Compendium Review Unit I: Cells1. Basic unit of life: Cells
2. Molecules of Life
4. Cell Structures
5. Tissues
BASIC UNIT OF LIFE- CELLS. "All living things, --- are made up of one or more cells (Ramel). I agree, it is quite amazing to think that each creature crawling around, plants sprouting
for the season, birds flying through the sky, and our own beginning of life are all made up of cells!! In the first section of the text it describes the characteristics that all living things share. To begin; atoms bind together, forming molecules, which make up a cell. This organization is like a ladder, starting with: atom, molecule, cell, tissue, organ, organ system, organism, population, community, ecosystem, and biosphere. The environment is also a critical part of the ladder, being that we need the nourishment and energy it provides us with. Reproduction and Growth and development are ongoing until death. Homeostasis and Stimuli are both essential responses to our bodies. Evolution is a process that changes with time, but also helps trace back to our ancestry. There are two different types of cells. Prokaryotes (Bacteria) which do not have a nucleus, mitochondria, or any membrane bound organelle. They are single-celled and "as far as we know life began as a singe celled organism, which are essential to all life" (Ramel). The second group is Eukaryotes (Animals, Plants) which have a nucleus and organelles. They are multi-cellular and "arose much, much later in time, when the unicellular organisms learned they could be more successful working together" (Ramel).
MOLECULES OF LIFE. There are four main categories of organic molecules that are important to cells: Carbohydrates, Lipids, Proteins, and Nucleic Acid. I will briefly touch on each of these categories, which basically makes up the molecules of life. Think of CHO as fuel, it gives the cell the energy it needs to maintain its function. A couple examples are: glucose and starches. Lipids have the highest amount of energy, in that can not dissolve in water, and have a structured form (carbon and hydrogen). A few functions that are important are: "long-term energy storage, insulates against heat loss, and forms a protective cushion around major organs" (Mader 30). One of the most important functions of Protein is the role of enzymes, which regulates all of the cellular reactions (Carpi). I did not realize before that hair, hemoglobin and muscles are all part of protein. Nucleic Acids are divided into two types: DNA and RNA. DNA stores, replicates, and transmits genetic information. Which in turn is the role of RNA, it interprets the information from the DNA. The structure of the double- stranded DNA are: Thymine(T) - Adenine(A) and Guanine(G) - Cytosine(C). These bases form the hydrogen strung ladder. "ATP is the energy carrier within the cells" (Mader 36).PLASMA MEMBRANE AND ITS MOVEMENT . The process a cell goes through to allow certain particles, substances, or molecules from entering or exiting its home is amazing. By surrounding this little cell, the plasma membrane helps keep the cell functioning. It is made of a phospholipid layer, which changes consistency with different temperatures. Since it is picky as to what enters or not, it is called selective permeable. Diffusion allows molecules to move, as they please, from high concentrations to low concentrations across the plasma membrane. Osmosis is diffusion of water across the plasma membrane. Facilitated Transport are helped across the membrane by protein carriers, which move with little bursts of energy. Active Transport is the process from low to high concentration, therefore, it needs energy to help it through. ATP, as mentioned in the previous paragraph, is used in this process. The energy is broken down to move across the membrane. Endocytosis is also known as phagocytosis, where a vesicle is pinched off and are engulfed. Exocytosis, the vesicles attach to the plasma membrane.
CELL STRUCTURES. The cell is formed by many different parts, which have important functions. The first part, which many of us are well acquainted with is the heart of the cell, the Nucleus. This structure is important for the cells DNA, or genetic information. Ribosomes are scattered in the cytoplasm, or attached to the endoplasmic reticulum. The main function for ribosomes is, protein synthesis. "The transcription phase (mRNA pairs up with an exposed DNA base) of protein synthesis, takes place in the cell nucleus" (Carpi). "The endomembrane system consists of : endoplasmic reticulum, the Golgi apparatus, lysosomes, and vesicles" (Mader 50). Cilia (short) and Flagella(long) are two types of sweeping movements within the cell. Mitochondria is another structure that aids in "converting the chemical energy of glucose products into the chemical energy of ATP molecules" (Mader 52). While researching an author stated the mitochondria is like a "power plant" pertaining to the energy it produces (Carpi). Within the cell, the chemical reactions such as, the jobs of enzymes and co-enzymes, are functioning parts for metabolism and cellular respiration (the breakdown of glucose to carbon dioxide and water).
TISSUES. "A tissue is composed of specialized cells of the same type that perform a common function in the body" (Mader 62). There are four main tissues within our bodies: Connective, Muscular, Nervous, and Epithelial. When you bend your knee, you probably don't realize, but the Connective tissue is very structured by supporting and connecting tissues. It branches into 3 categories: Fibrous (adipose, tendons), Supportive (cartilage and bone) and Fluid(blood and lymph). Muscular Tissue help with movement. 3 types are: Skeletal(fast), Smooth and Cardiac(heart). Nervous Tissue supply nourishment to neurons. A neuron has 3 parts to it: a cell body, axon and dendrites(sensory strings attached to the body). Epithelial Tissue is like a blanket of protection. Types are: Simple(squamous, cuboidal, columnar) and Pseudostratified Columnar. All the systems in our body are important to maintain homeostasis. A few examples are Cardiovascular system( heart) Digestive System(liver) Respiratory System(lungs) Urinary(kidneys). Our bodies have many functions that continuously cycle on a daily basis.
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