Genetic Variations of Inheritance

Genetic Variations of InheritanceStar Daganskaia-KnightonGeneticsTAQ1 What argon agents and chromosomes and what do they do?A gene is a unit of desoxyribonucleic acid needed to make a protein, they range between hundreds and millions of base pairs. These pairs control development and switch on and off depending on environmental factors, an example is a gene switching on when an immune cell meets a bacterium to produce antibodies to destroy it. DNA is what we argon, distributively mortal has their own set of DNA which makes up their characteristics, except for identical twins who share the same DNA. The human genome is composed of approximately 3 billion bases of DNA. DNA is mixed baged into structures call(a)ed chromosomes, each cell containing 23 pairs of chromosomes unmatched set from each parent. The reiterate helix coils around hist adept proteins, they wind together and lock into densely gyrate chromatin. Each single gene encodes a protein and each of those proteins resu lts in a distinct or contagious trait e.g. attached ( governing) or free hiatus earlobes (recessive). Allele are a similar gene for eye colour, these are also recessive or dominant. The dominant gene is an allele for brown eyeball so to inherit single or cardinal alleles for brown eye meat you allow for have brown eye whereas an allele for blue eyes is recessive so a person must inherit two copies of allele for blue eyes to have blue eyes.TAQ2 Discuss the work of the Austrian Monk Gregor Mendel1. Mendel was a Monk with a love for science, he disc overed the police forces of inheritance by working with pea plant plants. His work on pea plants went over eight years, with this he deducted that genes come in pairs and and are then inherited one pair from each parent. He monitored the look of the offspring from each pea plant and tracked which genes were dominant or recessive (he could track this by the look of the leaves, seeds, taste). Unfortunately his results were not unders tood or appreciated until 1900.Mendel had three rules of lawLaw of segregation two copies of each heredity factors segregate during the production of gametes so that one factor from each parent can be acquired by the offspring.Law of independent assortment this is the law of bechance, it is by chance which characteristics in particular will occur in the individual offspring.Law of dominance and recessiveness one factor in the pair of traits will dominate the gene and become inherited unless both genes are recessive.2. Punnett diagram of the recessive homozygous (non-toungue rolling father) and dominant heterozygous (tongue rolling mother). If they were to have four children then two of them would be open to roll their tongues and two would not, with their genetics or 50% of their children would be able to roll their tongues. This is the genotype the beings genetic make up which is a combination of alleles. The phenotype is the physical characteristic you can see e.g. eye co lour, earlobes, hair type (curly uninterrupted etc.) and tongue rolling.Mother amaze/TttTttttTttt3. Phenylthiocarbamate (PTC) is a chemical that some concourse envision incredibly bitter to taste and others cant taste at all. There is a difference in taste thresh hold between different populations and ages, the ability to taste the chemical comes from the dominant gene. Below is a Punnett diagram showing that if both parents are hetrozygous then there is or 25% chance of having a child who can taste PTC. This means if they had 4 children, three of them may not be able to taste PTC. Mendalian law explains monohybrid is inheritance of one through two generations.Mother Father /FfFFFFfffFff4.Mother Father /TFTftFtfTfTTFfTTffTtFfTtffThis Punnett diagram shows that if the mother is a homozgous tongue roster and a non PTC taster marries a man who is a heterozygous tongue roller and is heterozygous PTC taster and then goes on to have 16 children all of the children will be tongue rol lers as it is the dominant gene show in the punnett diagram as a T. 8 of those 16 children (50%) will be PTC tasters as the dominant gene (F) is carried on to half of their children.Mendalian law explains dihybrid as inheritance two through two generations.5.MotherFather /TFTftFtfTFTTFFTTFfTtFFTtFfTfTTFfTTffTtFfTtfftFTtFFTtFfTtFFttFftfTtFfTtffttFfttffThis shows the dehybrid blow and the independent segregation of traits, proving Mendels second law. This is also known as Phenotype distribution. This punnett diagram explains that if a mother and father who are both heterozygous tongue rollers and PTC tasters have 16 children they will come out as a 9331 ratio of traits. 9 children will be TTFF dominant, 3 children will be Tff, 3 children will be ttF and 1 child will be a double recessive ttff meaning they are unable to taste PTC and are unable to roll their tongues.TAQ31. Explain genetic connectednessage and why it is important in the transmission of genetic characteristics.Genetic linkage was discovered when Thomas lean Morgan did experiments of fruit flies and notices a difference in eye colour dependant on the sex of the fruit fly. Genetic linkage is the crop in which if two genes are close to each other on a chromosome they are frequently inherited together during meiosis. In many cases two alleles inherited from one parent tend to stay together and is the same for the other parent this is called linkage. Two alleles make up an autosome, so two associated genes on a chromosome would be hair and eye colour. These two genes are close to each other on the genetic strand (locus) so are un in all likelihood to cross over and mix, the most likely outcome is that one parent will have the dominant gene and give child X brown eyes and blond hair instead of red hair (recessive gene) and blue eyes (recessive). This does now contradict Mendels law of independent assortment and begs the question how did Mendel not get together linkage?.2. Explain how sex or gender i s de considerationined.Autosomes are the first 22 chromosomes that subside everything but your gender, the 23rd chromosome pair will every decide you to be fe manful (XX) or male (XY). The mother will always pass on the X chromosome and the father will either pass on a X chromosome in the sperm creating a female baby or will pass on a Y chromosome creating a male baby.Mother /Father XYXXXXXXXYXYThe Punnett diagram above shows that there is a 50% chance that the check will have a boy or a girl, this is the same theory as to when you flip a coin over and over once again you will eventually have even results. Of course some families will have more boys than girls or more girls than boys but when the gos are counted worldly concern wide the malefemale ratio is fairly even.Explain the crossing over of chromosomes and the role it plays in transmission of genetic characteristics.Chromosomal crossover is the process of two chromosomes that have paired up during prophase 1 of meiosis ex change DNA. This happens when two homologous chromosomes rive and reconnect at the same place and reconnecting with the other chromosome, if they break at the same base pair they exchange alleles this is called genetic recombination. If too few chromosomal crossovers are formed gametes end up with the wrong number of chromosomes, this can cause infertility, pregnancy miscarriage and chromosomal disease (Downs Syndrome). Shuffling the DNA is the best thing for the next generation as it accounts for genetic adaptation so the offspring will have a different set of alleles and genes to their parents. Chromosomal crossover means that people will look different to each other (apart form identical twins), diseases can be eradicated, evolution, being able to adapt and natural selection. Hemophilia is a blood clotting disease that is inherited, this means that if the carrier of the disease has a child then their child may inherit the gene. Hemophilia usually occurs in males but there are t he uncommon exceptions. A Punnett diagram below shows how the disease can be inherited. Females are carriers with rare exceptions of getting the disease. Males are effectuate from mildly to severely. The red chromosome is the one effected, spreading.MotherFather /XXXXXXXYXYXYTAQ 4 Using examples, explain the difference between continuous and discontinuous variations.Depending on the features of an organism they will show continuous and discontinuous variation. A continuous variation is something that can change gradually over a period of time such as height, weight and foot length. These goes from one extreme to the other, if you plotted the height of new born babies the variation could be from 30cm to 55cm depending a variation of factors from genes, environmental factors during gestation and whether or not they were born premature or full-term. Continuous variation is the combined effect of many genes know as polygenic inheritance, this is also effected by the environment.Disco ntinuous variation isnt effected much by environmental factors, it is when a person is or isnt part of a group, there is no in-between. They are either one blood type of the other, they are either male of female, they have either blue, green or brown eyes. Of course some people are born with indeterminate sex and others have have heterochromia (different eye colours, often inherited from parent or from injury to the eye).TAQ 5Define the term mutation and explain how it is caused.The organic structure constantly needs new cells a mutation occurs when stands of DNA are separated and replicated, each strand becomes a double strand, eventually a mistake occurs during the copying process (1 in 100,000,000). When stultification does occur the bodies cells will repair the damage, however if DNA breaks the body is more likely to make mistakes trying to fix the problem , these mistakes can shorten lifespan. Environmental mutations are caused by chemicals, radiation and ultraviolet light, t hey are all enemies of DNA. They attack and damage by swapping part of the DNA which becomes a problem when they start to replicate meaning more harmful DNA is replicating with chemicals that dont behave.Describe de novo mutations and appropriate one example.A de novo mutation is a new mutation of a cell. Gene mutations are either inherited or acquired during a lifetime. Mutations passed from parent to child are heritable or germline mutations as they are in the sperm or egg, this mutation will be in in every cell in the persons body and lasting a lifetime. De novo mutations that occur after fertilization explain genetic disorders which effect the childs every cell but has no family fib of the disorder. Somatic (acquired) mutations in DNA that occur in individual cell some point in a persons life are environmentally caused by radiation, chemical or by mistakes being made during cell division. Acquired mutations cannot be passed on to the next generation. De novo mutations can ca use Autism when there is no parental link to the disorder. Schizophrenia has been linked to de novo mutation in the pateribonucleic acidl germ line from older fathers. Hemophilia is also an inherited disease but a trio of cases are caused by gene mutation, this is when the blood doesnt clot and lowers the blood clotting factor levels for coagulation meaning someone will bleed for longer.Describe mosaicism and provide one example.Mosaicism happened when the egg (zygote) starts to divide after fertilization, new cells form and duplicate so there are enough chromosomes. Errors occur and a cell ends up with a different number of chromosomes, every time that cell duplicates it will have a different chromosomal number. Having more than one type of chromosomal make-up is called mosaiciam, this means that an extra cell will have trisomy 21 (chromosome 21 dictates Downs Syndrome), others will have the right amount of chromosomes. Mosaic Downs Syndrome is detected either during pregnancy or after birth via a karyotype test (a photograph of the chromosomes from one cell using skin, blood, bone marrow or amniotic fluid), chromosomes in 20 cells are counted and if two or more are normal (without the chromosome 21) the baby is said to have mosaic downs syndrome.Describe polymorphism and provide one examplePolymorphism is a word that come from the Greek language meaning Many (poly) Form (Morph). Polymorphism is discontinuous genetic variations where two or more forms exist in the same species of a population such as blood type (A, B, AB, O) and sexual dismorphism (male or female), height cannot be a polymorphism as this is a continuous variation. Polymorphism is seen in every species (dogs there are hundreds of breeds of dog that look completely different but they are still the same species) and counts towards natural selection e.g. some may be able to reproduce to a higher degree than others.TAQ 6 Protein synthesis and the two main stages explained.Protein synthesis is fo rmed of two steps that use protein (amino acid). For every three base pairs of DNA codes there is one amino acid , in total the body makes 20 different amino acids, other come from the diet. This process rewrites base sections of DNA and creates proteins, it all takes place on the ribosome in the cytol or the the rough Endoplasmic Reticulum.The two main stages of protein synthesis are Transcription and Translation.Transcription starts by the DNA double helix unwinding, this shows the single stranded DNA. nonpareil of these side of the DNA will act as a template for the formation of mRNA (messenger ribonucleic acid). In this process the matching RNA nucleotides base pairs substance to form a strand of mRNA, mRNA detaches from the DNA to move out of the nucleus through openings called nucleus pores and into the cytoplasm. Translation starts when the mRNA is drawn towards the ribosome which has two parts a small and large subunit used as different binding sites. mRNA binds to the sm all ribosome subunit which instructs a strand of tRNA (transfer RNA) to visit a place (specific codon sequence) to to bind the mRNA, they attach together holding the amino acid. The larger subunit come to complete the structure, ribosome surrounding the strands of RNA and have another(prenominal) strand of tRNA carrying amino acid different to the first. Again they bind in the specific codon sequence. These to amino acids bind with help from cellular energy and the ribosome to form adenosine triphosphate (ATP). This process is repeated, the codons and anti-codons match up to form base pairs which then create a 3D shape meaning the protein (polypeptide) is complete.Reference ListGenes (27/08/14) Online http//www.bbc.co.uk/schools/gcsebitesize/science/21c/genes/genetic_diseasesrev1.shtml (27/08/14) prison cell division (27/08/14) Online http//www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/celldivision/celldivision1.shtml (27/08/14)Gregor Mendel (27/08/14) Online http//ww w.dnalc.org/view/16151-Biography-1-Gregor-Mendel-1822-1884-.html (27/08/14)Genetics (27/08/14) Online http//www.bbc.co.uk/bitesize/higher/biology/genetics_adaptation/dihybrid_cross/revision/1/ (27/08/14)Hemophilia (28/08/14) Online http//www.nhlbi.nih.gov/health/health-topics/topics/hemophilia/ (28/08/14)Linkage (28/08/14) Online http//www.nature.com/scitable/definition/linkage-51 (28/08/14)Crossover (28/08/14) Online http//www.sciencedaily.com/articles/c/chromosomal_crossover.htm (28/08/14)Variation (29/08/14) Online http//www.bbc.co.uk/bitesize/ks3/science/organisms_behaviour_health/variation_classification/revision/3/ (29/08/14)Mutation (29/08/14) Online http//science.howstuffworks.com/life/genetic/dna-mutation.htm (29/08/14)Mosaicism (29/08/14) Online http//www.theupsideofdowns.org/down-syndrome/what-is-mosaicism (29/008/14)Polymorphism (01/09/14) Online http//users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Polymorphisms.html (01/09/14)Protein synthesis (01/09/14) Online http/ /biology.about.com/od/cellularprocesses/ss/protein-synthesis-translation_2.htm (01/09/14)BBC Protein Synthesis (01/09/14) Online http//www.bbc.co.uk/bitesize/higher/biology/cell_biology/rna/revision/2/ (01/09/14)