Agenda Anticipation guide Cell differentiation/specialization Abnormal Development Chernobyl (video) Break (5 min) Types of tissues In class work
Anticipation Guide A or DQuestionA or D All cells in the body of an animal are specialized The environment has little to no impact on cell specialization. It is possible for an animal to be born a Cyclops. Like some plants, animals have four main tissues. Cells that are near one another may impact cell specialization
3.1 Cells and Tissues The adult human body is estimated to have between 75 to 100 trillion cells! Some of these cells are non-specialized while most of the cells are specialized (i.e. differentiated)
Cell Differentiation/Specialization There are 3 main factors that influence cell specialization 1. The contents of the cell’s cytoplasm 2.Environmental conditions 3.The influence of neighbouring cells Let’s look at each of these factors individually
Factor 1: Influence of the Cytoplasm on Cell Specialization In mitosis each daughter cell receives identical sets of chromosomes. However, each cell will contain a different cytoplasmic content (i.e. larger vacuole, more ribosomes, etc) ◦ This results in the production of different signals for cell specialization.
Factor 2: Environmental Influence on Cell Specialization Some environmental factors that can impact cell specialization are: ◦ Temperature E.g. Siamese Cats dark feet, tails, ears and nose due to cold temperatures ◦ Presence or lack of nutrients ◦ Toxins
Factor 3: The Effect of Neighbouring Cells on Cell Specialization Neighbouring cells tend to have the largest impact on cell specialization. ◦ They send signals to nearby cells which alters their DNA. ◦ E.g. Digit (finger) formation during development.
The Effect of Neighbouring Cells on Cell Specialization E.g. 2: 12 Day Old Chick Embryo
Abnormal Development The environment plays a critical role in normal development of the embryo. If exposed to toxins, contaminants, radiation, or other harmful chemicals the embryo may develop abnormalities. Cyclops lamb: Veratrum Californicum (contains cyclopamine)
Human Abnormal Development Approximately 6% of worldwide babies born each year are born with an abnormality! ◦ With increasing abnormalities, it will be “normal” to have an abnormality.
From Cells to Tissues When a group of cells come together to carry out a specific function they form a TISSUE Animals have four main tissues: ◦ Epithelial ◦ Muscle ◦ Nervous ◦ Connective
Epithelial Tissue Lines the inner and outer surfaces of the human body (including organs) ◦ Functions of epithelial cells include secretion, absorption, protection and transcellular transport. Can be subdivided into skin epithelia and columnar epithelia
Types of Epithelial Tissue ◦ Skin Epithelia: Creates a barrier between the inside and the outside of the body Mainly for protection ◦ Columnar Epithelia: Found in the small intestine, stomach and glands. It functions to absorb nutrients and secrete mucus.
Muscle Tissue Consists of elastic-like cells that contract. Can be subdivided into skeletal muscle, smooth muscle, and cardiac muscle.
Types of Muscle Tissue Skeletal Muscle: Connects to the bone allowing movement. ◦ Voluntary Smooth Muscle: Found along the walls of blood vessels and internal organs (i.e. oesophagus and stomach) ◦ Involuntary Cardiac Muscle: Found only in the heart
Nervous Tissue Made of cells called neurons. Function to receive and conduct electrical signals. ◦ Relay signals to the central nervous system (brain and spinal cord). ◦ Detects and responds to external stimuli.
Connective Tissue Tissue that functions to strengthen, support, protect, bind, or connect cells and other tissues. ◦ Can be subdivided into Bone Tissue, Fat (adipose tissue), and Blood Tissue.
Types of Connective Tissue Bone: Made of many cells enveloped in calcium. Fat: A collection of large, tightly packed cells found under the skin and around organs. Blood: A collection of red and white blood cells, platelets, and plasma.
Anticipation Guide Revisited A or DQuestionA or D All cells in the body of an animal are specialized The environment has little to no impact on cell specialization. It is possible for an animal to be born a Cyclops. Like some plants, animals have four main tissues. Cells that are near one another may impact cell specialization
Test Your Knowledge Which tissue prevents harmful bacteria from entering your body? Which tissues are responsible for supporting and forming bone? Imagine you are opening a water tap in your washroom. Immediately after touching the water, you realized the water was boiling. Which tissues are involved in moving your hand away quickly? Which tissue is responsible for controlling the contraction of blood vessels?
Homework/ In Class Work Read pages 85-92. Practice Questions 1,3, 4 (page 90)
Agenda Story Time Stem Cells Pluripotency vs Totipotency Use of Embryonic Stem Cells Controversy of Stem Cells Pros and Cons of Embryonic Stem Cells (T-Chart) Different types of Stem Cells In-class work/Assignment
Stem Cells Analogous to the meristematic cells in plants Are unspecialized non-differentiated cells
Totipotent Stem Cell Toti- : Means Total -potent : Means Potential By combining the prefix and suffix we can make sense of the meaning of the word. Totipotent cells are therefore cells that have the potential of forming all total cells possible
Pluripotent Stem Cells Pluri- : Means plural or multi -potent : Means Potential By combining the prefix and suffix we can makes sense of the meaning of the word. Pluripotent cells are therefore cells that can make many different types of cells (but not all).
Pluripotent vs Totipotent Fertilized egg Early Embryo Embryo (Day 5) Blastocyst Trophoblast
Embryonic Stem (ES) Cells Found in early embryo’s (<1 week old) Are pluripotent Are used by scientists to treat various illnesses and conditions
E.g. 1 Use of ES Cells Cardiovascular disease Lack of oxygen kills heart cells Heart cells cannot replenish themselves ES cells can be inserted into the heart to regenerate new heart cells
E.g. 2 Type 1 Diabetes Cells in the pancreas that produce insulin (controls blood sugar) are attacked by the own body’s immune system ◦ ES Cells help replenish insulin producing cells
Controversy Attaining a sample of ES cells involves destroying an embryo. ◦ These embryo’s are usually in vitro (fertilized in a test tube) Is it ethically right to kill an embryo for the sake of medical advancement?
Additional Types of Stem Cells Adult Stem Cells Are tissue specific stem cells. (i.e. Neural stem cells can produce all types of nerve cells Commonly used to restore bone marrow cells in patients that have received chemotherapy.
Fetal Stem Cells Taken from fetus (10 weeks old) Are tissue-specific Cord Blood Stem Cells Taken from umbilical cord at birth Used to treat the blood system after cancer treatments (i.e. chemo) Additional Types of Stem Cells
Induced Pluripotent Stem Cells (iPS) Reprogramming of specialized cells (i.e. skin cells) into an embryonic stem cells. ◦ Are pluripotent ◦ Behave slightly different that ES cells. Additional Types of Stem Cells
Assigned Work Reread section 3.1 Answer questions #4-8 Assignment ◦ Create a newspaper article documenting one use (treatment) for embryonic stem cells. ◦ The article should include the 5W’s and the How component. ◦ Due Monday
E.g. Burn Victims and Stem Cells Burned tissue takes up to 30 days to begin healing in patients with 2 nd degree burns By placing ES cells at the region that is burned using a spray on method, the recovery can be reduced by over 3 weeks.