell. As the host cell multiplies, it creates a cell clone carrying that specific gene. The method used depends primarily on the cell type.

Transformation and Transduction in Bacteria

In prokaryotes like bacteria, DNA introduction occurs through the following processes:

Transformation

This occurs naturally in certain bacteria and can be achieved artificially by subjecting cells to physical treatments, such as heat or electric shock, and specific chemicals. The cell captures DNA molecules from the external environment, internalizes them, and incorporates them into its genome.

Transduction

This method involves introducing...