Biology 1113 Exam 3 Actual Questions
and verified Answers
Importance of cell division - ANSWER-Cells divide to make new cells, source of reproduction in asexually
reproducing species, growth and development for multicellular species, maintenance and repair of
tissues
Mitosis - ANSWER-Nucleus divides to create identical daughter cells, asexual
Genome - ANSWER-All the DNA in all cells. Full complement of DNA, in all cells, every cell produced by
mitosis has this in full
Chromosome - ANSWER-Condensed DNA during cell division, piece of DNA
sister chromatids - ANSWER-Identical copies of DNA attached at centromere, form DNA takes when
eukaryotic cells are ready to divide
Somatic cells - ANSWER-Body cells, have 2 copies of each chromosome, diploid, chromosomes come in
twos
Gametes - ANSWER-Sex cells, have only one copy of each chromosome, haploid, sperm and eggs
Animal life cycle - ANSWER-Animal —> meiosis —> egg and sperm —> fertilization —> fertilized egg —>
mitosis —> animal
Interphase - ANSWER-90% of cell cycle, consists of G1, S-phase, G2
G1 - ANSWER-No DNA change, cell growth
S-phase - ANSWER-DNA synthesis, copies and divides DNA
G2 - ANSWER-No DNA change, cell growth, duplication of organelles, production of ATP
Mitotic (M) phase - ANSWER-10% of cell cycle, division of nucleus, cytokinesis divides cytoplasm
Cytokinesis - ANSWER-Divides cytoplasm
Mitosis - ANSWER-Division of nucleus into two daughter nuclei, sister chromatids split and each nucleus
receives one copy, daughter cells are identical
Before mitosis (interphase) - ANSWER-Sufficient resources and "spare parts" to make 2 cells,
chromosomes replicated (sister chromatids), centromeres replicated (animals and fungi)
Centrosome - ANSWER-A structure in animal cells containing centrioles from which the spindle fibers
develop
Prophase - ANSWER-Chromosomes condense and mitotic spindle begins to form, centrosomes split
Prometaphase - ANSWER-Nuclear envelope breaks down, spindle fibers contact chromosomes at
kinetochore
Metaphase - ANSWER-Chromosomes complete migration to the middle of the cell
Anaphase - ANSWER-Sister chromatids separate, chromosomes are pulled to opposite poles of the cell
by the spindle fibers
Telophase - ANSWER-The nuclear envelope reforms, spindle apparatus disintegrates, creates one cell
with two nuclei
Cytokinesis - ANSWER-Division, two daughter cells form
Cytokinesis in animals - ANSWER-Actin and myosin filament ring forms just inside the plasma membrane,
myosin interacts with ATP to tighten ring, membrane moves with actin, eventually pinches off
, Cytokinesis in plants - ANSWER-Golgi-derived vesicles that contain cell-wall material move to center and
fuse with each other and cell wall, eventually splitting the cell into two
Mitotic spindle - ANSWER-Produces mechanical forces that move chromosomes, made of microtubules,
assembled in prophase, in animals it begins at the centriole
Chromosomal movement - ANSWER-Have kinetochores attach to the plus end, causing the plus end to
lose tubulins, therefore moving the chromosome to the minus end
Control of the cell cycle - ANSWER-Cell division is closely regulated, failure of regulation can be
dangerous and result in cancer or other disease
Cell cycle regulatory molecule - ANSWER-MPF
MPF - ANSWER-Maturation promoting factor, cytoplasmic signal that tells nucleus to enter m-phase,
used by all eukaryotes, 2 polypeptide subunits needed for activity (kinase and cyclin)
Cyclin dependent kinase (cdk) - ANSWER-a protein kinase that is only active when attached to a
particular cyclin
G1 checkpoint - ANSWER-Cell size is adequate, nutrients are sufficient, social signals are present, DNA is
undamaged
G0 - ANSWER-Mature cells are in the phase
G2 checkpoint - ANSWER-Chromosomes have replicated successfully, DNA is undamaged, activated MPF
is present
M-phase checkpoint - ANSWER-Chromosomes have attached to spindle apparatus, chromosomes have
properly segregated, MPF is absent
Cells get past the G2 checkpoint by: - ANSWER-CDKs bound to cyclins phosphorylating other proteins
that activate cyclins
Cancer - ANSWER-Loss of control of the cell cycle, cells that should be in G0 phase enter M-phase and
continue to divide
Tumors form from: - ANSWER-Cells dividing out of control
Benign tumor - ANSWER-May continue to divide but are not invasive, do not spread from original tumor
Malignant tumor - ANSWER-Divide and spread to adjacent tissues and to distant tissues through
lymphatic vessels and blood vessels
RAS protein - ANSWER-Common mitogen, signals cell growth, activates phosphorylation cascade that
stimulates mitosis
Proto-oncogene - ANSWER-Gene that could become cancerous if mutated (ex: RAS protein)
Defects of RAS common in cancer cells - ANSWER-Remains active always, signal transduction pathways
constantly stimulate, cells undergo excessive mitosis
tumor surpressor - ANSWER-Genes that code for proteins with repair mechanisms
P53 "Guardian of the Cell" - ANSWER-Senses DNA damage, tells cells to make proteins that halt mitosis,
can trigger apoptosis
Apoptosis - ANSWER-Programmed cell death
Cancers - ANSWER-Each a unique combination of errors, most involve loss of control of the G1
checkpoint, genetic predispositions exist but need many mutations for cancer to develop
homologous chromosomes - ANSWER-Chromosome pairs, inherited from parents, contain identical
genes, may differ in sequence
and verified Answers
Importance of cell division - ANSWER-Cells divide to make new cells, source of reproduction in asexually
reproducing species, growth and development for multicellular species, maintenance and repair of
tissues
Mitosis - ANSWER-Nucleus divides to create identical daughter cells, asexual
Genome - ANSWER-All the DNA in all cells. Full complement of DNA, in all cells, every cell produced by
mitosis has this in full
Chromosome - ANSWER-Condensed DNA during cell division, piece of DNA
sister chromatids - ANSWER-Identical copies of DNA attached at centromere, form DNA takes when
eukaryotic cells are ready to divide
Somatic cells - ANSWER-Body cells, have 2 copies of each chromosome, diploid, chromosomes come in
twos
Gametes - ANSWER-Sex cells, have only one copy of each chromosome, haploid, sperm and eggs
Animal life cycle - ANSWER-Animal —> meiosis —> egg and sperm —> fertilization —> fertilized egg —>
mitosis —> animal
Interphase - ANSWER-90% of cell cycle, consists of G1, S-phase, G2
G1 - ANSWER-No DNA change, cell growth
S-phase - ANSWER-DNA synthesis, copies and divides DNA
G2 - ANSWER-No DNA change, cell growth, duplication of organelles, production of ATP
Mitotic (M) phase - ANSWER-10% of cell cycle, division of nucleus, cytokinesis divides cytoplasm
Cytokinesis - ANSWER-Divides cytoplasm
Mitosis - ANSWER-Division of nucleus into two daughter nuclei, sister chromatids split and each nucleus
receives one copy, daughter cells are identical
Before mitosis (interphase) - ANSWER-Sufficient resources and "spare parts" to make 2 cells,
chromosomes replicated (sister chromatids), centromeres replicated (animals and fungi)
Centrosome - ANSWER-A structure in animal cells containing centrioles from which the spindle fibers
develop
Prophase - ANSWER-Chromosomes condense and mitotic spindle begins to form, centrosomes split
Prometaphase - ANSWER-Nuclear envelope breaks down, spindle fibers contact chromosomes at
kinetochore
Metaphase - ANSWER-Chromosomes complete migration to the middle of the cell
Anaphase - ANSWER-Sister chromatids separate, chromosomes are pulled to opposite poles of the cell
by the spindle fibers
Telophase - ANSWER-The nuclear envelope reforms, spindle apparatus disintegrates, creates one cell
with two nuclei
Cytokinesis - ANSWER-Division, two daughter cells form
Cytokinesis in animals - ANSWER-Actin and myosin filament ring forms just inside the plasma membrane,
myosin interacts with ATP to tighten ring, membrane moves with actin, eventually pinches off
, Cytokinesis in plants - ANSWER-Golgi-derived vesicles that contain cell-wall material move to center and
fuse with each other and cell wall, eventually splitting the cell into two
Mitotic spindle - ANSWER-Produces mechanical forces that move chromosomes, made of microtubules,
assembled in prophase, in animals it begins at the centriole
Chromosomal movement - ANSWER-Have kinetochores attach to the plus end, causing the plus end to
lose tubulins, therefore moving the chromosome to the minus end
Control of the cell cycle - ANSWER-Cell division is closely regulated, failure of regulation can be
dangerous and result in cancer or other disease
Cell cycle regulatory molecule - ANSWER-MPF
MPF - ANSWER-Maturation promoting factor, cytoplasmic signal that tells nucleus to enter m-phase,
used by all eukaryotes, 2 polypeptide subunits needed for activity (kinase and cyclin)
Cyclin dependent kinase (cdk) - ANSWER-a protein kinase that is only active when attached to a
particular cyclin
G1 checkpoint - ANSWER-Cell size is adequate, nutrients are sufficient, social signals are present, DNA is
undamaged
G0 - ANSWER-Mature cells are in the phase
G2 checkpoint - ANSWER-Chromosomes have replicated successfully, DNA is undamaged, activated MPF
is present
M-phase checkpoint - ANSWER-Chromosomes have attached to spindle apparatus, chromosomes have
properly segregated, MPF is absent
Cells get past the G2 checkpoint by: - ANSWER-CDKs bound to cyclins phosphorylating other proteins
that activate cyclins
Cancer - ANSWER-Loss of control of the cell cycle, cells that should be in G0 phase enter M-phase and
continue to divide
Tumors form from: - ANSWER-Cells dividing out of control
Benign tumor - ANSWER-May continue to divide but are not invasive, do not spread from original tumor
Malignant tumor - ANSWER-Divide and spread to adjacent tissues and to distant tissues through
lymphatic vessels and blood vessels
RAS protein - ANSWER-Common mitogen, signals cell growth, activates phosphorylation cascade that
stimulates mitosis
Proto-oncogene - ANSWER-Gene that could become cancerous if mutated (ex: RAS protein)
Defects of RAS common in cancer cells - ANSWER-Remains active always, signal transduction pathways
constantly stimulate, cells undergo excessive mitosis
tumor surpressor - ANSWER-Genes that code for proteins with repair mechanisms
P53 "Guardian of the Cell" - ANSWER-Senses DNA damage, tells cells to make proteins that halt mitosis,
can trigger apoptosis
Apoptosis - ANSWER-Programmed cell death
Cancers - ANSWER-Each a unique combination of errors, most involve loss of control of the G1
checkpoint, genetic predispositions exist but need many mutations for cancer to develop
homologous chromosomes - ANSWER-Chromosome pairs, inherited from parents, contain identical
genes, may differ in sequence
