Unit 2 DB: Cancer Risk Factors (Biology)
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Post_BIO120-Unit2A.pdf
BIO120 Concepts of Biology
Unit 2 Lecture Part One: Cell Biology
Microscopy
Cell Structure
Osmosis & Diffusion
In 1665, Robert Hooke was the first person to describe a cell, because no one ever had a lens powerful enough to see one. His first specimen was a piece of cork, the cells reminded him of little rooms (cella). Hence the name.
Discovering Cells
Microscopy
Discovering Cells
Discovering Microbes
Modern Light Microscopes
Cell Image
Electron Microscope
Size of Cells
Cell Structure
Osmosis & Diffusion
Although Hooke was the first person to see a cell, Leeuwenhoek described the most cells in about 1683. He was first to see bacteria and other microbes, because his lens was 10 times more powerful than Hooke’s.
Discovering Microbes
Microscopy
Discovering Cells
Discovering Microbes
Modern Light Microscopes
Cell Image
Electron Microscope
Size of Cells
Cell Structure
Osmosis & Diffusion
Most modern light microscopes can magnify objects up to 400 or 1,000 times the size of what you can see with the naked eye. Some light microscopes are dissecting microscopes, which have a lower magnification, but allow biologist to examine larger objects.
Modern Light Microscopes
Bright Field MicroscopeDissecting Microscope
Microscopy
Discovering Cells
Discovering Microbes
Modern Light Microscopes
Cell Image
Electron Microscope
Size of Cells
Cell Structure
Osmosis & Diffusion
This image shows uterine cervix cells, viewed through a light microscope. The cells were obtained from a Pap smear during a gynecological exam. The cells on the left are normal. The cells on the right are infected with human papillomavirus, which can cause cervical cancer. These potential cancerous cells are bigger and appear to be dividing. The cells are blue, because they have been stained to help see them better.
Cell Image
Microscopy
Discovering Cells
Discovering Microbes
Modern Light Microscopes
Cell Image
Electron Microscope
Size of Cells
Cell Structure
Osmosis & Diffusion
Even more powerful than a light microscope is an electron microscope. Electron microscope uses electrons instead of light to form images and can magnify images 100,000 x. The top images shows the amazing details on an ant head. The lower image shows Salmonella infecting human cells.
Electron Microscope
Microscopy
Discovering Cells
Discovering Microbes
Modern Light Microscopes
Cell Image
Electron Microscope
Size of Cells
Cell Structure
Osmosis & Diffusion
This image summarizes the sizes of cells and their components and what can be seen by the naked eye, light microscope, and electron microscope.
Size of Cells
Microscopy
Discovering Cells
Discovering Microbes
Modern Light Microscopes
Cell Image
Electron Microscope
Size of Cells
Cell Structure
Osmosis & Diffusion
Cells can be classified as either prokaryotes or eukaryotes depending on whether a nucleus is present or absent. Prokaryotes are cells that lack a nucleus. They are single- celled organisms such as the E.Coli bacteria that lives in your intestine. Eukaryotes are cells that contain a nucleus,
and are found in animals, plants, and fungi. Some single-cell organisms such as amoebas are eukaryotes. The membrane surrounding the nucleus is called the nuclear envelope.
Prokaryote vs Eukaryote
Prokaryote
Eukaryote
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
One key characteristic of cells is that they are surrounded by a plasma membrane, a phospholipid bilayer with embedded proteins. Membrane proteins help control which molecules pass into and out of cells. Membrane proteins also play a role in communication between cells and adhesion of cells to each other and the surface. In eukaryotes, membranes surround organelles, allowing different parts of the cell to have specialized functions.
Membranes
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
Cells contain proteins that provide internal structural support similar to how we need our bones to stand up right and move.
In eukaryotes, there are three types of cytoskeletal molecules from largest to smallest:
• Microtubules
• Intermediate filaments
• Microfilaments (actin filaments)
Cytoskeleton
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
Mitochondria are the powerhouses of the cells, because they synthesize large quantities of ATP, the main energy carrier in the cell.
Mitochondria
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
Chloroplasts are found in plant cell and other cells that perform photosynthesis: the synthesis of sugar from light, water, and carbon dioxide. Chlorophyll is the pigment inside chloroplasts that absorb light and give these organelles their green appearance.
Chloroplasts
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
The endomembrane system is an interconnected system of membranes from several organelles: nuclear envelope, endoplasmic reticulum (ER), Golgi apparatus, plasma membrane, lysomes, and vacuoles.
The rough endoplasmic reticulum (RER) synthesizes membrane proteins & secreted proteins that are then modified by the Golgi apparatus and sorted to their final destination.
Endomembrane System
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
Exocytosis is the process in which cells secrete molecules such as hormones, neurotransmitters, and growth factors by fusing a vesicle with the plasma membrane
Exocytosis
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
Endocytosis is the process in which cells internalize molecules. There are three forms:
• Phagocytosis: plasma membrane surrounds the particle (which can be the size of bacteria) and pinches it off to form an intracellular vacuole.
• Pinocytosis: the cell membrane surrounds a small volume of fluid and pinches off to form a vesicle.
• Receptor-mediated endocytosis: molecules bind to specific receptors on the membrane that pinch off and internalize the molecule. (credit: modification of work by Mariana Ruiz Villarreal)
Endocytosis
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
After endocytosis, the vesicles are sorted to different parts of the cells. For example, macrophages are a type of white blood cells that destroy bacteria. During phagocytosis of a bacterium, the vesicle fuses with a lysosome that contains enzymes that will breakdown the bacterium.
Phagocytosis
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
Cells also secrete molecules that surround the cell, forming the extracellular matrix that play several roles include protecting the cells.
Extracelluar Matrix
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
Cells form four types of connections with other cells:
a. Plasmodesmata is a channel between the cell walls of two adjacent plant cells.
b. Tight junctions form water-tight seal between adjacent animal cells.
c. Desmosomes join two animal cells together. They form strong connections but are not as water-tight as tight junctions.
d. Gap junctions act as channels between animal cells. Both gap junctions and plasmodesmata connect the cytoplasm between adjacent cells allow the tissue to act together.
Intercellular Connections
Microscopy
Osmosis & Diffusion
Cell Structure
Prokaryote vs. Eukaryote
Membranes
Cytoskeleton
Mitochondria
Chloroplasts
Endomembrane System
Exocytosis
Endocytosis
Phagocytosis
Extracelluar Matrix
Intercellular Connections
Diffusion is the process of molecules moving from an area of high concentration to a low concentration (concentration gradient). Some nonpolar molecules can diffuse through membranes. Polar and charged molecules require transport proteins to cross the membrane.
Diffusion
Microscopy
Cell Structure
Osmosis & Diffusion
Diffusion
Osmosis
Tonicity
Electrochemical Gradient
Na/K Pump
Osmosis is the diffusion of water through a semi-permeable that allows water but not large molecules to move across. Water flows from higher to lower amount of water until the concentration of solutes is equivalent on both sides of the membrane.
Osmosis
Microscopy
Cell Structure
Osmosis & Diffusion
Diffusion
Osmosis
Tonicity
Electrochemical Gradient
Na/K Pump
Tonicity is the concentration of salt and other solutes.
Hypertonic solution have high salt concentration that draws water out of the cells and shrink them.
Isotonic solution are balanced with the cytoplasm resulting in no net change in water or shape.
Hyptonic soltions are low salt concentrations, forcing water into the cell and expanding them or causing them to lyse (break apart).
In plant cells, the cell wall resists this change in cell shape, creating an opposing pressure called turgor pressure
Tonicity
Microscopy
Cell Structure
Osmosis & Diffusion
Diffusion
Osmosis
Tonicity
Electrochemical Gradient
Na/K Pump
The movement of charge molecules is dependent upon two forces:
• The diffusion from high to low concentration (concentration gradient).
• The diffusion towards the opposite electrical charge (electrical gradient).
The end result is a electrical potential across the membrane of about – 60 mV
Electrochemical Gradient
Microscopy
Cell Structure
Osmosis & Diffusion
Diffusion
Osmosis
Tonicity
Electrochemical Gradient
Na/K Pump
The sodium-potassium pump uses energy from ATP to moves potassium and sodium ions across the plasma membrane in order to main and regulate the electrochemical potential across the membrane.
Na/K Pump
Microscopy
Cell Structure
Osmosis & Diffusion
Diffusion
Osmosis
Tonicity
Electrochemical Gradient
Na/K Pump
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