Chromosomes Sentence Examples
The number of chromosomes in the nucleus of the two spores, pollen-grain and embryo-sac, is only half the number found in an ordinary vegetative nucleus.
Humans have 46 chromosomes arranged into 23 pairs.
Humans have 46 chromosomes, which are matched into 23 pairs.
Eight chromosomes appear again in the ultimate divisions which give rise to the carpospores.
The chromosomes can be seen by obtaining a blood sample.
He finds that eight chromosomes appear in karyokinesis in the ordinary thallus cells, but sixteen in the gonimoblast filaments derived from the fertilized carpogonium.
When a baby is conceived by combining one sperm cell with one egg cell, the baby receives 23 chromosomes from each parent, for a total of 46 chromosomes.
Chromosomes contain genes that regulate the function and development of the body.
The 46 chromosomes in the human body are divided into pairs based on their physical characteristics.
In answer to this question a recent writer, Yamanouchi, states in a preliminary communication that he has found that in Polysiphonia violacea the germinating carpospores exhibit forty chromosomes, and the germinating tetraspores twenty chromosomes.
AdvertisementMoreover, it is known that the reduction in the number of chromosomes which occurs at the initiation of the gametophyte generation in Pteridophyta occurs of the various constituent groups.
The nuclei of the cells of the sexual generation possess a definite number of chromosomes and this number is also characteristic of the sexual cells.
It is possible, however, that the segregation of characters in the gametes may depend upon something far more subtle and elusive than the chromosomes or even of possible combinations of units within the chromosomes, but so far as we can see at present these are the only structures in the cell with which it can be satisfactorily associated.
From numerous investigations which have been made to trace the chromosomes through the various stages of the nuclear ontogeny of plant cells, it appears that the individuality and continuity of the chromosomes can only be conceived as possible if we assume the existence of something like chromosome centres in the resting nucleus around which the chromosomes become organized fon purposes of division.
A female child inherits two X chromosomes, while a male child inherits an X chromosome from one parent and a Y chromosome from the other.
AdvertisementChromosomes are made up of hundreds of small units known as genes, which contain the genetic material necessary for an individual to develop and function.
However, this affects males and females differently because males and females have a different number of X chromosomes.
An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes.
He or she starts with the detailed history of the family's background, looks at the child's features and orders blood tests to look at the 46 chromosomes and possibly at specific genes on those chromosomes.
A special type of blood test called a karyotype may be done to analyze the girl's chromosomes if the doctor suspects Turner's syndrome or another genetic disorder.
AdvertisementA female who carries a defective recessive gene on one of her two X chromosomes will not have the disease because she also has one good X chromosome.
X-linked-A gene carried on the X chromosome, one of the two sex chromosomes.
Sometimes, the genetic sex (as indicated by chromosomes) may not match the appearance of the external sex organs.
As of 2004, the A-T diagnosis is usually based on the characteristic clinical findings and supported by laboratory tests that point to a defect of DNA (genes and chromosomes) and to an inability to repair some types of damage to DNA.
Cells of the body, with the exception of the egg and sperm cells, contain 23 pairs of chromosomes.
AdvertisementEach parent normally gives a child 23 chromosomes.
Any abnormality in chromosomes or sex hormones, or in the unborn baby's response to the hormones, can lead to an intersex state in a newborn.
Individuals with A-T have an increased frequency of spontaneous breaks in their chromosomes as well as an increased frequency of chromosomal rearrangements.
Turner syndrome is a chromosomal abnormality occurring only in females in whom one of the X chromosomes is missing or defective.
Cytogenic and molecular genetic studies, which assess the structure and composition of chromosomes and genes, may also be used to diagnose osteosarcoma.
Unlike the other MPS conditions, MPS II is inherited in an X-linked recessive manner, which means that the gene causing the condition is located on the X chromosome, one of the two sex chromosomes.
Because they have two X chromosomes, they are carriers of the disorder if one of their X chromosomes has the gene that causes the condition, while the other X chromosome does not.
X-linked gene-A gene carried on the X chromosome, one of the two sex chromosomes.
Genes are located on chromosomes and serve to direct specific developments and processes within the body.
In about 5 percent of cases, retardation is transmitted genetically, usually through abnormalities in chromosomes, such as Down syndrome or fragile X syndrome.
Approximately 5 to 8 percent of individuals with retinoblastoma possess a chromosomal abnormality involving the RB1 gene that can be detected by looking at their chromosomes under the microscope.
If this type of chromosomal abnormality is detected in a child, then analysis of the parents' chromosomes should be performed.
X chromosome-One of the two sex chromosomes (the other is Y) that determine a person's gender.
Normal males have both an X and a Y chromosome, and normal females have two X chromosomes.
Children normally inherit 23 chromosomes from each parent, for a total of 46 chromosomes.
Sometimes a child may end up with more than 46 chromosomes because of problems with the father's sperm or the mother's egg or because of mutations that occurred after the sperm and the egg fused to form the embryo (conception).
There is no production of extra chromosomes, but a portion of each affected chromosome is "misplaced" (translocated) to another chromosome.
Karyotyping involves the separation and isolation of the chromosomes present in cells taken from an individual.
The 22 non-sex linked chromosomes are identified by size, from largest to smallest, as chromosomes 1 through 22.
Chromosomes are separated from cells, stained, and arranged in order from largest to smallest so that their number and structure can be studied under a microscope.
Mosaicism-A genetic condition resulting from a mutation, crossing over, or nondisjunction of chromosomes during cell division, causing a variation in the number of chromosomes in the cells.
A balanced translocation occurs when pieces from two different chromosomes exchange places without loss or gain of any chromosome material.
An unbalanced translocation involves the unequal loss or gain of genetic information between two chromosomes.
In autosomal dominant inheritance, a single abnormal gene on one of the autosomal chromosomes (one of the first 22 non-sex chromosomes) from either parent can cause the disease.
Genetic-Refers to genes, the basic units of biological heredity, which are contained on the chromosomes.
Chromosomes are structures in the nucleus of every cell in the human body that contain the genetic information necessary to direct the growth and normal functioning of all cells and systems of the body.
Most commonly, an individual with Turner syndrome will be born with 45 chromosomes in each cell rather than 46.
In contrast, females have two X chromosomes.
A deletion occurs when the genetic material in the chromosomes does not recombine properly during the formation of sperm or egg cells.
With regard to genetic factors, the disorder has been tentatively linked to loci on chromosomes 11 and 13.
Chromosomes are units of genetic information that exist within every cell of the body.
Twenty-three distinctive pairs, or 46 total chromosomes, are located within the nucleus (central structure) of each cell.
Sometimes, an accident in the production of a sperm or egg cell causes that cell to contain 24 chromosomes.
When this defective cell is involved in the conception of a baby, that baby will have a total of 47 chromosomes.
For this reason, the existence of three such chromosomes is sometimes referred to as trisomy 21.
Each cell still has 46 chromosomes, but the extra piece of chromosome 21 results in the signs and symptoms of Down syndrome.
Chemical stain is added to make the characteristics of the cells and the chromosomes stand out.
Chemicals are added to prompt the cells to go through normal development, up to the point where the chromosomes are most visible, prior to cell division.
The photograph is used to sort the different sizes and shapes of chromosomes into pairs.
The final result of such testing, with the photographed chromosomes paired and organized by shape and size, is called the individual's karyotype.
When a person receives both chromosomes from the same parent it is called "uniparental disomy."
When a person receives both chromosomes from his or her mother, it is called "maternal uniparental disomy."
Human beings have 46 chromosomes in the cells of their body.
An individual's chromosomes are inherited from his or her parents.
A child receives 23 chromosomes from the egg and 23 chromosomes from the sperm.
When viewed under a microscope, chromosomes within the same pair appear identical because they contain the same genes.
Most chromosomes have a constriction near the center called the centromere.
Chromosomes in the same pair contain the same genes.
Maternal uniparental disomy-A chromosome abnormality in which both chromosomes in a pair are inherited from one's mother.
Uniparental disomy-Chromosome abnormality in which both chromosomes in a pair are inherited from the same parent.
The results of these tests showed that 97 percent of the blue-eyed people in the study showed an identical mutation on thirteen of their chromosomes.
Every species has a set number of chromosomes, which contain all the information necessary to make up the organism.
In humans, there are 23 pairs of chromosomes, including the X or Y sex chromosomes that determine gender.
These sex chromosomes offer important clues about your family history.
Genealogy DNA testing examines the information contained on the X and Y chromosomes and helps determine whether, and to what extent, two individuals are related.
Both men and women have X chromosomes and can take this test.
Exploring the question of whether males can become pregnant can help us understand reproduction, chromosomes, and modern medical experiments.
Men and women are structurally different and this begins with chromosomes.
Women have two X chromosomes and men have an X and a Y chromosome.
A person who has XXY chromosomes creates an unusual situation that gives rise to the question of gender identity and male pregnancies.
In fact, sperm with the X chromosomes are viable longer than their male counterparts.
Alterations in chromosomes causing Down syndrome and Trisomy 18 birth defects are considered structural genetic birth defects.
Research continues to look at genetics and the developing chromosomes of the human embryo in hopes of reducing the number of incidences where alterations in chromosomes occur during and after fertilization.
The female eggs contain only X chromosomes (X is the female chromosome).
The combination of the two chromosomes makes gender.
Fathers cannot transmit Fragile X to sons, since they contribute only Y chromosomes to male children.
In females who have two X chromosomes, it is possible that the DNA will be masked or compensated for by the other X inherited by the father or mother.
It forms a part of the 1mm or plastin network of the nucleus and may become impregnated with varying quantities of chromatin stored up for use in the formation of the chromosomes and other nuclear activities.
Many observers hold the view that the chromosomes are pulled apart by the contraction of the fibres to which they are attached.
The spindle figure is probably the expression of forces which are set up in the cell for the purpose of causing the separation of the daughter chromosomes.
This is a necessary consequence of the fusion of two nuclei in fertilization, unless the chromosomes are to be doubled at each generation.
Boveri in fact has put forward the view that the chromosomes are elementary units which maintain an organic continuity and independent existence in the cell.
It is further stated by Olive that the chromosomes undergo longitudinal fission, and that for the same species the same number of chromosomes appear at each division.
The doubling process is provided by the act of fertilization, where an antherozoid with the single number of chromosomes fuses with an oosphere also with the single number to provide a fertilized egg with the double number.
Other observers have in recent years demonstrated a similar relation in other genera between the number of chromosomes in the nuclei of the two generations.
At the first division, the maternal and paternal chromosomes fuse together to form a bivalent, during which crossing-over occurs.
In extremely unusual cases a female may inherit two abnormal X chromosomes, in which case she will also be affected by the disorder.
The end result of the first division is two daughter cells each with one of the two homologous chromosomes.
Gaps increased 4-fold, breaks 2-fold, and dicentric chromosomes and acentric fragments 10-fold.
However, that does not mean GM constructs located on bacterial chromosomes do not transfer.
Their uniqueness is further assured by a process of crossing-over between maternal and paternal chromosomes whereby parts of chromosomes are exchanged.
The mitotic index is the fraction of cells in a microscope field which contain condensed chromosomes.
In Xenopus oocytes both isoforms located to the lateral loops of lampbrush chromosomes.
This probe mixture is hybridized to normal human reference metaphase chromosomes.
Fruit flies also have large polytene chromosomes, whose barcode patterns of light and dark bands allow genes to be mapped accurately.
The BLM protein plays a role in helping ensure that chromosomes are copied properly during cell division.
To develop a flow karyotype for the pig based on FACS sorted chromosomes.
On your chromosomes are specific sections called genes, which code for proteins and enzymes and so on - the cellular machinery.
The process by which the chromosomes divide during the production of egg and sperm cells is termed meiosis.
If the chromosomes of such cells are selectively stained with a dye such as acetic orcein, stages in mitosis can be observed.
Nucleus a cell organelle which contains the chromosomes whose genes control the structure of proteins within the cell.
Chromosomes are arranged in pairs and each cell contains 22 pairs of chromosomes and two others called sex chromosomes.
How do sex chromosomes influence the evolution of polygenic traits?
Research showed that there had been an exchange of material between chromosomes 9 and 22 - called a translocation.
I had what was known as a balanced reciprocal translocation, involving chromosomes 8 and 12.
Reduction Divisions (Meiosis).The divisions which take place leading to the formation of the sexual cells show a reduction in the number of chromosomes to one-half.
On the other hand, the complex structure of the nucleus with its separate units, the chromosomes, and possibly even smaller units represented by the chromatin granules, and the means taken through the complex phenomena of mitosis to ensure that an exact and equal division of the chromosomes shall take place, emphasizes the importance of the nucleus in heredity.
Further, it is only in the nucleus and in its chromosomes that we have any visible evidence to account for the Mendelian .segregation of characters in hybrids which are known to occur.
Visible differences in the chromosomes have even been observed, especially in insects, which are due apparently to an unequal division by which an additional or accessory chromosome is produced, or in some cases one or two extra chromosomes which differ in size from the others.
These differences indicate a separation of different elements in the formation of the chromosomes and have been definitelyassociated with the determination of sex.
These appearances are probably due toa pathological mitosis, commonly found in cancer, in which there is an irregular diminution in the number of chromosomes; some are cast out and become degenerated or some pass over to one of the daughter cells, leaving a reduced number in the other, and thus give rise to asymmetrical mitosis.
He had discovered, and seen, chromosomes.
In 1902, an American named Walter Sutton noticed that chromosomes duplicated themselves before cells divided so that each new cell had a full copy of the chromosomes.
It was formed from a reciprocal rearrangement of two ancient chromosomes.
Sexual reproduction requires the number of chromosomes to be halved.
One pair among the 23 pairs are the sex chromosomes.
Chromosomes are large enough to be seen under a microscope once they have been stained with certain dyes.
All tortoiseshell cats are females, except in very rare cases where the cat has a disorder of the chromosomes !
Cytogenetic analysis of tumor chromosomes, for example, can identify structural abnormalities that may explain the unique origins of cancer in an individual child.
Spectral karyotyping (SKY), an advanced method of screening chromosomes for numeric and structural abnormalities, is used to evaluate pediatric tumors.
Gene studies may be done to detect abnormalities on chromosomes 17 and 22.
Chromosomes contain the genetic information necessary to direct the development and functioning of all cells and systems in the body.
Autosomal refers to the first 22 pairs of chromosomes that are the same in males and females.
However, females have two X chromosomes and, therefore, have two copies of the Cx32 gene.
Females pass on one or the other of their X chromosomes to their children-sons or daughters.
The sex of a child is determined through the inheritance of strands of DNA called chromosomes.
Because chromosomes are inherited in pairs, each individual receives two copies of each chromosome and likewise two copies of each gene.
The sex determining chromosomes are also identified.
A normal individual has a total of 46 chromosomes in each cell, two of which are responsible for determining gender.
Normally, females have two X chromosomes, and males have one X and one Y chromosome.
In Turner syndrome, an error occurring very early in development results in an abnormal number and arrangement of chromosomes.
In rare cases, a parent may carry rearranged chromosomes that can result in Turner syndrome in a daughter, which is the only situation in which the Turner syndrome is inherited.
This is about 20 cm (7.8 inches) shorter than the height of women with normal chromosomes.
Turner syndrome is confirmed on the basis of genetic analysis of chromosomes, which can be done prior to birth.
Mosaic-A term referring to a genetic situation in which an individual's cells do not have the exact same composition of chromosomes.
In Down syndrome, this may mean that some of the individual's cells have a normal 46 chromosomes, while other cells have an abnormal 47 chromosomes.
Genes, which are linked together on chromosomes, have two functions.
The chromosomes that determine whether a person is male or female are called the X and Y chromosomes.
A person with two X chromosomes is female, while a person with one X and one Y is male.
Women are not usually affected by X-linked diseases, since they will likely have one unaffected copy between the two chromosomes.
Because a female child always receives two X chromosomes, she will nearly always receive at least one normal X chromosome.
In rare cases, a hemophiliac father and a carrier mother can pass on the right combination of parental chromosomes to result in a hemophiliac female child.
Humans normally have 23 pairs of chromosomes.
A person inherits one set of 23 chromosomes from each parent.
A child conceived with such an egg or sperm cell may inherit an incorrect number of chromosomes.
Definitive diagnosis is achieved through karyotyping, which involves drawing the baby's blood for a microscopic examination of the chromosomes.
Using special stains and microscopy, individual chromosomes are identified, and the presence of an extra chromosome 18 is revealed.
Normally, a person has a total of 46 chromosomes in each cell, two of which are responsible for determining that individual's sex.
The combination of these two types of chromosomes determines the sex of a child.
Females have two X chromosomes (the XX combination); males have one X and one Y chromosome (the XY combination).
Most commonly, a male with Klinefelter syndrome will be born with 47 chromosomes in each cell, rather than the normal number of 46.
Mosaic Klinefelter syndrome occurs when some of the cells in the body have an extra X chromosome and the other have normal male chromosomes.
Boys with several extra X chromosomes have distinctive facial features, more severe retardation, deformities of bony structures, and even more disordered development of male features.
Diagnosis of Klinefelter syndrome is confirmed by examining chromosomes for evidence of more than one X chromosome present in a male.
The autosomal chromosomes are the nonsex chromosomes.
Chromosome analysis, also called karyotyping, involves staining the chromosomes and examining them under a microscope.
Females can have the defective gene, but since they have two X chromosomes, there will be a normal gene on the other X chromosome to counter it.
The mother passes one of her two X chromosomes down to her child, and the father passes either an X or a Y chromosome to the child.
Most trisomies occur because of improper division of the chromosomes during formation of eggs or sperm.
Some cases of holoprosencephaly are caused by trisomy of chromosome 13, while others are due to abnormalities in chromosomes 7 or 18.
Human cells contain 22 pairs of autosomes and one pair of sex chromosomes.
Autosomal dominant trait-One of the non-X or non-Y chromosomes that will always express itself when present.
Genes are situated on larger structures called chromosomes that contain several thousand genes each.
Every cell in the body has 23 pairs of chromosomes containing two copies of every gene.
Sex is determined at the moment of conception by sex chromosomes.
Females have two X chromosomes, while males have one X and one Y chromosome.
Genetic defects sometimes result in changes in the chromosomes.
Chromosomes can be analyzed, and gonads can be, but rarely are, biopsied.
Y-carrying sperm move faster than sperm carrying X chromosomes.
In order to effect this the individual chromosomes must become associated in some way, for there is no diminution in the actual amount of nuclear substance, and this leads to certain modifications in the division which are not seen in the vegetative nuclei.
It seems to be fairly well established that in the meiotic phase there is a truequalitative division brought about by the pairing of the chromosomes during synapsis, and the subsequent separation of whole chromosomes to the daughter nuclei.
The nucleus in its vegetative stage shows a fine network throughout containing in the meshes the so-called nuclear-sap; attached to the network are the chromosomes, in the form of small irregular masses, which have a strong affinity for the " basic dyes."
Blackman, who also succeeded in showing that the nuclei of the sporophyte generation contain twice as many chromosomes as the nuclei of the gametophyte.
If sex chromosomes are involved, there is a change in the development of sexual characteristics.
It has been suggested that synapsis may be connected with the early longitudinal splitting of the thread or with the pairing of the chromosomes, but it is possible that it may be connected with the transference of nucleolar substance to the nuclear thread.
Doncaster (1906-1907) on the eggs of sawflies, the number of chromosomes is not reduced in parthenogenetic egg-nuclei, while, in eggs capable of fertilization, the usual reduction-divisions occur.
Rosenberg (1909) adduces evidence fox the existence of chromosomes or prochromosomes in resting nuclei in a large number of plants, but most observers consider that the chromosomes during the resting stage become completely resolved into a nuclear network in which no trace of the original chromosomes can be seen.
He finds no spindle fibres or true chromosomes, and considers the division direct, not indirect.
E, Chromosomes ox the spindle.
It consists in an unequal number of chromosomes passing over to each of the daughter nuclei, so that one may become hypochromatic, the other hyperchromatic. When this happens the resulting cleavage of the cytoplasm and nucleus is also unequal.
F, Separation of the chromosomes into two groups G, Chromosomes grouped at opposite ends of the spindle to forn the daughter nuclei.
After the division and cleavage of the chromosomes of the original nucleus have taken place they pass from the equator to the poles of the spindle, rearranging themselves close to the separated centrosomes to form daughter nuclei.
As is well known, the dividing nuclei of the cells of the sporophyte generation of the higher plants exhibit a double number of chromosomes, while the dividing nuclei of the cells of the gametophyte generation exhibit the single number.