Cell Division

Front 1

Distinguish between the following similar words: chromosome, chromatin, chromatid

Back 1

Chromosomes are tightly the tightly coiled form of DNA, while chromatin is the loosely packed network of
DNA strands dispersed in the nucleus during interphase. Chromatids are the chromosomes linked together as
twin or sister chromatids following DNA synthesis just prior to mitosis.

Front 2

Distinguish between the following similar words: centriole, centrosome, centromere

Back 2

Centrioles are organelles with a core of microtubules within them which are involved in organizing the
microtubule network of the cytoskeleton and play an important role during cell division. The centrosome is the
area of the cell where the centrioles are located, and where the microtubule network of the cell are anchored.
Centromeres are the area on chromosomes where twin chromatids are tied together after they form in S phase
and are pulled apart during anaphase.

Front 3

How many total chromosomes do the following cells have?
A somatic cell at G1 of the cell cycle
a sperm cell
an egg cell
A somatic cell after completing S phase

Back 3

-46 chromosomes: 23 pairs (1 pair = 1 from mom, 1 from dad)
-23 chromosomes
-23 chromosomes
-46 twin chromatids (96 chromosomes but duplicates are held together until anaphase)

Front 4

Describe the process by which a chromosome is duplicated. (key vocabulary to include: DNA polymerase,
nuclotides, complementary base pairing, twin chromatids, centromere).

Back 4

The two DNA strands of the double helix are separated by breaking the weak hydrogen bonds holding the
strands together, exposing the bases. DNA nucleotides floating in the nucleoplasm come in and form hydrogen bonds with the exposed bases by complementary base pairing: cytosine nucleotides bond with guanine nucleotides, and adenine nucleotides bond with thymine nucleotides. DNA polymerase catalyzes bond formation between the newly attached nucleotides, attaching the deoxyribose sugar of one nucleotide to the phosphate of the adjacent nucleotide. In this way, DNA polymerase moves along the DNA strand and creates a new paired strand to form a new double helix. A similar process occurs on the second DNA strand. Using the original two stranded double helix, two chromatids are formed, each containing one original strand and one newly synthesized strand. The two chromatids are held together at a region called the centromere, preventing the duplicate chromosomes from drifting apart until they are pulled apart during anaphase.

Front 5

Describe the role of the centrioles in cell division.

Back 5

Two pairs of centrioles are formed in interphase, and they move apart toward opposite poles of the cell during prophase of mitosis. As they move, an array of microtubules lines up between them across the cell, forming the spindle. Twin chromatids attach to spindle fibers and the microtubules exert the pull that separates chromatids during anaphase, leaving each end of the cell with identical sets of DNA.

Front 6

How does a tumor form? What is metastasis?

Back 6

Tumors form when a cell loses the normal controls that regulate cell division. This results in a cell with rapid, uncontrolled rate of division and forms a mass, or tumor, or the offspring of that cell. Metastasis is the process when cells break away from the original tumor and travel to other areas of the body via the bloodstream or lymph vessels, where they establish new tumors and disturb organ function.

Front 7

For each of the following cell stages, describe the principle event(s).
G1
S
G2
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

Back 7

->duplication of organelles and addition of membrane to restore cell to normal size; normal cell
activities
->duplication of DNA forming 46 twin chromatids from 46 individual chromosomes
-> final protein synthesis of enzymes needed for mitosis
-> movement of centrioles and formation of spindle, nuclear membrane dissolves
- > chromatids line up along midline of spindle (metaphase plate)
-> chromatids are pulled apart, moving individual chromosomes to each pole of cell
-> nuclear membrane re-forms at each end of cell around chromosomes
-> Plasma membrane pinches in across center of cell, splitting cytoplasm and organelles into
two separate cells each with their own nucleus.

Front 8

mitosis

Back 8

the nuclear division of somatic cells; each cell produced has 23 pairs of chromosomes (2n for humans-n=23)

Front 9

meiosis

Back 9

produces sex cells (sperm,eggs) with 23 single chromosomes (1n)

Front 10

interphase

Back 10

includes 3 stages: G1, S, G2
most somatic cells spend majority of their lives in the phase

Front 11

G1

Back 11

growth phase 1
normal cell functions
growth of cell
duplication of organelles
protein synthesis
ass more membrane to allow cell to grow in size
make more ribosomes

Front 12

S

Back 12

synthesis phase
-DNA duplication
starting to wind down and get ready for division

Front 13

G2

Back 13

growth phase 2
-short phase, final protein synthesis:enzymes needed for mitosis
-completion of centriole division

Front 14

cytokinesis

Back 14

a process in which the cytoplasm divides, overlaps with the end of mitosis but is a separate event from mitosis

Front 15

prophase

Back 15

centrioles move away toward poles with spindle fibers between them. nuclear membrane eventually disappears

Front 16

metaphase

Back 16

chromosomes line up at metaphase plate in center of cell

Front 17

anaphase

Back 17

chromatids separate and chromosomes are pulled to opposite ends of cell

Front 18

telaphase

Back 18

nuclear membranes re-form, chromosomes de-coil
mitosis=complete
cytokinesis=complete

Front 19

dna polymerase`

Back 19

an enzyme that works to allow DNA bases floating in the nucleoplasm to bind to exposed bases on the DNA strand

Front 20

centromere

Back 20

holds chromatids together

Front 21

centriole

Back 21

organelles that sever as microtubule organizing center
-reside within centrosome

Front 22

spindle fibers

Back 22

chromosomes attach to them

Front 23

twin chromatids

Back 23

what the copied chromosomes stayed together as

Front 24

cell differentiation

Back 24

process of specialization
results from inactivation of particular genes
-produces populations of cells with limited capabilities
-influenced by neighboring cells and chemicals
-differentiated cells form tissues

Front 25

neoplasm

Back 25

new growths produced by abnormal cell division (tumors)

Front 26

benign

Back 26

harmless

Front 27

malignant

Back 27

invasive
-spread via metastasis (very easy)

Front 28

metastasis

Back 28

spread of primary tumor cells
-cells at edge break off bc they dont listen to normal control region and spread