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UNIT 2 REVIEW. Parts of a Cell: Animal. Parts of a Cell: Plant. The basics of a cell.
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The basics of a cell • A cell is the basic unit of life. Everything in our bodies is made up of cells, about 10 trillion to 100 trillion of them. In a cell there are organelles, they are smaller parts that have specific functions such as; intake of nutrients, exchange of gases, movement, growth, response to stimuli, waste removal, and reproduction.
Types • There are two major differences among cells are that some are plant cells and some are animal cells. These cells both include smaller parts within them, these are;
Organelles and Their Functions: • Nucleus: the control center organelle of the cell. • Nucleolus: a small dense area within the nuclei. • Endoplasmic reticulum: an organelle that is made of a series of interconnected small tubes that carry materials through the cell. Rough endoplasmic reticulum is associated with making proteins. Smooth endoplasmic reticulum is associated with the production of fats and oils. • Ribosome: small, dense-looking organelles that may be attached to the rough endoplasmic reticulum or free in the cytoplasm. Ribosome are the sites where proteins are assembled. • Central vacuole: stores water for the cell. • Cytoskeleton: An internal network of fibers, made up of protein filaments. It helps maintain the cell’s shape. • Cytoplasm: a jelly-like substance that fills the cell and surrounds the organelles. Cytoplasm contains the nutrients required by the cell to carry on its life processes.
Chloroplasts: These organelles contain a green substance called chlorophyll. Chlorophyll uses energy from the Sun to convert carbon dioxide and water into sugar and oxygen in a process called photosynthesis. • Cell wall: is a rigid frame around the cell that provides strength, protection, and support. • Cell membrane: a protective barrier around the cell. • Mitochondrion: supply that energy. Reactions occur in these organelles to convert the chemical energy in sugar into energy that the cell can use. • Golgi Apparatus: receives proteins from the endoplasmic reticulum. The function of the Golgi apparatus is to modify, sort, and package these proteins for delivery throughout the cell or outside of the cell. • Lysosomes: organelles where digestion takes place. • Vacuoles: membrane-bound organelles that store nutrients, wastes, and other substances used by the cell. • Central vacuole: stores water for the cell.
Difference between Plant and Animal Cells: • *** Animal and plant cells are not identical, For example the cell wall and the chloroplasts are only found in plant cells as they have to do with photosynthesis. Some other differences are; • 1. Plant cells contain the chemical compound chlorophyll, which makes photosynthesis possible. • 2. Plant cells have a large vacuole, whereas animal cells have a small vacuole. • 3. Some plants store energy as starch or oil ( cornstarch/canola oil ) whereas animal energy is stored as glycogen, carbohydrate, or lipid (fats) • 4. Some animal cells contain special compounds such as hemoglobin (red blood cells) or cholesterol (other cells) • 5. Animal cells have centrioles which are involved in cell diffusion, whereas plants do not have these.
Determining Drawing Magnifications • Measure the low power field of view (FOV) in mm using a clear ruler. • Record the Low, Medium and High power magnifications. • Calculate the field of view for medium and high power. • Look at the specimen and estimate how many specimens will fit across the diameter of the field. • Calculate the actual size of the specimen. • Draw your specimen using the drawing rules. • Measure your specimen drawingin mm. Use the same dimension as used in estimating the number of specimens across the field of view. • Calculate the magnification of your drawing. • Example • FOV low = 4.5 mm • Low, Medium, High power magnification: Low = 4X. Medium = 10X. High = 40X. • If low magnification = 4X and FOV low = 4.5 mm. Then; • Medium 10x FOV = 4.5 mm x (4/10) = 1.8 mm • High 40x FOV = 4.5 mm x (4/40) = 0.45 mm • EX: 6.5 specimens (widthwise) fit across the HIGH power field • Calculate actual size. • Actual Size = field of view • # of specimens across • Actual Size = 0.45 mm • 6.5 specimens • = 0.069 mm / specimen • After drawing specimen, and measuring it in mm,
Drawing Magnification = Drawing Measurement (mm) Actual Size (mm) = 20mm 0.069mm = 290 X (round to whole number)
Cell Cycle: • Interphase • Prophase • Metaphase • Anaphase • Telophase and cytokinesis
Interphase • Interphase is not a part of mitosis. It is when DNA has been duplicated in the S phase and appears as threads in the nucleus.
Prophase • The first phase of mitosis, where the chromatin that makes up the chromosomes condenses. The chromosome is actually two identical copies called sister chromatids attached together at the centromere.
Metaphase • The second stage of mitosis, the chromosomes line up at the centre of the cell.
Anaphase • This is the phase where the sister chromatids separate into individual chromosomes and move to opposite poles.
Telophase and cytokinesis • The last stage of mitosis, where the mitotic spindle breaks down and two new nuclei form. The chromosomes lose their distinct shape. The cytoplasm and the cell membrane pinch in half to form two new daughter cells.
CANCER CELLS What are cancer cells? • A cell reproducing uncontrollably is called a cancer cell. How does a cancer cell occur? • Cancer cell occurs when there is a change in a cell and it affects the cell division. When a change in the DNA occurs then the cells may turn to a cancer cell. Mutation can cause cancer cells. Mutation: A change in the cell’s DNA is called mutation. • Mutation can also be caused by smoking or ultraviolet radiation,
Difference between Cancer Cells and Normal cells Apoptosis: Controlled death of cell that is no longer useful. Apoptosis occurs when a cell is too old or damaged the lysosome breaks and digest the cell.
Cell Specialization • What are unspecialized cells in plants called? Meristematic cells. • Where are unspecialized cells located in the plant? In the growing roots tip and in a layer of the stem called the cambium. • What is the purpose of stem cells? The purpose of the stem cell is to divide and become specialized, to form all the different cells in your body. • How does a stem cell specialize? A stem cell specializes when exposed to specific environmental conditions. Otherwise, they continue to divide. • What advantages does cell specialization have? Through cell specialization, an organism can help fulfil all the life processes it needs. It also ensures that the cells specialized for that specific task are very good at what they do (their function). Ultimately, it is an evolutionary advantage for the cells to specialize.
Tissues • How many plants tissues are there? Name them. There are four plant tissues – meristematic, epidermal, ground and vascular tissue. • How many animal tissues are there? Name them. There are four types of animal tissues – epithelial, connective, muscle and nervous tissue. • What does connective tissue do? It forms blood, stores fat, fills up empty space and protects and supports structures. • What are the two types of vascular tissue, what is the difference? Xylem and phloem. Xylem transports substances such as water and nutrients to the leaves. Phloem on the other hand transports the glucose made in the leaves to other parts of the plant. • Where is ground tissue found (three places)? It is found in the roots, where it stores food and water. It is found in the stem, where it is used for strength and support. Lastly, it is found in the leaves where it is used in photosynthesis (as mesophyll).
Organ Systems: Digestive System • Mouth: digestion begins in the mouth where food is chewed and salivary glands secrets saliva which moist the food. • Epiglottis: stops food from going to trachea. • Esophagus: helps food reach to the stomach. • Stomach: this is where food is chemically digested. Stomach secrets Hcl and pepsin which digests the food chemically. • Lever/gallbladder: lever makes chemical called bile which is stored in the gall bladder. The bile then breaks down fat from food. • Pancreas: breaks down carbs in the body. • Small intestine: The small intestine is the real hero of the digestive system. As the food passes through, it is mixed with the new chemicals and soon our "food" is now digested small enough to be put to use by the body. Along the walls of the intestine are thousands of tiny fingers called villi. • Douednum:the bile and digestive enzymes empty in the duodenum. • Large intestine: Whatever the body cannot put to use is sent to the large intestine. Then the waste get removed through the anal opening when we go to the bathroom.
Respiratory System: • The purpose of this system is to release co2 and obtain o2. Air enters through the nose or mouth the. • Then air is filtered by cilia, moistened by mucus and warmed up by blood vessels. • Then it passes through pharynx and larynx. • Then air enters through trachea which is divided into bronchi which takes air into lungs. • Bronchi divided into small branches known bronchioles which contains alveoli. • Alveoli is the gas exchange between air and capillaries.
Circulatory System • The circulatory system is composed of vessels and muscles that control the flow of blood around the body. This process of blood flowing around the body is called circulation. The main components of the circulatory system are the heart, arteries, capillaries and the veins. Blood leaves the heart from the left ventricle into the biggest artery, called the aorta. The heart is a strong muscle, which is divided into 4 compartments (the left and right atrium and ventricles). It is important that fresh blood from the aorta goes directly to the brain, because the brain needs oxygen constantly otherwise we get irreversible damage. Another important organ for the blood to pass through is the lung. Here waste carbon dioxide is replaced with fresh oxygen. The pressure in the arteries is higher than in the veins. Blood returns to the heart through the veins
Plant Organs • What is the purpose of the roots in a plant? The roots are used to anchor the plant in place, to ensure that the plant doesn’t topple over. It also collects water from the surrounding soil, and stores food made in other parts of the plant. • What is the purpose of the stem? The stem supports the leaves and flower. It also allows for the transport of water and nutrients throughout the plant. • What is the purpose of the leaf? The leaf is where photosynthesis occurs. • What are the components of the flower and how do they work together to reproduce? The flower holds both male and female reproductive organs. The male organ, called the stamen, is composed of the anther which produces pollen (the male sex cells). The female reproductive organs, called the pistil, consist of the ovary, style and stigma. The eggs are held in the ovaries. When the eggs become fertilized, it becomes a seed. • The epidermal tissue secretes a waxy substance which forms a protective layer and prevents water loss. What is this waxy substance called? The cuticle.
