The Cell Flashcards
Where are all organisms on Earth descended from?
They descended from a common prokaryotic ancestral cell about 3.5 billion years ago.
Theory of Endosymbiosis
About 1.5 billion years ago. Eukaryotic cells emerged when mitochondria and chloroplasts, once free-living prokaryotes, took up permanent residence inside larger cells.
Eukaryotic Cell
Complex cell with nucleus and internal membranes that compartmentalize the cell. They led to the evolution of multi-celled organisms. They make up every other form of life.
Cell Size
10-100 micrometers; human red blood cells are about 8 micrometers
Cell Theory: Schleiden and Schwann
All living things are composed of cells; Cells are the basic unit of all organisms; All cells arise from preexisting cells
Cells in General
Cells are enclosed by a membrane that regulates the passage of material between the cell and tis surrounding. They also contain nucleic acid which directs the cell’s activities and controls inheritance.
Prokayotic Cells
Have no nucleus or other internal organs.
Eukaryotic Cell
Complex cell with nucleus and internal membranes that compartmentalize the cell. They led to the evolution of multi-celled organisms. DNA wrapped with histone proteins into chromosomes, ribosomes are larger, metabolism is aerobic, cytoskeleton present, mainly multicellular with differentiation and cells are larger.
Prokayotic Cells
Have no nucleus or other internal organs. Circular, naked DNA. Ribosomes are small, metabolism in anaerobic/aerobic, cytoskeleton is absent, mainly unicellular and cells are very small.
Prokayotic Cells
Have no nucleus or other internal organs. Circular, naked DNA. Ribosomes are small, metabolism in anaerobic/aerobic, cytoskeleton is absent, mainly unicellular and cells are very small.
Microscopes
Main tool for studying cells. They magnify an image over 100,000 times. Resolution, high magnification and high resolution are characteristics of a good microscope.
Microscrope: Resolution
clarity of the image
Microscopes and People to Know
Antoine van Leeuwenhoek developed the first microscope and Robert Hooke advanced it which enabled him to study and name cells in a cork.
Microscopes and People to Know
Antoine van Leeuwenhoek developed the first microscope and Robert Hooke advanced it which enabled him to study and name cells in a cork.
Light Microscopes
Microscopes that use light passing through a living/dead specimen to form an image. Cells/tissue can be staines to make organelles easier to see however stains may kill cells.
Electron Microscopes
Microscopes that use electrons passing through a specimen to form an image. They have superior revolve and magnification power. However, they cannot be used to view live specimens because the specimen preparation kills the cells.
Transmission Electron Microscopes
Used to study the interiors of cells. The images appear flat and 2D. The tissues must be cut into very small pieces and exposed to a fixative that stops all biochemical activity. The tissue is then dehydrated, embedded in a polymer, cured overnight and sliced on an ultramicrotome.
Scanning Electron Microscopes
Used to study the surface of cells. The images appear 3D. Specimens are coated with a heavy metal such as gold and are placed directly on the microscopes for observing. Specimens are not alive.
Phase-Contrast Microscopes
Used to examine unstained, living cells. It is often used to examine cells growing in tissue culture.
Phase-Contrast Microscopes
Used to examine unstained, living cells. It is often used to examine cells growing in tissue culture.
Cell Fractionation
Using an ultracentrifuge to spin liquids at high speeds and separate them based on differences in density. Tissues/cells are first mashed up in a blender to form a homogenate. The most dense particles such as nuclei are pushed to the bottom, followed by mitochondria and ribosomes. The supernatant, liquid above the pellet, can be poured off an re-spun.
Cell Fractionation
Using an ultracentrifuge to spin liquids at high speeds and separate them based on differences in density. Tissues/cells are first mashed up in a blender to form a homogenate. The most dense particles such as nuclei are pushed to the bottom, followed by mitochondria and ribosomes. The supernatant, liquid above the pellet, can be poured off an re-spun.
Freeze Fracture and Freeze-Etching
Multistep techniques used to prepare a detailed cast of the membrane. The tissue is then digested away leaving only the cast which can be examined under the electron microscope.
Tissue Culture
Used to study the properties of specific cells in vitro. Cell lines can be grown in culture for years and while the cells are growing they can be studied with a phase-contrast microscope.
Tissue Culture
Used to study the properties of specific cells in vitro. Cell lines can be grown in culture for years and while the cells are growing they can be studied with a phase-contrast microscope.
Tissue Culture
Used to study the properties of specific cells in vitro. Cell lines can be grown in culture for years and while the cells are growing they can be studied with a phase-contrast microscope.
Nucleus
Contains chromosomes
Nucleus
Contains chromosomes which are wrapped with special proteins into a chromatin network. It’s surrounded by a selectively permeable membrane or envelope that contains pores to allow for the transport of molecules which are too large to diffuse directly through the envelope.
Nucleolus
An interphase in the nucleus contains this region where components of ribosomes are synthesized. 1 to 2 nucleoli may be visible. Nucleoli are not membrane-bound structures but are actually a tangle of chromatin and unfinished ribosome precursors.
Ribosomes
The site of protein synthesis. They can be found free in the cytoplasm or attached to the endoplasmic reticulum.
Endoplasmic Reticulum
A membranous system of channels and flattened sac that traverse the cytoplasm.
Rough ER
The site of protein synthesis resulting from the attached ribosomes.
Smooth ER
Assists in the synthesis of steroid hormones and other lipids; connects rough ER to the Golgi apparatus; Carrier out various detoxification processes
Golgi Apparatus
Lies near the nucleus and consists of flattened membraneous sacs stacked net to one another and surrounded by vesicles. They package substances produced in the rough ER and secrete them to other cell parts or the cell surface for export.
Golgi Apparatus
Lies near the nucleus and consists of flattened membraneous sacs stacked net to one another and surrounded by vesicles. They package substances produced in the rough ER and secrete them to other cell parts or the cell surface for export.
Lysosomes
Sacs of hydrolytic (digestive) enzymes surrounded by a single membrane. They are a site of intracellular digestion. The cells can continually renew itself by breaking down and recycling its parts. Apoptosis occurs with a cell’s own hydrolytic enzymes which is essential for multi-celled organisms.
Peroxisomes
Found in both plant and animal cells. They contain catalase which converts hydrogen peroxide (waste product of cellular respiration) into water with the release of oxygen atoms. They also detoxify alcohol in liver cells.
Mitochondria
The site of cellular respiration. All cells have them but a very active cells could have 2,000+. They have an outer double membrane and an inner series of membranes called cristae. They contain their own DNA.
Vacuoles
Single, membrane-bound structure for storage. Vesicles are smaller version of these. Contractile vesicles pump out extra water; they’re found in freshwater protista.
Plastids
Only found in plants and algae. Have a double membrane.
Plastids: Chloroplasts
Site of photosynthesis. In addition to the double outer membrane so they have an inner one that forms a series of structure called grana. The grana consist of thylakoids and lie in the stroma. They contain their own DNA.
Plastids: Leucoplasts
Store starch and are found in roots like turnips or in tubers like the potato.
Plastids: Chromoplasts
Store carotenoid pigments and are responsible for the red-orange-yellow of carrots, tomatoes and daffodils.
Cytoskeleton
Complex network of protein filaments that extend through the cytoplasm and gives the cell its shape and enables it to move. It also anchors organelles to the plasma membrane.
Cytoskeleton: Microtubules
Hollow tubes made of the protein tubulin that make up the cilia, flagella, and spindle fibers. Cilia and Flagella help with locomotion. Spindle fibers help to separate chromosomes during meiosis and mitosis.
Spindle Fibers: Structure
Microtubules organized into 9 triplets with no microtubules in the center.