CELL DIVISION Flashcards
(114 cards)
1
Q
- An integral part of the cell cycle
- Results in genetically identical daughter cells
- Cells duplicate their genetic material
- Before they divide, ensuring that each daughter cell receives an exact copy of the genetic material, DNA
A
Cell Division
2
Q
genetically identical daughter cells Before it divides, genetic material is duplicated
A
Mitosis
2
Q
Chromosomes are composed of a complex of DNA and protein called _____ that condenses during cell division
A
chromatin
2
Q
Cell cycle consists of
A
Interphase- normal cell activity
mitotic phase-cell divsion
2
Q
Cell cycle
Each of the 46 chromosomes is duplicated
A
S
2
Q
Cell cycle
The cell “double checks” the duplicated chromosomes for error, making any needed repairs.
double checks, to proofread. If it cannot be repaired, the cell will undergo apoptosis. Erroneous cells divided into Erroneous cells again
A
G2
2
Q
Cell cycle
Cell cycle arrest.
cell at rest, not making new materials, in homeostasis
A
Go
2
Q
Cell cycle
duplicated Cellular contents, the excluding the chromosomes.
preparing for the following phases, and maintenance of genetic structure. Not duplicating chromosomes yet
A
G1
2
Q
Functions of Cell division
A
Reproduction
Growth and development
Tissue renewal
2
Q
Geneatic information - genome
packaged into chormosomes
A
DNA
2
Q
DNA + Histone
A
nucleosome
2
Q
An average eukaryotic cell has about _________ more DNA than an average prokaryotic cell.
A
1,000 times
2
Q
fiber packed into chromosomes
A
chromatin fiber
3
Q
single, circular DNA molecule in a ________ cell
A
prokaryotic
3
Q
Most _______ have between 10 and 50 chromosomes in their body cells.
A
eukaryotes
3
Q
________ exists as a single, long, double-stranded fiber extending chromosome’s entire length.
A
DNA
3
Q
DNA in a _______ cell is organized into several linear chromosomes
A
eukaryotic
3
Q
All _________ cells store genetic information in chromosomes.
A
eukaryotic
3
Q
hormone that tells the cell when to divide
A
Cyclin dependent kinase
3
Q
Each unduplicated chromosome contains one DNA molecule, which may be several inches long
A
true
3
Q
Human cells have _ chromosomes
_ nearly-identical pairs
A
46
23
3
Q
The degree of coiling can vary in different regions of the chromatin:
A
true
3
Q
refers to loosely coiled regions in chromatin where genes can be expressed
A
Euchromatin
3
Q
refers to highly coiled regions in chromatin where genes aren’t expressed
A
Heterochromatin
3
1 to 22 paired chromosomes in the human genome are
autosomes
3
23rd paired chromosome in the human genome
sex chromosomes
3
In preparation for cell division, DNA is replicated and the chromosomes condense
Each duplicated chromosome has two ___________, which separate during cell division
sister chromatids
3
Look different
* Control different traits
* Sex chromosomes
* Are distinct from each other in their characteristics
* Are represented as X and Y
* Determine the sex of the individual
Non-homologous chromosomes
3
Inside the nucleus, chromosomes are at random, not in pairs
true
3
In a diploid cell, the chromosomes occur in pairs. The 2 members of each pair are called
homologous chromosomes or homologues
3
Two chromosomes in a pair
* Look the same
* Control the same traits
* May code for different forms of each trait
* Independent origin - each one was inherited from a different parent
Homologous chromosomes:
3
eukaryotic cell mitosis explnation
A eukaryotic cell has multiple chromosomes, one of which is represented here.
Before duplication, each chromosome has a single DNA molecule.
Once duplicated, a chromosome consists of two sister chromatids connected at the centromere.
Each chromatid contains a copy of the DNA molecule.
Chromosome duplication (including DNA synthesis)
Mechanical processes separate the sister chromatids into two chromosomes and distribute them to two daughter cells.
3
A cell possessing a single copy of each chromosome (human sex cells)
Haploid
3
A chromosome, once duplicated, a chromosome consists of two sister chromatids connected at the centromere.
truth
4
Centromere Designation location
Middle
Metacentric
4
P arm of chromosome
shorter
4
Implications of Low number of chromosomes
low numbers, the small errors and variations may mean the death of the organism
4
Implications of High number of chromosomes
gene duplication just in case a gene gets an error, it may have a backup. More resources would be needed.
4
Q arm of chromosome
longer
4
Centromere Designation location
Close to end
Acrocentric
4
Centromere Designation location
At end
Telocentric
4
Centromere Designation location
Between middle and end
Submetacentric
5
Homologous chromosomes can be made up of sister chromatids joined at the .
centromere
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A cell possessing two copies of each chromosome (human body cells).
Diploid
6
Each duplicated chromosome contains 2 identical DNA molecules (unless a mutation occurred), one in each chromatid
true
7
>Some haploid & diploid cells divide by mitosis.
>Each new cell receives one copy of every chromosome that was present in the original cell.
>Produces 2 new cells that are both genetically identical to the original cell.
Mitosis
8
What happens when Mitotic spindle fibers make mistakes at times?
Aneuploidy.
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in anaphase, cohesin needs to be removed by this protein
Separase
9
protein that acts like a stapler. Makes sure that the sister chromatids are near and attached to each other, most at the middle
Cohesin or Rec8
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protein present in the middle of the chromosome, protects the cohesin
Shugoshin
11
explain how the phrgmoplast is formed and integrates itself in the new cell
During telophase and cytokinesis, vesicles collect along the center of the cell and coalesce (or come together), forming the cell plate. As vesicles fuse, the cell plate grows, building a cell wall.
The phragmoplast appears at the side of the cells, facilitating the formation of the cell plate, which eventually becomes the new cell wall between daughter cells. It involves the guided movement of vesicles and the remodeling of microtubules to create the cell plate.
The cell plate will continue to grow until it eventually attaches to the plasma membrane.
12
Assembly of spindle microtubules begins in the _________, the microtubule organizing center
centrosome
12
includes the centrosomes, the spindle microtubules, and the asters
apparatus of microtubules controls chromosome movement during mitosis The centrosome replicates, forming two centrosomes that migrate to opposite ends of the cell
The Mitotic Spindle
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An ________ (a radial array of short microtubules) extends from each centrosome
aster
13
Mitosis
Daughter nuclei are forming Meanwhile, cytokinesis has started: The cell plate, which will divided the cytoplasm in two, is growing toward the perimeter of the parent cell.
Telophase
13
Mitosis
The chromatin is condensing The nucleolus is beginning to disappear. Although not yet visible in the micrograph, the mitotic spindle is staring to from.
Prophase
14
Mitosis
The chromatids of each chromosome have separated, and the daughter chromosomes are moving to the ends of cell as their kinetochore
Anaphase
14
Mitosis
We now see discrete chromosomes; each consists of two identical sister chromatids. Later in prometaphase, the nuclear envelop will fragment.
Prometaphase
14
Mitosis
The spindle is complete, and the chromosomes, attached to microtubules at their kinetochores, are all at the metaphase plate.
Metaphase
15
How do plants replicate without centrioles
They have MTOC - place where the microtubules originates in plants, effectively the same as animals Does not undergo cleavage furrow, uses cell plate formation
16
centrioles vs centrosome
Centrioles are microtubule structures, while centrosomes are larger organelles that contain centrioles and pericentriolar material. The centrosome is essentially a microtubule-organizing center (MTOC) in animal cells, and it's responsible for organizing microtubules during cell division, while centrioles are part of this structure.
17
Meiosis II
A nuclear envelope forms around each set of chromosomes. The cytoplasm divides.
Telophase II and cytokinesis
17
Living organisms are distinguished by their ability to reproduce their own kind
true
17
Is the transmission of traits from one generation to the next
Heredity
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Shows that offspring differ somewhat in appearance from parents and siblings
Variation
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are segments of DNA, units of heredity
Genes
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acquire genes from parents by inheriting
chromosomes
One set from Mother and one set from father
Offspring
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Each gene in an organism's DNA has a specific locus on a certain chromosome
true
22
Two parents give rise to offspring that have unique combinations of genes
inherited from the two parents
true
23
* 1 parent
* Binary Fission in bacteria
* Single cell eukaryotes : mitotic cell division
* DNA is copied and divided equally between daughter cells
Asexual Reproduction
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Multi-cellular organisms asexual reproduction method
Budding
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Each offspring in asexual reproduction is called a __________
In asexual reproduction, one parent produces genetically identical offspring by mitosis
clone
25
Disadvantages of asexual reproduction:
*No variation to help adapt to changing environments or resist diseases.
* A single disease or change in conditions can wipe out the entire population.
Population control issues
*Some asexually reproducing organisms can reproduce rapidly-may lead to overpopulation and resource depletion.
No genetic repair through recombination
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in (sexual/asexual) reproduction, recombination can fix or mask harmful mutations.
sexual
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2 parents
Results in greater variation than asexual reproduction
▪ Offspring vary genetically from siblings and both parents due to behavior of chromosomes during the sexual lifecycle
Sexual Reproduction
27
In (sexual/asexual) reproduction, harmful mutations are passed directly to the offspring
asexual
28
Fertilization and meiosis alternate in sexual life cycles
A life cycle is the generation-to- generation sequence of stages in the reproductive history of an organism
true
29
Unlike somatic cells, sperm and egg cells are ________ cells, containing only one set of chromosomes
haploid
30
At sexual maturity the ovaries and testes produce ________ gametes by meiosis
haploid
31
During fertilization, sperm and ovum fuse forming a ______
develops into an adult organism
diploid zygote
32
* Reduces the chromosome number such that each daughter cells have half
* Cell has a haploid set of chromosomes
* Ensures that the next generation will have:
* Diploid number of chromosome
* Exchange of genetic information (combination of traits that differs from that of either parent)
Meiosis
32
Meiosis reduces the number of chromosome to half that of somatic cells.
Reduction Division (RD)
33
If fertilization occurred without RD, what would the result be in humans?
If fertilization occurred in humans without reduction division (meiosis), the resulting embryo would have twice the normal number of chromosomes.
33
Which step is part important in meiosis? 1 or 2
Meiosis 1
34
Meiosis does two things
1) Meiosis takes a cell with two copies of every chromosome (diploid) and makes cells with a single copy of every chromosome (haploid).
2) Meiosis scrambles the specific forms of each gene that each sex cell (egg or sperm) receives
34
Meiosis
The chromosomes condense, and the nuclear envelope breaks down.
Crossing-over occurs.
Prophase I
35
Meiosis
Pairs of homologous chromosomes move to the equator of the cell.
Metaphase I
35
Meiosis
Homologous chromosomes move to the opposite poles of the cell.
Anaphase I
36
Meiosis II
A new spindle forms around
the chromosomes.
Prophase II
36
Meiosis
Chromosomes gather at the poles of the cells. The cytoplasm divides.
Telophase I
37
Meiosis II
Centromeres divide. Chromatids move to the opposite poles of the cells.
Anaphase II
37
Meiosis II
chromosomes
line up at the equator
Metaphase II
38
a protein structure that forms between homologous chromosomes during meiosis, particularly during prophase I
Synaptonemal complex
39
The period of time between meiosis I and meiosis II is called
interkinesis
39
Meiosis involves the same four phases seen in mitosis
prophase
metaphase
anaphase
telophase
They are repeated during both meiosis I and meiosis II.
40
Stages of Prophase I
Chromosomes, which have already been duplicated, begin to condense and become visible as thin threads.
Leptotene
40
No replication of DNA occurs during interkinesis because the DNA is already duplicated
True
41
Stages of Prophase I
Leptotene, zygotene, Pachytene, Diplotene, Diakinesis
42
a protein structure that holds the homologous chromosomes together
synaptonemal complex
42
Stages of Prophase I
This pairing process, called synapsis, involves the formation of a synaptonemal complex in Homologous chromosomes
zygotene
43
Stages of Prophase I
This is the stage where crossing over (the exchange of genetic material between non-sister chromatids of homologous chromosomes) occurs.
Pachytene
44
refers to the pairing of homologous chromosomes
Synapsis
44
Stages of Prophase I
The synaptonemal complex begins to dissolve, and homologous chromosomes start to separate.
Diplotene
45
occupies more than 90% of the time required for meiosis
Prophase I
45
Metaphase I
# of possible combinations =
2 raised to the power of the # of chromosomes in the genome
humans 2^ 23 =8,388,608
46
is the exchange of genetic material between those paired chromosomes
crossing over
46
Each tetrad usually has_________ number of Chiasmata, X-shaped regions where crossing over occurred
one (or more)
47
Stages of Prophase I
The chromosomes are maximally condensed and coiled.
The nuclear envelope and nucleolus break down.
The spindle fibers are assembled in preparation for metaphase I
Diakinesis
48
During synapsis, an exchange of homologous parts between non-sister chromatids occur. This exchange is
Crossing over
48
the 2 members of each homologous pair of chromosomes line up side-by-side, aligned gene by gene, to form a tetrad consisting of 4 chromatids
Synapsis
49
Metaphase I leads to independent assortment of maternal and paternal chromo- somes into the gametes.
true
49
Phase where only one side of the centrosome (kinetochore) faces outwards toward microtubules
This one sided attachment is different from mitosis where kinetochores on both sides of centromere bind to microtubules.
Metaphase I
49
* DNA duplication followed by 2 cell divisions
* Synapsis
* Crossing-over
* One diploid cell produces 4 haploid cells
* Each new cell has
a unique combination of genes
Meiosis
50
Homologous chromosomes do not
pair up
No genetic exchange between homologous
chromosomes
One diploid cell produces 2 diploid cells or one haploid cell produces 2 haploid cells
New cells are genetically identical to original cell
(except for mutation)
Mitosis
