Bio 9

Front 1

Cell cycle

Back 1

The life of a cell from the time it is first formed from a dividing parent cwll until its own division into 2 daughter cells

Front 2

Most cell division results in...

Back 2

Genetically identical daughter cells

Front 3

Most cell division involves the distribution of _____ to 2 _____.

Back 3

Identical genetic material (DNA);

DAUGHTER CELLS

Front 4

A dividing cell duplicates its ______, distributes the 2 copies to _______, and then splits into daughter cells.

Back 4

DNA;

OPPOSITE ENDS OF THE CELL

Front 5

Genome

Back 5

The genetic material of an organism

(All of an organism's genes & nucleic acid sequences)

Front 6

Before the cell can divide to form identical daughter cells, what must happen to the DNA?

Back 6

The DNA must be copied/replicated;

Each copy of DNA must be separated so each daughter cell ends up with a complete genome

Front 7

Why is the replication and distribution of so much DNA manageable?

Back 7

Because the DNA molecules are packaged into chromosomes

Front 8

Chromosomes

Back 8

Cell structure;

Consisting of one DNA molecule and associated protein molecules

Front 9

What does each eukaryotic chromosome consist of?

Back 9

One very long and linear DNA molecule associated with many proteins

Front 10

The DNA molecule carries...

Back 10

Several hundred to several thousand genes

Front 11

Genes

Back 11

The units of information that specify an organism's inherited traits

Front 12

What do the associated proteins in a chromosome do?

Back 12

They maintain the structure of the chromosome and help control the activity of the genes

Front 13

What is chromatin?

Back 13

The entire complex of DNA and proteins that is the building material of chromosomes

Front 14

Somatic cells

Back 14

All body cells except for the reproductive cells

Front 15

The nuclei of human somatic cells each contain _____ chromosomes, made up of 2 sets of _____ (one set inherited from each parent)

Back 15

46;

23

Front 16

Gametes

Back 16

Sperm and eggs

Front 17

How many chromosomes do gametes have?

Back 17

One set of 23 chromosomes in humans

Front 18

What form are each chromosomes in one cell is not dividing?

Back 18

In the form of a long thin chromatin fiber

Front 19

When do the chromosomes condense as a part of cell division?

Back 19

After DNA replication

Front 20

What does each chromatin fiber do when it condenses?

Back 20

Each chromatin fiber becomes densely coiled and folded.

(Making the chromosomes much shorter and so thick that we can see them with a light microscope)

Front 21

Each duplicated chromosome has two _________.

Back 21

SISTER CHROMATIDS

Front 22

Sister chromatids

Back 22

Two copies of a duplicated chromosome;

Attached to each other by proteins at the centromere and along the arms

Front 23

While joined, two sister chromatids make up how many chromosomes?

Back 23

ONE

Front 24

The two sister chromatids each contain an identical...

Back 24

DNA molecule

Front 25

What forces cause the sister chromatids to attach to each other?

Back 25

Protein complexes called cohesins; this attachment is known as sister chromatid cohesion

Front 26

Centromere

Back 26

The region on each sister chromatid where they are closely attached to each other by proteins that bind to specific DNA sequences

Front 27

What is the arm of a chromatid?

Back 27

The part of a chromatid on either side of the centromere

Front 28

Later in the cell division process the two sister chromatids of each duplicated chromosome...

Back 28

Separate and move into two new nuclei;

One forming at each end of the cell

Front 29

Mitosis

Back 29

The division of the genetic material in the nucleus

Front 30

What happens right after mitosis?

Back 30

Cytokinesis

Front 31

Cytokinesis

Back 31

The division of the cytoplasm

Front 32

After cytokinesis, are the two new cells genetically equivalent to the parent cell?

Back 32

Yes!

Front 33

How do you produce sperm/eggs?

Back 33

By meiosis

Front 34

How many chromatids are in a duplicated chromosome?

Back 34

2

Front 35

A chicken has 78 chromosomes in its somatic cells.

How many chromosomes did the chicken inherit from each parent?

How many chromosomes are in each of the chicken's gametes?

How many chromosomes will be in each somatic cell of the chicken's offspring?

Back 35

39;

39;

78

Front 36

Mitotic (M) Phase

Back 36

Phase of the cell cycle that includes mitosis & cytokinesis

(Shortest part of the cell cycle)

Front 37

Interphase

Back 37

Period in the cell cycle where the cell is not dividing.

Accounts for 90% of cell cycle

Front 38

What happens during interphase?

Back 38

Cellular metabolic activity= HIGH

Chromosomes & organelles= DUPLICATED

Front 39

What are the subphases of interphase?

Back 39

G1 phase,

S phase,

G2 phase,

Front 40

G1 phase

Back 40

The first gap, or growth phase, of the cell cycle.

Portion of interphase before DNA synthesis begins.

Front 41

S phase

Back 41

SYNTHESIS phase of the cell cycle;

the part of interphase where DNA is replicated.

Front 42

G2 phase

Back 42

The second gap, or growth phase, of the cell cycle.

The part of interphase after DNA synthesis

Front 43

During the 3 subphases of interphase, a cell that will eventually divide grows by...

Back 43

Producing proteins & cytoplasmic organelles (such as mitochondria & ER)

Front 44

When are chromosomes duplicated?

Back 44

Only during S PHASE

Front 45

Simply put... what are the steps of the cell cycle?

Back 45

1) a cell grows (G1)

2) cell continues to grow as it copies its chromosomes (S)

3) cell grows more as it completes preparation for cell division (G2)

4) cell divides (M phase)

Front 46

How long does each phase of the cell cycle last?

Back 46

Cell cycle = about 24 hours...

M phase = 1 hour

S phase = 10-12 hours

G1 phase = 5-6 hours

G2 phase = 4-6 hours

Front 47

What are the 5 stages of mitosis?

Back 47

Prophase, prometaphase, metaphase, anaphase, & telophase

Front 48

Prophase

Back 48

1st stage of mitosis

*chromatin condenses into seperate chromosomes (visible w/ a light microscope)

*mitotic spindle begins to form

*nucleolus disappears (nucleus remains intact)

Front 49

Prometaphase

Back 49

2nd stage of mitosis

* the nuclear envelope breaks apart

* the spindle microtubules attached to the kinetochores of the chromosomes

Front 50

Metaphase

Back 50

3rd stage of mitosis

* the spindle is complete

* the chromosomes, attached to microtubules at the kinetochores, are all aligned at the metaphase plate

Front 51

Anaphase

Back 51

4th stage of mitosis

* the chromatids of each chromosome have separated

* the daughter chromosomes are moving to the poles of the cell

Front 52

Telophase

Back 52

5th & final stage of mitosis

* daughter nuclei are forming

* cytokinesis has begun

Front 53

During G2, does a nuclear envelope encase the nucleus?

Back 53

YES

Front 54

During G2 of interphase, the nucleus contains one or more...

Back 54

Nucleoli

Front 55

During G2 of interphase, two centrosomes have formed by...

Back 55

Duplication of a single centrosome

Front 56

Centrosomes are regions in animal cells that organize the...

Back 56

Microtubules of the spindle

Front 57

During g2 of interphase, why can't the chromosomes (duplicated during S phase) be seen individually?

Back 57

Because they have not yet condensed

Front 58

During prophase, what do the chromatin fibers do?

Back 58

They become more tightly coiled; condensing into separate chromosomes that are observable with a light microscope

Front 59

What happens to the nucleoli during prophase?

Back 59

They disappear

Front 60

During prophase, each duplicated chromosome appears as...

Back 60

Two identical sister chromatids joined at their centromeres

Front 61

When does the mitotic spindle begin to form?

Back 61

During prophase

Front 62

During prophase, where do the centrosomes move?

Back 62

Away from each other

Front 63

What happens to the nuclear envelope during prometaphase?

Back 63

It breaks apart

Front 64

During prometaphase, the micro tubules extending from each centrosome can now...

Back 64

Invade the nuclear area

Front 65

During prometaphase, the chromosomes become even more...

Back 65

Condensed

Front 66

During prometaphase, each chromatid of each chromosome now has a...

Back 66

Kinetochore (a specialized protein structure at the centromere)

Front 67

During prometaphase, some of the microtubules attach to the kinetochores, becoming...

Back 67

Kinetochore microtubules, which jerk the chromosomes back and forth

Front 68

During prometaphase, what do nonkinetochore microtubules do?

Back 68

Interact with others from the opposite pole of the spindle

Front 69

During metaphase, where are the centrosomes?

Back 69

At opposite poles of the cell

Front 70

During metaphase, the chromosomes assemble at the...

Back 70

METAPHASE PLATE;

a plane that is equidistant between the spindle's two poles

(the chromosome's centromeres lie at the metaphase plate)

Front 71

During metaphase, for each chromosome, the kinetochores of the sister chromatids are attached to...

Back 71

Kinetochore microtubules coming from opposite poles

Front 72

What is the shortest stage of mitosis?

Back 72

Anaphase

Front 73

When does anaphase begin?

Back 73

When the cohesin proteins are cleaved

Front 74

During anaphase, what do the sister chromatids of each pair do?

Back 74

Seperate

Front 75

During anaphase, the now separated daughter chromosomes begin moving towards...

Back 75

Opposite ends of the cell,

as their kinetochore microtubules shorten

Front 76

During anaphase, why do the chromosomes move centromere first towards the ends of the cell?

Back 76

The centromeres are attached to the microtubules

Front 77

During anaphase, why does the cell elongate?

Back 77

The nonkinetochore microtubules lengthen

Front 78

By the end of anaphase, the two ends of the cell have...

Back 78

Equivalent and complete collections of chromosomes

Front 79

During telophase, two daughter _____ form in the cell.

Back 79

NUCLEI

Front 80

During telophase, where do the nuclear envelopes arise from?

Back 80

From fragments of the parent cell's nuclear envelope and other portions of the endomembrane system

Front 81

During telophase, do nucleoli reappear?

Back 81

YES

Front 82

During telophase, the chromosomes become...

Back 82

Less condensed

Front 83

During telophase, what happens to remaining spindle microtubules?

Back 83

They are depolymerized (shortened)

Front 84

What does the end of telophase mean?

Back 84

Mitosis is now complete

Front 85

Why do the two daughter cells appear super fast after the end of mitosis?

Back 85

Because the division of the cytoplasm is usually well under way by late telophase

Front 86

In animal cells, cytokinesis involves the formation of a ...

Back 86

CLEAVAGE FURROW,

which pinches the cell in two

Front 87

What is the mitotic spindle?

Back 87

A collection of microtubules and associated proteins that is involved in the movement of chromosomes during mitosis

Front 88

While the mitotic spindle assembles, what do the other microtubules of the cytoskeleton do?

Back 88

They partially disassemble, providing the material used to construct the spindle

Front 89

How do the mitotic spindle microtubules elongate?

Back 89

They incorporate more subunits of the protein tubulin

(and shortened by losing subunits of tubulin)

Front 90

Where does the assembly of spindle microtubules start?

Back 90

Centrosome

Front 91

During interphase, the single centrosome duplicates, forming two centrosomes, which remain together near the...

Back 91

Nucleus

Front 92

The two centrosomes move apart during prophase and metaphase of mitosis as...

Back 92

Spindle microtubules grow out from them

Front 93

What is an aster?

Back 93

A radial array of short microtubules;

Which extends from each centrosome

Front 94

What does the mitotic spindle consist of? (3 things)

Back 94

-the centrosomes

-the spindle microtubules

-the asters

Front 95

What links each sister chromatid to the mitotic spindle?

Back 95

Kinetochores

(structures of proteins attached to the centromere)

Front 96

The chromosome's 2 kinetochores face in opposite directions. During prometaphase, what attaches to these kinetochores?

Back 96

Some of the spindle microtubules.

These are now called kinetochore microtubules

Front 97

What happens when one of the chromosomes kinetochores is "captured" by microtubules?

Back 97

The chromosome begins to move toward the pole,

from which those microtubules extend

Front 98

What happens when microtubules from the opposite poles attached to the other kinetochore?

Back 98

Tug of war!

The chromosomes move in one direction, then the other, back and forth, finally settling midway between the two ends of the cell.

Front 99

At metaphase, where are the centromeres of all the duplicated chromosomes located?

Back 99

The metaphase plate,

The plane midway between the spindle's two poles

Front 100

While the chromosomes are doing tug of war, what have the microtubules that do not attach to kinetochores been doing?

Back 100

ELONGATING

(and by metaphase, they overlap & interact with other nonkinetochore microtubules from the opposite pole of the spindle)

Front 101

By metaphase, the microtubules of the asters have grown and are in contact with the...

Back 101

Plasma membrane

Front 102

When does anaphase commence?

Back 102

When the cohesins (holding together the sister chromatids of each chromosome) are cleaved by an enzyme called separate

Front 103

How do chromosomes move along the kinetochore microtubules?

Back 103

Motor proteins on the kinetochores "walk" the chromosomes along the microtubules

Front 104

In a dividing animal cell, what are responsible for elongating the whole cell during anaphase?

Back 104

The nonkinetochore microtubules

Front 105

What is cleavage?

Back 105

The pinching of the plasma membrane

Front 106

What is the first sign of cleavage?

Back 106

The appearance of a cleavage furrow,

A shallow groove in the cell surface near the old metaphase plate

Front 107

On the cytoplasmic side of the cleavage furrow is a...

Back 107

Ring of actin microfilaments associated with molecules of the protein myosin

Front 108

The actin microfilaments interact with the meiosis and molecules causing...

Back 108

The ring to contract

Front 109

The contraction of the dividing cells ring of microfilaments is like...

Back 109

Pulling a drawstring;

The cleavage furrow deepens until the parent cell is pinched in two producing two completely separate cells each with own nucleus, cytosol, organelles and other subcellular structures

Front 110

Since there is no cleavage furrow in cytokinesis in plant cells, how do they go through cytokinesis?

Back 110

1) during telophase, vesicles move along microtubules to the middle of the cell producing a cell plate

2) cell wall materials carried in the vesicles collect in the cell plate as it grows

3) the cell plate enlarges until its surrounding membrane fuses with the plasma membrane along the perimeter of the cell

4) two daughter cells result, each with its own plasma membrane

5) meanwhile, a new cell wall arising from the contents of the cell plate is formed between the daughter cells

Front 111

What is binary fission?

Back 111

Asexual reproduction by dividing in half.

* in prokaryotes, binary fission does not involve mitosis. But in single-celled eukaryotes that undergo binary fission, mitosis is part of the process.

Front 112

In bacteria, what are most genes carried on?

Back 112

A single bacterial chromosome that consists of a circular DNA molecule and associated proteins

Front 113

In bacteria, when is cell division initiated?

Back 113

When the DNA of the bacterial chromosome begins to replicate at a specific place on the chromosome called the origin of replication

Front 114

In binary fission, well the chromosome is replicated, the cell...

Back 114

ELONGATES

Front 115

In binary fission, when replication is complete and the bacteria has reached twice its initial size, what happens to the plasma membrane?

Back 115

The plasma membrane pinches inward,

dividing the parent cell into two daughter cells

Front 116

Where are origins of replication located?

Back 116

Opposite ends of the cell

Front 117

What supports the hypothesis that mitosis evolved from a simpler prokaryotic mechanism of cell reproduction?

Back 117

Some of the proteins involved in binary fission are related to the eukaryotic proteins that function in mitosis

Front 118

As eukaryotes with nuclear envelopes and larger genomes evolved, what gave rise to mitosis?

Back 118

The ancestral process of binary fission

Front 119

What drives the cell cycle?

Back 119

Specific signaling molecules present in the cytoplasm

Front 120

Cell cycle control system

Back 120

Cycle of molecules in eukaryotic cells;

triggers & coordinates key events in the cell cycle

Front 121

CHECKPOINT

Back 121

A control point in the cell cycle where stop-and-go signals regulate the cycle

Front 122

What do signals report at cell cycle checkpoints?

Back 122

Whether crucial cellular processes that should have occurred by that point have been completed correctly & thus whether or not the cell cycle should proceed

Front 123

Where are the 3 major checkpoints located?

Back 123

G1, G2, and M phases

Front 124

Why is the G1 checkpoint considered the most important checkpoint?

Back 124

If a cell receives a "go-ahead" signal at the G1 checkpoint, it will usually complete the G1, S, G2, and M phases and divide

Front 125

What happens if a cell does not recieve a "go-ahead" signal at the point?

Back 125

It will exit the cycle,

switching into a non dividing state called the G0 phase

Front 126

How is the cell cycle regulated at the molecular level?

Back 126

By a set of regulatory proteins & protein complexes (including kinases) & proteins called cyclins

Front 127

Describe the M phase checkpoint

Back 127

-a cell in mitosis recieves a stop signal when any of its chromosomes are not attatched to spindle fibers

-when all chromosomes are attatched to spindle fibers from both poles, a go-ahead signal allows the cell to proceed into anaphase

Front 128

What might delay anaphase?

Back 128

If some kinetochores are unattached to spindle microtubules, the sister chromatids remain together, delaying anaphase

Front 129

When the kinetochores of all the chromosomes are properly attached to the spindle, what becomes activated?

Back 129

The appropriate regulatory protein complex

Front 130

Once activated, the regulatory protein complex does what?

Back 130

The complex sets off a chain of molecular events that activates the enzyme seperase, which splits the cohesins, allowing the sister chromatids to seperate

Front 131

What is an example of an external factor that would cause a cell not to divide?

Back 131

Lacking an essential nutrient

Front 132

Growth factor

Back 132

A protein released by certain cells that stimulates other cells to divide

Front 133

In fibroblasts, what allows the cells to pass the G1checkpoint & divide?

Back 133

-fibroblasts have PDGF receptors on their plasma membranes

-the binding of PDGF molecules to these receptors triggers a signal transduction pathway

-this allows the cells to pass the G1 checkpoint & divide

Front 134

When do platelets release PDGF?

Back 134

When an injury occurs

Front 135

Density - dependent inhibition

Back 135

A phenomenon when animal cells become too close to eachother, they stop dividing

Front 136

In density-dependent inhibition, what (molecularly) causes the cells to stop dividing?

Back 136

The binding of a cell-surface protein to its counterpart on an adjoining cell sends a cell division-inhibiting signal to both cells, preventing them from moving forward in the cell cycle.

Front 137

Anchorage dependence

Back 137

To divide, the cell must be attached to a substratum (underlying layer or substance. a foundation or basis)

Front 138

Cancer cells do not need ________ to grow and divide.

Back 138

Growth factors

Front 139

Why do cancer cells grow without stopping?

Back 139

Either...

-they make a growth factor themselves

-they have an abnormality in the signaling pathway that conveys the growth factor's signal to the cell cycle control system

Front 140

What is {usually} the basis of the abnormality in signal pathways in cancer cells?

Back 140

A change in one or more genes that alters the function of their protein products...

resulting in faulty cell control

Front 141

If cancer cells stop dividing, when do they do so?

Back 141

Random points in the cell cycle,

rather than at the normal checkpoints

Front 142

Can cancer cells divide indefinitely?

Back 142

YES.

if given a continual supply of nutrients.

Front 143

Do cancer cells undergo apoptosis?

Back 143

NO, they avoid the normal controls that trigger a cell to undergo apoptosis when something is wrong.

(ex: when an irreparable mistake has occured during DNA replication before mitosis)

Front 144

Transformation

Back 144

The conversion of a normal cell to a cancerous cell

Front 145

Can the body identify a cancer cell?

Back 145

Yes, the immune system usually recognizes a transformed cell as an intruder & destroys it.

However... if the cell evades destruction, it will multiply & form a tumor.

Front 146

Benign tumor

Back 146

A mass of abnormal cells;

Specific genetic & cellular changes that the cells can't survive at a new site & remain at the site of the tumor's origin

Front 147

Malignant tumor

Back 147

A cancerous tumor;

Has genetic & cellular changes that make it capable of invading & surviving new sites

Front 148

What are some changes in malignant tumors (other than excessive multiplication)?

Back 148

-they may have unusual # of chromosomes

-their metabolism may be disabled

Front 149

What allows malignant to spread into nearby tissues?

Back 149

Abnormal changes on the cell surface cause the cancer cells to lose attachment to neighboring cells & ECM.

Front 150

What can cancer cells secrete to increase their size?

Back 150

Signaling molecules that cause blood vessels to grow toward the tumor

Front 151

How does cancer travel through the body?

Back 151

A few tumor cells may seperate from the original tumor, enter blood vessels & lymph vessels, and travel to other parts of the body.

(There, they may multiply & form a new tumor)

Front 152

Metastasis

Back 152

The spread of cancer cells to locations distant from their original site

Front 153

What causes the side effects of chemo?

Back 153

The drugs' effects on normal cells that divide often.