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Bio Cell Test
Terms in this set (59)
What is cell theory?
all living things are composed of cells and that all cells come from other cells
What is an electron microscope?
uses magnets to focus an electron beam through or onto the surface of a specimen. An electron microscope achieves a hundredfold greater resolution than a light microscope; cannot be used to study living things
What is the plasma membrane?
the membrane at the boundary of every cell that acts a a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer with embedded proteins
What is a prokaryotic cell?
a type of cell lacking a membrane-enclosed nucleus and other membrane-enclosed organelles; found only in the domains Bacteria and Archaea
What is a eukaryotic cell?
a type of cell that has a membrane-enclosed nucleus and membrane-enclosed organelles. All organisms except bacteria and archaea are composed of eukaryotic cells
What is cytosol?
the semifluid portion of the cytoplasm
What is a ribosome?
a cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm. In eukaryotic cells, the ribosomal subunits are constructed in the nucleolus. They use instructions from the nucleus, written in mRNA, to build proteins. Ribosomes that are free are suspended in cytosol whereas bound ribosomes are attached to outside the ER or nuclear envelope
What is cytoplasm?
the contents of a eukaryotic cel between the plasma membrane and the nucleus; consists of a semifluid medium and organelles; can also refer to the interior of a prokaryotic cell
What is the nucleoid?
a non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated
What is a flagellum?
a long cellular appendage specialized for locomotion. The flagella of prokaryotes and eukaryotes differ in both structure and function. Like cilia, eukaryotic flagella have a (9+2) arrangement of microtubules covered by the cell's plasma membrane
What is the capsule?
jellylike outer coating of many prokaryotes
What is the fimbriae?
attachment structures on the surface of some prokaryotes
What are the organelles involved in the manufacture, distribution, and breakdown of molecules?
endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and peroxisomes
What are the organelles involved with energy processing?
mitochondria in all cells and chloroplasts in plant cells
What are the organelles involved in structural support, movement, and communication between cells?
cytoskeleton, plasma membrane, and plant cell wall
What is the plasmodesmata?
cytoplasmic channels through cell walls that connect adjacent cells
What is cellular metabolism?
all the chemical activities of a cell
Identify the structures in the plant cell that are not present in the animal cell
chloroplasts, central vacuole, cell wall, and plasmodesmata
What is the nucleus?
the organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made of chromatin
What is chromatin?
the complex of DNA and protein that makes up eukaryotic chromosomes; often used to refer to the diffuse, very extended form taken by chromosomes when a cell is not dividing
What is the nuclear envelope?
a double membrane that encloses the nucleus, perforated with pores that regulate traffic with the cytoplasm; phospholipid bilayer
What is the nucleolus?
a structure within a nucleus where ribosomal RNA is made and assembled with proteins imported from the cytoplasm to make ribosomal subunits
Describe the processes that occur in the nucleus.
DNA is copied and passed onto daughter cells in cell division; rRNA is made and ribosomal subunits assembled; protein-making instructions in DNA are transcribed into mRNA
What role do ribosomes play in carrying out the genetic instructions of a cell?
ribosomes synthesize proteins according to the instructions of messenger RNA, which was transcribed from DNA in the nucleus
What is the endomembrane system?
a network of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles
What is a vesicle?
a sac made of membrane in the cytoplasm of a eukaryotic cell
What is the endoplasmic reticulum?
an extensive membranous network in a eukaryotic cell, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome free (smooth) regions
Describe the smooth ER.
- liver cells have large amounts of it
- plays role in drug addiction
What is a transport vesicle?
a small membranous sac in eukaryotic cell's cytoplasm carrying molecules produced by the cell. The vesicle buds from the ER or Golgi and eventually fuses with another organelle or the plasma membrane, releasing its contents
Explain why we say the the endoplasmic reticulum is a biosynthetic workshop.
The ER produces a huge variety of molecules, including phospholipids for cell membranes, steroid hormones, and proteins (synthesized by bound ribosomes) for membranes, other organelles, and secretion by the cell
What is the Golgi Apparatus?
an organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the ER. Golgi enzymes modify carbohydrate portions of glycoproteins made in the ER. Finished products may become part of the plasma membrane
1. One side of a Golgi star serves as a receiving dock for transport vesicles produced by the ER
2. Vesicle fuses with a Golgi stack, adding its membrane and contents to receiving side
3. Products of the ER are modified as the Golgi stack progresses through the sac
4. Shipping side is a depot
What is the relationship of the Golgi Apparatus to the ER in a protein-secreting cell?
the Golgi apparatus transports vesicles budded from the ER that contain proteins synthesized by bound ribosomes. Golgi finishes processing proteins and dispatches transport vesicles to plasma membrane, where proteins are secreted
What is a lysosome?
a digestive organelle in eukaryotic cells; contains hydrolytic enzymes that digest engulfed food or damaged organelles. The enzymes and membranes of lysosomes are made by rough ER and processed in the Golgi apparatus. Lysosomes fuse with food vacuoles and digest food nutrients then released into cytosol. Lysosomes are also recycling centers.
What are vacuoles?
a membrane-enclosed sac that is part of the endomembrane system of a eukaryotic cell and has diverse functions in different kinds of cells. Sopkes collect water from the cell. In plants, some vacuoles have a digestive function similar to that of lysosomes in animals cells. Vacuoles may contain poisons or unpalatable compounds that protect the plant against herbivores
What is the central vacuole?
in a plant cell, a large membranous sac with diverse roles in growth and the storage of chemicals and wastes
Is a food vacuole part of the endomembrane system? Explain.
Yes; if forms by pinching in from the plasma membrane, which is part of the endomembrane system
What is peroxisome?
an organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen, producing and then degrading hydrogen peroxide
How do transport vesicles help tie together the endomembrane system?
Transport vesicles move membranes and the substances they enclose between compound of the endomembrane system
What are mitochondria?
organelles in eukaryotic cells where cellular respiration occurs. Enclose by two membranes, it is where most of the cell's adenosine triphosphate (ATP) is made
What is the mitochondrial matrix?
the compartment of the mitochondrion enclosed by the inner membrane and substrates for the citric acid cycle; contains mitochondrial DNA and enzymes that catalyze some of the reactions of cellular respiration
What is the crista?
an infolding of the inner mitochondrial membrane; increase membrane's surface are, enhancing the mitochondria's ability to produce ATP
What is cellular respiration?
a process that converts the chemical energy of sugars and other food molecules to the chemical energy of ATP
What is a chloroplast?
an organelle found in plants and algae that absorbs sunlight and uses it to drive the synthesis of organic compounds (sugars) from carbon dioxide and water
What is the stroma?
the dense fluid within the chloroplast that surrounds the thylakoid membrane and is involved in the synthesis of organic molecules from carbon dioxide and water. Sugars are made in the stroma by the enzymes of the Calvin cycle
What is the thylakoid?
a flattened membranous sac inside a chloroplast. Thylakoid membranes contain chlorophyll and the molecular complexes of the light reactions of photosynthesis.
What is the granum?
a stack of membrane-bounded thylakoids in a chloroplast. Granae are the sites where light energy is trapped by chlorophyll and converted to chemical energy during the light reactions of photosynthesis.
Which membrane in a chloroplast appears to be the most extensive? Why might this be so?
The thylakoid membranes contain chlorophyll for photosynthesis
What is the endosymbiont theory?
the theory that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism.
all eukaryotes have mitochondria, but not all have chloroplasts. What is the evolutionary explanation?
the first endosymbiosis would have given rise to eukaryotic cells containing mitochondria. A second endosymbiotic event gave rise to cells containing chloroplasts as well as mitochondria.
What is cytoskeleton?
a network of protein fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules.
What are microtubules?
the thickest of the three main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a hollow tube made of globular proteins called tubules; found in cilia and flagella. Microtubules shape and support the cell and also act as tracks along which organelles equipped with motor proteins move; guide movement of chromosomes when cells divide
What is the centrosome?
a structure found in animal cells from which microtubules originate and that is important during cell division. A centrosome has two centrioles
What is the intermediate filament
an intermediate-seized protein fiber that is one of the three main kinds of fibers making up the cytoskeleton of eukaryotic cells. Intermediate filaments are rope like, made of fibrous proteins; reinforce cell shape, more permanent fixtures in cell
What is microfilament?
the thinnest of the three main kinds of protein fibers making up the cytoskeleton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin
Which component of the cytoskeleton is most important in (a) holding the nucleus in place within the cell; (b) guiding transport vesicles from the Golgi to the plasma membrane; (c) contracting muscle cells?
(a): intermediate filaments
What is the extracellular matrix (ECM)?
the meshwork surrounding animal cells; consists of glycoproteins and polysaccharides synthesized and secreted by cell
What is integrin?
a trans membrane protein that interconnects the extracellular matrix and the cytoskeleton in animal cells; transmit signals so cytoskeleton can influence organization of ECM
Describe the structures that provide support to the plasma membrane.
The membrane is attached through membrane proteins (integrins) to microfilaments in the cytoskeleton and collagen fibers of the ECM
Describe the rough ER
- makes membrane proteins and secretory proteins
- insulin produced by rough Er ribosomes
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