Notes, summaries, assignments, exams, and exercises for Biology for Secondary education

Epithelial Tissue

Functions

Epithelial tissue is responsible for secretion, absorption, protection and sensory perception.

Classification

Epithelia and glands are classified according to the number of cell layers and the shape of the cells in the outermost layer.

• Simple: a single layer of cells.
• Stratified: more than one layer of cells.

Types of Epithelium

• Simple cuboidal epithelium: a single layer of cube-shaped cells.
• Stratified cuboidal epithelium: several layers of cube-shaped cells.
• Simple squamous epithelium: a single layer of flattened cells.
• Stratified squamous epithelium: several layers of flattened cells, so tightly packed that the individual layers are hard to distinguish.
• Keratinized stratified squamous epithelium: contains keratin, a protein

Discovery and Structure of the Cell

Cell: Robert Hooke was the first to observe structures resembling cells in cork tissue.

An Italian scientist was the first to draw animalcules (microorganisms) from pond water.

Pasteur's simple experiment demonstrated that organic matter does not spontaneously create life; life must exist beforehand.

The Cell Theory

The cell theory, developed by Schwann and Schleiden, consists of three main postulates:

• All organisms are composed of cells.
• Cells perform three vital functions: nutrition, relationship (interaction), and reproduction.
• Every cell arises from a pre-existing cell.

Cell Composition and Types

A typical cell is composed of a membrane, cytoplasm, and genetic material (DNA).

We know two main cell types:

• Prokaryote:

The Molecular Basis of Gene Expression

Transcription: Synthesizing RNA from DNA

Transcription is the process where genetic information encoded in DNA is copied into an RNA molecule. This process involves three main stages:

1. Initiation

   The enzyme RNA polymerase binds to the promoter region of the DNA near the beginning of the gene. In different cells, RNA polymerase binds to promoters of different genes, depending on internal and external cellular conditions. The binding of RNA polymerase requires the DNA double helix near the promoter to separate, forming a transcription bubble.

2. Elongation

   The RNA polymerase moves along the template strand of DNA, catalyzing the addition of complementary RNA nucleotides to the growing RNA molecule. As the polymerase

Non-Infectious Diseases

In addition to diseases caused by microorganisms, other diseases are caused by different reasons:

a) Diseases Affecting the Functioning of the Equipment

These include circulatory diseases, which affect the respiratory tract (such as asthma or bronchitis), and those that affect bones or joints (osteoarthritis and osteoporosis).

b) Cancer

This occurs when certain cells, for reasons not yet fully clarified, undergo a metamorphosis that makes them divide rapidly and uncontrollably. As a result, it creates a mass of abnormal cells, called a tumor, which causes the destruction of nearby tissue.

c) Deficiency Diseases

These are caused by a poor diet lacking in certain nutrients. Examples include vitamin deficiency or anemia.

d) Traumatic

Genetic Mutations and Heredity

Mutations: Changes in genetic material.

Types of Genetic Alterations

• Genetic mutations: The alteration affects the chemistry and structure of genes.
• Chromosomal mutations: Alteration affecting chromosome structure.
• Numerical or genomic mutations: Alterations affecting the number of chromosomes.

Causes of Mutations

• Physical mutagenic agents
• Chemical substances
• Biological agents: Viruses

Karyotype and Sex Determination

Karyotype: Chromosomal characteristics of a species.

Sex homogametic / heterogametic: Homogametic individuals produce gametes with...

Levels of Organization: These correspond to degrees of complexity in organized matter. The levels are: subatomic, atomic, molecular, cellular, tissue, system, organelle, and body.

Cell Structure: Eukaryotic cells possess several key elements:

• Plasma Membrane: A thin layer surrounding the cell, composed of proteins and lipids.
• Cytoplasm: An aqueous solution containing organelles.
• Nucleus: A spherical structure containing genetic material, formed by the nuclear membrane, nucleoplasm, chromatin, and the nucleolus.

The major organelles of eukaryotic cells include: mitochondria, endoplasmic reticulum, ribosomes, Golgi complex, vacuoles, lysosomes, and the centrosome.

Tissues: A tissue is a collection of similar cells with a very similar structure that...

Biological Organization: From Tissue to Organism

Levels of Structural Organization

The body is organized hierarchically, starting from specialized cells:

• A tissue is a set of specialized cells of the same type that perform a particular function.
• The union of several tissues forms an organ.
• The set of several organs whose functions are related is an apparatus or system. We speak of a single system when a predominant tissue exists.
• The set of all apparatuses and systems constitutes a multicellular organism.

Tissues, Organs, and Systems

Tissues and Their Functions

Tissues are specialized for specific roles:

• Protection: Integument (skin), Mucosa.
• Reserve: Fat (Adipose tissue).
• Support: Bone tissue.
• Secretion: Glandular tissue.
• Union/Connection: Connective tissue.

The Process of Fertilization

1. The female gamete, or egg, is captured by the fimbriae (finger-like extensions) of the fallopian tube. Thanks to the muscular contractions of the tube's walls and the movement of its cilia, the egg is gently propelled towards the uterus.
2. Sperm that have entered the vagina begin their ascent through the reproductive tract.
3. The surviving sperm continue their journey to the cervix. This region contains glands that produce a specialized mucus fluid. This discharge facilitates the passage of some sperm while trapping others and removing seminal fluid remnants.
4. Once through the cervix, sperm penetrate the uterine cavity, traverse it, and begin their ascent into the fallopian tubes.
5. The meeting of sperm and egg, known as fertilization,

Soma Cells: These cells comprise the whole body, excluding the germ cells.

Germ Line: Specialized cells in reproductive organs responsible for producing gametes.

Karyogamy: The fusion of cell nuclei.

Sexual Dimorphism: Morphological differences between males and females of a species.

Fecundity: The ability to produce offspring.

Withers: When two hermaphroditic individuals mate and fertilize each other.

Parthenogenesis: A phenomenon where an unfertilized egg develops into a normal adult.

Receptaculum Seminis: A storage location for sperm after mating.

Spermatophores: Packets containing sperm that are transferred to females.

Segmentation: A series of rapid cell divisions during early embryonic development.

Morula: A solid ball of cells in the early embryo....

The Human Urinary System

The urinary system consists of two kidneys, two ureters, the bladder, and the urethra.

Kidney Anatomy

• Cortex: The outer zone of the kidney. It has a pale red, granular appearance because it contains the Malpighian corpuscles and the distal nephron tubules.
• Medulla: The inner, dark red area of the kidney, shaped into fluted structures called Pyramids of Malpighi.

The Nephron

The nephron is the functional anatomical unit of the kidney. Nephrons are small tubes distributed throughout the cortical and medullary areas, which are highly vascularized.

Glomerulus

The glomerulus is a specific structure responsible for filtration. It consists of a ball of capillaries surrounded by the first segment of the renal tubule, known as Bowman'