Cell Structure and Function 2
Terms
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- What is the Cell Theory?
- States that all living things are composed of cells and that cells come from other cells.
- Cell Wall
- Contains cellulose fibrils. Plants only. Support and protection.
- Plasma memebrane
- Phospholipid bilayer with embedded proteins. Function- Define cell boundary; regulation of molecule passage into and out of cell.
- Nucleus
- Nuclear envelope surrounding nucleoplasm, chormatin, and nucleoli. Function-Storage of genetic information; synthesis of DNA and RNA.
- Nucleolus
- Concentrated area of chromatin, RNA, and proteins. Funciton-Ribosomal formation.
- Ribosome
- Protein and RNA in two subunits. Function-Protein synthesis.
- Endoplasmic Reticulum
- Membranous, flattened channels and tubular canals. Function-Synthesis and/or modification of proteins and other substances, and transport by vesicle formation.
- Rough ER
- Studded with Ribosomes. Function-Protein synthesis
- Smooth ER
- Has no ribosomes. Function-Various functions; lipid synthesis in some cells
- Golgi apparatus
- Stack of membranous saccules. Function-Processing, and distributing proteins and lipids.
- Vacuole and vesicle
- Membranous sacs. Fucntion-Storage of substances.
- Lysosome
- Membranous vesicle containing digestive enzymes. Function-Intracellular digestion.
- Peroxisome
- Membranous vesicel containing specfic enzymes. Function-Various metabolic tasks.
- Mitochondrion
- Membranous cristae bounded by an outer membrane. Function-Celluar respiration
- Chloroplast
- Plants only. Membranous cristae bounded by two membranes. Function-Photosynthesis.
- Cytoskeleton
- Microtubules, intermediate filaments, and actin filaments. Function-Shape of cell and movement of its parts.
- Cilia and flagella
- 9 + 2 pattern of microtubules. Function-Movement of cell.
- Centriole
- 9 + 0 pattern of microtubules. Function-Formation of basal bodies.
- What is the smallest unit of living matter?
- Cells-are the structural and functioinal units of all organisms.
- What did Matthias Schleiden and Theodar Schwann do?
- Matthias stated that all plants are made of cells and Theodar stated that all animals are made of cells.
- What did Virchow do?
- Said cells come only from preexisting cells. Cells are capable of self-reproduction.
- What size are cells?
- Range in size from frog’s egg (1 mm) to one micrometer
- What is surface-area-to-volume ratio?
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Ratio of a cell's outside area to its internal volume. As cells get larger in volume, relative surface area decreases.
Limits how large actively metabolizing cells can become. - What is a bright field microscope?
- Uses light rays forcused by glass lenses.
- What is a transmission electron microscope?
- Uses electrons passing through specimen.
- What is a scanning electron microscope?
- Uses electrons scanned across metal-coated specimens.
- Magnification?
- Function of wavelengths; shorter wavelengths of electrons allow greater magnification
- Resolution?
- Minimum distance between two objects before they are seen as one larger object
- Immunofluorescence microscopy?
- Uses fluorescent antibodies to reveal proteins in cells
- Confocal Microscopy?
- Uses laser beam to focus on shallow plane.
- Video-ehanced contrast microscopy?
- Accentuates the light and dark regions.
- Bright-field, phase contrast, differential interference and darkfield?
- Different types of light microscopy that improve ability to see various features
- What are Prokaryotic cells?
- Lack a membrane-bounded nucleus. Bacteria belong to domain Bacteria; 1-10 mm in diameter
- What is the function of a cell wall in bacteria?
- Maintains the shape of the cell even if the cytoplasm should happen to take up an abundance of water. Composed of peptidoglycan. May be surrounded by capsule and/or gelatinous sheath called slime layer
- What are fimbriae in bacteria?
- Are samml birstlelike fiver that sprout from the cell surface, short appendages that help attach to appropriate surface.
- What bacteria has flagella?
- Motile bacteria usually have flagella
- What is the plasma membrane in bacteria?
- Has the same composition of eukaryotic cell-it is a phospholipid bilayer with both embedded and peripheral proteins. Important in regulating the entrance and exit of substances into the cytoplasm.
- What does the cytoplasm consist of in a bacteria cell?
- Cytosol
- What are ribosomes?
- Coordinate synthesis of proteins
- What is a nucleoid?
- contains most genes in circular DNA molecule
- What are plasmids in bacteria?
- Small accessory rings of DNA
- What are thylakoids of bacteria?
- Flattened discs with light-sensitive pigment molecules. Photosynthesis
- What consists of eukaryotic cells?
- Protists, fungi, plants, and animals. Have a membrane bound nucleus which houses the DNA. Much larger than prokaryotic cells.
- What does the nucleus do?
- Membrane-bounded nucleus houses DNA in threadlike structures called chromatin
- What do eukaryotic and prokaryotic cells have in common?
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Have plasma membrane and cytoplasm.
More complex than prokaryotic cells; have organelles, including true nucleus, and organized lattice of protein filaments called cytoskeleton - How big is the nucleus?
- Diameter about 5 um.
- What is chromatin?
- Threadlike material that coils into chromosomes before cell division; contains DNA, protein, and some RNA.
- What is chromosomes?
- rodlike structures formed during cell division
- What is nuceloplasm?
- semifluid medium of nucleus
- What is the nuclear envelope?
- Double membrane separating nucleoplams from cytoplasm.
- What is a nuclelous?
- Is a dark region of chromatin where a type of RNA, called ribosomal RNA is produced and where rRNA joins with proteins to form the subunits of ribosomes. (dark-staining spherical bodies in nucleus; sites where rRNA joins proteins to form ribosome)
- What are nuclear pores?
- Permit passage of proteins into nucleus and ribosomal subunits.
- What is the nucleus's major Function?
- Site of DNA and determines characteristics of cell by coding for proteins.
- How big are ribosomes?
- 20 nm x 30 nm
- What is apart of ribosomes?
- Two subunits, one large and one small. Each subunit has own mix of proteins and rRNA.
- What are polyribosomes?
- Several ribosomes synthesizing same protein; may be attached to ER or free.
- What do Ribosomes do?
- Involved in protein synthesis (joining of amino acids to form protein). They recieve mRNA from the nucleus, and this nucleic acid carries a coded message from DNA indicating the correct sequence of amino aicds in a protein. Proteins are synthesized by cytoplasmic ribosomes in the cytoplasm and those attached in up in the ER.
- What is the endomembrane system?
- Series of intracellular membranes. This system compartmentalizes the cell so that particular enzymatic reactions are restricted to specfic regions.
- What is the Endoplasmic Reticulum?
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System of membrane channels continuous with outer membrane of nuclear envelope.
Contains channels and saccules. - What is Rough ER?
- Contains ribosomes; *site where proteins are synthesized and then processed and modified
- What is smooth ER?
- Lacks ribosomes; *site of synthetic processes, detoxification, and storage; forms transport vesicles. Continous with roughER, does not have attached ribosomes.
- What is the golgi apparatus?
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Named for Camillo Golgi, discovered in 1898
⬢ Stack of 3-20 slightly curved saccules
⬢ Receives protein-filled vesicles that bud from ER
⬢ Vesicle fuses with membrane of Golgi apparatus or moves to outer face after proteins repackaged
⬢ Discharge contents at plasma membrane as secretions - What are Lysosomes?
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Membrane-bounded vesicles produced by Golgi apparatus and contain digestive enzymes.
Digest contents of cells that fuse with membrane; disposal units of cell; “suicide bags†- What is apotosis?
- programmed cell death, normal part of development
- Explain how the endomembrane system works together?
- The ER and the Golgi apparatus are essentially flattened saccules, and lysosomes are specialized vesicles. Proteins produced in the rough ER and lipids in the smooth ER are carried in transport vesicles to the Golgi apparatus where they are further modified before being packaged in vesicles that leave the Golgi. Utilising signaling sequences, the Golgi apparatus sorts proteins and packages them into vesicles that transport them to various cellular destinations. Secretory vesicles take the proteins to the plasma membrane where they exit. Secretion by exocytosis.
- What are Peroxisomes?
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Membrane-bound vesicles that contain specific enzymes.
Abundant in liver; form hydrogen peroxide that is broken down to water and oxygen by catalase.
Occur in leaves where they give off carbon dioxide that can be used in photosynthesis and in germinating seeds where they convert oils into sugars used as nutrients by growing plant. - What are Vacuoles?
- - large membranous sac; vesicles are smaller than vacuoles.
- Central Vacuole?
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More prominent plant cell vacuoles (usually one or two) are water-filled and give support to cell.
Plant vacuoles store water, sugars, salts, pigments, and toxic substances to protect plant from herbivores. - What do Vacuoles in protozoans include?
- Digestive vacuoles and water-regulating contractile vacuoles
- What are chloroplasts?
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- membranous organelles that are sites of photosynthesis.
About 4-6 mm in diameter and 1-5 mm in length
Type of organelle called plastid; plastids include amyloplasts, which store starch, and chromoplasts, which contain red and oragne pigments. - What is photosynthesis?
- Photosynthesis - process where solar energy is converted to chemical energy of carbohydrates; only plants, algae, and certain bacteria are capable of photosynthesis