Bio 1.1.3 - Explain how instructions in DNA lead to cell differentiation AND RESULT IN CELLS SPECIALIZED TO PERFORM SPECIFIC FUNCTIONS IN MULTICELLULAR ORGANISMS.
A cell is the basic unit of structure and function of living things. Multicellular organisms are made up of many different
types of cells and tend to be specialized. These specialized cells are all different and made to perform a specific
function. Below is a chart that shows you examples of some specialized cells.
types of cells and tend to be specialized. These specialized cells are all different and made to perform a specific
function. Below is a chart that shows you examples of some specialized cells.
Cell Type |
Special Function |
Red Blood Cells |
Carry oxygen in the blood |
Skin Cells |
Form protective layer over the body; reduce water loss |
Muscle Cells |
To contract; allowing movement |
White Blood Cells |
Fight bacteria; attack Infection |
Nerve Cells |
Conduct electrical impulse and transmit
message from one part of the body to another |
Basic information:
- Multicellular organisms begin as undifferentiated masses of cells and that variation in DNA expression and gene activity determines the differentiation of cells and ultimately their specialization.
- During the process of differentiation, only specific parts of the DNA are activated; the parts of the DNA that are activated determine the function and specialized structure of a cell.
- Because all cells contain the same DNA, all cells initially have the potential to become any type of cell; however, once a cell differentiates, the process cannot be reversed.
- Nearly all of the cells of a multicellular organism have exactly the same chromosomes and DNA.
- Different parts of the genetic instructions are used in different types of cells and these cells can be influenced by the cell's environment and past history.
![Picture](/uploads/2/8/1/7/28177325/1504055.jpg?305)
- Red blood cells are a specialized type of cell that helps to transport nutrients (oxygen) and remove wastes (carbon dioxide) throughout your body
- They're shaped like a biconcave disc that is round and flat, sort of like a shallow bowl. This shape allows them to carry hemoglobin (a molecule specifically designed to hold oxygen) efficiently throughout the body
- They do not contain a nucleus
- They have a limited lifespan of about three months
![Picture](/uploads/2/8/1/7/28177325/8335813.jpg?352)
- The largest organ of the human body is your skin
- It contains sensory receptors which transmits information to the nervous system
- Acts as a barrier against the outside environment
- The skin is made up of two layers – the epidermis and the dermis
- The epidermis is tough, flexible, and waterproof which is shed or washed away every 4-5 weeks
- There are no blood vessels in the epidermis (which is why you don’t always bleed when you scratch yourself)
- The dermis has blood vessels, glands, nerve endings, sensory receptors, smooth muscle, and hair follicles. This portion of the skin interacts with other body systems to help maintain homeostasis (an internal balance)
![Picture](/uploads/2/8/1/7/28177325/914905.jpg?363)
- White blood cells are part of the immune system and they are specialized to help fight infections and foreign invaders
- In a normal adult body there are 4,000 to 10,000 (average 7,000) white blood cells per microliter of blood.
- When the number of white blood cells in your blood increases, this is a sign of an infection somewhere in your body
- Most white blood cells are made in bone marrow
- There are 5 different types of white blood cells
- Different types of white blood cells target different invaders, an example being the two "main" white blood cells, which is Neutrophil that attacks bacteria and fungi while Lymphocytes which helps fights off virus-infected and tumor cells
![Picture](/uploads/2/8/1/7/28177325/91469.png?364)
- Nerve cells are also called neurons
- Neurons are specialized to carry "messages" through an electrochemical process
- Neurons have specialize cell parts called dendrites and axons. Dendrites bring electrical signals to the cell body and axons take information away from the cell body
- Neurons contain some specialized structures (for example, synapses) and chemicals (for example, neurotransmitters)
- The human brain has approximately 100 billion neurons
- Three types of Neurons: Sensory (or afferent), Motor (of efferent) and Interneurons
- Sensory neurons send information from sensory receptors (ex. smell, sight, touch, taste and hearing) TOWARD the central nervous system
- Motor neurons send information AWAY from the central nervous system to the muscles or glands
- Interneurons send information between sensory neurons and motor neurons. Most Interneurons are located in the central nervous system.
![Picture](/uploads/2/8/1/7/28177325/7602022.jpg?360)
- Stem cells are undifferentiated biological cells that can differentiate into specialized cells and can divide through mitosis to produce more stem cells
- They are found in multicellular organisms
- In mammals, there are two broad types of stem cells: embryonic stem cells, which are produced in fetuses, and adult stem cells, which are found in various tissues
- In adult organisms, stem cells and act as a repair system for the body, replenishing adult tissues
- In a developing embryo, stem cells can differentiate into all the specialized cells like the ones mentioned above, but also maintain the normal turnover of regenerative organs, such as blood, skin, or intestinal tissues
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