Cell Reproduction

genetic material of an organism
Define: Genome
carriers of genetic material that are found in the nucleus
Define: Chromosome
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any cell in a multicellular organism except egg or sperm
Define: Somatic Cells
a haploid reproductive cell (egg or sperm)
Define: Gametes
complex of DNA and proteins that makes chromosomes
Define: Chromatin
either of two copies of a duplicated chromosome attached to each other at the centromere
Define: Sister Chromatids
cell division
Define: Mitosis
division of the cytoplasm to from separate daughter cells
Define: Cytokinesis
cell division: two cell divisions and one DNA replication; creates four daughter cells with half the number of chromosomes; process of reducing the number of chromosomes passed to the offspring
Define: Meiosis
shortest phase, includes mitosis and cytokinesis
Define: Mitotic Phase
cell grows
Define: G1 Phase
copies chromosomes
Define: G2 Phase
cell continues to grow and completes preparations for divisions
Define: S Phase
assemblage of microtubules that involve chromosome movements during mitosis
Define: Mitotic Spindle
contains two centrioles and functions as a microtubules organizing center
Define: Centrosome
readial array of short microtubules that are present during mitosis
Define: Aster
structure of proteins that is attached to the centromere that links each sister chromatids to the mitotic spindle
Define: Kinetochore
In animal cells, cytokinesis occurs through a cleavage furrow while plant cells’ cytokinesis occurs through a cell plate. With the differences between the cleavage furrow and cell plate, animal cells are pinched separate and the plant cells simply shove them to separate.
Plant Cytokinesis vs. Animal Cytokinesis
Binary fission is the method of an asexual reproductive organism reproducing by “dividing by half.” In prokaryotes, binary fission does not involve meiosis; but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process. In a bacteria cell the first step of binary fission is when the chromosome replication begins and soon after one copy of the chromosome moves toward the other end of the cell by a mechanism not yet fully understood. After this, replication continues while one copy of the origin is now at each end of the cell while the cell elongates. Replication then finishes as the plasma membrane grows inward and a new cell wall is deposited. There are two daughter cells as the result of binary fission.
Explain Binary Fission
mitosis is derived from binary fission as eukaryotes got more complex
Explain the hypothetical evolution of mitosis.
The cell cycle control system tell how long and often division of cells takes place. Checkpoints are the go and stop signals that they send out.
Explain the cell cycle control system and checkpoints.
protein that activates ligase which activates cell division
Define: Cyclin
cyclin-dependant kinases
Define: Cdk’s
maturation promoting factor; protomotes the cell’s passage past the G2 checkpoint into M phase
Define: MPF
a protein released by certain cells that stimulates other cells to divide
Define: Growth Factor
a phenomenon in which crowded cells stop dividing
Define: Density Dependant Inhibition
a cell must be attached to a substratum in order to divide
Define: Anchorage Dependence
conversion of a cell to a cancerous cell
Define: Transformation
a mass of abnormal cells that remain at the origin
Define: Benign Tumor
a mass of abnormal cells that spread through the nervous system
Define: Malignant Tumor
spread of cancer to locations distant from their original site
Define: Metastasis
Asexual reproduction has a single individual as the sole parent while in sexual reproduction two parents give rise to offspring. In asexual reproduction the single parent passes on all of its genes to its offspring while in sexual reproduction each person passes on half of its genes to the offspring. In asexual reproduction offspring are genetically identical to the parent while in sexual reproduction the offspring inherit a unique combination of genes inherited from both parents. Asexual reproduction does not consist of the fusion of gametes while sexual reproduction does.
Asexual vs. Sexual
the generation to generation sequence of stages in reproduction of an organism
Define: Life Cycle
chromosome pairs ordered by size and shape within a cell
Define: Karyotype
exactly the same chromosomes except for one is from the mother and the other from the father
Define: Homologous Chromosomes
a chromosome responsible for determining the gender of offspring
Define: Sex Chromosomes
not a sex chromosome
Define: Autosome
a cell containing two sets of chromosomes
Define: Diploid Cell
a cell containing only one set of chromosomes
Define: Haploid Cell
a sperm and egg fuse creating a zygote
Define: Fertilization
an egg and sperm fused
Define: Zygote
by arranging in pairs starting with the largest chromosome
How are karyotypes prepared?
the sporophyle generation produces a gametophyle as its offspring and from there it alternates
Define: Alteration of Generations
1) reducing the number of chromosomes for offspring from diploid to haploid
2) create four daughter cells that are genetically different from parents
What are the two goals of meiosis?
Meiosis includes synapsis and crossing over, homologs on the metaphase plate, and teh separation of homologs that mitosis doesn’t include. Meiosis reduces the number of chromosomes from diploid to haploid while Mitosis maintains diploid sets.
Mitois vs. Meiosis
1) Independent Assortment- percentage of it being male or female
2) Crossing Over- mixes of both parents in offspring
3) Random Fertilization- any of the thousands of sperms and egs can be fertilized
Three Sources of Genetic Variation in Meiosis:
What is the name for the special region on a duplicated chromosome that holds the sister chromatids together?
Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?
During which phase of mitosis are the two centrosomes arranged at opposite poles of the cell?
During which phase of mitosis do the centrioles begin to move apart in animal cells?
During which phase of mitosis do the centromeres uncouple, sister chromatids are separated, and the two new chromosomes move to opposite poles of the cell?
A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei containing how many chromosomes?
c) the nuclear envelope disappears
All of the following occur during prophase of mitosis in animal cells except
a) the centrioles move apart toward opposite poles
b) the nucleolus can no longer be seen
c) the nuclear envelop disappears
d) chromosomes are duplicated
e) the spindle is organized
If a cell has 8 chromosomes at metaphase of mitosis, how many chromosomes will it have during anaphase?
a cell plate begins to form at telophase, wheras animals a cleavage furrow is initiated at that stage
Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants…
the daugher cells have the same number of chromosomes and the same amount of DNA
How do daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle in comparison to chromosomes and amount of DNA?
a plant cell undergoing cytokinesis
The formation of a cell plate is beginning across the middle of the cell and nuclei are reforming at opposite ends of the cell. What kind of cell is this?
the fibers of the mitotic spindle
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. What must taxol effect?
Golgi-derived vesicles
What is primarily responsible for cytokinesis in plant cells?
What is an example of an organism that does not reproduce cells by mitosis and cytokinesis?
prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis
What is the sequence of steps in the M phase of the cell cycle?
from G2 of interphase through metaphase
During which phases of mitosis are chromosomes composed of two chromatids?
d) prevents shortening of microtubules
Movement of the chromosomes during anaphase would be most affected by a drug that
a) reduces cyclin concentrations
b) increases cyclin concentrations
c) prevents elongation of microtubules
d) prevents shortening of microtubules
e) prevents attachment of the microtubules to the kinetochores
microtubules; actin microfilaments
Cytoskeletal elements play important roles in cell division. The mitotic spindle apparatus is made of ________ and pulls siter chromatids apart, wheras the contractil ring is made of ________ and required for the separation of daughter cells at the end of the mitotic phase of the cell cycle.
What cell cycle phase are nerve and muscle cells always in?
During what phase of cell cycle is DNA replicated?
If the liver cells of an animal have 24 chromosomes, how many chromosomes do its sperm cells have?
a female somatic cell
What is a human cell that contains 22 pairs of autosomes and two X chromosomes called?
II, III, and V
Eukaryotic sexual life cycles show tremendous variation. Of the following elements, which do all sexual life cycles have in common? (can be more than one)
I. alternation of generations
II. meiosis
III. fertilization
IV. gametes
V. spores
half; one-fourth
How do cells at the completion of meiosis compare with cells that have replicated their DNA and are just about to begin meiosis?
They have _________ the number of chromosomes and _________ the amount of DNA.
b) crossing over
Which of the following terms belongs with the words synapsis, tetrads, and chiasmata?
a) haploid
b) crossing over
c) autosomes
d) prophase II
e) fertilization
metaphase I
During what phase of meiosis do the tetrads of chromosomes line up at the center of the cell and independent assortment soon follows?
prophase I
During what phase of meiosis does the synapsis of the homologous chromosomes occur and possibly crossing over?
anaphase II
During what phase of meiosis do the centromeres of sister chromatids uncouple and chromatids separate?
c) four haploid cells result
Which of the following is true of the process of meiosis?
a) two diploid cells result
b) four diploid cells result
c) four hapoid cells result
d) four autosomes result
e) four chiasmata result
in only mitosis
Does a cell divide to produce two daughter cells that are geneticlaly identical occur in only mitosis, only meiosis I, only meiosis II, in both mitosis and meiosis I, or in both mitosis and meiosis II?
only for meiosis I
Do homologous chromosomes synapse and cross over occur in only mitosis, only meiosis I, only meiosis II, in both mitosis and meiosis I, or in both mitosis and meiosis II?
both mitosis and meiosis II
Do centromeres uncouple and chromatids are separated from each other occur in only mitosis, only meiosis I, only meiosis II, in both mitosis and meiosis I, or in both mitosis and meiosis II?
only for meiosis I
Does independent assortment occur in only mitosis, only meiosis I, only meiosis II, in both mitosis and meiosis I, or in both mitosis and meiosis II?
for mitosis and meiosis I
Is the process proceeded by replication of DNA occur in only mitosis, only meiosis I, only meiosis II, in both mitosis and meiosis I, or in both mitosis and meiosis II?
tetrads lined up at the center of the cell
You have in your possession a microscope slide with meiotic cells on it and a light microscope. What would you look for if you wanted to identify metaphase I cells on the slide?
tetrads form
What occurs in prophase I of meiosis and not in prophase of mitosis?
b and d: synapsis and the production of daugher cells
Which of the following occurs in meiosis but not in mitosis? (may be more than one)
a) chromosome replication
b) synapsis
c) production of daughter cells
d) alignment of tetrads at metaphase plate
the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I
Independent assortment of chromosomes is a result of…
b) crossing over plays a role in both sexual and asexual reproduction
Which of the following statements about crossing over is incorrect?
a) crossing over combines sections of the maternal and paternal chromosomes
b) crossing over plays a role in both sexual and asexual reproduction
c) there are on average one to three crossover events per chromosome
d) crossing over increases the extent of genetic variation beyond what is posible through independent assortment alone
e) crossing over results in reombinant chromosomes
The parent cell is duplicated in mitosis so that the daughter cell is genetically identical to the parent. The chromosomes are also doubled at the beginning of mitosis.
What is duplicated during mitosis?
Cancer occurs when cells continuously reproduce while not keeping in mind the space that they are taking up in the tissue.
How is cancer related to cell reproduction?
Meiosis begins with prophase I, and then metaphase I, and then anaphase I, and then telophase I with cytokinesis I, which then moves onto prophase II, and then metaphase II, and then anaphase II, and then telophase and cytokinesis II.
What is the sequence of phases in meiosis?
Independent assortment occurs because each homologous pair of chromosomes is positioned independently of the other pairs at metaphase I, the first meiotic division results in each pair sorting its maternal and paternal homologs into daughter cells independently of every other pair.
Define: Independent Assortment

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