Cellular Organelles, Tissues, and Body Systems
Membranous Organelles
Endoplasmic Reticulum
A network of flattened membranous sacs.
- Rough ER: Connected to the nuclear envelope, covered with ribosomes, synthesizes proteins.
- Smooth ER: Lacks ribosomes, synthesizes lipids.
Golgi Complex
Network of membranous sacs with dilated ends. A pile of these sacs forms a dictyosome. It produces lysosomes.
Mitochondria
Rod-shaped, double membrane (inner and outer). Inner membrane has folds called cristae. The space inside is the matrix. They specialize in synthesizing
Human Reproduction: From Gametes to the Reproductive System
Human Reproduction
Reproductive functions are a set of processes by which a living thing produces another living being identical or similar to it, which ensures the continuity of the individual, not as an isolated organism, but as a species.
Asexual vs. Sexual Reproduction
There are two modes of reproduction among living organisms: asexual and sexual. The first requires the participation of an individual and does not require the formation of sex cells. The human species reproduces sexually, so there
Read MoreUnderstanding Genetics: From Mendel’s Laws to Mutations
Mendel’s Laws of Inheritance
1st Law: Law of Uniformity
When crossing two purebred individuals that differ in one character, all individuals of the first-generation offspring are identical for that character.
2nd Law: Law of Segregation
The genes determining a character separate during the formation of gametes and are reunited during fertilization.
3rd Law: Law of Independent Assortment
The genes that determine each character are inherited independently.
Key Genetic Concepts
Allele
An allele is each of the
Read MoreHuman Cell Biology: Structure, Function, Tissues, and Diseases
Human Cells: An Introduction
Human cells: The cell is the basic unit of all living beings. The human body is composed of many cells. These are eukaryotic cells, meaning they contain a nucleus. The nucleus houses DNA and is enclosed by a double membrane called the nuclear membrane. During cell division, the nuclear membrane fragments, and the genetic material compacts into chromosomes.
Organelles in Human Cells and Their Functions
The Nucleus:
Controls all cell functions through DNA.
Ribosomes:
Composed
Nervous and Endocrine Systems: Functions and Structures
The Nervous and Endocrine Systems
Interaction: Basic Life Process
The basic life process of interaction consists of a series of functions which help the body to:
- Adapt to change
- Coordinate different systems
There are two systems involved in this process:
- Nervous system
- Endocrine system
The Nervous System
The nervous system is responsible for:
- Interpreting information received from the sensory organs
- Working out appropriate responses to this information
- Sending instructions to the effectors
- Coordinating the functions
Biotic and Abiotic Factors in Ecosystems: Population Dynamics
Measuring Biotic Components of the Ecosystem
Abundance (relative representation of a species in an ecosystem) for motile organisms:
Direct Methods
- Pitfall traps: Pots buried in the soil in which animals walk into and cannot escape from.
- Homemade Pooter: Plastic straws are attached to a pot. One tube is put in the mouth: suction creates a negative pressure in the pot so that animals are drawn into it.
Indirect Methods
- Lincoln Index: The “capture-mark-release-recapture” technique. It involves:
- Collecting