The two strands of a double helix of DNA are linked by what kind of bond? sugar-
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The two strands of a double helix of DNA are linked by what kind of bond? sugar-phosphate linkages hydrogen bonds between bases hydrogen bonds between sugars and phosphates sugar-base linkages The replication of DNA molecule results in: two DNA molecules, each with one old and one new two DNA molecules, one being made of the old strands, and one being made of two new strands two DNA molecules, both of which are made of completely new strands four unwound DNA strands Which of the following is true about both sperm and egg production? Millions of mature gametes are produced daily All resulting gametes are haploid All cells that result from meiosis function as gametes All resulting gametes are the same size Initiation of meiosis is continuous after puberty How similar is your genetic information to that of your parents? You have a set of genes similar to those your parents inherited from their parents For each gene, one of your alleles is from one parent and the other is from the other parent. Depending on how much crossing over happens, you could have a lot of one parent's genetic information and little of the other parent's genetic information. You contain the same genetic information as each of your parents, just half as match. What is the cause of Huntington disease? A somatic cell mutation that cause cells to proliferate without control a mutation that results in defective DNA polymerase loss of the chromosome with the gene for a blood protein a mutation that results in defective amino acid synthesis a mutation in which there are repeating groups of three nucleotides Normal cell operations and growth occur during the 'gap' period called: G1 M S G3Explanation / Answer
7. b. The two strands of DNA double helix is connected by hydrogen bonds between bases.
8. a.The replication of DNA is semi conservative (parental double helix is half conserved). The two stranded parental DNA unwinds, get seperated and each parental strand serve as template for the synthesis of the new complimentary strand producing two identical daughter double helics. So two DNA molecules, each with one old (parental) and one new (complimentary) strand are produced.
9. b. The male (sperm) and female gametes (egg) are haploid. They contain half of the chromosome. During reproduction these gametes fuse together to form zygote, which is diploid.
10.b. We inherit half of our DNA from each parent, but it need not be in 50:50 proportions. In the 50% of DNA we inherit from each parent, over 49% will be identical to the half inherited from the other parent. This is vivid for women, who have two symmetrical pairs of X chromosomes, whereas men have a shorter Y chromosome inherited from their father. The Y chromosome is 2.5 times smaller than the X chromosome, pointing to the fact that men inherit more DNA from their mothers. The Y chromosome remains virtually unchanged over generations unlike the autosomes + X, which are recombined at each generation. Barring few minor mutations occurring at each generation, some hundreds of generations may be gone, to effect a significant change on a sequence of 60 millions bases. The 0.5% to 0.1% of DNA that differs between two individuals are called alleles or SNP's (single nucleotide polymorphism), which in reality matters.
Crossing over results in the exchange of genes between two chromosomes, resulting in non-identical chromatids which results in the production of entirely distinct gametes. Because of crossing over, genes are inherited independently (independent assortment) of each other in future generations and result in siblings having different combinations of parents' genes.
11. d. HD results from genetically programmed degeneration of nerve cells( neurons) in certain areas of the brain. The genetic defect responsible for HD occurs on genes in chromosome 4. The normal copy of the gene has three DNA bases, CAG, which produces a protein called huntingtin. In people with HD, this sequence abnormally repeats itself dozens of times and produces a mutant form of huntingtin. Over time, and with each successive generation, the number of CAG repeats may expand further.
12.a. During G1 phase, ( first gap phase) the cell grows, copies organelles, and makes the molecular building blocks needed in later phases
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