bicd100
How many different types of gametes can be formed by indi- viduals of the following genotypes? What are they in each case? (a) AaBb, (b) AaBB, (c) AaBbCc, (d) AaBBcc, (e) AaBbcc, and (f) AaBbCcDdEe?
(a) 2x2=4 gametes (b) 2x1=2 gametes (c) 2x2x2=8 gametes (d) 2x1x1=2 gametes (e) 2x2x1=4 gametes (f) 2x2x2x2x2=32 gametes
Describe the central dogma of molecular genetics and how it serves as the basis of modern genetics.
The central dogma of molecular genetics refers to the relationships among DNA, RNA, and proteins. The process of transcription and translation are integral to understanding these relationships. The central dogma is that DNA is a template for making RNA, which encodes the order of amino acids in proteins. It serves as the basis of modern genetics because it creates the proteins needed to ultimately "sustain life." DNA → RNA → protein
Define genotype and phenotype. Describe how they are related and how alleles fit into your definitions.
The genotype of an organism is defined as the sum of all its genes. The phenotype of an organism is the observable physical or biochemical characteristics of an organism, determined by both genetic make-up and environmental influences. Genotype is also used to refer to the pair of alleles present at a single locus.
How do we know whether an organism expressing a dominant trait is homozygous or heterozygous?
To identify whether an organism exhibiting a dominant trait is homozygous or heterozygous for a specific allele, a scientist can perform a test cross. ... If the test cross results in any recessive offspring, then the parent organism is heterozygous for the allele in question. test cross w a homozygous recessive organism
How was Mendel able to derive postulates concerning the behavior of "unit factors" during gamete formation, when he could not directly observe them?
by noting that traits passed unaltered from parental to subsequent generations, Mendel not only postulated the "unit" of "particulate" nature of hereditary elements, but he also described their behaviorresults of various crosses provided the basis for knowing that factors can remain hidden in some circumstances, thereby implying two participating elements, one dominating the other. predictable ratios in crosses supported the hypothesis of two hereditary elements involved in the expression of a given trait.
How do we know that specific genes are located on the sex- determining chromosomes rather than on autosomes?
several diseases or sidorders more prevalent in one gender when compared to another. male is more vulnerablethan female. male has only 1 x chromosome, fmelae has 2. hence, the gene that controls sight is located on the sex chromosome. genes responsible for the traits are on X chromosome
Forgeneswhoseexpressionseemstobetiedtothegenderof individuals, how do we know whether a gene is X-linked in con- trast to exhibiting sex-limited or sex-influenced inheritance?
complemetation analysis Cross between two different recessive mutations genes -> wild-type phenotype. means the two mutations are not alleles bc gene for wild-type must have come from another chromosome if the two genes were alleles there could have been only tan eyed (mutation) progenies, but since they are not, the gene for wild-type mustve come from another chromosome. the two recessive mutations are not alleles Cross between two different recessive mutations genes -> mutation phenotype. means the two mutations may be alleles bc combination results in same phenotype https://www.chegg.com/homework-help/three-autosomal-recessive-mutations-drosophila-tan-eye-color-chapter-4-problem-23pdq-solution-9780134047799-exc
How were early geneticists able to ascertain inheritance patterns that did not fit typical Mendelian ratios?
did expiriments and not all inheretence data fit mendelian. codominance creation of a new allele
For Problems 25-30, consider a diploid cell that contains three pairs of chromosomes designated AA, BB, and CC. Each pair contains a maternal and a paternal member (e.g., Am and Ap). Using these designations, demonstrate your understanding of mitosis and meiosis by drawing chromatid combinations as requested. In mitosis, what chromatid combination(s) will be present during metaphase? What combination(s) will be present at each pole at the completion of anaphase?
duplicated chromosomes Am, Ap, Bm, Bp, Cm, and Cp, will align at metaphase, with the centromeres dividing and sister chromatids going to opposite poles at anaphase.
Consider three independently assorting gene pairs, A/a, B/b, and C/c, where each demonstrates typical dominance (A9, B9, C9) and recessiveness (aa, bb, cc). What is the probability of obtain- ing an offspring that is AABbCc from parents that are AaBbCC and AABbCc?
find probability of individual parts of product (AA, Bc, Cc). then multiply them together
https://www.chegg.com/homework-help/questions-and-answers/drosophilia-grey-color-dominant-ebony-body-color-long-wings-dominant-vestigial-wings-assum-q25082022 dihybrid stuff
https://www.chegg.com/homework-help/questions-and-answers/mendel-crossed-peas-round-green-seeds-peas-wrinkled-yellow-seeds-f1-plants-seeds-round-yel-q26699402 result of testcross
How did geneticists determine that inheritance of some phenotypic characteristics involves the interactions of two or more gene pairs? How were they able to determine how many gene pairs were involved?
one phenotypic expression controlled by many genes (eg blood type), bombary phenotype lack of one gene overrides experssion of the gene that controls blood type, interactions of multilple genes (epistasis) result in deviation from mendelian ratios, also several genes linked on same chromosomes dont separate independently (genetic linkage) not taken into acount by mendelian ratios, mode of inheritance of other species not supported by mendels four postulates
A diploid cell contains three pairs of homologous chromosomes designated C1 and C2, M1 and M2, and S1 and S2. No crossing over occurs. What combinations of chromosomes are possible in (a) daughter cells following mitosis, (b) cells undergoing the first mei- otic metaphase, (c) haploid cells following both divisions of meiosis?
(a) In mitosis, two genetically identical daughter cells are produced. Thus, the only possible combination of chromosomes is C1/C2/M1/M2/S1/S2 since all genetic material is inherited (b) The first meiotic division serves to split homologous pairs into two different cells, which are now haploid. There are 8 possible combinations of chromosomes (2 chromosomes for each homologous pair). For instance, a cell at this stage could inherit C1/M1/S1, or C2/M1/S1, or C1/M2/S1, etc. one homologous chromosome from each triplet (c) The same 8 combinations as above. The second meiotic division splits double-stranded chromosomes of each of these haploid cells into two daughter cells each so that only single-stranded chromosomes remain. Since no crossing over occurs, the two cells descended from each haploid cell will be genetically identical to the cell it came from. For instance, if the first meiotic division produces a cell with the combination C1/M1/S1, the second meiotic division of this cell will produce two more cells with the combination C1/M1/S1. The difference is that the end of meiosis I produces cells with double-stranded chromosomes, while the end of meiosis II produces cells with single-stranded chromosomes.
Shown are F2 results of two of Mendel's monohybrid crosses. State a null hypothesis that you will test using chi-square analysis. Calculate the x2 value and determine the p value for both crosses; then interpret the p values. Which cross shows a greater amount of deviation? (a) Full pods: 882 Constricted pods: 299 (b) Violet flowers: 705 White flowers: 224
(a)X2 = sum ( o-e )^2/e Null hypothesis: bc mendel in this case, Ho is that the data fits a 3:1 ratio. and alternative hypothesis (Ha) is that it does not fit a 3:1 ratio. df = 2-1 = 1 https://www.chegg.com/homework-help/shown-f2-results-two-mendel-s-monohybrid-crosses-state-null-chapter-3-problem-15pdq-solution-9780134047799-exc
Why was the garden pea a good choice as an experimental organ- ism in Mendel's work?
-has numerous visible features -easy to cultivate -can be crossbred -is naturally self fertilizing -fast generations
Considering Problem 15, predict the number of different haploid cells that could be produced by meiosis if a fourth chromosome pair (W1 and W2) were added.
16 combinations
Two parents without albinism have five children, four with- out albinism and one with albinism. parents genotypes = Aa and Aa
A male without albinism and a female with albinism have six children, all without albinism. parents genotypes = AA and aa
Discuss the concepts of homologous chromosomes, diploidy, and haploidy. What characteristics do two homologous chromosomes share?
Chromosomes that are homologous share many properties including:-overall length, position of centromere, banding patterns, type and location of genes, autoradiographic patternDiploidy =2n. It means that both members of a homologous pair of chromosomes are present. the change from diploid (2n) to haploid (n) occurs during meiosis 1. https://www.chegg.com/homework-help/discuss-concepts-homologous-chromosomes-diploidy-haploidy-ch-chapter-2-problem-3pdq-solution-9780321751027-exc Chromosomes that are homologous share many properties, including the following: Overall length : look carefully at the figures above to see that each cell, prior to anaphase I, contains two chromosomes in which a homolog is of approximately that same overall length. The position of the centromere (metacentric, submetacentric, acrocentric, telocentric): Again, look carefully at F2.2 and F2.3. Notice that if there is one metacentric chromosome, there will be another metacentric chromosome. Banding patterns : using a various cytological technique, bands can be induced in chromosomes. Homologous chromosomes of pair #1 , for example, will have the same banding pattern. Although the overall length of chromosome pairs #16 and #17 appears to be the same, the banding patterns of these nonhomologous chromosomes will be different.Sister chromatids have identical banding patterns, as would be expected since sister chromtids are with the exception of mutations, identical copies of each other. We would expect that homologous chromosomes would have banding patterns that are very similar (but not identical) because homologous chromosomes are gentically similar but not genetically identical.
If two chromosomes of a species are the same length and have similar centromere placements and yet are not homologous, what is different about them?
Overall length and centromere placement/position are but two factors required for homology.Most important, Genetic Content in non-homologous chromosomes is expected to be quite different.Other factors including banding pattern and time of replication during S phase would also be expected to vary among non-homologous chromosomes.(BOOK)
In a problem involving albinism (see Problem 4), which of Men- del's postulates are demonstrated?
Postulate 2: Alleles demonstrate dominance/recessive relationships - heterozygous individuals are unaffected because they possess one dominant allele.
During meiosis I, assuming no crossing over, what chromatid combination(s) will be present at the completion of prophase I? Draw all possible alignments of chromatids as migration begins during early anaphase.
During meiosis I three tetrads consisting of (AmAm/ApAp), (BmBm/BpBp), and (CmCm/CpCp) will form by synapsis such that eight possible arrangements can occur. These arrangements include: (look at the arrangements of maternally (AmAm BmBm and CmCm or paternally (ApAp BpBp CpCp )derived chromosomes above and below the / mark carefully or you won't be able to make any sense of the differences among a, b, c or d.a. AmAm/ApAp BmBm/BpBp CmCm/CpCpb.. AmAm/ApAp BmBm/BpBp CpCp/ CmCmc. AmAm/ApAp BpBp/BmBm CpCp/ CmCmd. ApAp /AmAm BpBp/BmBm CpCp/ CmCm and etc. for a total of eight combinations. The get the possible alignments of chromatids during early anaphase I take the chromatids above the / and put them together and take those below the / and put them together. So, for a. you get AmAm BmBm CmCm and ApAp BpBp CpCp, for b. you should get AmAm BmBm CpCp and ApAp BpBp CmCm. You can repeat the process for b., c., d., and the other 4 pairs that I didn't show. In anaphase those above the hash line (/) would be pulled to the 'north' pole of the meiotic anaphase nucleus and those below the hash line would be pulled to the 'south' pole. These would end up in different cells after karyo- and cytokinesis in telophase I.
Given the end results of the two types of division, why is it nec- essary for homologs to pair during meiosis and not desirable for them to pair during mitosis?
During meiosis, I chromosomes number is reduced to haploid complements. This is achieved by synapsis of homologous chromosomes and their subsequent separation. It would seem to be more mechanically difficult for genetically identical daughters to form from mitosis if homologous chromosomes paired. By having chromosomes unpaired at metaphase of mitosis, only centromere division is required for daughter cells to eventually receive identical chromosomal complements. synapsis = is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. This takes place during prophase I of meiosis I.
Contrast chromosomes and genes.
Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are structures within cells that contain a person's genes. A gene is one section of a chromosome, and a chromosome may carry many genes. A chromosome is composed of DNA complexed with proteins, and many genes are found along the length of a single chromosome.
How is genetic information encoded in a DNA molecule?
Genetic information is encoded by the matching letter bases, such as AT or CG, to determine a specific protein. Genetic information is encoded in DNA by the sequence of bases.
Distinguish between homozygosity and heterozygosity.
Homozygous means two copies of the same allele, such as two dominant alleles. Heterozygous means one of each type of allele, one dominant and one recessive.
Explain why meiosis leads to significant genetic variation while mitosis does not.
Mitosis creates two identical daughter cells that each contain the same number of chromosomes as their parent cell. ... Apart from this reduction in chromosome number, meiosis differs from mitosis in yet another way. Specifically, meiosis creates new combinations of genetic material in each of the four daughter cells. Crossing over happens at a higher rate in meiotic cells and Through independent assortment at anaphase I of meiosis, daughter cells contains different sets of chromosomes.
What is the probability that, in an organism with a haploid number of 10, a sperm will be formed that contains all 10 chromosomes whose centromeres were derived from maternal homologs?
Most of the animal sperm cells are haploid means one chromosome of each set moves to one sperm which makes sperm cell have 10 chromosomes. this propability is 50% so the prpability of getting all the peternal or maternal chromosomes in sperm is 50%^10('^'is squire) it can be written as 0.5^10 for easy calculation. (50% or 0.5% means it happens half of the times). So the answer is 0.5^10= 0.00097 or 9.7^10-4 in other words 1/0.00097 gives us a chance of 1 in 1030.
