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Genetics

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Maryjane Konopelski

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What is a chromosome

A chromosome is a threadlike strand of DNA in the cell nucleus that carries the genes in a linear order. It is also known as tightly wound DNA. It is a structure that DNA wraps around.

MORE INFORMATION:

A chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.

Chromosomes vary widely between different organisms. The DNA molecule may be circular or linear, and can be composed of 10,000 to 1,000,000,000 nucleotides in a long chain.

Cells may contain more than one type of chromosome; for example, mitochondria in most eukaryotes and chloroplasts in plants have their own small chromosomes.

Chromosomes are the essential unit for cellular division and must be replicated, divided, and passed successfully to their daughter cells so as to ensure the genetic diversity and survival of their progeny.

Chromosomal recombination plays a vital role in genetic diversity. If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastrophe and die, or it may aberrantly evade apoptosis leading to the progression of cancer.

In practice "chromosome" is a rather loosely defined term. In prokaryotes and viruses, the term genophore is more appropriate when no chromatin is present. However, a large body of work uses the term chromosome regardless of chromatin content. The simplest genophores are found in viruses: these DNA or RNA molecules are short linear or circular genophores that often lack structural proteins.

Chromosomal DNA encodes most or all of an organism's genetic information; some species also contain plasmids or other extrachromosomal genetic elements.
Structure in nucleus made of DNA and protein. Sections of a chromosomes are genes.
structure in a cell's nucleuse thaat contians genetic material
A chromeosome is organized structure of DNA and protein that is found in cells.
coiled strands of genetic material
coiled strands of genetic material

What is an allele

a form of a gene apex

What are chromosomes

Basically is genetic info.

Different organisms have different types of chromosomes.

In bacteria (prokaryotic cells) a chromosome consists of a loop of DNA; it has no end. Along the length of the DNA are segments called genes, which contain information that the cell uses for growth and development. Most bacteria have only one chromosome, but some have more (the cholera organism Vibrio cholerae has two).

In eukaryotic cells, chromosomes are linear (they have two ends). The DNA is associated with proteins called histones. There is always more than one chromosome in a eukaryotic cell. After cell division and before DNA replication, there is only one molecule of DNA in each chromosome. After DNA replication, there are two DNA molecules in each chromosome; these are separated at the next cell division. In higher organisms, including humans, genes make up only part of the DNA. * * *

A chromosome is a single large macromolecule of DNA, and constitutes a physically organized form of DNA in a cell. It is a very long, continuous piece of DNA. * * * A chromosome refers to the colored thread observed localized within the nucleus. It is the genetic information carrier, and it may be extended (in interphase) or highly condensed (during mitosis or meiosis). The number of chromosomes is species-specific and if any alteration occurs it leads to disease condition or move forward towards evolution. In humans the total number of chromosomes is 46 or 23 pairs; mouse has 44 or 22 pairs; Onion - 16 or 8 pairs; Drosophila - 8 or 4 pairs. A chromosome after DNA replication has a pair of threads called chromatids held together by a primary constriction called a centromere. Chromatids consists of supersolenoid and scaffold structure followed by solenoid structure. Solenoid structure is formed by compaction of polynucleotides bound by histones and non-histone proteins. It leads to a fundamental structure called a nucleosome which consists of a nucleic acid part and a protein part. The protein part consists of positively-charged histones rich in lysine, arginine, and glycine. Histones consists of core subunit made of octamer made of 2 copies of H2A, H2B, H3 and H4. Linker histone H1 connects 2 nucleosomes. Chromosomes are classified based on various criteria: 1) The chromosomes which are common to both males and females are referred to as autosomes or body chromosomes and the chromosomes which determine the sex of an organism are called sex chromosome or allosomes (look dissimilar). In humans we have 22 pairs of autosomes and 1 pair of sex chromosomes (X and Y chromosomes). 2) Classified based on the position of centromere or primary constriction. The either sides of the centromere is referred to as arms (p- petite or short arm; q - quadran or long arm). When p=q (V shaped) - metacentric chromosome; When p<=q (L shaped) - submetacentric chromosome;When p<<< 3) Chromosomes are classified based on the banding pattern. Human chromosomes are classified into 7 groups A - G. A - 1-3; B - 4,5; C - 6-12, X; D - 13-15; E - 16 - 18; F - 19, 20; G - 21, 22, Y. Humans do not have any telocentric chromosomes. He has 5 pairs of acrocentric chromosomes (13 - 15, 21,22).
Chromosomes are structures composed of DNA coiled tightly around proteins called histones. In eukaryotic cells chromosomes are located in the cell nucleus. Chromosomes control the cell's activities and heredity.

What happens during telophase

During telophase the cell membrane gets "pinched" and the orgenelles and DNA are split. following telophase is cytokinesis when the cell membrane is sealed off and the mother cell becomes two sister cells.

The final stage of meiosis or mitosis, in which the separated chromosomes reach the opposite poles of the dividing cell and the nuclei of the daughter cells form around the two sets of chromosomes.

This answer contributed by The Scientific Theory Academy of Science (STAOS)

In telophase nuclear membrane is begin to reform at both ends of the cell and spindle fibers disappear. chromosomes uncoil and return to chromatin form in preparation for Interphase. Cytokinesis coincides with this stage of mitosis.

All of this is true but a much easier answer to this question is that telophase is when a new nucleus forms around each copy of dna.

Division of the cytoplasm following mitosis

Cytokinesis. Happens during telophase.

Another name for the Normal Distribution

Gaussian distribution. Some people refer to the normal distribution as a "bell shaped" curve, but this should be avoided, as there are other bell shaped symmetrical curves which are not normal distributions.

Which of the following are shown in a karyotype

what combination of sex chromosomes is shown in the image: XY (APEX)

Is color blindness a dominant or a recessive trait

Color blindness is a recessive sex linked trait.

How did Mendel make the F1 generation for his experiment

he crossed two pure lines

How is DNA in a prokaryote different from DNA in a eukaryote

DNA prokariyotes is circular. Eukariyotes have linear shape.

A plant can have green (G) or yellow (g) leaves. It can also have a long (K) or short (k) stem. A scientist is preparing a Punnett square for a dihybrid cross of a plant with a genotype GGKk. What pos

Gk, gk

Which best describes probability

the likelihood that something will happen

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