Comparing Mitosis and Meiosis with reference to i. Chromosomesii.
Biological significance
i. Chromosomes
ii. Biological significance
Modern cell theory states that all cells are derived from other cells.
This means cells must have a way of copying themselves. This is cell
division; two types of cell division are Meiosis and Mitosis. The
comparison will be between Meiosis 1 and Mitosis, because Meiosis 2 is
much the same as Mitosis.
Dividing cells have a regular pattern of events, known as the cell
cycle. This cycle may be divided into two basic parts; The Interphase
and the actual division (Meiosis / Mitosis).
Interphase is when the cell is not dividing but duplicating its DNA
and organelles. Both Meiosis 1 and Mitosis cells undergo a lot of
chemical activity during this stage. The amount of DNA and organelles
are doubled. Interphase is divided into three phases. The first stage
is known as the growth stage, this follows cell division and is when
cell organelles are synthesised. The second stage is known as the
synthesis stage, this is when the DNA replicates. The finally the
third stage is known as the 2nd Growth stage and this is when the
centrioles replicate and energy stores increase.
Prophase
In the Mitosis Prophase the chromosomes become visible. Chromosomes
are long thread like structures between 0.25 mm and 50 mm long. Each
chromosome is made up of two chromatids joined at a point called the
centromere. They are made of 70% protein, 15% DNA and 10% RNA and are
not visible in a non-dividing cell until the onset of cell division.
The chromosomes first become visible as long tangled treads, which
gradually shorten and widen. The centrioles migrate to opposite ends
of poles of the cell. Microtubules develop and form a star-shaped
structure called the spindle. The nucleolus and the nuclear envelope
disappear leaving the chromosomes.
Prophase in Meiosis 1 is similar to prophase in mitosis, as the
chromosomes become visible, shorten and widen but it different because
they associate in their homologous pairs. Organisms consist of two
sets of chromosomes where any two chromosomes, which decide the same
characteristic, are called a homologous pair.
In Meiosis these homologous pairs come together by a process called
synapsis and each pair is called a bivalent. The chromosomes are made
of two chromatids,...
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...lly reproducing organism. Therefore Meiosis is important in
order for variety in organisms, and allowing them to evolve.
b. The creation of genetic variety by the random distribution of
chromosomes during metaphase 1
When the pairs of homologous chromosomes arrange themselves on the
equator of the spindle during metaphase 1 of meiosis, they do it
randomly. Even though each one of the pair determines the same general
features, they’re detail of the feature is different. The randomness
of this distribution and independent assortment of these chromosomes
produces new genetic combinations.
c. The creation of genetic variety by crossing over between homologous
chromosomes
During prophase 1 of meiosis, equal portions of homologous chromosomes
may be swapped. In this way new genetic combinations are made and
linked genes separated.
The variety which meiosis brings vital for to the process of
evolution. By providing a varied stock of individuals it allows the
natural selection of those best suited to the existing conditions and
makes sure that species constantly change and adapt when these
conditions change. This is the main biological significance of
meiosis.
Do you want to hear about the first national park that is the first and only dedicated to a president? Theodore Roosevelt National Park was established in 1947. The Mountains are over 55 million years old. The badlands of Theodore Roosevelt national park is dry with occasional monsoon showers. The park is located in Medora, North Dakota, and is home to some amazing animals including wild horses, reptiles and mammals.
Trisomy 13 or Patau Syndrome” Trisomy 13 is a genetic disorder found in babies. It is also called Patau syndrome in honor of the physician who first described it, Krause Palau. Trisomy 13 is a genetic disorder in which there is three copies of chromosomes on Chromosome 13. Patau first described the syndrome and its involvement with trisomy in 1960. It is sometimes called Bartholin-Patau syndrome, named in part for Thomas Bartholin, a French physician who described an infant with the syndrome in 1656.
Each cell contains the same genetic code as the parent cell, it is able to do this because it has copied it’s own chromosomes prior to cell death. division. The. Meiosis consists of two divisions whilst mitosis is followed. in one division; both these processes involve the stages of interphase, prophase, metaphase, anaphase, and telophase.
Proposed Great Smoky Mountains National Park, North Carolina-Tennessee. Map. S.l., 1926. Mapping the National Parks. Lib. of Congress. 15 March 2010.
Sexual reproduction is that the union of male and feminine gametes to create a fertilised egg or zygote. The ensuing offspring inherit one-half their traits from every parent. Consequently, they 're not genetically similar to either parent or siblings, except within the case of identical twins. As theorised by Mendel, adults are diploid, meaning as 2N, having 2 alleles offered to code for one attribute. The gametes should be haploid, signified by N, containing just one allele in order that once 2 haploid gametes mix, they manufacture a traditional diploid individual. The method where haploid sex cells are created from diploid parents is known as meiosis, and it happens solely within the reproductive organs.
Even though perspectives of wilderness have changed and will continue to change Yellowstone was established with the purpo...
The exercise involved a series of ‘mating’ events resulting in 6 generations. Each mating event produced offspring with ‘possible’ newly inherited traits. The idea of ‘chance’ was included through simple coin tosses. Also, ideas of selection and mutations were introduced into the ‘gene pool’, which presented a deeper and more clear understanding of Mendelian inheritance and the Hardy-Weinberg equilibrium. Upon reaching the third generation, A B1 mutant allele was introduced to the blue locus-influencing fin shape and a G1 mutant allele was introduced to the green locus-influencing Mouth
16. Describe two evolutionary consequences if the process of crossing over in meiosis ceased to occur. If crossing over in meiosis ceased to occur there would be less genetic variations and no diversity among a species. This would essentially mean that a species would not be able to adapt to an issue that could arise in the future, meaning that its species could potentially become extinct due to climate change or other arising events.
Meiosis is a kind of cell division that is the key for sexual reproduction to operate contrary to mitosis, a form of asexual reproduction that serves the purpose of growth, repair, and regeneration of cells. Due to the fact that meiosis produces four non-identical haploid daughter cells, it is of vital importance so to allow variation in a population that provides the foundation for evolution, as it permits a species to adapt to changes in their environment. As I briefly mentioned before, meiosis is separated into two stages – meiosis I and II. These stages are further chara...
A chromosome is made up of two identical structures called chromatids. The process of nuclear division is called interphase; each DNA molecule in a nucleus makes an identical copy of itself. Each copy is contained in the chromatid and a characteristic narrow region called the centromere holds the two chromatids together. The centromere can be found anywhere along a chromosome but the position is the characteristic for a particular chromosome. Each Chromatid contains one DNA molecule. DNA is the molecule of inheritance and is made up of a series of genes. The fact that the two DNA molecules in the sister chromatids, and hence their genes, are identical is the key to precise nuclear division.
The differences between the phases of mitosis and meiosis are that in mitosis, it has 1 cell division, duplicates the DNA, occurs in somatic cells, and no crossing over happens. In meiosis, it has 2 cell divisions, reduces the DNA, occurs in gametes or sperm and egg cells, while crossing over happens. They are both similar in which they both create daughter cells, headed by at least one round of DNA replication, and have similar stages for cell division.
A male makes one thousand new sperm per second, that is two trillion over a lifetime and they all are one of a kind, very unique. A woman has all her eggs from birth. The process starts out as meiosis, this is where 30,000 genes are then there are forty six chromosomes. Twenty three comes from your mother and twenty three come from your father, they only come together in meiosis in pairs, but they are not the same. Chromosomes make an exact copy of themselves then they condense making an X shape, chromosomes get a partner then embrace. The chromosomes cling close together in big chunks, the cell then divides pulling the pair apart with twenty three chromosomes. The cell alone is incomplete, but holds many promises. Every cell holds di...
Second, cells are the smallest units of life and third, cells arise only from preexisting cells. These three facts are referred to as the cell theory. All cells can be categorized into two basic cell types. They are prokaryotic and eukaryotic. To distinguish where cells are placed in the two categories, what is inside the cell must first be looked at.
In Meiosis 1, chromosomes in a diploid cell resegregate, producing four haploid daughter cells. It is this step in Meiosis that generates genetic diversity.Meiosis 2 is similar to mitosis. However, there is no "S" phase. The chromatids of each chromosome are no longer identical because of recombination. Meiosis II separates the chromatids producing two daughter cells each with 23 chromosomes (haploid), and each chromosome has only one chromatid.
Once the sperm fuses with the ovum both chromosomes will pair up and begin the first stages of cell division.