Quiz 2 bio
What are the key differences between the process of mitosis and meiosis? For each of the differences, make sure you clearly explain what it is that mitosis does and what it is that meiosis does. Also compare the functions and products of each process.
Mitosis ---> somatic cell division & produces two identical daughter cells with equal number of chromosomes (cytokinesis & karyokinesis). Meiosis ----> a reduction division occurs in reproductive germ cells in which allosomes determine sex determination finally generates half of the chromosomes in daughter cells
Two babies are mixed up at the hospital nursery. It is your job to match the correct baby to the correct set of parents. Show ALL of your work. BABY #1 - Type O BABY #2 - Type AB Couple X has blood types O and B Couple Y has blood types AB and A
couple x baby 1 couple y baby 2
Describe in detail the structure of a DNA molecule including the basic building blocks and how they are arranged. Explain how the molecule stores genetic information and also how that information can be changed.
Genetic information is carried in the linear sequence of nucleotides in DNA. Each molecule of DNA is a double helix formed from two complementary strands of nucleotides held together by hydrogen bonds between G-C and A-T basepairs. Duplication of the genetic information occurs by the use of one DNA strand as a template for formation of a complementary strand. The genetic information stored in an organism's DNA contains the instructions for all the proteins the organism will ever synthesize. In eucaryotes, DNA is contained in the cell nucleus. Genes carry the genetic code, which is a collection of "codons" of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). These codons contain the information about polypeptide chain sequencing during "translation." Changing the base sequence changes the genetic information.
Genetic engineering is being used to benefit humans in many ways, including agriculture. Describe 2 potential benefits genetically modified crops can provide as well as 2 potential risks associated with their use. Be specific.
Genetically engineered crops are used in agriculture and have following advantages or disadvantages: A. Advantages They have high yeilds per unit area of field as compared to normal variety of crop. They have increased pest resistance and can fight infections more robustly (eg BT cotton). They have increased shelf life (eg. Flavr Savr tomato) They have increased nutritional value (eg. Golden rice) B. Disadvantages They may be associated with un-observed genetic abberations. They might be accompanied with unknonw genetic mutations which could be damaging in long terms. Un-noticed genetic abberations might be harmful for the environment, soil quality, insects, microbes and birds. Based upon these informations, the GMOs have been debated all over the world for their benefits and drawbacks.
Certain traits such as color-blindness and hemophilia are seen more often in men than in women. Explain why this is true then answer all parts of the problem. Start by showing the genotypes of both parents. Problem: If a man who is not colorblind has children with a woman who is also not colorblind, but whose father was colorblind, what percentage of their children would be expected to be colorblind? What percentage of their daughters would be expected to be colorblind?
Both hemophilia and color blindness is a recessive X-linked genetic disorder. Females have 2 X while males have only 1 X. So in case of defective gene the women have one more set of X which can compensate the function. While for men this is not possible. So even though women possess the defective gene they only remain as a carrier while male with only one X show the phenotype of the defective gene and acquire hemophilia and colour blindness. The man who is not colour blind the genotype will be XY - normal male (assuming no familial history of colorblind as it was not mentioned in question) For the women whose father was colour blind, X*Y + XX -----------------> X*X (represnting X* as affected gene) (affected father) (normal mother) (unaffected but carrier female) Now if this carrier female and normal male are about to have a child then the punnett square will be, 25% chances that the born child is colour blind, 50% chances if it is a boy. 25% chances that the daughter might be carriers but will not be affected by colourblindness.
This question explores the meaning of dominance. Please answer both parts. a) It is often said that certain traits "skip generations." What kind of trait might do this? Can brown eyes skip generations? What about blue eyes? Why? b) Human beings can suffer from a large variety of genetic ailments. While many of these are relatively benign — or at least, mild enough that the sufferers can live with them for a lifetime — some are not. Some are always lethal. One lethal genetic disorder is TaySachs disease. This disease is always fatal; sufferers die before the age of five, and thus never reproduce. Tay Sachs disease is caused an autosomal recessive allele. Why doesn't a disease like Tay Sachs simply disappear from the species, since it is completely selected against (i.e., no sufferer ever has children)?
a)Traits 'skip' generations precisely because most traits are not accounted for by a single gene, but by their combination with other genes. There is no brown hair gene, or blue eye gene. These traits may be controlled by recessive genes, so they seem to skip a generation from grandparent to you. For example, if a trait is produced by a recessive gene, one of your parents may be a carrier but not possess the trait (because she inherited a dominant gene that overrode the recessive one). However, when her genes were recombined to produce the ovum from which you grew, and when that combined with your father's DNA, the trait may resurface. Recessive traits can skip a generation. Under the standard assumption that the brown eye allele (B) is dominant over the recessive blue eye allele (b) ... Both parents are homozygous: One parent has brown eyes and one parent has blue eyes. That means the parental cross is: P = BB x bb The offspring will have: F1 genotypes: 100% Bb F1 phenotypes: 100% brown eyes So the blue eye trait has disappeared. Now one of these kids later mates with a heterozygous brown eyed person, who would be Bb. F1 = Bb x Bb Their offspring would have: F2 genotypes: BB = 25%, Bb = 50%, bb = 25% F2 phenotypes: brown eyes = 75%, blue eyes = 25% So the blue eyes have appeared again. The disease is recessive, so carriers (heterozygotes, with 1 dominant 'normal' allele and 1 disease allele) do not suffer from the disease. Therefore, the recessive allele can remain present in the population since heterozygotes will live to reproduce. b) Tay-Sachs disease is caused by a genetic mutation in the HEXA gene on (human) chromosome 15(autosomal) . in gene with recessive alleles for the gene to be expressed the alleles should be homozygously recessive i mean consider TT normal homozygous dominant functional gene a person with no disease now consider a taysachs diseased children he must have recessive allele(say defectivelle) tt for the disease to be progressed so if the children has one recessive allele (t) and one functional allele (T) of the gene responsible for the disease he will be a carrier of the disease to the disease but not affected because on gene is functional . so thats why it doesnot disappears from the species but skips generations.
A normal human karyotype shows 46 chromosomes. Describe how a karyotype with 47 chromosomes could be produced. Briefly discuss 2 specific human disorders characterized by a karyotype with 47 chromosomes.
Trisomy of human chromosomes arises due to a chromosomal abberation during meiosis. This results in failure of separation of homologous chromosomes and consequently results in formation of a triad of chromosomes. The daughter cells then formed are comprised of abnormal number of chromosomes for that set, i.e. 3. This is knonw as trisomy syndromes and a karyotype of 47 chromosomes will be produced. Examples of trisomy or 47-karyotype associated disorders in human: 18th trisomy: The trisomy of 18th chromosome in human results in Patau syndrome. The offsprings with Patau syndrome display microcephaly, lowered intellignece and intellect, low IQ and lowered set ears. 21st trisomy: The trisomy of 21st chromosome in human results in Down's syndrome. Individuals with Down's syndrome shows protruded tongure, large head, widely set eyes, mental retardation, hearing problems and wide spaces between toe and fingers.
