Week 3 Lecture: Plant Cell Cycle (Mitosis and Meiosis)

Question 1

Dictated by continuous generation of new cells. Achieved through cell expansion and cell division

Answer 1

Growth

Question 2

Thread-like structures in a cell’s
nucleus that are visible under the microscope only during cell division. Consists of proteins and a single large molecule of DNA that contains hundreds of
thousands of different gene.

Answer 2

Chromosomes

Question 3

How many chromosomes does a cabbage have?

Answer 3

20 chromosomes per cell (10 pairs per cell)

Question 4

How many chromosomes does a Haplopappus gracilis have?

Answer 4

4 chromosomes per cell (2 pairs per cell)

Question 5

How many chromosomes does a Olea europea have?

Answer 5

46 chromosomes (23 pairs per cell)

Question 6

How many chromosomes does a Ophioglossum reticulatum have?

Answer 6

1262 chromosomes per cell (631 pairs
per cell)

Question 7

Members of a chromosome pair that are similar in size, shape, and genetic constitution. Carry information governing the same genetic traits, although is not necessarily identical.

Answer 7

Homologous chromosomes

Question 8

A ___ carrying a gene that specifies flower color, but each chromosome may specify different colors of petals.

Answer 8

homologous pair

Question 9

A cell in which each chromosome occurs in pairs.

Answer 9

Diploid (2n)

Question 10

A cell that has a single set of chromosomes.

Answer 10

Haploid (n)

Question 12

• Two chromosomes
• Represented by 2n
• Somatic cells
• Created by Mitosis

Answer 12

Diploid

Question 13

• Single chromosome
• Represented by n
• Gametes
• Created by Meiosis

Answer 13

Haploid

Question 14

The ___ is the successive series of events in the life of a dividing eukaryotic cell.

Answer 14

cell cycle

Question 15

What are the two main phases of the cell cycle?

Answer 15

Interphase and M phase

Question 15

Often represented as a circle and consists of two main phases (interphase and M phase)

Answer 15

Cell cycle

Question 16

The period between two successive
divisions, represented by a complete revolution of the circle, is the ___.

Answer 16

generation time

Question 17

• Preparatory phase
• Performs Cell growth and DNA
  duplication

Answer 17

Interphase

Question 18

• Mitosis
• Meiosis I
• Meiosis II

Answer 18

M (Mitosis/Meiosis) Phase

Question 19

Localized areas of the plant body where mitosis and cytokinesis take place most of the time. Occur in the shoot and root tips (the apical meristems) and in some plants, in thin cylindrical regions that run the entire lengths of stems and roots except at the tips (the lateral meristems)

Answer 19

Meristems

Question 20

Allows the production and subsequent
elongation of new cells, causing an increase to the length of growing stems and roots. Occur to the shoot and roo t tips.

Answer 20

Apical meristems

Question 21

Produce additional wood and bark tissues that
add girth and thickening or widening to stems and roots of trees and shrubs. Occurs in thin cylindrical regions that run the entire lengths of stems and roots except at the tips

Answer 21

Lateral meristems

Question 22

The stage *between *successive cell divisions or the between phases. The cell synthesizes needed materials and grows. Chromosomes undergo duplication during this phase although not readily visible.

Answer 22

Interphase

Question 23

What are the subphases of the interphase?

Answer 23

1. Gap I Phase (GI Phase) or Pre-synthesis gap
2. Synthesis phase (S Phase)
3. Gap II (GII Phase) or Post-synthesis

Question 24

* Second stage of Interphase * Duplication of nucleus * Synthesis of DNA and protein * “Replicated chromosomes”- chromosomes after * S phase

Answer 24

Interphase: Synthesis Phase (S)

Question 24

* First stage in Interphase * Pre-synthesis phase * Cell growth * Duplication of organelles * Cell’s nucleus contains single * nucleolus and light chromatin * materials * Does not involve DNA * replication * GI checkpoint

Answer 24

Interphase: First Gap Phase (G1)

Question 25

* Third step, next to S Phase * Post-synthesis phase * Allows the cells to grow more * More proteins and organelles (e.g.mitochondria, chloroplasts, etc.) are being made * Larger nucleus; nucleus contain two nucleoli and darker chromatin materials. * Prepares the cell for the actual division (M Phase)

Answer 25

Interphase: Secondary Gap Phase (G2)

Question 26

* Gap zero phase or Resting Phase * Cells may opt to enter this phase or may directly enter the G1 phase up to cell division ➢ Intrinsic and extrinsic factors (resource availability, nutritional deprivation, etc.) * A cell is performing its function without actively preparing to divide * Quiescent stage ➢ Cells enter G0 phase, phase temporarily * Senescent stage ➢ Cells enter G0 phase permanently

Answer 26

Interphase: Gap Zer0 Phase (G0)

Question 27

Cells enter G0 phase, phase *temporarily*

Answer 27

Quiescent stage

Question 28

Cells enter G0 phase *permanently*

Answer 28

Senescent stage

Question 29

What are the important processes under Interphase?

Answer 29

1. DNA Replication 2. Transcription 3. Translation

Question 30

A process of *duplicating DNA* through semi-conservative replication. Initiation, Transcription, and Translation

Answer 30

DNA Replication

Question 31

The genetic information in the *DNA is transferred to RNA* through the catalytic action of RNA polymerase

Answer 31

Translation

Question 32

Translation is the *synthesis of a protein from an mRNA template*. Synthesize proteins, which are used for millions of cellular functions

Answer 32

Translation

Question 33

Indicates or *signals the completion of interphase.* Visible changes associated with the division of the nucleus take place. Most cellular activities (e.g. Protein synthesis) are suspended during this phase

Answer 33

Mitosis

Question 34

What are thr four stages of the M Phase?

Answer 34

1. Prophase 2. Metaphase 3. Anaphase 4. Telophase

Question 35

__ is a carefully controlled process that *organizes and separates the chromosomes correctly*. After the cells separate the chromosomes and *build new nuclei*, they *divide their cytoplasm by cytokinesis* and *form two distinct cells.*

Answer 35

Mitosis

Question 36

The portion of the chromosome centromere to which the *mitotic spindle fibers attach*.

Answer 36

Kinetochore

Answer 36

Prophase

Question 36

* *Chromatin condenses into duplicated chromosomes* consisting of two chromatids attached at centromeres. * *Chromosomes become shorter and thicker and individually visible* under a compound light microscope. * *Nuclear envelope disappears*. The *nucleolus shrinks and disappears* * *Spindle microtubules* attached to kinetochores and chromosomes *move toward midplane.*

Answer 36

Prophase

Question 37

A specialized region of a chromosome. At prophase, *sister chromatids are joined* in the vicinity where they are located.

Answer 37

Centromere

Question 38

Function in *chromosome distribution* during mitosis.

Answer 38

Microtubules

Question 38

Small, membrane-enclosed sacs

Answer 38

Vesicles

Question 39

The structure consisting mainly of microtubules that provides the framework for chromosome movement during cell division

Answer 39

Spindle

Question 40

* The *spindle microtubules grow and shrink* as they move toward the center of the cell in a “search and capture” process. * If a *microtubule comes near the centromere of a chromosome*, *the microtubule “captures” it*. * As the now-tethered chromosome continues moving toward the cell’s midplane, *a spindle microtubule from the cell’s other pole attaches to the opposite side of the centromere.*

Answer 40

Mitosis: Prophase

Question 41

* This phase* begins as the sister chromatids separate.* * *Sister chromatids* (now called chromosomes) *separates and move to opposite ends of the cell.* * *Ends when all the chromosomes have reached the poles*

Answer 41

Mitosis: Anaphase

Question 41

* The division of the cytoplasm that usually accompanies mitosis, generally begins during telophase. * Occurs by the formation of a cell plate, a partition between the newly formed nuclei in the equatorial region of the cell. * Forms two daughter cells.

Answer 41

Cytokinesis

Question 41

* Duplicated chromosomes *line up on the midplane of the cell * *Mitotic spindle is completely visible* and composed of numerous microtubules that extend from pole to pole. * Each *chromatid is quite condensed and appears thick and distinct*. * *Individual chromosomes are more distinct* in this phase

Answer 41

Mitosis: Metaphase

Question 41

* The *final stage of mitosis* in which *chromosomes arrive at the poles and return to their interphase condition.* * The *chromosomes begin to elongate by uncoiling and then become invisible chromatin threads* * Two separate nuclei form.

Answer 41

Mitosis: Telophase

Question 41

* *Reproductive cells* (egg and sperm cells) *which have half the diploid number of chromosomes*. * Form a complete, new organism by uniting

Answer 41

Gametes

Question 41

*Reduces the number of chromosomes in reproductive cells by half*. It means *“to make smaller”*

Answer 41

Meiosis

Question 41

As a result of ___, each gamete has only one chromosome of each pair, resulting in an egg or sperm cell with a *haploid,* or n, number of chromosomes.

Answer 41

meiosis

Question 41

A *fertilized egg* produced upon union of the female gamete (egg) and the male gamete (sperm cell).

Answer 41

Zygote

Question 42

___ *separates the members of each homologous pair of chromosomes.* No two offspring of the same parents will be exactly alike

Answer 42

Meiosis

Question 42

What are the two cell divisions that *meiosis* consists of?

Answer 42

First and second meiotic divisions (meiosis I and meiosis II)

Question 43

* The chromosomes duplicate during the S Phase of Interphase before the complex movements of meiosis actually begin. * The homologous chromosomes come together to lie side by side lengthwise and *synapse, crosing over takes place.* * A spindle forms consisting of microtubules. * The nuclear envelope and nucleolus disappear * In cells with large chromosomes, the association of the four chromatids of each

Answer 43

Meiosis I: Prophase I

Question 43

Pairing of homologous chromosomes

Answer 43

Synapsis

Question 43

* The sharing of genetic material between two non-sister chromatids of paired homologous chromosomes * Produces new combination of genes.

Answer 43

Crossing over

Question 44

* Homologous chromosomes line up in pairs along the *midplane*. * Both kinetochores of one duplicated chromosome are attached by spindle microtubules to the same pole. * Both kinetochores of the duplicated homologous chromosome are attached to the opposite pole

Answer 44

Meiosis I: Metaphase I

Question 45

* The paired homologous chromosomes separate, with one chromosome moving toward one pole and its homologue moving toward the other pole. * Sister chromatids remain attached at their centromeres. * Each pole receives a random combination of maternal and paternal chromosomes, but only one member of each homologous pair is present at each pole.

Answer 45

Meiosis I: Anaphase I

Question 46

* There would be two duplicated chromosomes, one of each homologous pair, at each pole. * The nuclei often reorganize, the chromatids generally elongate, and cytokinesis may take place.

Answer 46

Meiosis I: Telophase I

Question 46

___ are formed at the end of Meiosis I.

Answer 46

Two haploid cells

Question 47

* *Sister chromatids separate* and *chromosomes condense again.* * There is *no pairing of homologous chromosomes and no crossing over occurs.* * Main features: *Chromosomes become shorter and thicker*, and their two-stranded nature once more becomes apparent.

Answer 47

Meiosis II: Prophase II

Question 48

* The chromosomes, each consisting of two sister chromatids, line up on the midplanes of their cells * There are two chromatids of a single chromosome * Main features: 1. The *centromeres of the chromosomes become aligned along the equator*. 2. New *spindles become conspicuous and complete.*

Answer 48

Meiosis II: Metaphase II

Question 49

* The paired chromosomes separate, with one chromosome moving toward one pole and its homologue moving toward the other pole. * Only one member of each homologous pair is present at each pole. * Main features: The *centromeres and chromatids of each chromosome separate and migrate to opposite poles*

Answer 49

Meiosis II: Anaphase II

Question 49

Main features: 1. The coils of the chromatids (now called *chromosomes* again) *relax so that the chromosomes become longer and thinner.* 2. *New nuclear envelopes and nucleoli reappear for each group of chromosomes.*

Answer 49

Meiosis II: Telophase II

Question 50

Result in f*our haploid daughter cells*, each containing one of each kind of chromosome. Each resulting haploid cell has a different combination of genes.

Answer 50

Meiosis I and Meiosis II

Question 50

* There is *one member of each homologous chromosome pair at each pole*. Each chromosome is in an unduplicated state. * *Nuclear enveloped then re-form *around each set of chromosomes. * The *chromosomes gradually elongate into threadlike chromatin.* * Cytokinesis occurs.

Answer 50

Meiosis II: Telophase II

Question 50

Two sources of genetic variation: 1. *DNA segments are exchanged* between maternal and paternal homologues *during crossing over* 2. During Meiosis, the *maternal and paternal chromosomes of homologous pairs separate independently* so that each member of a pair is randomly distributed to one of the poles at anaphase.

Answer 50

Meiosis I and Meiosis II