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87 terms

Biology Test #3- Fall 2011

STUDY
PLAY
The ______ of the ECM allows cartilage to resist compression
strength
The ECM provides _____ for animal skeletons
structural support
The role of the ECM in cell ______ is important for the attachment of tendons to bones
organization
The role of the ECM in sensing the environment is provided by its ______ function
cell signaling
The _________ is flexible and allows cells to increase in size
primary cell wall
The ______ provides considerable strength for the plant cell
secondary cell wall
the main component of the cell wall is ______
cellulose
In plants, _______ is a metabolite that hardens the wall
lignin
Plant cell wall polysaccharides are made of repeating ______ molecules
glucose
Plant cells are attached to each other by the ________
middle lamella
Animal cells attach to each other using _______ proteins
cell junction
Junctions called _______ permit communication between plant cells
plasmodesmata
Animal cells use _________ to attach to the ECM
hemidesmosomes
Animal cells form close seals between cells using ________
tight junctions
Cell connections called ________ help adjacent animal cells communicate
gap junctions
In animals, which of the following structures is largely composed of ECM?
eye
What is NOT a function of the ECM?
provides an important source of energy for the organism
Which ECM molecule provides tensile strength?
collagen
State the best description about the ECM
its components are produced and secreted by the cell
The major macromolecules of the ECM are polysaccharides and _______
proteins
Which ECM molecule provides structure while allowing certain tissues to expand and contract (e.g., lungs during breathing, intestine during digestion)?
elastin
This polysaccharide is an important ECM component for the exoskeleton of many insects and shellfish.
chitin
This forms a seal that prevents the movement of substances between cells, for instance from the intestinal lumen into the blood.
tight junctions
What structure cements plant cells together?
middle lamella
One can inject dyes of different sizes into a liver cell and determine those molecules that can readily pass through gap junctions. What sized molecules can pass through gap junctions?
< 1,000 Daltons
Which of the cell adhesion molecules is critical to transducing changes in the ECM to a change in the cell?
integrins
The alpha subunit of the G-protein is activated by _________
replacing the GDP with GTP
The activated alpha subunit binds to______
the calcium ion channel
Initially bound to the alpha subunit of G protein is _______
GDP molecule
Lipid-soluble hormones________
diffuse through the cell membrane
Once inside the cell, lipid-soluble hormones ________
bind with a specific receptor molecule inside the cytoplasm
After the lipid-soluble hormones bind with a specific receptor, __________
the receptor-hormone complex binds with a DNA molecule to produce a mRNA molecule
In _______, signals pass through a cell junction from one cell to adjacent cells
direct intracellular signaling
Membrane-bound signals bind to receptors on adjacent cells in the process of ___________
contact-dependent signaling
In _______, cells release signals that affect nearby target cells
paracrine signaling
Cells release signals that travel long distances to affect target cells during _________
endocrine signaling
Intracellular receptors are activated by signaling molecules that ________ the plasma membrane
pass through
In extracellular signaling, ligands bind to ________
cell surface receptors
Most types of enzyme-linked receptors function as __________
protein kinases
In mammals, receptors for ________ are intracellular
steroid hormones
What is the advantage of second messengers?
amplification of the signal
Chloroplasts are the organelles responsible for carrying out photosynthesis in plants and algae
True
CO2 from the atmosphere is utilized during the light reaction as a source of carbon.
False
The addition of an oxygen molecule to ribulose bisphosphate (RuBP) resulting in phosphoglycolate is most accurately referred to as ___________
photorespiration
Calvin Cycle reactions occur in the ____________, while light reactions occur in the __________
stroma, thylakoid membrane
Pigments are molecules that are able to deflect light energy
False
When an electron absorbs energy and exists in an excited state, the electron can________
drop back down to its original energy level and release light, be removed from one molecule and transferred to a different molecule, and drop back down to its original energy level and release heat
A primary electron acceptor in PSII is __________
pheophytin
The absorption of light in PSII results in an electron with a higher energy level than was attained in PSI.
False
The most common storage form of carbohydrate in chloroplasts is _____
starch
C$ plants are particularly suited for conditions of high temperatures and intense sunlight due to _____________
the physical separation of mesophyll cells and bundle sheath cells
The first product synthesized from photosynthesis in CAM plants is ______
oxaloacetate
Photorespiration occurs when O2 levels are high and CO2 levels are low
True
A response by a living cell to a change in its environment is called __________
adaptation
A ligand is most accurately defined as a(n) __________
enzyme that phosphorylates amino acids of other proteins
The small molecules or ions that bind surface receptors in the plasma membrane of a cell are most accurately referred to as __________
first messengers
Cyclic AMP may be synthesized by adenylyl cyclase via ATP
True
Neurotransmitters being released from a nerve cell and binding to another nerve cell or a muscle cell would be an example of which type of cell signaling?
paracrine signaling
What is the type of cell signaling used when a signal molecule stimulates all surrounding cells, as well as the signaling cell?
autocrine signaling
Ligands bind so specifically to their receptors because the interactions are covalent
False
Most types of enzyme-linked receptors function by __________
phosphorylation of a protein from ATP in their intracellular domain
the receptor for the steroid hormone 'estrogen' is found __________
in the nucleus
Receptor Tyrosine Kinases can be found in__________
animals
An enzyme that transfers a phosphate group to another molecule is called a __________, and an enzyme that removes a phosphate group from another molecule is called a __________
kinase, phosphate
Activated subunits of PKA are inactivated when they reassociate with the regulatory subunits in the presence of low levels of cAMP
True
What is the cellular function of a G-protein?
activate adenylyl cyclase and phospholipase C
What is an advantage of second messengers?
speed and size
Gap junctions rely on the functioning of membrane proteins called cell adhesion molecules or CAMs.
False
What is not a major protein component of the ECM in animals?
Glycosaminoglycans
Collagens are __________, which form a __________
proteins, triple helix
Which molecule would likely be found in the lumen of the endoplasmic reticulum?
procollagen
Which cell junction is found in plants?
plasmodesmata
A(n) __________ relies on a cell adhesion molecule called an integrin
focal adhesion
A(n) __________ relies on a cell adhesion molecule called a cadherin
adherins junction
What type of protein would be found in a tight junction?
claudin
What molecule cannot pass through a gap junction?
mRNA
Loewenstein determined that the size exclusion of a gap junction is approximately __________
900 Daltons
Pectins can be found in both the primary cell wall and middle lamella in plants
True
Plasmodesmata are __________
the function equivalent in plant cells of gap junctions in animal cells
The covalent linkage that connects monomers in a nucleic acid macromolecule is most accurately referred to as a(n) __________
phosphodiester linkage
The first way that DNA is compacted is by wrapping itself around a group of proteins called __________
histones
The amount of DNA required to wrap around the histone octamer is __________ base pairs
146-147
Nucleosomes are organized into a more compact structure that is __________ in diameter
30 nm
The 30 nm fiber forms __________
3D zigzag
Wrapping around the histones, and the formation of the 30 nm fiber shorten the folded DNA by __________
49x
The term __________ is used to describe the highly compacted regions of chromosomes
heterochromatin
The term __________ is use to describe the less condensed regions of chromosomes
euchromatin