Bootcamp.com - Cell Division

_____ is nuclear division followed by cytokinesis

cell division

what is another word for nuclear division?

karyokinesis

_____ is the division of the cytoplasm that happens at the end of cell division

cytokinesis

what is ploidy?

the number of chromosome sets found in a cell

______ are any chromosomes that are non-sex chromosomes, while ______ are X and Y chromosomes that determine sex and other characteristics

autosomes; sex chromosomes

in _____ cells, there are two copies of every chromosome, forming a pair called _____ chromosomes

diploid; homologous

humans have _____ chromosomes, _____ homologous pairs, and a total of _____ chromatids (depending on the stage of division)

46, 23, 92

a _____ is one of two identical parts of a duplicated chromosome

chromatid

_____ is the general packaging of DNA around histone proteins

chromatin

microtubule organizing centers (MTOCs) are called _____ in animal cells

centrosomes

(MTOCs are just called MTOCs in plants/fungi)

MTOCs are found outside the _____ during interphase

nucleus

centrosomes (animal cell MTOCs) contain a pair of _____

centrioles

what are gametes?

haploid cells used during sexual reproduction. The fusion of two gametes of opposite sexes will conceive a zygote that is diploid

usually there is/are _____ MTOC(s) per cell; however, cells replicate their MTOCs during _____

1; S phase

there is/are _____ MTOC(s) before cell division (after the S phase of interphase)

2

_____ occurs in somatic cells and _____ occurs in gametes (egg, sperm, pollen)

mitosis; meiosis

mitosis occurs in _____ cells and meiosis occurs in _____ (egg, sperm, pollen)

somatic; germ cells (to create gametes)

what is fertilization?

the fusion of two haploid gamete nuclei to make one diploid zygote

what is syngamy?

fertilization - i.e., the fusion of two haploid gamete nuclei to make one diploid zygote

_____ is the phase of cell division, in which the nucleus disassembles and the nucleolus disappears

prophase

_____ is the phase of cell division in which chromatin condenses into chromosomes

prophase

_____ is the phase of cell division, in which the nuclear envelope breaks down

prophase

_____ is the phase of cell division in which chromosomes line up in a single file in the center

metaphase

_____ is the phase of cell division in which each chromatid is complete with a centromere and attached kinetochore

metaphase

_____ is the phase of cell division in which replicated centrosomes are at opposite ends of the cell

metaphase

_____ is the phase of cell division in which karyotyping is performed

metaphase

_____ is a visual depiction of one's chromosomes by homologous pairs, and it is usually performed during metaphase

karyotyping

_____ is the phase of cell division in which kinetochore microtubules shorten

anaphase

_____ is the phase of cell division in which polar microtubules lengthen

anaphase

_____ is the phase of cell division in which each chromosome is pulled apart to opposite poles (disjunction)

anaphase

once separated at anaphase, each _____ is considered a _____

chromatid; chromosome

at the end of _____, each pole has a complete set of chromosomes

anaphase

what is the shortest step of cell division?

anaphase

_____ is the phase of cell division when karyokinesis occurs

telophase

(karyokinesis = nuclear division - notice the formation of 2 nuclei)

_____ is the phase of cell division in which the nuclear envelopes re-develop

telophase

_____ is the phase of cell division in which chromosomes de-condense back into chromatin

telophase

_____ is the phase of cell division in which nucleoli reappear

telophase

the presence of chromosomes means _____ is occurring

mitosis/meiosis

(cell division)

in metaphase, a chromosome consists of two closely attached _____

sister chromatids

to keep track of the total number of chromosomes during cell division, count the number of _____

centromeres

in _____, the chromosome number doubles

anaphase

at the end of anaphase, there would be a total of _____ chromosomes (separated chromatids) if a cell has 46 chromosomes at the beginning

92

unlike meiosis, NO _____ occurs in mitosis

genetic variation

during cytokinesis, animal cells separate via creation of the _____

cleavage furrow

during _____ in animals, actin and myosin microfilaments shorten and the plasma membrane is pulled into the center, creating a _____

cytokinesis; contractile ring/cleavage furrow

plant cells undergo cytokinesis via formation of a _____

cell plate

as plant cells undergo cytokinesis, vesicles from _____ migrate and fuse to form a cell plate

golgi bodies

during plant cell division, the cells don't actually separate from each other because the _____ cements adjacent cells together

middle lamella

_____ begins after mitosis and cytokinesis are complete

interphase

only the somatic cells that divide by _____ undergo interphase

mitosis

gametes do undergo _____ after they are made

interphase

what are the phases of interphase?

G1 (possibly G0), S, and G2 phase

what are the three *main* phases of the cell cycle?

mitosis, cytokinesis, interphase

90% of the cell cycle is spent in _____

interphase

the phase of interphase in which a checkpoint ensures everything is ready for DNA synthesis

G1

cells produce protein, ribosomes, and mitochondria in the _____ stage of interphase

G1

in what phase of the cell cycle will DNA synthesis occur?

the S phase of interphase

a second molecule of DNA is replicated from the first to provide sister chromatids in the _____ of interphase

S phase

the phase of interphase in which rapid cell growth occurs

G2

the cell prepares its genetic material for cellular division during the _____ of interphase

S phase

cells replicate their organelles during the _____ phase

gap 2 (G2)

when surface/volume ratio is _____, cellular exchange becomes easier

large

what happens when the surface/volume ratio is small?

the cell is unsustainably large and is pressured to divide

what happens as the genome/volume ratio decreases (volume gets bigger)?

the cell exceeds the ability of its genome to produce sufficient amounts of regulation for cellular activities

some large cells (paramecium, human skeletal muscle) are _____ to deal with problems associated with ever decreasing genome/volume ratios

multinucleated

what is the most important checkpoint of the cell cycle?

the G1 checkpoint

_____ is assessed and _____ conditions are checked during the G1 checkpoint

cell growth; favorable

what happens if the G1 checkpoint fails?

the cell enters G0

the _____ is viewed as either an extended G1 phase, where the cell is neither dividing nor preparing to divide, or a distinct quiescent stage that occurs outside of the cell cycle

G0 phase

some cells (liver, kidney) can be _____ of G0, while some cells (nerve, muscle) _____ in G0

induced out; permanently remain

cells can either never proceed from the _____ of interphase, or they can wait until the cell is ready to divide

G0 phase

at the end of the_____, the cell evaluates the accuracy of DNA replication and signals whether to begin mitosis

G2 phase

cells check for sufficient _____ levels during the G2 checkpoint and if there is a sufficient amount, the cell will proceed into the M phase

mitosis promoting factor (MPF)

the M checkpoint occurs during _____

metaphase

the _____ stops division to check if the chromosomes are attached to spindle fibers

M checkpoint

what happens if kinetochores are not attached to microtubules during the M checkpoint?

the cell will not proceed to anaphase until the appropriate connections have been made

_____ are enzymes that activate proteins, which regulate the cell cycle by phosphorylation

cyclin-dependent kinases (CDKs)

_____ is a protein that activates CDKs

cyclin

how does phosphorylation impact the cell cycle?

phosphorylation of certain substances signals for progression to the next cell cycle stage, while the absence of phosphorylation signals to pause the cell cycle

the plasma membrane has receptors for _____ that stimulate cells for division (such as damaged cells)

growth factors

cells stop dividing when surrounding cell density reaches a maximum - this is called _____

density-dependent inhibition

most cells only divide when attached to an external surface, such as neighboring cells or the side of a culture dish - this is called _____

anchorage dependence

cancer cells defy the five cell-specific regulations in place - such cells are called _____ cells

transformed

cancer drugs that inhibit mitosis do so by disrupting the ability of _____ to separate chromosomes during anaphase, thus stopping replication

microtubules

cancerous cells are a manifestation of defective cell _____ & cell cycle _____

differentiation; regulation

in meiosis I, crossing over occurs during _____, which introduces genetic variation to gametes

prophase I

_____ is how archaea, bacteria, and certain organelles (mitochondria and chloroplasts) reproduce

binary fission

when do organisms/organelles that undergo binary fission replicate their genomes?

as cell division is taking place

(replication of DNA + division occur simultaneously)

unlike mitosis, binary fission lacks _____ to guide chromosomes through karyokinesis

spindle apparatuses

the _____ is the region where crossing over occurs between non-sister chromatids during prophase I of meiosis I

chiasmata

_____ describes the process when homologous chromosomes pair up during prophase I of meiosis I

synapsis

the _____ is a protein structure that temporarily forms between homologous chromosomes during prophase I of meiosis I

synaptonemal complex

paired homologous chromosomes are referred to as _____ or _____ during early meiosis I

tetrads; bivalents

_____ are groups of 4 chromatids (due to the pairing of 2 homologous chromosomes) seen early in meiosis I

tetrads

(analogous to a bivalent)

_____ are pairs of homologous chromosomes

bivalents

what happens during the diakinesis sub-step of prophase I?

chromosomes complete condensing, the nuclear envelope begins to fragment, and tetrads/bivalents are ready for metaphase

(diakinesis is the final sub-step of prophase I)

chromosomes line up in _____ during metaphase I

double file

in meiosis, disjunction of homologs occurs during _____

anaphase I

what are the conditions for anaphase I to commence?

the cell must determine that each bivalent has at least one chiasmata and each homolog in a bivalent needs to be attached to a kinetochore microtubule

_____ is the phase of meiosis I in which each pole forms a new nucleus that now has half the number of chromosomes

telophase I