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Cell Biology - Exam 2

Terms in this set (37)

Gyrase
nicks DNA ahead of replication fork to relax supercoiling in the DNA
Primase
synthesizes RNA primers for DNA synthesis
Helicase
unwinds double-stranded DNA
Ligase
covalently links breaks in the sugar-phosphate backbone
Which of the following is a primary structural constituent of the plant cell secondary wall?
- collagen
- cellulose
- extensin
- pectin
- hemicellulose
cellulose
Each of the following is a good functional match between animal & plant extracellular structures or fibers except
- elastins-extensins
- fibronectins-pectins
- extracellular matrix-cell wall
- collagens-cellulose
- proteoglycans-hemicelluloses
elastins-extensins
Each of the following is a component of the plant cell wall network except
- pectin
- extensin
- cellulose
- hyaluronate
- hemicellulose
hyaluronate
In animals, the extracellular matrix plays important roles in each of the following processes except
- DNA replication
- cell adhesion
- cell division
- cell motility
- cell differentiation
DNA replication
Fibronectin interacts with each of the following except
- collagen
- heparin
- integrin
- fibrin
- pectin
pectin
Polarized cells are characterized by
- random orientation within a tissue
- junctions only to ECM & not to other cells
- distinct apical & basolateral ends of the cell
- being surrounded on all sides by a basement membrane
- formation of several connected layers of cells
distinct apical & basolateral ends of the cell
An example of a purine is
- deoxyribose
- guanine
- thymine
- cytosine
- ribose 5-phosphate
guanine
Which of the following is the correct order of the levels of DNA packaging in eukaryotic chromosomes?
- chromosomes, chromatin fiber, looped domains, heterochromatin
- chromatin fiber, heterochromatin, nucleosome, looped domain
- chromatin fiber, nucleosome, looped domain, heterochromatin
- heterochromatin, nucleosome, chromatin fiber, looped domain
- nucleosome, looped domain, chromatin fiber, heterochromatin
chromosomes, chromatin fiber, looped domains, heterochromatin
For a dsDNA molecule in which 40% of the bases are either G or T, what can you conclude about its content of the base A?
- 20%
- 50%
- Nothing
- 60%
- 30%
Nothing
Which of the following statements is true regarding mitochondrial & chloroplast genomes?
- they contain mostly interspersed & tandemly repeated DNA
- they only encode for ribosomal & transfer RNAs
- they are degenerate bacterial genomes that don't contain important protein-coding genes
- they contain all the genes necessary for aerobic respiration
- they are able to replicate independently of the nuclear DNA
they are degenerate bacterial genomes that don't contain important protein-coding genes
DNA is different from RNA in that
- in general, RNA molecules are longer than DNA molecules
- RNA is made up of 5 bases, whereas DNA is made up of 4
- RNA can't exist as a double helix
- RNA contains an additional oxygen atom on the ribose sugar
- all of these statements are true
RNA contains an additional oxygen atom on the ribose sugar
Each of the following structures is found within the nucleus of a eukaryotic cell except
- transfer RNA
- the nucleolus
- plasmids
- histones
- all of these are found in the nucleus
all of these are found in the nucleus
Spontaneous hydrolysis reactions between DNA & surrounding water molecules commonly cause
- depurination
- pyrimidine dimer formation
- deletion mutations
- double-stranded DNA breaks
- tautomeric shifts
depurination
Which of the following is involved in proofreading during DNA replication?
- 3' to 5' endonuclease activity of DNA polymerase
- 5' to 3' exonuclease activity of DNA polymerase
- 3' to 5' exonuclease activity of DNA polymerase
- 5' to 3' endonuclease activity of DNA polymerase
- RNA polymerase
3' to 5' exonuclease activity of DNA polymerase
Which step of the double helix Holliday junction pathway is directly responsible for ensuring that no information is lost at the site of the original DNA double-strand break?
- nuclease trimming of the exposed ends of the DNA at the break
- Holliday junction resolution
- recognition of the DNA double-strand break
- DNA strand invasion
- DNA synthesis
DNA synthesis
The DNA polymerase reaction occurs in the _____ as incoming nucleotides are added to _____ end(s) of the growing DNA chain
- 3' to 5' direction; the 5'-phosphate
- 5' to 3' direction; the 3' hydroxyl
- 5' to 3' direction; the 3' phosphate
- 5' to 3' direction or the 3' to 5' direction; both
- 3' to 5' direction; the 5'-hydroxyl
5' to 3' direction; the 3' hydroxyl
Nonhomologous end joining is used to
- remove modified or depurinated bases
- avoid deletion or insertion of bases
- fix double-strand DNA breaks
- avoid deletion or insertion of bases & removes modified or depurinated bases
- correct base mismatches in newly synthesized DNA
fix double-strand DNA breaks
SOS repair & translesion synthesis employ
- repair endonucleases & exonuclease
- excinuclease
- repair endonucleases that removes damaged bases
- proteins that bind to deaminated bases
- bypass DNA polymerases that can continue synthesizing DNA from a damaged DNA strand
bypass DNA polymerases that can continue synthesizing DNA from a damaged DNA strand
Which of the following proteins is observed exclusively in association with prokaryotic DNA replication?
- helicase
- single-stranded binding proteins
- primase
- telomerase
- DNA polymerase I
DNA polymerase I
Mismatch repair targets improperly paired nucleotides. In prokaryotes, the incorrect member of an abnormal base pair can be differentiated from the correct member because
- the correct member has been deaminated
- the original strand of DNA contains methylated bases while newly synthesized DNA does not; thus the correct member has undergone a hydroxylation reaction
- the incorrect member has undergone a hydroxylation reaction
- newly synthesized DNA contains uracil
- the incorrect member doesn't match the surrounding bases
the original strand of DNA contains methylated bases while newly synthesized DNA does not; thus the correct member has undergone a hydroxylation reaction
Which of these junctions form a barrier to prevent the passage of fluid material between cells?
- tight junctions
- desmosomes
- gap junctions
- focal adhesions
- all of the above
tight junctions
Focal adhesion
type of adherens junction connecting actin filaments to the extracellular matrix
Connexin
protein subunit of gap junctions
Adhesive junction
anchors cytoskeleton of one cell with that of a neighboring cell
Gap junction
connects the cytoplasm of two cells
Connexons
hollow cylinders associated with gap junctions
Hemidesmosome
an adhesive junction that connects an epithelial cell to the basal lamina
Desmosome
button-like point of strong adhesion between two cells
In the Ran/importin pathway _____ provides the energy for transport of proteins into the nucleus
GTP
_____ is the process of creating an RNA copy of the information in DNA
Transcription
______ are amino acid sequences that are recognized by importin, allowing proteins to enter the nucleus
...
The name given to double-stranded DNA that is twisted upon itself is ________
supercoiled DNA
______ is the process of synthesizing proteins based on the base sequences in mRNA molecules
Translation
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