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Genetics

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Mary Runte

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โˆ™ 2021-10-17 18:35:49
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Cards in this guide (29)
What is a gene
GeneThe central dogma of genetics was that one gene coded for one enzyme this was later altered to one gene coded for one polypeptide.

As we learn more about genetics, this begins to look like an overly simplistic view of the concept of gene. The exact definition of the term gene is in debate at the moment, as is the use of the term at all in the future. The discovery of very short RNA's (miRNA, siRNA's) which influence gene expression (without translation into peptides) are part of this debate.

Definitions

A gene is a unit of heredity in a living organism. It is normally a stretch of DNA that codes

for a type of protein or for an RNA chain that has a function in the organism. All proteins and functional RNA chains are specified by genes. All living things depend on genes. Genes hold the information to build and maintain an organism's cells and pass genetic traits to offspring. A gene is a unit of in a living organism. It is normally a stretch of DNA that codes for a type of protein or for an RNA chain that has a function in the organism.

Genes hold the information to build and maintain an organism's cells and pass genetic traits to offspring. A gene is a part of a DNA molecule that codes for a particular trait of an organism. It provides instructions on how to make a polypeptide. For example, one gene may code for the production of tyrosinase, which is an enzyme (protein) used in the synthesis of melanin (a pigment responsible for dark colors in skin and fur).

By the traditional definition, a gene is 'transcribed' into mRNA which is then 'translated' into a protein, which will produce the desired effect in an organism's cell. Some genes may contain instructions for the production of RNA that is not translated into a protein, such as tRNA, rRNA, miRNA and siRNA.

Conclusion

In essence, a gene is a section of a DNA molecule that has a unique and specific biological function.

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 anaphase

The chromatids are pulled apart.

When is mitosis complete

When two nuclei have formed

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.

What is a gamete

a sperm or egg cell produced by meiosis

What is the role of microfilaments in cytokinesis

Discuss the role of microfilaments in cytokinesis.

How is mitosis different in plants and animals

In plants, a new cell wall forms to split the cell.

In animals, the cell membrane pinches together.
in animals, asters are formed which connect the spindle fibres of the chromosome, however, in plants, mitosis occurs without the formation of spindle fibres

What happens during S phase

DNA is replicated.

Chromosomes are duplicated.
During S Phase, there is the occurrence of DNA replication.

What happens during G2 phase

Chromosomes are checked for errors.
In the G2 phase, growth and preparation for cell division occurs.

A species has homologous chromosomes What does this say about the species

A species that has homologous chromosomes is known as a diploid species. Homologous chromosomes are chromosomes that come in identical pairs.Ê

What is the role of microfilaments in cell division

They pull the cell membrane in.

They Split The Cell During Cytokinesis.

When is S Phase complete

S phase is complete when each chromosome has been duplicated.

Which is a reason cells divide

They divide so the can make NEW cells to replace the ones that died.

To reproduce

To replace damaged cells~

Which phase occurs directly after G1

S Phase - period of DNA replication - 10% shorter than G1.
After G1 phase S phase occurs.

Genetic disorders can result when chromatids fail to separate properly. During with phase is this problem most likely to occur

Anaphase

Why are karyotypes prepared using cells in mitosis rather than cells in interphase explain.

in mitosis (specifically Prophase) the chromosomes are dense and therefore visible for a karyotype. during interphase they do not have to be ready to be pulled apart so they are not wound tightly.

A mitosis inhibitor is a medication that is designed to prevent mitosis in certain cells why would these be helpful in the treatment of tumors

it would prevent tumor cells from reproducing.

A species has homologous chromosomes what does this say about the species-

If a species has homologous chromosomes it means there is little genetic variation in the species.

A mitosis inhibitor is a medication that is designed to prevent mitosis in certain cells. How could these be helpful in the treatment of tumors

It would prevent tumor cells from reproducing.

How did Avery help build our understanding of genetics

He showed that DNA is a Transforming factor.

How is the DNA in a prokaryote different from the DNA in a eukaryotes

dna in eukaryotes is located in the nucleus

Humans are a diploid species. what does this say about their chromosomes

They have homologous chromosomes

How are meiosis and mitosis different

mitosis only has to do with celluar reproduction

meiosis has to do with sex cells reproducing
Mitosis creates new cells that are used for development, repair, asexual reproduction and growth. Meiosis creates cells in order for organisms to reproduce sexually.

A human baby is born with two X chromosomes. What must be true about this baby

Answer this question… A human baby is born with two X chromosomes. What must be true about this baby?

an organism has a haploid number of 20 what is the organism diploid number

40

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