Biology

AAA TTA CGG to AAA TTA CGA would be what type of mutation?

Substitution mutation

What is the basic structure of DNA? What molecules make up the specific parts?

(The Double Helix) DNA is made up of six smaller molecules -- a five carbon sugar called deoxyribose, a phosphate molecule and four different nitrogenous bases (adenine, thymine, cytosine and guanine).

The 3 sources of genetic recombination/variability?

1. Crossing over in prophase I. 2. Independent assortment of paired chromosomes along the metaphase I plate. 3.Combining of chromosomes of genetically different gametes during fertilization.

Benefits that meiosis provides organisms?

1. Tremendous storehouse of genetic variation provides for adaptations to changing environment 2. Asexual organisms depend primarily on mutations to generate variation 3. Meiosis produces genetic variation

What is a codon? Anticodon? Where are they found?

A codon is a three-base sequence (three nitrogen bases in a row) on mRNA. It calls for a specific amino acid to be brought to the growing polypeptide. An anticodon is a three-base sequence on tRNA. It matches the codon. That's how the right amino acid is put onto the polypeptide next. The tRNA must fit its anticodon onto the mRNA codon like a jigsaw puzzle piece. Each tRNA can only bring one kind of amino acid.

How do sex-linked traits work? Which sex is most likely to show recessive x-linked traits? Why?

A particularly important category of genetic linkage has to do with the X and Y sex chromosomes. These not only carry the genes that determine male and female traits but also those for some other characteristics as well. Genes that are carried by either sex chromosome are said to be sex linked. Men normally have an X and a Y combination of sex chromosomes, while women have two X's. Since only men inherit Y chromosomes, they are the only ones to inherit Y-linked traits. Men and women can get the X-linked ones since both inherit X chromosomes. X-linked recessive traits that are not related to feminine body characteristics are primarily expressed in the observable characteristics, or phenotype click this icon to hear the preceding term pronounced, of men. This is due to the fact that men only have one X chromosome. Subsequently, genes on that chromosome not coding for gender are usually expressed in the male phenotype even if they are recessive since there are no corresponding genes on the Y chromosome in most cases. In women, a recessive allele on one X chromosome is often masked in their phenotype by a dominant normal allele on the other. This explains why women are frequently carriers of X-linked traits but more rarely have them expressed in their own phenotypes.

What is a population? Community? Ecosystem? Habitat?

A population comprises all the individuals of a given species in a specific area or region at a certain time. Its significance is more than that of a number of individuals because not all individuals are identical. Populations contain genetic variation within themselves and between other populations. Even fundamental genetic characteristics such as hair color or size may differ slightly from individual to individual. More importantly, not all members of the population are equal in their ability to survive and reproduce. Community refers to all the populations in a specific area or region at a certain time. Its structure involves many types of interactions among species. Some of these involve the acquisition and use of food, space, or other environmental resources. Others involve nutrient cycling through all members of the community and mutual regulation of population sizes. In all of these cases, the structured interactions of populations lead to situations in which individuals are thrown into life or death struggles. In general, ecologists believe that a community that has a high diversity is more complex and stable than a community that has a low diversity. This theory is founded on the observation that the food webs of communities of high diversity are more interconnected. Greater interconnectivity causes these systems to be more resilient to disturbance. If a species is removed, those species that relied on it for food have the option to switch to many other species that occupy a similar role in that ecosystem. In a low diversity ecosystem, possible substitutes for food may be non-existent or limited in abundance. Ecosystems are dynamic entities composed of the biological community and the abiotic environment. An ecosystem's abiotic and biotic composition and structure is determined by the state of a number of interrelated environmental factors. Changes in any of these factors (for example: nutrient availability, temperature, light intensity, grazing intensity, and species population density) will result in dynamic changes to the nature of these systems. For example, a fire in the temperate deciduous forest completely changes the structure of that system. There are no longer any large trees, most of the mosses, herbs, and shrubs that occupy the forest floor are gone, and the nutrients that were stored in the biomass are quickly released into the soil, atmosphere and hydrologic system. After a short time of recovery, the community that was once large mature trees now becomes a community of grasses, herbaceous species, and tree seedlings. A habitat is the natural home or environment of an animal, plant, or other organism.

What are somatic cells? Are they diploid/haploid?

A somatic cell is any cell of the body except sperm and egg cells. Somatic cells are diploid, meaning that they contain two sets of chromosomes, one inherited from each parent.

What is Rachael Carson known for in terms of her work and its related ecological impacts?

American marine biologist and conservationist whose book Silent Spring and other writings are credited with advancing the global environmental movement. Carson began her career as an aquatic biologist in the U.S. Bureau of Fisheries, and became a full-time nature writer in the 1950s. Her widely praised 1951 bestseller The Sea Around Us won her a U.S. National Book Award,[2] recognition as a gifted writer, and financial security. Her next book, The Edge of the Sea, and the reissued version of her first book, Under the Sea Wind, were also bestsellers. This sea trilogy explores the whole of ocean life from the shores to the depths.

How do the terms "heterozygous" and "homozygous" apply to phenotypes and genotypes?

An organism can be homozygous dominant, if it carries two copies of the same dominant allele, or homozygous recessive, if it carries two copies of the same recessive allele. Heterozygous means that an organism has two different alleles of a gene.

What happens in anaphase?

Anaphase is the stage of mitosis or meiosis when chromosomes are split and the sister chromatids move to opposite poles of the cell. Anaphase accounts for approximately 1% of the cell cycle's duration.

Unique features of meiosis vs mitosis

Both mitosis and meiosis are associated with cytokinesis. The end result of both are daughter cells produced from a parent cell. The fundamental sequence of events in mitosis is the same as in meiosis (in meiosis it happens twice). Both processes include the breakdown of the nuclear membrane, the separation of genetic material into two groups, followed by cell division and the reformation of the nuclear membrane in each cells. The processes differ in two fundamental. Meiosis has two rounds of genetic separation and cellular division while mitosis only has one of each. In meiosis homologous chromosomes separate leading to daughter cells that are not genetically identical. In mitosis the daughter cells are identical to the parent as well as to each other.

RE: Karyotype lab, what is colchicine and why is it used?

Colchicine is an oral drug used for treating acute gout and familial Mediterranean fever (FMF). In acute gout there is severe inflammation in response to the presence of uric acid crystals that form in bony joints. This causes severe pain, redness, and swelling of the affected joint(s).

What is cytokinesis?

Cytokinesis is the physical process of cell division, which divides the cytoplasm of a parental cell into two daughter cells. It occurs concurrently with two types of nuclear division called mitosis and meiosis, which occur in animal cells.

How are chromatids, chromatin, chromosomes, sister chromatids, and DNA related? When does one type become another?

DNA, the blueprint of life, is organized into structures called chromosomes. In prokaryotic cells, chromosomes are circular, whereas in eukaryotic cells, they are linear strands. Different organisms have different numbers of chromosomes: human cells usually have 46 chromosomes, dogs have 78 chromosomes, while kangaroos have only 12 chromosomes. When you add all these chromosomes up, each cell actually contains about 2m of DNA. And all this DNA has to fit into a tiny nucleus of 5-10um in diameter. This is like trying to stuff a piece of string 2km long (it will take you about 20 minutes to walk from one end to the other) into a tiny bead smaller than 1cm. To do this seemingly impossible feat, cells devised an ingenious packaging system: it wraps DNA around proteins called histones. The resulting DNA-protein complex is called chromatin. At the beginning of cell division (S-phase), the DNA is replicated, producing two identical copies of DNA, which are connected to each other at the centromere. This replicated X-like structure is now called a sister chromatid pair. A chromatid is therefore just one of the strands.

What does haploid and diploid mean?

Diploid cells contain two complete sets (2n) of chromosomes. Haploid cells have half the number of chromosomes, contains only one complete set of chromosomes.

Define the 3 diseases: Down Syndrome, Klinefelter Syndrome, and Turner Syndrome.

Down syndrome, Turner syndrome, and Klinefelter syndrome constitute the most common chromosomal abnormalities encountered by primary care physicians. Down syndrome typically is recognized at birth, Turner syndrome often is not recognized until adolescence,and many men with Klinefelter syndrome are never diagnosed. Although each syndrome is caused by an abnormal number of chromosomes, or aneuploidy, they are distinct syndromes with learning disabilities and a predisposition toward autoimmune diseases,endocrinologic disorders, and cancers. Optimal health care requires a thorough knowledge of the unique health risks, psychoeducational needs, functional capabilities, and phenotypic variation associated with each condition. Syndrome-specific health care should complement standard preventive health care recommendations. Checklists and syndrome-specific growth grids should be used. Ongoing communication between specialists and primary care physicians and between pediatric and adult clinicians is essential. Support groups and Internet resources can benefit affected individuals and their families immensely. Klinefelter syndrome, also known as the XXY condition, is a term used to describe males who have an extra X chromosome in most of their cells. A genetic chromosome 21 disorder causing developmental and intellectual delays. A chromosomal disorder that affects only females.

Which parts make up the "rungs" which make up the "sides" of the DNA structure?

First of all to the guy above me, DNA is deoxyribonucleic acid, so it cant be made of itself. Next off, the rungs are made of bases. The bases are Adenine, Guanine, Cytosine, and Thymine. The sides are made up of a sugar molecule and a phosphate. Together the base, sugar, and phosphates make up a nucleotide, which is the subunit of DNA.

Who were the scientists involved in the early discovery of DNA structure and function? What were the major findings of their experiments?

Frederick Miescher - is the man who discovered DNA. The Swiss physician isolated a high phosphorous-containing substance from white blood cell nuclei in 1869. It was DNA, which he called 'nuclein' because it had come from the nucleus. He did not know its true nature. Phoebus Levene - the Russian-American biochemist discovered the order of components of nucleic acids; phosphate-sugar-base. He coined the term 'nucleotide.' He also discovered the ribose sugar in RNA, the deoxyribose sugar in DNA, as well as identifying the way the nucleic acids - RNA and DNA - are put together. Oswald Avery - in 1944 he discovered that DNA transmitted hereditary information. This was a revolutionary concept, because the scientific consensus at the time was that DNA was too simple for this task, and that proteins were more likely to be the candidates. Erwin Chargaff - in 1950 he demonstrated that the nucleotide composition varies amongst species. This was different from Levene's view that the same nucleotides repeat in the same order. He also found that in any given species the ratio of adenine to thymine was roughly equal, and the ratio of cytosine and guanine was also roughly equal. This is known as Chargaff's rule and it helped to pave the way for Crick and Watson's studies. Rosalind Franklin - her X-ray diffraction image of DNA structure, named 'Photo 51' was a significant piece of evidence in determining DNA structure. She was briefly mentioned in Crick and Watson's proposal of the double helix structure in the journal Nature in April 1953. Watson, Crick, and Wilkins shared the Nobel Prize in Physiology or Medicine in 1962 for their work. Franklin was not acknowledged because she had died by this time and the award cannot be given posthumously. The significance of her role in DNA structure discovery was only realized after the publication of Watson's book The Double Helix in 1968. Linus Pauling - the methods he used to work out the structure of proteins were adopted by Crick and Watson. They were a combination of model building, chemistry, and physics. Maurice Wilkins - obtained the first X-ray image of DNA. He taught Francis Crick about DNA, and his images of DNA inspired James Watson. He shared the 1962 Nobel Prize in Physiology or Medicine with Crick and Watson. Francis Crick and James Watson - published their paper in Nature, in April 1953. It was one of the most important pieces of research in the history of science.

How does gel electrophoresis function and how can it be used to separate molecules?

Gel electrophoresis is a method for separation and analysis of macromolecules (DNA, RNA and proteins) and their fragments, based on their size and charge. It is used in clinical chemistry to separate proteins by charge and/or size (IEF agarose, essentially size independent) and in biochemistry and molecular biology to separate a mixed population of DNA and RNA fragments by length, to estimate the size of DNA and RNA fragments or to separate proteins by charge.[1] Nucleic acid molecules are separated by applying an electric field to move the negatively charged molecules through a matrix of agarose or other substances. Shorter molecules move faster and migrate farther than longer ones because shorter molecules migrate more easily through the pores of the gel. This phenomenon is called sieving.[2] Proteins are separated by charge in agarose because the pores of the gel are too large to sieve proteins. Gel electrophoresis can also be used for separation of nanoparticles.

Who was Gregor Mendel & what was his work?

Gregor Johann Mendel was a German-speaking Moravian scientist and Augustinian friar who gained posthumous fame as the founder of the modern science of genetics.

Who was Griffith?

Griffith's experiment, reported in 1928 by Frederick Griffith, was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation.

Difference between heterozygous and homozygous?

If a mutation occurs in just one copy of the gene then that individual is considered heterozygous. On the other hand if both copies of a gene are mutated then that individual is homozygous genotype.

How are the types of substitution mutations different? Silent, nonsense, and missense?

In genetics, a type of mutation due to replacement of one nucleotide in a DNA sequence by another nucleotide or replacement of one amino acid in a protein by another amino acid. Substitution is a type of mutation where one base pair is replaced by a different base pair. The term also refers to the replacement of one amino acid in a protein with a different amino acid.

What is a karyotype? How is it made? What kind of mutations can it detect?

Karyotyping can be done from blood, hair, or any other tissue. However, most karyotyping for medical diagnostic purposes is done on embryonic or fetal cells from unborn babies still in the uterus. The cells are usually collected by one of two methods: amniocentesis click this icon to hear the preceding term pronounced or chorionic villi sampling click this icon to hear the preceding term pronounced. Preliminary testing is now commonly done with a less invasive ultrasound examination of the fetus within the uterus and an analysis of specific fetal chemicals in the mother's blood. The goal of all of these tests is to determine whether or not the baby will be abnormal. This information can be the basis for a decision to perform an abortion or to prepare parents for the difficulties of raising a child with serious abnormalities and health problems.

3 parts of nucleotide? Which part/s change to make the different nucleotides?

Like DNA, RNA polymers are make up of chains of nucleotides *. These nucleotides have three parts: 1) a five carbon ribose sugar, 2) a phosphate molecule and 3) one of four nitrogenous bases: adenine, guanine, cytosine or uracil.

Can you complete monohybrid punnet squares?

MAKE SURE YOU CAN...

Are you able to perform a dihybrid cross? What is the phenotypic ratio if both parents are heterozygous for BOTH parents?

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Are you able to perform crosses with traits that use simple dominance, incomplete dominance, codominance, sex-linked traits, and multiple alleles?

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Are you able to tell if a trait is completely dominant, codominant, etc based on the possible phenotypes?

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Be able to ID different types of chromosomal mutations as given in Chapter 8 (inversion, duplication, and deletion, etc)

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Be able to ID metacentric, submetacentric, and acrocentric centromere position if given example chromosomes to examine.

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Be able to answer plot-related questions about Gattaca.

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Be able to discuss bioethics based on the film Gattaca.

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Be able to make basic conclusions about molecules in a gel based on a finished gel diagram.

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Be able to predict a parents' genotype based on their offspring's genotypes.

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Be able to predict the phenotype of offspring based on the parents' genotype.

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Be able to transcribe DNA to RNA, the translate the RNA into proteins using the Codon Chart.

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Be familiar with particular traits that you've worked with frequently (ie color blindness, blood types, pea plant traits).

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Could you ID diagrams of each stage even if they're out of order?

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Know ALL the definitions of your main vocab words. PRACTICE.

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Know the basic functions of each key component of gel electrophoresis. For example, agarose, buffer, comb, electric current.

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Know what a keystone species is, and how are they important?

Make sure... A keystone species is a plant or animal that plays a unique and crucial role in the way an ecosystem functions. Without keystone species, the ecosystem would be dramatically different or cease to exist altogether. All species in an ecosystem, or habitat, rely on each other.

Be able to ID biotic and abiotic factors and examples.

Make sure...And remember... Biotic factors are the living parts of an ecosystem---the animals, plants and microorganisms. Abiotic factors are the non living parts of an ecosystem.

Who were Watson and Crick?

Many people believe that American biologist James Watson and English physicist Francis Crick discovered DNA in the 1950s. In reality, this is not the case. Rather, DNA was first identified in the late 1860s by Swiss chemist Friedrich Miescher. Then, in the decades following Miescher's discovery, other scientists--notably, Phoebus Levene and Erwin Chargaff--carried out a series of research efforts that revealed additional details about the DNA molecule, including its primary chemical components and the ways in which they joined with one another. Without the scientific foundation provided by these pioneers, Watson and Crick may never have reached their groundbreaking conclusion of 1953: that the DNA molecule exists in the form of a three-dimensional double helix.

Describe and identify what happens in each stage of meiosis 1 and 2.

Meiosis I has two main purposes: It is the reduction division, so it reduces the number of chromosomes in half, making the daughter cells haploid (when the parent cell was diploid). It is during meiosis I that most of the genetic recombination occurs. Meiosis II At the end of meiosis I, each chromosome still had two chromatids. That is double the amount of DNA that a cell should have. So, the entire reason to go through meiosis II is to reduce the amount of DNA back to normal-- basically, to split the chromosomes so that each daughter cell has only one chromatid per chromosome (the normal genetic content).

What are Mendel's Theories of Inheritance?

Mendel developed 3 principles of inheritance based on his experiments with pea plants, incl Fundamental Theory of Heredity. Our understanding of how inherited traits are passed between generations comes from principles first proposed by Gregor Mendel in 1866. Mendel worked on pea plants, but his principles apply to traits in plants and animals - they can explain how we inherit our eye colour, hair colour and even tongue-rolling ability.

What is a metaphase spread?

Metaphase chromosome spread is an important technique in cytogenetics. Metaphase chromosome spread is used for karyotyping including analysis of numerical or structural changes in chromosomes.

What happens in metaphase?

Metaphase is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their most condensed and coiled stage.

What is mitosis?

Mitosis is a part of the cell cycle process by which chromosomes in a cell nucleus are separated into two identical sets of chromosomes, each in its own nucleus.

Be able to describe/define monosomy/trisomy.

Monosomy - the presence of only one chromosome (instead of the typical two in humans) from a pair. Trisomy - the presence an extra chromosome (instead of the typical two in humans) from a pair giving 3.

How are proteins made? Know the details of transcription and translation.

Most genes contain the information needed to make functional molecules called proteins. (A few genes produce other molecules that help the cell assemble proteins.) The journey from gene to protein is complex and tightly controlled within each cell. It consists of two major steps: transcription and translation. Together, transcription and translation are known as gene expression. During the process of transcription, the information stored in a gene's DNA is transferred to a similar molecule called RNA (ribonucleic acid) in the cell nucleus. Both RNA and DNA are made up of a chain of nucleotide bases, but they have slightly different chemical properties. The type of RNA that contains the information for making a protein is called messenger RNA (mRNA) because it carries the information, or message, from the DNA out of the nucleus into the cytoplasm. Translation, the second step in getting from a gene to a protein, takes place in the cytoplasm. The mRNA interacts with a specialized complex called a ribosome, which "reads" the sequence of mRNA bases. Each sequence of three bases, called a codon, usually codes for one particular amino acid. (Amino acids are the building blocks of proteins.) A type of RNA called transfer RNA (tRNA) assembles the protein, one amino acid at a time. Protein assembly continues until the ribosome encounters a "stop" codon (a sequence of three bases that does not code for an amino acid). The flow of information from DNA to RNA to proteins is one of the fundamental principles of molecular biology. It is so important that it is sometimes called the "central dogma."

What is a mutagen? What are different things that can cause mutations?

Mutations happen for several reasons. 1. DNA fails to copy accurately Most of the mutations that we think matter to evolution are "naturally-occurring." For example, when a cell divides, it makes a copy of its DNA — and sometimes the copy is not quite perfect. That small difference from the original DNA sequence is a mutation. 2. External influences can create mutations Mutations can also be caused by exposure to specific chemicals or radiation. These agents cause the DNA to break down. This is not necessarily unnatural — even in the most isolated and pristine environments, DNA breaks down. Nevertheless, when the cell repairs the DNA, it might not do a perfect job of the repair. So the cell would end up with DNA slightly different than the original DNA and hence, a mutation.

What are P, F1, and F2 generations?

P generation is the parental generation in the cross pollination between two true-breeding plants that differ in a particular trait. F1 is (first filial) generation the hybrid offspring produced in the cross pollination of P generation plants. F2 is the progeny of self-pollinated F1 generation plants.

How is cytokinesis different in animal and plant cells?

Plants use a similar process with a few differences. For example, although a plant cell creates a mitotic spindle and has a centrosome, it lacks centrioles. The other major difference in plants is the way in which cytokinesis occurs. In animal cells, the plasma membrane pinches in along the midline of the cell, creating a cleavage furrow that will separate the cytoplasm in two. Plant cells have rigid cell walls that prevent this. Instead, they use two different approaches for cytokinesis. The plasma membrane and cell wall grow inward together, eventually separating the parent cell into two. Alternatively, the cell wall that will separate the two daughter cells starts growing in the middle of the cell between the two nuclei and continues toward the periphery. This is known as the cell plate. It continues growing until its edges reach the cell's outer surface, separating the parent cell into two daughter cells.

What happens in prophase?

Prophase is the first phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. During prophase, the complex of DNA and proteins contained in the nucleus, known as chromatin, condenses.

Sub-stages in order?

Prophase, metaphase, Anaphase, and telophase are the PHASES of mitosis. The subphases are the division of the nucleus and the division of the cytoplasm.

How does DNA make copies of itself? What is that process called?

Replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules. DNA replication is one of the most basic processes that occurs within a cell. Each time a cell divides, the two resulting daughter cells must contain exactly the same genetic information, or DNA, as the parent cell. To accomplish this, each strand of existing DNA acts as a template for replication.

Who was Franklin?

Rosalind Franklin - Her X-ray diffraction image of DNA structure, named 'Photo 51' was a significant piece of evidence in determining DNA structure. She was briefly mentioned in Crick and Watson's proposal of the double helix structure in the journal Nature in April 1953. Watson, Crick, and Wilkins shared the Nobel Prize in Physiology or Medicine in 1962 for their work. Franklin was not acknowledged because she had died by this time and the award cannot be given posthumously. The significance of her role in DNA structure discovery was only realized after the publication of Watson's book The Double Helix in 1968.

Structural and chemical differences between DNA and RNA? (Shape, location, composition?)

Structurally, DNA and RNA are nearly identical. As mentioned earlier, however, there are three fundamental differences that account for the very different functions of the two molecules. RNA has a ribose sugar instead of a deoxyribose sugar like DNA. RNA nucleotides have a uracil base instead of thymine.

Know the different types of mutations. Be able to ID if given examples.

Substitution A substitution is a mutation that exchanges one base for another (i.e., a change in a single "chemical letter" such as switching an A to a G). Such a substitution could: change a codon to one that encodes a different amino acid and cause a small change in the protein produced. For example, sickle cell anemia is caused by a substitution in the beta-hemoglobin gene, which alters a single amino acid in the protein produced. change a codon to one that encodes the same amino acid and causes no change in the protein produced. These are called silent mutations. change an amino-acid-coding codon to a single "stop" codon and cause an incomplete protein. This can have serious effects since the incomplete protein probably won't function. Insertion Insertions are mutations in which extra base pairs are inserted into a new place in the DNA. Deletion Deletions are mutations in which a section of DNA is lost, or deleted. Frameshift Since protein-coding DNA is divided into codons three bases long, insertions and deletions can alter a gene so that its message is no longer correctly parsed. These changes are called frameshifts. For example, consider the sentence, "The fat cat sat." Each word represents a codon. If we delete the first letter and parse the sentence in the same way, it doesn't make sense. In frameshifts, a similar error occurs at the DNA level, causing the codons to be parsed incorrectly. This usually generates truncated proteins that are as useless as "hef atc ats at" is uninformative. There are other types of mutations as well, but this short list should give you an idea of the possibilities.

What happens in telophase?

Telophase is the fifth and final phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. Telophase begins once the replicated, paired chromosomes have been separated and pulled to opposite sides, or poles, of the cell.

Who were Hershey and Chase?

The Hershey-Chase experiments were a series of experiments conducted in 1952 by Alfred Hershey and Martha Chase that helped to confirm that DNA is the genetic material. While DNA had been known to biologists since 1869, many scientists still assumed at the time that proteins carried the information for inheritance because DNA appeared simpler than proteins. In their experiments, Hershey and Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. Although the results were not conclusive, and Hershey and Chase were cautious in their interpretation, previous, contemporaneous and subsequent discoveries all served to prove that DNA is the hereditary material. Knowledge of DNA gained from these discoveries has applications in forensics, crime investigation and genealogy.

Different types of chromosomal mutations? Examples?

The four main types of chromosomal mutations are deletion, duplication, inversion and translocation. A fifth chromosomal mutation is known as a deficiency. This occurs when a chromosome is lost sometime during fertilization or development of a fetus.

Main goals of mitosis?

The goal of mitosis is to produce two daughter cells that are genetically identical to the parent cell, meaning the new cells have exactly the same DNA as the parent cell.

What is a Giemsa band?

The metaphase chromosomes are treated with trypsin (to partially digest the chromosome) and stained with Giemsa stain. Heterochromatic regions, which tend to be rich with adenine and thymine (AT-rich) DNA and relatively gene-poor, stain more darkly in G-banding.

What chromosome number would be found in gametes if nondisjunction occurs in Meiosis I or II?

The most common cause of aneuploidies is nondisjunction during meiosis. Nondisjunction means that a chromosome pair failed to separate during the meiotic division. This will create one daughter cell with an extra chromosome and another daughter cell with one too few chromosomes. If the nondisjunction occurs during the first meiotic division (meiosis I), all the gametes derived will be abnormal. Half of them will contain neither members of the chromosome pair, while the other half will contain both homologous chromosomes (Figure 1A). In humans, for example, if nondisjunction of chromosome 13 occurs during first meiotic division, half the gametes will have an extra copy of chromosome 13 and thus contain 24 chromosomes instead of the normal haploid number of 23. The other half of the gametes derived from this primary gametocyte will lack both copies of chromosome 13. Thus, these gametes will only have 22 chromosomes. When these gametes unite with the gamete of the opposite sex, no embryo will be viable. The zygotes would either contain 47 chromosomes (23 + 24) or 45 chromosomes (23 + 22). In the first instance, the fetus would contain three copies of chromosome 13 instead of two. This is called trisomy 13 and the fetus has extra fingers, cleft lip, small head, and triangular nose. Most of these fetuses die in the uterus, but those who survive to be born usually die within the first year. The other fetuses from this nondisjunction would lack any chromosome 13. This is called monosomy 13, and such embryos are unable to live.

Purpose of meiosis?

The purpose of meiosis is to increase the genetic variation. After meiosis there are four haploids, each with different sets of chromosomes. However, in mitosis the end result are two identical diploids. Meiosis is used in sexual reproduction, since to reproduce, an egg and a sperm have to come together for reproduction to occur. This further increases the genetic variation which allows for evolution and the adaptation of organisms to different environments.

Can you describe what happens throughout the cell during each stage of mitosis?

The sequence of events is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are prophase, prometaphase, metaphase, anaphase, and telophase. During mitosis, the chromosomes, which have already duplicated, condense and attach to fibers that pull one copy of each chromosome to opposite sides of the cell. The result is two genetically identical daughter nuclei. The cell may then divide by cytokinesis to produce two daughter cells. Errors during mitosis can induce apoptosis (programmed cell death) or cause mutations. Certain types of cancer can arise from such mutations.

What chromosome determines the sex of the baby?

The sex of a human baby is determined by the composition of its sex chromosomes (a single distinct pair among humans' 23 pairs of chromosomes). Females possess two copies of the same chromosome (referred to as the 'X' chromosome); males have one copy of the X chromosome and one copy of the smaller, hook-shaped Y chromosome. When fertilization occurs, the new gamete (the initial cell from which a fetus grows) always inherits one of the mother's X chromosomes, and either a X or a Y from the father, depending on which chromosome the fertilizing sperm cell happened to inherit. One could say, then, that the father—or, at least, his sperm—determines the sex of the child. On the other hand, the first sperm to reach the egg isn't necessarily the one that fertilizes it; human eggs are rather choosy about that sort of thing. So, in an indirect way, the maternal parent also has some influence on the sex of the child.

For each of these 3 diseases, what is the chromosomal mutation causing each one, what are the basic traits of each, and ID a karyotype of each one.

Turner syndrome is related to the X chromosome, which is one of the two sex chromosomes. People typically have two sex chromosomes in each cell: females have two X chromosomes, while males have one X chromosome and one Y chromosome. Turner syndrome results when one normal X chromosome is present in a female's cells and the other sex chromosome is missing or structurally altered. The missing genetic material affects development before and after birth. About half of individuals with Turner syndrome have monosomy X, which means each cell in the individual's body has only one copy of the X chromosome instead of the usual two sex chromosomes. Turner syndrome can also occur if one of the sex chromosomes is partially missing or rearranged rather than completely absent. Some women with Turner syndrome have a chromosomal change in only some of their cells, which is known as mosaicism. Women with Turner syndrome caused by X chromosome mosaicism are said to have mosaic Turner syndrome. Researchers have not determined which genes on the X chromosome are associated with most of the features of Turner syndrome. They have, however, identified one gene called SHOX that is important for bone development and growth. The loss of one copy of this gene likely causes short stature and skeletal abnormalities in women with Turner syndrome. Klinefelter syndrome is a condition related to the X and Y chromosomes (the sex chromosomes). People typically have two sex chromosomes in each cell: females have two X chromosomes (46,XX), and males have one X and one Y chromosome (46,XY). Most often, Klinefelter syndrome results from the presence of one extra copy of the X chromosome in each cell (47,XXY). Extra copies of genes on the X chromosome interfere with male sexual development, often preventing the testes from functioning normally and reducing the levels of testosterone. Most people with an extra X chromosome have the features described above, although some have few or no associated signs and symptoms. Some people with features of Klinefelter syndrome have more than one extra sex chromosome in each cell (for example, 48,XXXY or 49,XXXXY). These conditions, which are often called variants of Klinefelter syndrome, tend to cause more severe signs and symptoms than classic Klinefelter syndrome. In addition to affecting male sexual development, variants of Klinefelter syndrome are associated with intellectual disability, distinctive facial features, skeletal abnormalities, poor coordination, and severe problems with speech. As the number of extra sex chromosomes increases, so does the risk of these health problems. Some people with features of Klinefelter syndrome have the extra X chromosome in only some of their cells; in these individuals, the condition is described as mosaic Klinefelter syndrome (46,XY/47,XXY). Individuals with mosaic Klinefelter syndrome may have milder signs and symptoms, depending on how many cells have an additional X chromosome. Most cases of Down syndrome result from trisomy 21, which means each cell in the body has three copies of chromosome 21 instead of the usual two copies. Less commonly, Down syndrome occurs when part of chromosome 21 becomes attached (translocated) to another chromosome during the formation of reproductive cells (eggs and sperm) in a parent or very early in fetal development. Affected people have two normal copies of chromosome 21 plus extra material from chromosome 21 attached to another chromosome, resulting in three copies of genetic material from chromosome 21. Affected individuals with this genetic change are said to have translocation Down syndrome. A very small percentage of people with Down syndrome have an extra copy of chromosome 21 in only some of the body's cells. In these people, the condition is called mosaic Down syndrome. Researchers believe that having extra copies of genes on chromosome 21 disrupts the course of normal development, causing the characteristic features of Down syndrome and the increased risk of health problems associated with this condition.

What is methionine? Why is it important?

When in its natural L-form, methionine is a proteinogen amino acid. It is classed as an essential amino acid and cannot be synthesized by the body itself. This means that a sufficient supply of methionine in the diet or as a dietary supplement is of particular importance. Sulphur compounds occur in all living creatures and have a multitude of functions. Besides cysteine, methionine is the only sulphur-containing amino acid. Furthermore methionine plays an important role in the synthesis of other proteins, such as carnitine or melatonine. Methionine has a fat-dissolving effect and reduces the depositing of fat in the liver. Methionine is an important cartilage-forming substance.

What is a test cross? Why are they useful? How are they used?

first introduced by Gregor Mendel, involves the breeding of a phenotypically dominant individual with a phenotypically recessive individual, in order to determine the zygosity of the former by analyzing proportions of offspring phenotypes. Zygosity can either be heterozygous or homozygous.

AAA TTA CGG to TAA ATT ACG would be what type of mutation?

frameshift

What are the 3 types of RNA? Where are they found? What are their jobs?

mRNA or Messenger RNA mRNA transcribes the genetic code from DNA into a form that can be read and used to make proteins. mRNA carries genetic information from the nucleus to the cytoplasm of a cell. rRNA or Ribosomal RNA rRNA is located in the cytoplasm of a cell, where ribosomes are found. rRNA directs the translation of mRNA into proteins. tRNA or Transfer RNA Like rRNA, tRNA is located in the cellular cytoplasm and is involved in protein synthesis. Transfer RNA brings or transfers amino acids to the ribosome that correspond to each three-nucleotide codon of rRNA. The amino acids then can be joined together and processed to make polypeptides and proteins.

(2n and 1n) What is "n?" Is "n" always the same?

n = 1 complete set of chromosomes

What is the Law of Independent Assortment? (Mendel)

states that allele pairs separate independently during the formation of gametes. This means that traits are transmitted to offspring independently of one another.

What is the Law of Segregation? (Mendel)

stating that during the production of gametes the two copies of each hereditary factor segregate so that offspring acquire one factor from each parent.

What is nondisjunction? Potential results of nondisjunction?

the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.

What are the enzymes involved in DNA replication and what are their roles? (Remember: Primase, Helicase, Polymerase, Ligase)

unzipping the DNA helix (helicase) synthesizing the RNA primer (primase) adding bases to the new DNA chain; proofreading the chain for mistakes DNA (polymerase III) removing primer, closing gaps, repairing mismatches DNA (polymerase I) final binding of nicks in DNA during synthesis and repair (ligase) supercoiling (gyrase)