IB 105 Lecture Notes - Lecture 5: Gene Flow, Selective Breeding, Genetic Variation

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burgundybee439

7 Nov 2016

School

University of Illinois

Department

Integrative Biology

Course

IB 105

Professor

Harmon

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Document Summary

They can create variation in a population because mutations can delete or change nucleotides and even change the chromosome, which changes the instructions from the dna: alleles are different forms of the same gene. For example, there are alleles for brown eyes and blue eyes: alleles contribute to the differences in individuals because genetic recombination occurs when the genes get passed down to the offspring. Natural selection occurs naturally and selects against less fit individuals: gene flow is the natural transfer of genes from one population to another. Dna contains 4 paired nitrogenous bases (a with t) and (c with g): a=adenine t=thymine g=guanine. Sequences of bases form genes and alleles are alternate forms of genes. Changes to bases or chromosomes are called mutations and create new alleles. Reduction in gene flow can also lead to the creation of new species: allele frequencies and traits will begin to differ between different populations.

Related Questions

Which statement is not correct?

Mutations change the sequence of nucleotides in DNA.

Mutations can be caused by mistakes made during the copying ofDNA.

Mutations can be caused by toxic chemicals in theenvironment.

Mutations are not random.

Mutations can change the function of proteins.

Mutations are the basis for all of the genetic diversity thatexists.

Which statement is not correct?

Chromosomes contain genes.

Chromosomes are made of DNA wrapped around protein.

Eukaryotes have many, linear chromosomes in their cells.

Different species can have a different number ofchromosomes.

DNA is made by putting a string of amino acids together.

Which statement is not correct?

Cells with homologous chromosomes are diploid

Cells with homologous chromosomes are haploid

Gametes are haploid

Diploid cells have two sets of chromosomes in theirnucleus.

Which is not a good example of alleles?

Brown hair and red hair, for the hair gene.

Stripes and no stripes, for a striped gene.

Ear lobe gene and freckles gene.

Straight nose and pug nose, for a nose gene.

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Which of the following is most likely as a population goes through a bottleneck?

Heterozygosity decreases because genetic distance increases.

Genetic diversity increases because mutation rate increases while the population is going through the bottleneck

. Genetic diversity decreases because some alleles can be lost as the number of individuals dwindles

. The proportion of individuals that are heterozygous increases because there are fewer individuals.

2)What is meant when it says that genetic drift produces "non-adaptive" evolution?

Sometimes natural selection can favor a trait that is good for the current conditions, but when conditions change it is no longer helpful.

Evolution is just a genetic change in a population. If genes are lost from a population due to chance (i.e. genetic drift), that may not be adaptive, meaning the remaining organisms are no more fit.

Evolution isn't perfect, and sometimes it makes mistakes.

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1. Characters that show a continuous range of variation, such as height and eye color, usually are controlled:

a.	by a single gene with two alleles that are codominant.

b.	by many genes with an additive effect.

c.	by epistatic interactions between two genes.

d.	mainly by the environment, with only a small genetic component.

2. In humans, red-green colorblindness is inherited as a sex-linked recessive trait. In order for a woman to be red-green colorblind, which of the following statements must be true.

a.	Her mother must be red-green colorblind.

b.	All of her brothers must be red-green colorblind.

c.	Her father must be red-green colorblind.

d.	All of the above statements must be true if a woman is red-green colorblind.

3. The x-ray crystallography data collected by Rosalind Franklin suggested to Watson and Crick that the:

a.	structure of DNA is a double helix.

b.	two strands of the DNA molecule are joined by hydrogen bonds between the bases.

c.	four bases within DNA pair in a specific way.

d.	two strands of the DNA molecule are joined by covalent bonds between the bases.

4. In the genetic code, _________ one amino acid.

a.	one nucleotide specifies

b.	two nucleotides specify

c.	three nucleotides specify

d.	four nucleotides specify

5. During Meiosis I, a homologous pair of chromosomes may not separate, resulting in daughter cells that have extra chromosomes or are missing chromosomes. This can lead to genetic disorders, including Down Syndrome. This phenomenon is called:

a.	independent assortment.

b.	nondisjunction.

c.	segregation.

d.	crossing over.

6. You are a human geneticist studying the incidence of retinitis pigmentosa in the residents of Tristan de Cunha, a group of small islands in the middle of the southern Atlantic Ocean. The allele for retinitis pigmentosa, which causes a form of blindness, is inherited as an autosomal recessive. You have determined that the frequency of this allele (r) in the population is 0.4 (40%). Using the principles of the Hardy-Weinberg rule, you would estimate the frequency of individuals who are heterozygous for this allele (Rr) in the population to be:

a.	0.16 (16%)

b.	0.24 (24%)

c.	0.36 (36%)

d.	0.48 (48%)

7. Natural selection acts at the level of the:

a.	phenotype.

gene.

c.	population.

d.	nucleotide.

8. You are working with pea plants, trying to recreate the experiments that Mendel performed. You are doing a dihybrid cross with a plant that is heterozygous for both seed shape and seed color, with the genotype RrYy. Which allelic combinations would you expect to find in the gametes produced by this plant?

a.	This plant would produce only RY and ry gametes.

b.	This plant would produce only RrYy gametes.

c.	This plant would produce RY, Ry, rY, and ry gametes.

d.	You cannot determine which gametes this plant can produce without knowing the genotypes of its parents.

9. Biochemist Erwin Chargaff found that in DNA there is a special relationship between the four bases that we now call Chargaff's rule. His observation was that, in an organism's genome the:

a.	percentage of A nucleotides = the percentage of T nucleotides, and the percentage of C nucleotides = the percentage of G nucleotides.

b.	four bases all occur in an equal frequency (25%) within each organism.

c.	percentage of A nucleotides = the percentage of G nucleotides, and the percentage of C nucleotides = the percentage of T nucleotides.

d.	genetic material is composed of proteins, not DNA.

10. During DNA replication:

a.	each strand of the double helix acts as a template for the synthesis of a new strand.

b.	the enzyme DNA polymerase adds nucleotides to the strand being synthesized.

c.	the bases A,C,G and T are required.

d.	All of the above are true of DNA replication.

11. During translation, amino acids are joined by peptide bonds to make polypeptides. The formation of these peptide bonds is catalyzed by:

12. If an allele (R) at a gene with two alleles shows complete dominance, individuals with the genotypes ______ will have the same phenotype.

a.	RR and rr.

RR and Rr

Rr and rr

d.	Each of the three possible genotypes will have a different phenotype.

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IB 105 Lecture Notes - Lecture 5: Gene Flow, Selective Breeding, Genetic Variation

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