USABO COMPREHENSIVE TEST BANK
COMPLETE QUESTIONS AND ANSWERS
PRACTICE SOLUTION VERIFIED
◉ Eukaryote. Answer: An organism whose cells contain complex
structures enclosed within membranes. The defining membrane bound
structure thats sets them apart from prokaryotic cells is the nucleas or
nuclear envelope within which the genetic material is carried. All
species of large complex species are eukaryotes, including animals,
plants and funghi.
◉ Euchromatin. Answer: This shows as pale areas in the nucleas
under electro magnification. It is a less densly packed form of
chromatin; 10% is even less condensed and in this form it can be
actively transcribed to produce RNA.
◉ Heterochromatin. Answer: This shows as dark areas on the
eukaryotic nucleas; it is densly packed chormatin (DNA and protein
complex) which cannot be transcribed.
◉ Histones. Answer: Special proteins around which DNA is wrapped.
◉ Lamins. Answer: Intermediate filament proteins which protect the
structure of the nucleas, they polymerize to from a network of
,filaments that lie just within the nuclear membrane. The network of
these filament proteins is called the nuclear lamina.
◉ Nuclear Lamina. Answer: The network of intermediate nuclear
filament proteins (Lamins) which is located just below the nuclear
membrane and is linked to the membrane and chromatin.
◉ Nuclear Pores. Answer: 9nm (approx) gaps in the nuclear envelope
that allow the passage of RNA and ribosomes out of the nucleas and
the entry of selected small proteins and small water soluble
molecules.
◉ Prokarayotes. Answer: An organism of the kingdom of Monera,
comprising the bacteria and cyanobacteria. Characterised by the
abscence of a distinct, membrane bound nucleas or membrane bound
organelles and by DNA that is not organised in to chromosomes. Also
called moneran.
◉ Protoctist. Answer: Any of various unicellular eukaryotic
organisms and their multicellular, coenocytic or colocial descendants
that belong to the kingdom of Protocista according to some taxonomic
systems. The protoctists include protozoans, slime moulds, various
algae and other groups. In many new classification systems, all
proctists are considered protists.
◉ Signal Sequence. Answer: Affectionately known as the 'address
label' of a polypeptide. A short (3-60 amino acids long) peptide chain
that directs the transport of a protein. These may also be called
,targeting signals, signal peptides, transit peptides, or localization
signals.
The amino acid sequences of these direct proteins (which are
synthesized in the cytosol) to certain organelles such as the nucleus,
mitochondrial matrix, endoplasmic reticulum, chloroplast, apoplast
and peroxisome. Some signal peptides are cleaved from the protein by
signal peptidase after the proteins are transported.
◉ Endoplasmic Reticulum. Answer: The endoplasmic reticulum (ER)
is a eukaryotic organelle that forms an interconnected network of
tubules, vesicles, and cisternae within cells. Rough endoplasmic
reticula synthesize proteins, while smooth endoplasmic reticula
synthesize lipids and steroids, metabolize carbohydrates and steroids
(but not lipids), and regulate calcium concentration, drug metabolism,
and attachment of receptors on cell membrane proteins. Sarcoplasmic
reticula solely regulate calcium levels.
◉ Smooth endoplasmic reticulum. Answer: Cell organelle responsible
for attachment of receptors on cell membrane proteins, synthesizing
lipids and steroids, metabolizing carbohydrates and steroids (but not
lipids) and regulating calcium concentration and drug metabolism.
◉ Rough endoplasmic reticulum. Answer: Cell organelle responsible
for synthesizing proteins.
◉ Catalytic site. Answer: In molecular biology this site is part of an
enzyme where substrates bind and undergo a chemical reaction.The
majority of enzymes are proteins but RNA enzymes called ribozymes
, also exist. The active site of an enzyme is usually found in a cleft or
pocket that is lined by amino acid residues (or nucleotides in
ribozymes) that participate in recognition of the substrate. Residues
that directly participate in the catalytic reaction mechanism are called
active site residues.
◉ Vesicles. Answer: Small lipid-bounded spheres which transport
proteins, glyco proteins and newly synthesized lipids (which are
imbedded in the sphere itself) from the endoplasmic reticulum to the
Golgi Apparatus or from the Golgi apparatus to another destination.
They move short distances by the process of difussion, moving long
distances requires the assistance of proteins associated with
microtubules.
◉ Golgi apparatus. Answer: This is an organelle found in all
eukaryotic cells.It was identified in 1897 by the Italian physician
Camillo Golgi, after whom it is named. It processes and packages
proteins after their synthesis and before they make their way to their
destination; it is particularly important in the processing of proteins
for secretion. Its size varies in different types of cells depending on
cell function; a hormone secreting cell will contain a far larger version
of this organelle than a muscle cell for example. It also forms a part of
the cellular endomembrane system.
◉ Constitutive release. Answer: The constant release of small
amounts of a substances from the cell membrane.
◉ Regulated release. Answer: The release of substances from a cell
membrane only when specific conditions exist. A good example is the
COMPLETE QUESTIONS AND ANSWERS
PRACTICE SOLUTION VERIFIED
◉ Eukaryote. Answer: An organism whose cells contain complex
structures enclosed within membranes. The defining membrane bound
structure thats sets them apart from prokaryotic cells is the nucleas or
nuclear envelope within which the genetic material is carried. All
species of large complex species are eukaryotes, including animals,
plants and funghi.
◉ Euchromatin. Answer: This shows as pale areas in the nucleas
under electro magnification. It is a less densly packed form of
chromatin; 10% is even less condensed and in this form it can be
actively transcribed to produce RNA.
◉ Heterochromatin. Answer: This shows as dark areas on the
eukaryotic nucleas; it is densly packed chormatin (DNA and protein
complex) which cannot be transcribed.
◉ Histones. Answer: Special proteins around which DNA is wrapped.
◉ Lamins. Answer: Intermediate filament proteins which protect the
structure of the nucleas, they polymerize to from a network of
,filaments that lie just within the nuclear membrane. The network of
these filament proteins is called the nuclear lamina.
◉ Nuclear Lamina. Answer: The network of intermediate nuclear
filament proteins (Lamins) which is located just below the nuclear
membrane and is linked to the membrane and chromatin.
◉ Nuclear Pores. Answer: 9nm (approx) gaps in the nuclear envelope
that allow the passage of RNA and ribosomes out of the nucleas and
the entry of selected small proteins and small water soluble
molecules.
◉ Prokarayotes. Answer: An organism of the kingdom of Monera,
comprising the bacteria and cyanobacteria. Characterised by the
abscence of a distinct, membrane bound nucleas or membrane bound
organelles and by DNA that is not organised in to chromosomes. Also
called moneran.
◉ Protoctist. Answer: Any of various unicellular eukaryotic
organisms and their multicellular, coenocytic or colocial descendants
that belong to the kingdom of Protocista according to some taxonomic
systems. The protoctists include protozoans, slime moulds, various
algae and other groups. In many new classification systems, all
proctists are considered protists.
◉ Signal Sequence. Answer: Affectionately known as the 'address
label' of a polypeptide. A short (3-60 amino acids long) peptide chain
that directs the transport of a protein. These may also be called
,targeting signals, signal peptides, transit peptides, or localization
signals.
The amino acid sequences of these direct proteins (which are
synthesized in the cytosol) to certain organelles such as the nucleus,
mitochondrial matrix, endoplasmic reticulum, chloroplast, apoplast
and peroxisome. Some signal peptides are cleaved from the protein by
signal peptidase after the proteins are transported.
◉ Endoplasmic Reticulum. Answer: The endoplasmic reticulum (ER)
is a eukaryotic organelle that forms an interconnected network of
tubules, vesicles, and cisternae within cells. Rough endoplasmic
reticula synthesize proteins, while smooth endoplasmic reticula
synthesize lipids and steroids, metabolize carbohydrates and steroids
(but not lipids), and regulate calcium concentration, drug metabolism,
and attachment of receptors on cell membrane proteins. Sarcoplasmic
reticula solely regulate calcium levels.
◉ Smooth endoplasmic reticulum. Answer: Cell organelle responsible
for attachment of receptors on cell membrane proteins, synthesizing
lipids and steroids, metabolizing carbohydrates and steroids (but not
lipids) and regulating calcium concentration and drug metabolism.
◉ Rough endoplasmic reticulum. Answer: Cell organelle responsible
for synthesizing proteins.
◉ Catalytic site. Answer: In molecular biology this site is part of an
enzyme where substrates bind and undergo a chemical reaction.The
majority of enzymes are proteins but RNA enzymes called ribozymes
, also exist. The active site of an enzyme is usually found in a cleft or
pocket that is lined by amino acid residues (or nucleotides in
ribozymes) that participate in recognition of the substrate. Residues
that directly participate in the catalytic reaction mechanism are called
active site residues.
◉ Vesicles. Answer: Small lipid-bounded spheres which transport
proteins, glyco proteins and newly synthesized lipids (which are
imbedded in the sphere itself) from the endoplasmic reticulum to the
Golgi Apparatus or from the Golgi apparatus to another destination.
They move short distances by the process of difussion, moving long
distances requires the assistance of proteins associated with
microtubules.
◉ Golgi apparatus. Answer: This is an organelle found in all
eukaryotic cells.It was identified in 1897 by the Italian physician
Camillo Golgi, after whom it is named. It processes and packages
proteins after their synthesis and before they make their way to their
destination; it is particularly important in the processing of proteins
for secretion. Its size varies in different types of cells depending on
cell function; a hormone secreting cell will contain a far larger version
of this organelle than a muscle cell for example. It also forms a part of
the cellular endomembrane system.
◉ Constitutive release. Answer: The constant release of small
amounts of a substances from the cell membrane.
◉ Regulated release. Answer: The release of substances from a cell
membrane only when specific conditions exist. A good example is the
