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172 Cards in this Set
- Front
- Back
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How are cells related?
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By their descent from earlier cells, but they have been modified in various ways during their long evolutionary history.
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What are single-cell organisms called?
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Unicellular organisms.
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What are many-celled organisms called?
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Multicellular organisms.
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What do we use to study cells?
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Microscopy.
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What is cytology?
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The study of cell structure.
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What are the most important tools of cytology?
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Microscopes.
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How do light, or compound, microscopes work?
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Visible light passes through a specimen and lenses.
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How do lenses work in light/compound microscopes?
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They refract light and the image is enlarged.
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What is the maximum magnification of light/compound microscopes?
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1000x.
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What is the definition of resolution/resolving power?
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The ability to distinguish fine detail.
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What is the diameter of most cells?
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Between 1 and 100 micrometers.
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What is one micrometer?
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One millionth of a meter (10^-6).
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What are fluorescent microscopes used for?
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Used to detect the location of certain molecules in the cell.
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What do fluorescent stains do?
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Absorb light of short wavelength and UV radiation and release light of another wavelength.
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What does the emitted light from fluorescent stains do?
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Allows for observing the location of the molecules and the structures to which they are bound.
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What happens in electron microscopes?
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An energized electron beam is focused by electromagnets through the specimen or onto its surface.
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What does the term cell ultrastructure refer to?
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The cell anatomy as seen with the electron microscope.
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What are the two types of electron microscopes?
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Transmission electron microscope (TEM) and scanning electron microscope (SEM).
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What is the magnification of a TEM?
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200,000x or more.
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What is used to focus and magnify the image in TEM?
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Electromagnets.
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What is the first step in used a SEM?
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The specimen is coated with metal.
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What does the electron beam do in an SEM?
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It strikes the metal and dislodges electrons from the metal coat. Then those electrons are focused onto a screen.
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What kind of image is produced by a SEM?
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A three-dimensional figure of the surface of the specimen.
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What two things does modern cell biology integrate?
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Cytology and biochemistry in order to understand the relationship between structures and functions of organelles.
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What is cell fractionation?
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A method of purifying organelles and separating them from other cell structures in order to study their individual functions.
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What is used to fractionate a cell?
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A centrifuge.
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What are the most powerful centrifuges?
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The ulracentrifuge can spin at 130,000 rpms.
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What is homogenization?
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The breaking up of a cell.
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What two things does a centrifuged mixture become?
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The pellet and the supernatant.
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What happens in differential centrifugation?
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The supernatant is spun at successively higher speeds in order to separate the components on the basis of their different sizes and densities.
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What is the pellet?
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The heavier structures of the cell packed at the bottom of the test tube.
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What does the supernatant contain?
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The liquids and the suspended lighter structures of the cell.
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What are the two different types of cells?
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Prokaryotic and eukaryotic.
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What are prokaryotic cells considered to be?
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More primitive than eukaryotic cells.
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Where do prokaryotic cells have their DNA concentrated?
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A region called the nucleoid. But there is no membrane separating the nucleoid region from the rest of the cell.
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What kind of organelles do eukaryotic cells have?
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Highly organized membrane-bound organelles.
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What is the term used for the material inside the nuclear membrane?
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Nucleoplasm.
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What does the term cytoplasm refer to?
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The term used to refer to the part outside the nucleus of the cell. Also used for the material inside prokaryotic cells.
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What are organelles suspended in?
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The cytosol of the cytoplasm.
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What happens when a cell grows larger than a critical size?
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The number of molecules needed by the cell could not be transported into the cell fast enough to sustain its needs.
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Why do cells divide?
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In order to maintain an optimal ratio of surface area to volume.
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How large are microplasmas?
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0.1-1.0 micrometers in diameter. Smallest living cells known.
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How large are bacteria?
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Mostly between 1 and 10 micrometers in diameter.
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How large are eukaryotic cells?
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Between 10 and 100 micrometers in diameter.
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What does a cell's plasma membrane do?
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Separates the cell from the outside world and defines it as a distinct entity.
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What regulates the passage of materials in and out of the cell?
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The plasma membrane.
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What are some attributes of animal cells?
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They have lysosomes, centrioles, and flagellated sperm cells. They lack chloroplasts central vacuoles, tonoplasts, cell walls, and plasmodesmata.
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What are some attributes of plant cells?
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Seldom have lysosomes. Lack centrioles and flagellated sperm cells. They have chloroplasts, central vacuoles, tonoplasts, cell walls, and plasmodesmata.
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What do internal membranes do?
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Divide the cells into compartments that allow cells to conduct specialized activities.
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What does the compartmentalization of the cell allow?
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Allows incompatible chemical processes to occur simultaneously in the cell.
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In general, what do biological membranes consist of?
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A layer of lipids and phospholipids with proteins embedded in this layer or attached to its surface.
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What does a cell's nucleus do?
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It controls the functions of the cell.
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What two things does a cell's nucleus contain?
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The nucleolus and chromosomes.
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What is the nuclear envelope?
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Made of a double membrane (two concentric membranes that separate its contents from the cytoplasm).
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What do nuclear pores do?
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Allow the passage of material in and out of the nucleus.
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What is the pore complex?
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The nuclear pore ringed by proteins that regulate the passage of macromolecules in and out of the nucleus.
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What is the nuclear lamina?
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A netlike structure of proteins that line the nuclear side of the membrane. Maintains the shape of the nucleus.
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What is the nuclear matrix made of?
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A framework of fibers extending throughout the nuclear interior.
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What are ribosomes?
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Granules composed of RNA and protein.
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Where are ribosomes located?
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Some attached to inner membranes of the endolasmic reticulum or nuclear membrane. Others are free in the cytosol.
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What do ribosomes do?
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They aid in the synthesis of polypeptides.
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What do bound ribosomes do?
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They make proteins destined to make membranes.
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What do free ribosomes do?
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They make proteins that are usually dissolved in the cytosol.
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Can ribosomes alternate their roles in protein making?
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Yes.
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What is chromatin?
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Thin fibers made of DNA and its associated proteins.
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What are chromosomes formed from?
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Chromatin condenses as it coils up before cell division to form chromosomes.
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What do chromosomes contain?
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Genes.
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What is the nucleolus?
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Granular body within the nucleus that consists of RNA and protein.
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What is the nucleolus the site of?
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Ribosomal RNA synthesis and ribosome subunit assembly.
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How do membranes of the eukaryotic system pass material to each other?
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Direct physical contact or by means of vesicles.
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What are vesicles?
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Tiny sacs made of membrane.
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What does the endomembrane system consist of?
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Nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles, and plasma reticulum?
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What makes the plasma membrane part of the endomembrane system?
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It is connected to the endoplasmic reticulum.
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What is the function of the ER?
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It manufactures membranes and performs many other biosynthetic functions.
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What is the cisternae?
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The network of mambranous tubules and saces that make up the ER.
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What is the cisternal space?
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The internal space of the ER that is separated from the cytosol.
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What are the two regions of the ER?
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The rough ER and the smooth ER.
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What is the difference between the smooth and rough ER?
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The rough has ribosomes attached to the cytoplasmic surface while the smooth lacks them.
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How do the ER and the nuclear envelope interact?
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The ER is continuous with the nuclear envelope.
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What does the smooth ER do?
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Synthesises lipids, metabolises carbohydrates, detoxification of drugs and poisons.
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How does the smooth ER function in muscle cells?
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Release of Ca2+ in the cisternal space is released into the cytosol and the cell contracts.
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What does the rough ER do?
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Allows for proteins to be synthesized by the ribosomes attached to the rough ER.
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What are glycoproteins?
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Proteins covalently bonded to a carbohydrate.
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How does the rough ER help form glycoproteins?
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Specialized molecules built into the ER membrane catalyze the bond between the polypeptide and carbohydrate.
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What are oligosaccharides?
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Short chain saccharides.
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What does the golgi apparatus look like?
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Stacks of flattened membrane sacs.
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What does the GA do with proteins made in the ER?
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It receives them, modifies, them, and packages them into vesicles to be sent to other parts of the cell.
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Where is the cis face of the Golgi stack located?
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It sits facing the ER and receives vesicles from the ER.
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What does the trans face of the Golgi stack do?
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It gives rise to transport vesicles that pinch off and transport materials to other parts of the cell.
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What is the cisternal maturation model?
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The cisternae moving forward form the cis to the trans face carrying and modifying their protein cargo.
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What are lysosomes?
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Membranous sacs found in most eukaryotic cells.
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What is stored in lysosomes?
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Digestive (hydrolytic) enzymes.
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At what pH do hydrolytic enzymes work best?
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A pH of 5.
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What do lysosomes do?
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They fuse with food vacuoles for the digestion of engulfed particles (phagocytosis).
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Besides food, what else do lysosomes digest?
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Infecting bacteria and damaged organelles.
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When lysosomes engulf small portions of the cytoplasm and organelles, what is it called?
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Atophagy.
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What is apoptosis?
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Programmed cell death.
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How are food vacuoles formed?
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By phagocytosis, the engulfing of food particles.
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What do contractile vacuoles do?
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They regulate the amount of water in the cell.
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What is the central vacuole in plants?
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Large membranous sac occupying about 80% of the cell.
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What is the central vacuole formed from?
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The fusion of many small vacuoles derived from the ER and GA.
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What is the tonoplast?
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The single membrane of a vacuole.
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What does the tonoplast store?
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Ions like K+ and Cl-, proteins, food, pigments, poisons, salts, and wastes.
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What process are mitochondria involved in?
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Cellular respiration.
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What kind of membrane do mitochondria have?
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Two membranes, each a phospholipid bilayer.
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What is the space between two membranes called?
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The intermembrane space.
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What is the shape of the inner membrane of mitochondria?
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Folded to form cristae. It encloses the matrix.
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What is contained within the matrix?
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Enzymes, RNA, DNA, and ribosomes.
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How many enzymes involved in cellular respiration does mitochondrial DNA code for?
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13.
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What do the enzymes found in the matrix of mitochondria do?
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They catalyze some steps of cellular respiration.
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Where is the enzyme that makes ATP found?
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The inner membrane of mitochondria.
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How do mitochondria self-replicate?
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Fission, and then growth.
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What is the endosymbiont theory involve?
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It states that organelles are derived from certain prokaryotes entering an early eukaryotic-like organism and becoming symbionts within that organism.
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What are proplastids?
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Small, pale green or colorless organelles of the size of a mitochondrion.
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From where do all plastids develop?
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Proplastids.
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What are chromoplasts, where are they found, and what do they contain?
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They are a type of plastid, found in plant cells, and they contain pigments that give flowers and fruits their color.
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What are two types of leucoplasts?
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Amyloplasts and elaioplasts.
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What do amyloplasts do?
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Synthesize starch, especially in roots and tubers.
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What do elaioplasts do?
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Synthesize plant oils.
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What are chloroplasts and what do they do?
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They are specialized plastids that convert light to chemical energy during photosynthesis.
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What do chloroplasts contain?
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Chlorphyll and enzymes that function in the production of sugars.
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What does chlorophyll do?
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It captures light energy.
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What kind of form do chloroplasts have?
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It is a double membrane structure separated by a narrow intermembrane space and enclosing internal thylakoid membranes.
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What are thylakoids?
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Flattened membranous sacs arranged into stacks called grana.
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What is the fluid outside the thylakoids called?
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The stroma, which contains DNA and enymes.
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Where do peroxisomes and glyoxysomes made?
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They grow by incorporating proteins and lipids from the cytosol.
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What are peroxisomes?
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Single membrane sacs involved in metabolic reactions where hydrogen is transferred to oxygen to make H2O2.
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What do peroxisomes do with O2?
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They use it to detoxify harmful substances like alcohol and formaldehyde.
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What do peroxisomes do with O2- and hydroxyl radicals?
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They convert them to H2O2. Then catalase reduces H2O2 to water.
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What do peroxisomes do with fatty acids?
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They break them down into smaller molecules that can be transported to mitochondria for cell respiration.
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Where in the body are peroxisomes abundant?
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The liver and the kidneys.
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What are glyoxysomes?
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A type of peroxisome found in fat-storing tissues of plant seeds.
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What do glyoxysomes do?
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They converty fatty acids into sugars to provide energy to the emerging seedling.
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What is they cytoskeleton?
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A network of fibers extending throughout the cytoplasm.
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What does the cytoskeleton do during cell division?
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It separates the chromosomes.
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How does the cytoskeleton interact with other organelles?
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It anchors them and controls the movement of them.
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What does cell motility include?
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Displacement of cells from one location to another as well as movements of part of the cell.
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What are some examples of cell motility?
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Cilia and flagella movements, shape changes, muscle cell contraction, phagocytosis and vacuole formation.
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What types of fibers is the cytoskeleton made of?
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Microtubules, microfilaments, and intermediate filaments.
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What does the cytoskeleton interact with during cell motility?
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Motor proteins.
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What are 4 types of microtubules?
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Centrosomes, centrioles, cilia, and flagella.
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What are microtubules made of?
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Subunits of the globular protein tubulin.
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What are centrosomes?
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Clouds of cytoplasmic material that in animal cells contain the centrioles.
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What is another name for centrosomes?
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Microtubule-organizing center (MTOC).
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What are cilia?
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Relatively short projections extending from the surface of the cell.
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What anchors cilia to the cell?
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The basal body.
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What is the difference between flagella and cilia?
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Flagella are 10-20 micrometers long and cilia are 2-20 micrometers long.
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What are microfilaments?
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Solid, helical, twisted two subunits of the protein actin.
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What are microfilaments involved in?
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The changing of shape of cells and their movement.
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What do microfilaments interact with to make cells contract?
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Myosin.
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How wide are microfilaments?
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6-7 nanometers in diameter.
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How wide are intermediate filaments?
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8-12 nanometers in diameter.
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What are intermediate filaments made from?
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A family of proteins called keratins.
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What do the intermediate filaments do for the nucleus?
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They fix it in a permanent position.
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What is the boundary of the cell?
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The plasma membrane.
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What is one less obvious function of the cell wall of plants?
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It allows the plant to stand upright against gravity.
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What is the primary cell wall like in young plants?
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It is flexible until the cell stops growing and other substances are added to it.
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What is the middle lamella?
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A layer of sugars called pectins located between cell walls.
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What does the middle lamella do?
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It serves to glue cells together.
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What is the secondary cell wall?
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Layers between the plasma membrane the the primary cell wall.
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What surrounds most eukaryotic cells?
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A glycocalyx, or cell coat.
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What forms the glycocalyx/cell coat?
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Glycoproteins and glycolipids.
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What is the extracellular matrix?
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Substances that surround the cell.
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What does collagen do?
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It is the main structural protein of the ECM.
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What are proteoglycans?
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A network of fibers rich in carbohydrates.
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What two things are fibronectin proteins bound to?
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Collagen and integrins.
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What are integrins?
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Receptor proteins that are a part of the plasma membrane.
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What are plasmodesmata?
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Channels between adjacent plant cells.
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What are the three types of junctions in animal cells?
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Tight junctions, desmosomes, and gap junctions.
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What are tight junctions?
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Areas of contact between two cells held together by proteins linking them.
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What are desmosomes?
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Points of attachment between two adjacent cells.
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What are gap junctions?
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Protein channels between adjacent cells.
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