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Review and Discussion
Study Packet Questions
Angela - BROWN
State that some genes have more than 2 alleles (multiple alleles).
Most genes exist in large populations that are in forms of two or more alleles.
Explain how the sex chromosomes control gender by refering to the inheritance of X and Y chromosomes in humans.
The gender of an offspring is dependent on what kind of chromosome the sperm, which fertilizes the ovum, contains either the X or Y chromosome, while the ovum contains an X chromosome. The homologous regions in the Y chromosomes allow pairing with the X chromosome. During meiosis this allows behavior like homologous chromosomes within the testes.
Explain that the female carriers are heterozygous for X- linked recessive alleles.
Only one X gene in females is expressed even though they have two. The other X chromosome in an inactive structure which is also called the Barr body. So the chromosome has a possibility that is carries the recessive allele, but does not express it because of the inactivity.
Explain how meiosis results in an effectively infinite genetic variety in gametes through crossing over in anaphase I and random orientation in metaphase I.
With crossing over in anaphase I give chromosomes many combinations creating an infinite variability of genes. Random orientation also creates an infinite number of genes with the help of independent assortment. This causes an even larger number of varieties within genes.
Explain the relationship between Mendel’s law of independent assortment and meiosis.
Mendel's law of independent assortment is a reason for meiosis yielding many varieties of combinations of genes. The law states that the chromosomes separate independently from one another into cells in meiosis. So the distribution of genes in one trait does not have any affect on other distributions on genes of different chromosomes, which allows the great variety of genes created by meiosis.
Distinguish between autosomes and sex chromosomes.
A sex chromosome is the chromosome that determines the sex, gender. An autosome is every other chromosome that does not determine the sex. Ex: hair color, eye color, height, etc.
Explain an example of a cross between two linked genes.
An example of a cross between two linked genes is as follows:
Having an organism with the genes of AABB with another organism with the genes aabb, the F1 generation offspring that is resulted can only have the genes of AaBb. Also, the F2 generation offspring will result with genes that are in a 9:3:3:1 ratio.
Define genotype, phenotype, dominant allele, recessive allele, codominant alleles, locus, homozygous, heterozygous, carrier and test cross.
Genotype is the genetic makeup of an organism which includes recessive genes.. Phenotype is the physical characteristics of an organism. A dominant allele is the allele that is fully expressed in the phenotype. Recessive allele is the allele that is completely hidden in the phenotype. Codominant alleles is when both alleles are expressed in the phenotype. Locus is a particular place along the chromosome where a gene is located.Homozygous is two identical alleles for a given trait. Heterozygous is two different alleles for a given trait. A carrier is an individual that has one copy of a recessive allele that causes a genetic disease in individuals that are homozygous for this allele. A test cross is when you determine a genotype by using their dominant phenotype and crossing it to a homozygous recessive genotype.
Describe ABO blood groups as an example of codominance and multiple alleles.
Blood is an example of codominance because people can have type AB in which both A and B aggulutinogens are expressed in your phenotype. It is also an example of multiple alleles because there are more than 2 alleles for this given gene. There is A, B, and O and plenty of variations.
Describe the inheritence of colour blindness and hemophilia as examples of sex-linkage.
Color blindness and hemophilia are both examples of sex-linked traits. They are found on the X chromosome. If women inherit it the other X chromosome will mask it unless it carries the gene too. If men inherit it the Y has nothing to pair up with that gene and it will be in the phenotype. Their mother would have to be a carrier or have it because the Y will be from the dad. It's more common in males. It's rare for women to inherit 2 infected X chromosomes.
Predict the genotypic and phenotypic ratios of offspring of monohybrid crosses involving any of the above patterns of inheritence.
75% will have the normal phenotype while 25% will actually have color blindness.
Define linkage group.
Linkage groups are any group of genes inherited together because they are found on the same chromosome. Usually passed down to the next generation together.
. Explain how crossing over between non-sister chromatids of a homologous pair in prophase I can result in an exchange of alleles.
It results in the exchange of alleles when the chromosomes mixed or cross over. While they double and crossover the genes begin to get switched and multiple variations begin to open up. When crossing over occurs parts of chromosomes exchange including the genes which includes the alleles.
Identify which of the offspring are recombinants in a dihybrid cross involving linked genes.
The above picture indicates a dihybrid cross between RrYy and RrYy. Recombinants are when the offspring has a different combination of alleles from the parents. The recombinants in the above punnett square are: RRYY, RRYy, RrYY, RRyy, Rryy, rrYY, rrYy, Rryy, and rryy.
Liane - PURPLE
4.3.2 Determine the genotypes and phenotypes of the offspring of a monohybrid cross using a Punnett grid.
A genotype is the genetic make-up of an organism. An organism’s phenotype determines its physical appearance. In a monohybrid cross, phenotypes and genotypes are predicted through the use of a Punnett square. In an example of a BB and bb cross, the phenotype would be 100% black and 100% carriers of white, because of the recessive b. The genotype of this offspring would be 100% heterozygous (Bb).
A monohybrid cross yields a 3:1 ratio phenotypically.Genotypically, its ratio is 1:2:1.
4.3.6 State that some genes are present on the X chromosome and absent from the shorter Y chromosome in humans.
Some genes present in the X-chromosome are not in the Y-chromosome. For one thing, the shorter Y-chromosome does not have enough loci for a greater amount of genes to be stored in. Y-chromosomes have fewer genes present in it because during meiosis, there is no other Y-chromosome that it can pair with. The shorter Y chromosome, as a result, only contains “junk” genetic information as opposed to active genes.
While the X-chromosome holds a lot of genes, the Y-chromosome holds 78. One of these 78 is the sex-determining region Y, also called SRY. This gene determines an organism’s gender. Within the first few weeks of fertilization, an embryo is a female, because of the XX chromosome. The conversion of the SRY into the male sex (XY) makes the male population possible.
notice the shorter Y
4.3.7 Define sex linkage.
Sex linkage determines the phenotype of an organism through its sex chromosome. Sex linkage essentially means a trait is controlled by the sex chromosome. Men inherit Y-linked traits because of the Y-chromosome present in their DNA. Both men and women, though, are susceptible to X-linked traits because they both have X chromosomes.
4.3.9 State that a human female can be homozygous or heterozygous with respect to sex-linked genes.
Females are heterozygous because they inherit each of their X chromosomes from both their parents. Males can only receive the X chromosome through their mothers. As a result, when one gene in the X chromosome is a defect, a female’s second X chromosome can counteract this and have a normal phenotype. Genotypically, she will be a carrier of that defect or trait. If a male inherits a defected X chromosome, he will have a defective phenotype because he has no second X chromosome to cancel out the defect.
Homozygous means that one trait has the same alleles.
Females can be homozygous. This claim is attributed to their XX chromosome. When a trait is passed down to a female, the trait is homozygous dominant because both her chromosomes are X’s.
A heterozygous female means that she is a carrier of a trait. Take the case of hemophilia, for example. Since hemophilia is an X-chromosome disorder, males are more susceptible to it because the Y chromosome cannot cancel out the diseased X chromosome. Females are more likely to be carriers of the disease because of its recessive nature.
4.3.12 Deduce the phenotypes and genotypes of individuals in pedigree charts.
Pedigree charts are much like family trees in that they show the relationship between people in a certain family. The squares indicate that the organism is male, while a circle means an organism is female.
With a pedigree chart, knowing an organism’s phenotype and genotype is dependent on each other. If the phenotype is known, then the probability of knowing an organism’s genotype is greater because we can trace back to generation groups.
10.1.4 State Mendel's Law of Independent Assortment
Mendel’s Law of Independent Assortment states that when gametes for, the separation of one pair of alleles between the daughter cells is independent of the separation of another pair of alleles.
This law is evidenced by meiosis. When chromosomes line up during metaphase I, they can figure out the types of alleles and their ratios that the daughter cells will have. Assuming there is no crossing over that takes place, certain alleles don’t have to go along with another pair.
Simply put, one trait doesn’t follow any other trait from any other trait of that parent. For example, genes that code for a seed color does not interfere with genes that code for the flower color.
10.2.1 Calculate and predict the genotypic and phenotypic ratio of an offspring of a dihybrid cross involving unlinked autosomal genes.
A dihybrid cross of an organism yields a 9:3:3:1 ratio phenotypically. There will be 16 possible combinations for genetic inheritance. Nine out of sixteen will have the traits because they were both dominant. Three out of sixteen will be heterozygous. This will occur in two probabilities (2 three out of sixteen’s). One out of sixteen will have the homozygous recessive trait.
The genotypic ratio is 1:2:2:1:4:2:1:2:1. The same idea is applied to the phenotypic ratio, only more specific, as the carriers are determined.
Genetic Engineering and Biotechnology
Outline the use of polymerase chain reaction (PCR) to copy and amplify minute quantities of DNA.
A PCR machine is used in order to copy pieces of DNA so you can have a large sample to work with. In order to do so the PCR heats DNA to pull it apart and then is lowered to join primers and DNA nucleotides together. The end result is different sizes of DNA. They are allowed to be in different sizes since the primers start at a certain sequence in the DNA. It is a continuous process that results in many different pieces of DNA.
State that ,in gel electrophoresis, fragments of DNA move in an electric field and are seperated according to their size.
Gel electrophoresis is the step after PCR machine. It is used to seperate the different DNA fragments with the use of an electric current. The electric field goes from negative"---" to positive "+". The smaller pieces of DNA go to the bottom of the gel since they can move through it faster while the "fatter" or larger pieces of DNA tend to stay near the top of the gel. A dye is later on placed in order to see the DNA better.
Outline three outcomes of the sequencing of the complete human genome.
If we know the whole complete human genome then we could find out what causes certain diseases. To find out the number of genes in the human genome. By finding out all the sequences people could possibly design a baby by picking and choosing their genes. Also we could use these sequences to find possible cures to diseases by knowing the gene that causes it. Another outcome would be to compare the human genome to another species to study deeper into evolution. These are some of the outcomes in addition to genetically altering foods/animals.
Outline a basic technique used for gene transfer invovlving plasmids, a host cell (bacterium, yeast, or other cell), restriction enzymes (endonucleases) and DNA ligase.
First you need to isolate a plasimd in this case the Ti plasmid from the bacteria Agrobacterium which causes tumors in plants. After isolating the plasmid a restriction enzyme cuts the plasmid cuts where the defective gene is (in this case the gene that causes tumors) and replaces in with a gene of interest from another plant. They are binded together with DNA ligase. This new plasmid is called the recombinant plasmid and is introduced into plant cells. These cells are grown in tissue cultures and later re-located out to grow normally.
4.4.9 State two examples of the current uses of genetically modified crops or animals.
Genetically modifying crops and animals has long been a practice in different industries. Genetically modifying crops have helped industries produce better products.
An example of a genetically modified crop is the Golden Rice. It is very valuable to underdeveloped countries because of its nutritional benefits. Because diet is very limited in Asia and other Third World countries, it is important to pack more essential nutrients into one product. People in these countries do not have the luxury of getting their nutrients from several choices of food. They very rarely eat more than 2 meals per day, so they have to absorb nutrients from whatever those two pieces of food may be. Golden Rice is very rich in beta carotene, which strengthens eye sight. Beta carotene is a nutrient usually found in carrots.
Genetic modification is not limited to crops. Animals have also long since been genetically modified. A lot of the meat we eat today have been "genetically altered" in that they have been injected with hormones and such. This is done in order for the animal to produce more products. For example, a cow in a farm may be injected with a growth hormone that increases muscle development as well as milk production. They are also genetically modified in order to increase their omega-3 fatty acid content. While genetic modification of animals have faced criticisms, the modifications do have some benefits. Recently, one company developed a drug that prevented mad cow disease that was to be injected into the cows in the farm.
4.4.10 Discuss the potential benefits and possible harmful effects of one example of genetic modification.
One example of genetic modification is gene therapy. Gene therapy involves the modifying of genes in order to improve a person's condition. This form of genetic modification is one that yields the most controversies and discussions because of its implications. Ethically, the main concern is that gene therapy essentially means you're tampering with a person's make-up, genetically. Phrases like "playing God" are thrown around in conversations about this topic. There is a lot of truth to it though, as you're controlling someone's phenotype and genotype. It's much like shopping around for a human being.
While the controversies gene therapy entails puts it in such a bad light, there are also some positives to take out of it. Gene therapy gives diseased people some hope of getting better. Children with ADA, an untreatable disease, were given hope when it became the first disease to be approved for gene therapy. Because it is a disease that "lives" in one gene, it is easy to be altered through gene therapy (it's much easier to isolate). As this affected gene is altered, a child's immune system becomes less and less affected by the ADA.
4.4.11 Define clone.
The most common form of cloning we know is reproductive cloning. This is when we engineer a copy of another organism. With cloning, we genetically engineer another organism with the same DNA information as another organism's. Cloning could be achieved through the transfer of genetic material from the nucleus of a cell to an egg whose nucleus has been removed. The cell division is then simulated through electric current. Once an embryo is cloned, it is placed into a healthy mother's womb to develop until it is released in birth.
4.4.13 Discuss the ethical issues of therapeutic cloning on humans.
Therapeutic cloning is what we know better as stem cell research. It is the harvesting of stem cells not to clone organisms, but to grow specialized cells that can be developed into (essentially) anything. This is among the most valuable tool for a scientist. This may be the missing link we have to cure heart diseases, Alzheimers, and other degenerative diseases.
The only thing that's really stopping us are the ethical concerns of the research. Because of the extraction process of therapeutic cloning, many religious organizations and human rights groups have spoken out against it. Therapeutic cloning involves the extraction of stem cells from an embryo in its 14th day in the womb. The extraction process causes the embryo to be destroyed. The main concern is that these embryos never develop into people, and we are, essentially, killing babies. Part of the debate is the question of when "ensoulment" takes place. That is, when does an embryo turn into a human being? This question has long been left unanswered because it is highly debatable.
4.4.3 State that gel electrophoresis of DNA is used in DNA profiling
DNA profiling is the identification of individuals for crime scenes, paternity tests and
other things. Gel electrophoresis is an example of it.
4.4.4 Describe the application of DNA profiling to determine paternity and also in forensic investigations.
In forensics, DNA profiling is used to determine the guilt, especially when having a suspect
and DNA from the crime scene. Within a paternity test, DNA profiling is used so that a father
can be determined of a child if it is not known.
4.4.5 Analyze DNA profiles to draw conclusions about paternity of forensic investigations.
Conclusions to DNA profiles are the discovery of proteins and its functions, knowledge of
the number of human genes, and evolutinoary relationships.
4.4.7 State that, when genes are transferred between species, the amino acid sequence of polypeptides
translated from them is unchanged because the genetic code is universal.
5.4.1 Define evolution
Evolution is the change in genetic composition of a population overtime.
5.4.4 Explain that the consequence of the potential overproduction of offspring is a struggle for survival.
The environment can only support a certain amount of population and an overproduction of it is a cause of survival of the fittest. Few can survive and few may die because of the lack of food and space in the environment.
5.4.7 Explain how natural selection leads to evolution.
Natural selection is caused by changes in the environment which causes only the organisms adaptable to the environment to survive and the other die. This leads to evolution because of the changes of organisms that survive.
Liane - Purple
5.4.3 State that populations tend to produce more offspring than the environment can support.
Living organisms produce far more offspring than could ever survive. As a result, food, water, and territory become restricted. Competition then develops between and withing the species for survival. This is Darwin's theory of survival of the fittest. Only a few of the organisms who could withstand the conditions could survive and live on for the next generation. As this process repeats, the population then adapts better to the environment.
Sexual reproduction promotes variation in a species because of meiosis. Gametes are formed from each parent, so rather than just having the exact copy of one parent's chromosome, both parents chromosomes are recombined to form a more varied organism. As a species, variation is created by sexual reproduction in order to create a heterozygous advantage. If all organisms within a species were homozygous, the entire population could perish if there is an unsuitable environment. Heterozygotes could survive by repopulating the ecosystem with better suitable organsims (who are carriers of the stronger gene) who could adapt to the environment.
5.4.2. Outline the evidence for evolution provided by the fossil record, selective breeding of domesticated animals and homologous structures.
Fossil record can help show the evolutionary history of a specific species. It is evidence of evolution because it is the layers of sedimentary rock. They go from youngest to oldest in descending order. By looking at the fossils you can determine the similarities in the species and the changes. This is unreliable because it does not give exact dates and it is incomplete. The different layers represent environmental changes too. Seletive breeding of domesticated animals are also an evidence for evolution. It is evidence because through selective breeding you can tell if a species is related. Homologous structures are a structure that can adapt to different species such as the pentadactyl limb. It adapts to the different needs of each specific mammal. This adaption shows evolution in how we adapt to survive. An example would be the finches on the Galapagos Islands. Many of them died but the ones able to survive reproduced and over time slowly adapted.
5.4.5. State that the members of a species show variation.
The members of a species have many variations. They are able to interbreed and produce different possibilities giving the species a higher chance of survival if any allele disappeared then the variation of heterozygous genes could bring it back. An example of variation within a species is humans. Everyone is different: black hair, brown, blond, orange,etc. This is only hair there are many other differences.
5.4.8. Explain two examples of evolution in response to environmental change; one must be antibiotic resistance in bacteria.
One example of evolution in response to environmental change is the peppered moth. When the Industrial Revolution in England occured the gray moths stood out more to predators and the darker moths could be easily hidden. As the environment went back to normal the black moths stood out more and their overpopulation went back to the equilibrium it was at before. Before gray moths died of but thanks to the heterozygous advantage of recessive genes being able to make a come back they came back. Another example is the given antibiotic resistance which is when the body develops resistance to harmful bacteria which only become stronger when an antibiotic is applied. It will help for the moment but the disease will evolve and get stronger, more immune to the antibiotics. We can not produce antibiotics fast enough to fight it back and by the time they do the resistant gene has spread all around the world. The way they become stronger is due to the fact that treatments are not finished and only the most resistant strands remain. They reproduce and continue to evolve to become stronger and stronger.
6.2.5 Explain the relationship between the structure and function of arteries, capillaries and veins.
The function directly relates to the structure. Arteries which carry blood away from the heart have thick walls made of muscle and elastin allowing the artery to contract and expand as needed to maintain pressure. Arteries closer to the heart are larger, thicker, and have a large lumen which allows them to serve as a low-resistance pathway. Veins which carry deoxygenated blood to the heart are thin and have valves. These valves allow them to prevent backflow, keep the blood moving in one direction, to the heart and maintain pressure. Capillaries are very small and thin connecting arteries and veins through arterioles and venules. This allows them to be semi-permeable which allows for exchange of gases, wastes, hormones, etc. This is how function correlates to the structure of each blood vessel.
6.2.7. State that the following are transported by the blood: nutrients, oxygen, carbon dioxide, hormones, antibodies, urea, and heat
Blood has many functions and one is transport. It provides nutrients and oxygen to cells. It transports carbon dioxide from the cells to the lungs to be excreted. Other waste such as urea is sent to the kidney to be excreted. Hormones are transported from the endocrine glands to where necessary. Antibodies are transported in the plasma to help protect against disease. Heat is a waste transported out of the body.
H.5.3. Outline the mechanisms that control the heartbeat, including the roles of the SA (sinoatrial) node, AV (atrioventricular) node, and conducting fibers in the ventricular walls.
The SA is known as the pacemaker generates a wave of electrical signals throughout the atria causing the atria to contract. Then these signals proceed to the AV node where they are a little delayed. The impulse continues to move to the Bundle of His down the septum. After this the impulse is split to two branches (Purkinje fibers) through the walls of the ventricles causing it to contract. This is how the heartbeat is controlled.
6.2.1 Draw and Label a diagram of the heart showing the four chambers, associated blood vessels, valves, and the route of blood through the heart.
6.2.2 State that the coronary arteries supply heart muscle with oxygen and nutrients
The coronary artery supplies oxygen and nutrients to the heart muscle.
6.2.3 Explain the action of the heart in terms of collecting blood, pumping blood, and opening and closing of valves.
The right atrium is relaxed so that can be received from the superior and inferior vena cava. The right atrium is filled with blood and the pressure (SA node) allows the tricuspid valve to open. Once the right ventricle is filled with the blood collected from the atrium, the tricuspid valve closes. The AV node sends an impulse to the Bundle of His and to the Purkinje fibers to contract the muscle in the ventricle. The pulmonary valve opens and the blood leaves the ventricle into the pulmonary arteries. Oxygenated blood reaches the left atrium and the same process occurs as the right atrium and at the same time. Instead of the tricuspid it is the bicuspid. The blood leaves the left ventricle when the aortic valve opens and out through the aorta to the body.
6.2.4 Outline the control of the heartbeat in terms of myogenic muscle contraction, the role of the pacemaker, nerves, the medulla of the brain and epinephrine (adrenaline).
The pacemaker sends out signals from its location which is at the SA node in the wall of the atrium. The signal causes the heart to carry out a contraction. Myogenic means that the heart can beat all by itself without any other environmental help. The pacemaker receives messages from hormones and nerve. Adrenaline is secreted by the Sympathetic nerve that is carried to the brain so the pacemaker can speed up the heart
Liane - Purple
6.2.6 State that blood is composed of plasma, erythrocytes, leucocytes (phagocytes and lymphocytes) and platelets.
Blood is composed of plasma, erythrocytes, leucocytes, and platelets. Erythrocytes are red blood cells, and are without a nucleus. They make up about 50% of blood. They transport oxygen from the lungs to the rest of the body. Leucocytes are the white blood cells and they make up only a small portion of the blood, at around 1%. They are made from the bone marrow and are very helpful in fighting viruses, bacteria, and fungi. Platelets, like the RBC's, are without nuclei. They help clot blood in wounded areas of the body. Platelets are very small, only about a third the size of an RBC.
H.5.1 Explain the events of the cardiac cycle, including atrial and ventricular systole and diastole, and heart sounds.
The cardiac cycle begins with the heart muscle's relaxation, called diastole. As the atria relax, they fill with blood from the vena cava and pulmonary veins. The pulmonary semilunar valves and the aortic semilunar valves are closed, as well as the tricuspid and bicuspid. Pressure from the atria causes the 2 AV valves to open and the ventricles to fill. As the ventricles fill and stretch, the AV valves close. Both ventricles contract (systole). Pressure from the contraction of the ventricles causes the aortic and pulmonary semilunar vlves to open and the blood leaves the heart. The ventricles then relax and blood flows backward to the heart. The cusps of the semilunar valves are filled with blood and they close. The heart's sounds are "lub" and "dub". Lub us caused by the closing of the AV valves, and dub is caused by the closing of the semilunar valves.
H.5.4 Outline artherosclerosis and the causes of coronary thrombosis.
Artherosclerosis is a common occurrence today. It is the buildup of fatty materials in the circulatory system. It eventually leads to the blockage of the arteries and is very harmful when it continues. As these fatty materials thicken, they form calcium deposits, which are hard. Symptoms of artherosclerosis include hypertension, which is also known as high blood pressure. This results from the blood's struggle to pass through a person's arteries.
Coronary thrombosis is what is known to most as a heart attack. There are several causes to heart attacks. The main one is a blood clot in one of the 3 major arteries surrounding the heart. If this happens, no blood can supply the heart muscle and it will stop beating. Artherosclerosis can cause a coronary thrombosis. Family history also contributes to the causes of heart attacks.
H.5.5 Discuss the factors that affect the incidence of coronary heart disease.
Coronary heart disease is the narrowing of the blood vessels that supply blood to the heart. It is also caused by artherosclerosis, because the plaque build up prevents blood flow to the heart. High blood pressure can cause CHD because of the abnormal blood flow to the heart. Smoking is also a huge factor. Smokers, statistically, are at a higher risk of CHD because of the things in cigarettes. These materials, such as tar, can block the alveoli in the lungs and cause irregular heart beats.
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