bio chap 6 - a tour of the cell
Which of the following is FALSE in respect to cells' chromosomes? -chromosomes only exist when cells are actively synthesizing proteins -all cells possess one or more chromosomes -chromosomes only appear when the cell is about to divide -chromosomes are present throughout a cells reproductive cycle
-chromosomes only appear when the cell is about to divide is False
parts of an animal ECM ( extra cellular matrix )
-fibronectin and integrins, -collagen -microfilaments -proteoglycans
functions of Smooth ER
-synthesize lipids -metabolize carbs -stores calcium -detoxifies drugs and poisons
The organelle that is a plant cell's compartment for the storage of inorganic ions such as potassium and chloride is the __________.
Central vacuole Vacuoles are large vesicles derived from the endoplasmic reticulum and Golgi apparatus. Thus, vacuoles are an integral part of a cell's endomembrane system. Like all cellular membranes, the vacuolar membrane is selective in transporting solutes; as a result, the solution inside a vacuole differs in composition from the solution inside a cytosol. Mature plant cells generally contain a large central vacuole, which develops by the coalescence of smaller vacuoles. The solution inside the central vacuole, called cell sap, is the plant cell's main repository of inorganic ions, including potassium and chloride. The central vacuole plays a major role in the growth of plant cells, which enlarge as the vacuole absorbs water, enabling the cell to become larger with a minimal investment in new cytoplasm. The cytosol often occupies only a thin layer between the central vacuole and the plasma membrane, so the ratio of plasma membrane surface to cytosolic volume is sufficient, even for a large plant cell.
True or false: Components of the cytoskeleton often mediate the movement of organelles within the cytoplasm.
Components of the cytoskeleton often mediate the movement of organelles within the cytoplasm is true. The cytoskeleton, which plays a major role in organizing the structures and activities of the cell, is composed of microtubules, microfilaments, and intermediate filaments. Several types of cell motility (movement) involve the cytoskeleton. Intermediate filaments are specialized for bearing tension (like microfilaments) and are a diverse class of cytoskeletal elements. Microtubules shape the cell, guide organelle movement, and separate chromosomes in dividing cells. Cilia and flagella are motile appendages containing microtubules. Microfilaments are thin rods functioning in muscle contraction, amoeboid movement, cytoplasmic streaming, and microvillus support.
cytoskeleton parts facts
Intermediate filaments are specialized for bearing tension (like microfilaments) and are a diverse class of cytoskeletal elements. Microtubules shape the cell, guide organelle movement, and separate chromosomes in dividing cells. Cilia and flagella are motile appendages containing microtubules. Microfilaments are thin rods functioning in muscle contraction, amoeboid movement, cytoplasmic streaming, and microvillus support.
Microfilaments function in cell motility including __________.
Microfilaments function in cell motility including muscle contraction, amoeboid movement, and cytoplasmic streaming in plants.
The endosymbiont theory explains the origins of __________.
The endosymbiont theory explains the origins of mitochondria and chloroplasts.
The endosymbiont theory explains the origins of __________.
The endosymbiont theory explains the origins of mitochondria and chloroplasts. Mitochondria and chloroplasts display similarities with bacteria that led to the endosymbiont theory. This theory states that an early ancestor of eukaryotic cells engulfed an oxygen-using, nonphotosynthetic prokaryotic cell. Eventually, the engulfed cell formed a relationship with the host cell in which it was enclosed, becoming an endosymbiont (a cell living within another cell). Indeed, over the course of evolution, the host cell and its endosymbiont merged into a single organism, a eukaryotic cell with a mitochondrion. At least one of these cells may have then taken up a photosynthetic prokaryote, becoming the ancestor of eukaryotic cells that contain chloroplasts. This is a widely accepted theory of the origins of mitochondria and chloroplasts.
*What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane? tough question need to know
The functional connection between the nucleolus, nuclear pores, and the nuclear membrane is that subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores. The nuclear envelope (or nuclear membrane) encloses the nucleus, separating its contents from the cytoplasm. The nuclear envelope is a double membrane. The two membranes, each a lipid bilayer with associated proteins. A prominent structure within the nondividing nucleus is the nucleolus (plural, nucleoli). Here a type of RNA called ribosomal RNA (rRNA) is synthesized from instructions in the DNA. Also in the nucleolus, proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes. These subunits then exit the nucleus through the nuclear pores to the cytoplasm, where a large and a small subunit can assemble into a ribosome. At the lip of each pore, the inner and outer membranes of the nuclear envelope are continuous. An intricate protein structure called a pore complex lines each pore and plays an important role in the cell by regulating the entry and exit of proteins and RNAs, as well as large complexes of macromolecules.
ECM - extracellular matrix
The main ingredients of the ECM are glycoproteins and other carbohydrate-containing molecules secreted by the cells. (Recall that glycoproteins are proteins with covalently bonded carbohydrates, usually short chains of sugars.) The most abundant glycoprotein in the ECM of most animal cells is collagen, which forms strong fibers outside the cells. In fact, collagen accounts for about 40% of the total protein in the human body. The collagen fibers are embedded in a network woven out of proteoglycans secreted by cells. A proteoglycan molecule consists of a small core protein with many carbohydrate chains covalently attached, so it may be up to 95% carbohydrate. Large proteoglycan complexes can form when hundreds of proteoglycan molecules become noncovalently attached to a single long polysaccharide molecule. Some cells are attached to the ECM by ECM glycoproteins such as fibronectin. Fibronectin and other ECM proteins bind to cell-surface receptor proteins called integrins, which are built into the plasma membrane. Integrins span the membrane and bind on their cytoplasmic side to associated proteins attached to microfilaments of the cytoskeleton. The name "integrin" is based on the word integrate: Integrins are in a position to transmit signals between the ECM and the cytoskeleton and thus to integrate changes occurring outside and inside the cell.
cell motility
The term cell motility encompasses both changes in cell location and more limited movements of parts of the cell.
endosymbiont
a cell living within another cell .
cytoplasmic streaming
a circular flow of cytoplasm within cells. this is an example of an actin-myosin interaction function of microfilaments
actin myosin
a globular protein -a protein involved with actin in the process of muscle contractions produced from microfilaments which is commonly used in cell motility
cytoskeleton
a network of fibers extending throughout the cytoplasm that plays a major role in organizing the structures and activities of the cell. -the cytoskeleton is what provides a track for organelles to use their motor protein to walk to their destinations provided through the track. -also has a big function of give mechanical support to the cell and maintain its shape especially important for animal cells which lack cell walls It is composed of three major types of molecular structures : microtubules, micro filaments and intermediate filaments
nucleolus
a prominent structure within the non dividing nucleus. which appears through the electron microscope as a mass of densely stained granules and fibers adjoining part of the chromatin. -within the nucleolus, proteins are received from the cytoplasm and are assembled with rRNA into large and small subunits of ribosomes. these then exit the nucleus through the nuclear pores into the cytoplasm where a large and small subunit can be assembled into a ribosome
resolution
ability to observe to adjacent objects as distinct from each other
Endoplasmic reticulum
accounts for more than half of the total membrane in most eukaryotic cells and is continuous with the nuclear envelope
What are the similarities of all cells (eukaryotic and prokaryotic)?
all have the following -plasma membrane -cytosol / cytoplasm -chromosomes ( carry genes) -ribosomes (make proteins)
The organelle that is a plant cell's compartment for the storage of inorganic ions such as potassium and chloride is the __________.
central vacuole
Animal cells have unique organelles called __________ that are composed of structures called __________.
centrosomes , centrioles In animal cells, microtubules grow out from a centrosome, a region that is often located near the nucleus. These microtubules function as compression-resisting girders of the cytoskeleton. Within the centrosome is a pair of centrioles, each composed of nine sets of triplet microtubules arranged in a ring. Although centrosomes with centrioles may help organize microtubule assembly in animal cells, many other eukaryotic cells lack centrosomes with centrioles and instead organize microtubules by other means.
Basal bodies are most closely associated with which of the following cell components?
cilia, The microtubule assembly of a cilium or flagellum is anchored in the cell by a basal body, which is structurally very similar to a centriole, with microtubule triplets in a "9 + 0" pattern. In fact, in many animals (including humans), the basal body of the fertilizing sperm's flagellum enters the egg and becomes a centriole.
nucleus
contains most of the genes in the eukaryotic cell ( while some are located in mitochondria and chloroplast)
chromosomes
discrete unites within the nucleus that DNA is organized into. each chromosome contains one long DNA molecule associated with many proteins
nuclear envelope
encloses the nucleus separating its contents from the cytoplasm -double membrane( each a lipid bilayer) that is perforated by pore structures that regulate the entry a nd exit of proteins RNAs and large complexes of macromolecules
free ribosome
free floating ribosome not bound to the ER ( rough)
centrosomes
from which microtubules grow from. it is a region that is often located near the nucleus and contains a pair of centrioles within.
Observing a fluorescent micrograph cell with intermediate filaments would help you identify the cell as a __________.
human skin cell Intermediate filaments are named for their diameter, which is larger than the diameter of microfilaments but smaller than that of microtubules. Unlike microtubules and microfilaments, which are found in all eukaryotic cells, intermediate filaments are found only in the cells of some animals, including vertebrates
A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized __________.
in the rough ER
Describe the endomembrane system and the process
includes the nuclear envelope, the ER, the golgi apparatus, lysosome , various kinds of vesicles and vacuoles and the plasma membrane -synthesizes proteins -transports proteins into membranes and organelles or out of the cell -metabolism and movement of lipids -detoxification of poisons
dyneins
large motor proteins that are composed of several polypeptides -Dyneins are responsible for the bending movements of the organelle. A dynein molecule performs a complex cycle of movements caused by changes in the shape of the protein, with ATP providing the energy for these changes. -these are attached along each outer microtubules doublet. A typical dyne protein has two feet that walk along the microtubules of the adjacent doublet , using ATP for energy while the other foot releases and retouches one step further along the microtubules.
microtubles
largest of the three structures of the cytoskeleton -these are hollow rods contracted from a globular protein called tubulin. -each tubulin protein is a dimer, a molecule made up of two subunits. a tubulin dimer consists of two slightly different polypeptide, alpha tubular and beta tubular Function: shape and support the cell and serve as tracks along which organelles equipped with motor proteins can move. -guide vesicles from the ER to the golgi, from the golf to the plasma membrane - are also involved in the separation of chromosomes during cell division
light microscope vs electron microscope
light uses light to magnify objects -can magnify up to 1000x and are not powerful enough to see intracellular objects such as organelles electron uses a beam of electrons to magnify
Flagella motion, cilia motion, and centriole function are all structures that are composed of _______________.
microtubules
the three structures of the cytoskeleton: intermediate filaments, microtubules, microfilaments
microtubules are the thickest of the three types microfilaments are the thinnest intermediate filaments are in the middle range.
describe the patterns of microtubules
motile cilia and flagella share a common structure. -each motile cilium or flagellum has a group of microbuses sheathed in an extension of the plasma membrane. -"9+2" nine doublets of microtubules are arranged in a ring with two single microtubules in the center. referred to the 9+2 pattern is found in nearly all eukaryotic flagella and motile cilia -"9+0" - the pattern that non motile cilia possess, which lacks the central pair of microtubule. These anchored into the cell by the basal body.
Cell motility, which includes changes both in cell location and in the movement of cell parts, requires interactions of the cytoskeleton __________.
motor proteins
Cilia and flagella move due to the interaction of the cytoskeleton with which of the following?
motor proteins
the interaction of the cytoskeleton and ___________ ___________, cilia and flagella are able to move around?
motor proteins; Cilia and flagella move due to the interaction of the cytoskeleton with motor proteins.
Microfilaments function in cell motility including __________
muscle contraction, amoeboid movement, and cytoplasmic streaming in plants
intermediate filaments
named for their size ( in-between microfilaments and microtubules) -only found in cells of some animals, including vertebrates ( not in all eukaryotic like microfilaments and microtubules) -specialized for bearing tension and are a diverse class of cytoskeletal elements that are constructed from a particular molecular subunit belonging to a family of proteins shoes members include keratins -considered more permanent fixtures whereas microfilaments and microtubules are often disassembled and reassembled in various parts of a cell. -consisdered to be sturdy and the play important role in reinforcing the shape of the cell and fixing the position of certain organelles -make up the nuclear lamina
The endoplasmic reticulum is part of the endomembrane system, which also includes the __________.
nuclear envelope, golgi apparatus, lysosome, and vesicles
nuclear lamina
on the nuclear side of the nuclear envelope ( internal) a netlike array of proteins filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope. -there is also evidence of a nuclear matrix, a frame work of protein fibers extending throughout the nuclear interior. this is suspected to work along with the nuclear lamina to help organize the genetic material so it functions efficiently
Plastid
one of a family of closely related organelles that includes chloroplasts, chromoplasts, and amyloplasts. They are found in cells of photosynthetic eukaryotes.. -characteristic of storing food or pigment
__________ are membrane-bound metabolic compartments that specialize in the production of hydrogen peroxide (H2O2) and its conversion to water.
peroxisomes
what types of cells have a middle lamela?
plant cells.
Dye injected into a plant cell might be able to enter an adjacent cell through __________.
plasmodesmata
Cell junctions in plant cells are called __________, and communicating junctions in animal cells are called __________.
plasmodesmata ; gap junctions
golgi apparatus
receives transport vesicles from the ER. - the golgi is somewhat of a warehouse for receiving, sorting, shipping gand even some manufacturing . -Received products of the ER, such as proteins, and modifies and stores them until later they are sent out to other destinations. - it is made of flattened membranous sacs - cistern - looking like a stack of pita bread -the golgi stack has a distinct structural directionality within the membranes of the cisternae
bound ribosome
ribosome bound to the ER as opposed to a free ribosome that is free floating in the cytosol
Which of the following groups is primarily involved in synthesizing molecules needed by the cell?
ribosomes, rough ER, smooth ER,
vesicle
sacs of membrane that help transfer
golgi cis face and trans face
since the golgi has specific directionality traits it receives and processes proteins in a particular direction. Cis face - usually located closer to the ER and is the receiving end trans face - give rise to vesicles that pinch off and travel leave the golgi -products of the ER are usually modified during their transit from the cis region to the trans region of the golgi.
basal body
structurally very similar to centriole, possessing a microtubule triple in a 9+0 pattern. This anchors on a cilium or flagellum to the cell -
What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane?
subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores
Evidence that supports the prokaryotic origins of mitochondria and chloroplasts are all of the following except __________.
that mitochondria and chloroplasts have multiple copies of linear DNA molecules associated with their inner membranes need more information on this topic
Chromatin
the complex of DNA and proteins making up chromosomes is called chromatin the little squiggly lines in the nucleus
Cells are small because __________.
the geometric relationship between surface and volume
The walls of plant cells are largely composed of polysaccharides and proteins that are synthesized __________.
the rough endoplasmic reticulum and the golgi apparatus The walls of plant cells are largely composed of polysaccharides and proteins that are synthesized in the rough ER and in the Golgi apparatus. As a polypeptide chain grows from a bound ribosome, the chain is threaded into the ER lumen through a pore formed by a protein complex in the ER membrane. As the new polypeptide enters the ER lumen, it folds into its native shape. Most secretory proteins are glycoproteins, proteins that have carbohydrates covalently bonded to them. The carbohydrates are attached to the proteins in the ER by enzymes built into the ER membrane. Products of the endoplasmic reticulum are usually modified during their transit from the cis region to the trans region of the Golgi apparatus. For example, glycoproteins formed in the ER have their carbohydrates modified, first in the ER itself, then as they pass through the Golgi. The Golgi removes some sugar monomers and substitutes others, producing a large variety of carbohydrates. Membrane phospholipids may also be altered in the Golgi.
microfilaments
thin solid rods ( aka actin filaments ) that are built from molecules of actin -it is a twisted double chain of actin subunits,that can form structural networks when certain proteins bind along the side of such a filament and will allow a new filament to extend as a branch. -known for their role in cell motility. thousands of actin filaments and thicker filaments made of a protein called myosin interact to cause contraction of muscle cells. -this muscle contraction can be used to move cells by using pseudopodia. Functions: -seem to be present in all eukaryotic cells -help provide structures the cytoskeleton by tension ( pulling forces) a three dimensional network is formed inside the plasma membrane (cortical microfilaments) and helps support the cells shape. this network gives the outer cytoplasmic layer of a cell, cortex, the semisolid consistency of a gel, which contrasts with the more fluid state of the interior cytoplasm. -cell motility with myosin and actin
The function of the rough endoplasmic reticulum (RER) is __________.
to synthesize proteins that are synthesized as glycoproteins ( why specifically glycoproteins?) because proteins that are synthesized here are carried to the plasma membrane which is where glycoproteins are located
Components of the cytoskeleton often mediate the movement of organelles within the cytoplasm. true or false
true, The cytoskeleton, which plays a major role in organizing the structures and activities of the cell, is composed of microtubules, microfilaments, and intermediate filaments. Several types of cell motility (movement) involve the cytoskeleton. The term cell motility encompasses both changes in cell location and more limited movements of parts of the cell.
SEM Scanning electron microscope
use a beam of electrons onto the surface of a specimen and get a 3D look at the specimen
TEM Transmission electron microscope
use a beam of electrons to look through the specimen and can see internal structures
centriole
within the centrosomes, each of these ( two of them) are composed of of 9 sets of triplet microtubules arranged in a ring. -present in animal cells but are not present in other eukaryotic cells