Human Reproduction: From Puberty to Parenthood
The Reproduction of Human Beings
Humans reproduce sexually. Women produce ovules, and men produce sperm. These two cells unite to form a zygote. Fertilization is internal, so we are viviparous. Reproduction includes:
- Production of gametes (in specialized organs)
- Fertilization (the union of gametes within the female reproductive system)
- Development of the zygote (within the female reproductive system. The zygote becomes an embryo and then a fetus)
- Labor and birth (of a fully formed baby)
- Child Development
Interphase Nuclei: Structure and Function in Detail
Interphase Nuclei: Concept and Structure
Concept
A separate structure from the cytoplasm by a membrane envelope that acts as the cell’s genetic memory.
Basic Structure
The basic structure enables us to distinguish the nuclear envelope, chromatin, nucleolus, and nucleoplasm.
1. Nuclear Envelope
Formed by two membranes separated by a perinuclear space, crossed by pores, the outer membrane has ribosomes on its outer surface. The nuclear envelope has, on the nucleoplasm side, a dense inner membrane called
Read MorePlant Cell Wall Structure, Function, and Phloem Transport
**Item 1: Membership of the Physical Cell Wall**
Regarding the composition, a physical wall is formed by different layers that vary in thickness, chemical composition, and direction of microfibrils. Starting from the outside of the plasma membrane, we find the middle lamella, an intercellular space of the plant cell, the primary wall, and finally, the secondary wall.
- Middle Lamella: Formed principally by pectins without cellulose. The soft tissue is not lignified.
- Primary Wall: It is a flexible structure
Bacterial Cell Structure, Metabolism, and Nutrition
Peptidoglycan: Chemical Composition
The repeating unit is:
- N-acetylglucosamine (NAG)
- N-acetylmuramic (NAM)
These are joined together by β (1→4) bonds. The various disaccharide units are joined together by β (1→4) bonds. This link may be broken by lysozyme. The tetrapeptide chain running from the -COOH group of each NAM lactyl often contains:
- L-alanine
- D-glutamic acid
- m-DAP
- D-alanine
The Peptidoglycan of Gram-Negative Bacteria
- Usually, peptidoglycan (PG) has one layer.
- The chains are joined by peptide
Infectious Diseases: Understanding Microbes, Transmission, and Immunity
1. What Should Be Said to Treat Infectious Diseases in Countries Unable to Take Action?
Developed countries must show solidarity with those who cannot take action. It’s concerning that many developed nations prioritize their own spending over aiding countries in need.
2. What Is a Microbe? What Is an Antibiotic?
A microbe, or microorganism, is a living organism too small to be seen with the naked eye. Microbes are individual entities with a basic biological organization, unlike plants and animals.
Read MoreHuman Cell Biology and Anatomy: Structure, Function, and Systems
Study of Man
The human body moves, deliberates, and survives adverse conditions. Its construction is complex and survives because of its brain, which is able to think abstractly and enrich perceptions, reasoning, and actions. All life is made up of cells, tiny units that make up the body. The first human cell is the zygote, or fertilized egg. Cells breathe, eat, and are able to reproduce. In the body, there are 200,000 billion cells that collaborate in survival and reproduction. Each cell is an individual
Read More