BIOL2202 Lecture Notes - Lecture 7: Rna Virus, Dna Virus, Genome Size

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blueclam798

7 Sep 2018

School

Department

Biology

Course

BIOL2202

Professor

James Fraser

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Document Summary

Function of the genome: growth and replication, allow adaption to change, genotypic function of the gene is to replicate, phenotypic function of the gene is gene expression, the gene can evolve through mutation. The size of the genome does not determine the complexity of organism: rna virus as small as 3 genes, dna virus 9-150 genes, bacteria 2500-10000 genes. 0. 1% as big as the human genome. Bacteria only have 10% as many genes as humans: humans 20,000 25,000 genes. Humans also have alternative splicing and introns for more phenotypic complexity. Diploid: two copies of the genome, eg: somatic cells are diploid because they have two of the same gene (one from each parent) Haploid: represented b(cid:455) the letter (cid:862)n(cid:863, the cell contains half the number of chromosomes as the somatic cell of the organism, sex cells are haploid because they only have one set of chromosomes.

Related Questions

Ploidy refers to the number of complete sets of chromosomes (genes) present in a cell. The number of chromosomes in a complete set is a fixed characteristic of a species. Humans are diploid with two sets of 23 chromosomes. Fruit flies are diploid with two sets of 4 chromosomes. Sexually reproducing organisms are diploid, each somatic cell of an organism has two complete sets ("di" is a prefix indicating 2.). To complete a life cycle and reproduce new members of a species, mating is required. Mating brings a donation from a male and a donation from a female together. However, if the male and female cells remain diploid, the fertilization will result in a tetraploid zygote. In general, these are not viable. A mechanism is needed to form special haploid cells, gametes. The diploid set is split precisely into two complete haploid sets. That mechanism is meiosis.

The complete set of chromosomes of a species is also the complete set of genes of a species, the genome. (Yes, there is a minor contribution from mitochondria and chloroplasts. Inheritance of this information is "cytoplasmic".)

Please answer the following questions:

1. How many chromosomes in a brain cell of a fruit fly? How many chromosomes are in a liver cell of a human? Explain both answers.

2. How many chromosomes are in a fruit fly unfertilized egg? How many chromosomes are in a human egg? Explain both answers.

3. Why is meiosis necessary for sexually reproducing organisms? How many chromosomes are in a human zygote? Relate the two answers.

4. What is a gene allele? Suppose there is a gene called "bingo" and it is present once in a complete haploid set. How many alleles of "bingo" does a diploid individual have? How many copies or versions of the gene "bingo" are present in a diploid individual?

5. Modern DNA sequencing clearly identifies alleles by showing the different DNA sequence of each allele. These alleles may be termed structural alleles (I coined the term for this problem.). Classical genetics only dealt with phenotypes or visible traits. As a result, alleles of genes were identified by functionality, usually normal or non-functional. Using your knowledge of gene structure and gene expression, postulate a relationship between structural alleles and functional alleles. (include relative amounts; more, less, or equal).

Question 1: For each of the following terms, select the best definition:

gene, phenotype, chromosome, genotype, allele, genome

2.DNA that provides the instructions for synthesizing various types of small RNA molecules1.The complete set of genetic material in a cellan observable trait (or traits) of an organism

3.DNA that provides instructions for building a proteina variant of a gene

4.DNA of no known function

5.The genetic composition that underlies a trait (or traits)

6.A single molecule of DNA & its associated "helper" molecules

7.The portion of DNA that controls when and where proteins are synthesized

Question 2: Fill in the blank with these terms: dependent variable, independent variable, y-axis, x-axis

Understanding graphs is an important skill in science, since being able to visually depict data is often useful for identifying patterns, and can sometimes be the only tool for easily evaluating whether or not the data supports your hypothesis. When viewing a graph, the______ is plotted on the______, and the______we are measuring is plotted on the_____. For example, in one of the photosynthesis experiments last week, temperature was the______, while the size of the bubble at the end of the experiment was the_____

Question 3: For each of the following terms, select the best definition:

diploid cell, haploid cell, fertilization, zygote, gamete, somatic cell

1. The merging of two gametes

2. Any cell in an organism, except those used for reproduction

3. A cell with only one copy of each gene

4. The process of cell division

5. The cells used for sexual reproduction (generally eggs & sperm)

6. The initial cell of an organism

7. A cell that is capable of differentiating into multiple types of specialized cells

8. A cell with two copies of each gene