Cell Division

Question 1

Cancer is…

Answer 1

Uncontrolled Growth

Question 2

Cell Division occurs for:

Answer 2

Growth
Cell Replacement
Healing
Reproduction

Question 3

Binary Fission

Answer 3

How bacteria undergo cell division. Asexual reproduction. Lower likelihood of mutation per one replication than eukaryotic cells.

Question 4

Binary Fission Process

Answer 4

DNA molecule is attached to the inner membrane.
DNA replication begins bidirectionally around the circle
New strand of DNA is also attached to the inner membrane near the attachment site of the initial plasmid
The entire cell then elongates symmetrically around the midpoint, separating the DNA attachment sites
Cell division begins with the synthesis of new membrane and wall material at the midpoint
Continued synthesis complete the constriction and separates the daughter cells.

Question 5

Mitosis

Answer 5

Eukaryotic cell division

Question 6

Interphase

Answer 6

The time between two successive M phases. Lasts 10-14 hours. Cell makes preparations for division.

Question 7

G1

Answer 7

First “gap” phase in which size and protein content of the cell increase. Many regulatory proteins are made and activated, organelles are replicated

Question 8

S

Answer 8

Synthesis phase, all DNA in the cell is replicated

Question 9

G2

Answer 9

Second Gap phase in which the cell prepares for mitosis and cytokinesis

Question 10

G0

Answer 10

No active preparation for cell division. Present in cell types that don’t actively divide. Liver, nerve, lens of the eye

Question 11

Checkpoints

Answer 11

Spindle-Assembly Checkpoint: Are all chromosomes attached to the spindle (before Anaphase)
DNA damage checkpoint: (Before S phase)
DNA Replication Checkpoint: (At the end of G2), is all DNA replicated correctly?

Question 12

Cyclins

Answer 12

Production caused by growth factors that arrived from other cells. Concentration fluctuates depending on the stage of cell cycle.

Question 13

CDK’s

Answer 13

Cyclin-dependant kinases, bound to by cyclin, the Cyclin-CDK complexes phosphorylate target proteins that promote cell division. CDK is always at some observable level in the cell. CDK can be recycled even when cyclin is degraded.

Question 14

Tim Hunt

Answer 14

Sea urchin embryos as they replicated, saw that the level of cyclin fluctuated as the embryo goes through mitosis/cell cycle. Cyclin peaks at every mitosis.

Question 15

G1 Checkpoint

Answer 15

Growth factors arrive from other cells
Increase cyclin and E2F concentrations
Cyclin binds to CDK, and CDK is phosphorylated
Rb inactivates E2F by binding to it
Inactivating phosphate is removed from CDK and active CDK phosphorylates Rb.
Phosphorylated Rb releases E2F
E2F triggers production of S-phase proteins

Question 16

G1 Checkpoint Significance

Answer 16

Subject to social control

Question 17

E2F

Answer 17

Transcription Factor

Question 18

p53

Answer 18

Found in the nucleus. Acts as a transcription factor that turns on genes that inhibit the cell cycle.
DNA damage activates protein kinases that phosphorylate p53. Inhibiting the cell cycle gives time to repair the DNA damage, or cause the cell to undergo apoptosis.

Question 19

Peyton Raus

Answer 19

Experimented with chicken cancer. Took cancer from one chicken, filtered it, and injected into another chicken and found that the cancer grew. Determined that there are virus caused cancers.

Question 20

Oncogene

Answer 20

Cancer-causing gene, E2F

Question 21

Proto-oncogene

Answer 21

Normal genes important in cell division that have the potential to become cancerous if mutated, Cyclin

Question 22

Tumor Suppressor

Answer 22

Encode proteins whose normal activities inhibit cell division, Rb

Question 23

Karyotype

Answer 23

Shows an individuals complete set of chromosomes

Question 24

Autosome

Answer 24

Non-sex related chromosome

Question 25

Homologous Chromosomes

Answer 25

Paired chromosomes, each comes from one parent in the example of humans, and they have the same length and loci

Question 26

Loci

Answer 26

Gene position

Question 27

Sister Chromatids

Answer 27

Identical copies formed of each chromosome during replication, joined together by a centromere

Question 28

Kinechore

Answer 28

Proteins that reside on either side of the centromere that attach to the mitotic spindle

Question 29

Diploid

Answer 29

Two chromosomes of each type. Two (one from each parent) of chromosome 1, Two of chromosome 12, 2 of chromosome 19 etc.

Question 30

Phases of Mitosis

Answer 30

Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis

Question 31

Prophase

Answer 31

Occurs after replication, chromosomes condense, centrosomes radiate microtubules and migrate to opposite poles, nuclear envelope starts to break down.

Question 32

Chromatin Fibers

Answer 32

Condensed, tightly coiled DNA wrapped around histone proteins that makes up chromosomes

Question 33

Prometaphase

Answer 33

Microtubules of the mitotic spindle attach to chromosomes, nuclear envelope breaks down

Question 34

Metaphase

Answer 34

Chromosomes align along the middle of the cell. 'Metaphase plate'. Spindle fibers coordinate movement.

Question 35

Anaphase

Answer 35

Sister chromatids separated at kinechores and pulled apart. Poles of the cell move further apart.

Question 36

Telophase

Answer 36

Spindle fibers disperse, nuclei and nucleoli form, chromosomes arrive at opposite poles.

Question 37

Cytokinesis

Answer 37

ring of actin filaments called the contractile ring contracts around the equator, dividing the cell in two.

Question 38

Phases of Meiosis

Answer 38

Prophase 1 Prometaphase 1 Metaphase 1 Anaphase 1 Telophase 1 Prophase 2 Prometaphase 2 Metaphase 2 Anaphase 2 Telophase 2

Question 39

Prophase 1

Answer 39

Homologous chromosomes condense and pair together, goes through synapsis. Nuclear envelope breaks down

Question 40

Synapsis

Answer 40

The matching up of homologous chromosomes for possible crossing over to occur.

Question 41

Bivalent

Answer 41

The pairing of homologous chromosomes is called a bivalent.

Question 42

Crossing Over

Answer 42

When parts of the chromosome can be switched between two paired homologous chromosomes. Creates two recombinant chromatids and two parent chromatids.

Question 43

Chiasma

Answer 43

Where crossing over occurs between the homologous chromosomes in the bivalent

Question 44

Meiosis 2

Answer 44

Steps are repeated, except the sister chromatids are separated, which give one cell the recombinant chromatid and the other the parent chromatid

Question 45

Meiosis 1

Answer 45

Same steps as mitosis, except homologous chromosomes are separated, giving one cell the copy from one parent and the other cell the copy from the other parent.

Question 46

Haploid

Answer 46

Only have one of each chromosme

Question 47

Origins of mitosis and meiosis

Answer 47

Mitosis is present in all eukaryotes. Meiosis is present in most, but not all eukaryotes. Meiosis likely evolved in a common ancestor but was lost in some groups.

Question 48

Oocyte

Answer 48

Can develop into a functional egg cell, where most of the cytoplasm is retained from meiosis

Question 49

Polar body

Answer 49

The leftover cytoplasm/cell products from meiosis previously combined with the oocyte

Question 50

Sperm development

Answer 50

Cytoplasm is eliminated, nucleus remains in the head and a flagellum

Question 51

Zygote

Answer 51

Formed during fertilization, when a full two sets of chromosomes are restored

Question 52

Nondisjunction

Answer 52

Failure of a pair of chromosomes to separate during anaphase of cell division. Gametes will have an extra copy or no copy of the chromosome. More common in the first division than the second division