chpt 24 bio 112 sp17

If a gene is found in different groups, it is said to be

conserved.

The protein-coding gene sequences in humans and chimpanzees

are more than 99% alike.

Which of the following causes an extra copy of a chromosomal region to occur?

duplication

Each probe on a microarray is typically _______ nucleotides long.

15-25

If one end of a transposable element contained the following sequence: 5'-ATTCCGATG-3' 3'-TAAGGCTAC-5' what would be the sequence of the other end?

5'-CATCGGAAT-3' 3'-GTAGCCTTA-5'

Some of the olfactory receptor (OR) genes in humans

have been inactivated, reducing our olfactory capabilities compared to other primates.

What is a microarray?

An arrangement of oligonucleotide probes on a slide

One of the ways that two species can be compared, and information about the genetic basis of human diseases extracted, is by using their sequenced genomes and

looking at the conserved sequences.

Choose the true statements about the role of genome analysis in crop improvement. Check all that apply.

Conservation of synteny will hinder our ability to find agriculturally important genes in plants. Sequencing of the rice genome was important because it is related to many other cereal crop plants. Insertion of genes from beneficial microbes into plant genomes can be used to improve crop yields.

Why would the sequencing of commercially unimportant Arabidopsis be useful for crop improvement?

Highly conserved genes of Arabidopsis can be used to identify orthologues in crop species.

Which one of the following statements about horizontal gene transfer is false?

Horizontal gene transfer was common early in life, but is absent today.

Which of the following CANNOT be determined by a microarray? (Check all that apply)

If a certain gene was expressed in an extinct ancestor. The nucleotide sequence of a certain gene in an organism.

Why might a duplication be a positive evolutionary force?

If there are two genes, one is free to mutate and take on a different function that may make it more fit.

Choose the true statements about orthologs and paralogs

Orthologs are likely to have the same function. The sequence of an ortholog is more likely to be conserved than the sequence of a paraloge. Paralogs are more likely to be pseudogenes than are orthologs. Incorrect Paralogs often evolve new functions.

Choose the true statements about the genomes of plants (especially Arabidopsis and rice), animals, and fungi.

Plants, animals, and fungi share most of the same genes for intermediary metabolism, genome replication, and protein synthesis. Correct "Plant" genes include those coding for photosynthetic pathways and morphology.

Genome sequencing of the parasitic protist Plasmodium falciparum has been completed. One of the results is

Plasmodium has a chloroplast-like apicoplast that could be targeted by drugs.

Choose the true statements about pseudogenes.

Premature stop codons can produce pseudogenes. Missense mutations can produce pseudogenes.t Pseudogenes have DNA sequences very similar to a functional gene.

The pair of related genes STC1 and STC2, is found in both zebrafish and humans. All four STC genes have similar patterns of exon and intron sequences. The amino acid sequences of the human and zebrafish STC1s are more similar to each other than to the STC2 genes. Based on these facts, what is the most likely explanation for the origin of these genes?

STC1 and STC2 genes arose from a duplication event that occurred before the divergence of fish and mammals.

Choose the true statement about synteny.

Synteny refers to the conservation of gene order along chromosomes.

Genes are found in the same order for large stretches of the X chromosome in the rat and mouse genomes, indicating

conservation of synteny.

Horizontal gene transfer

is the transfer of DNA between different genomes.

Over long segments of chromosomes, the linear order of mouse and human genes is preserved. This is called conserved ______________.

synteny

Choose the true statements about the human and chimpanzee genomes.

A comparison of genomes confirms that humans and chimpanzees are closely related species. Some insertion-deletions (indels) lead to loss of function changes in the two genomes.

Repetitive, retrotransposon DNA that does not code for proteins is very similar between the human and mouse genome. This suggests that

the repetitive, retrotransposon DNA in humans and mice have a function even though it does not code for proteins.

Arabidopsis thaliana and the pufferfish (Fugu rubripes) are examples of _________________ organisms whose genomes have been sequenced

model

Recent research has suggested that some pseudogenes and non-protein-coding DNA code for RNAs that affect transcription of coding regions. This suggests that

non-protein-coding DNA may regulate gene expression.

The method used in horizontal gene transfer is

nonhomologous recombination.

The breast cancer gene BRCA1 has a very similar sequence in humans, mice, and gorillas, due to its origination in a common ancestor. The BRCA1 genes in these species are examples of __________________.

orthologs

Hox genes are a family of transcription factors that regulate development throughout the animal kingdom. Studies of Hox genes in mice and Drosophila showed that many Hox genes are conserved between both species, and several Hox genes duplicated into new genes with novel functions within mice. Some Hox genes have even lost all function. Hox genes provide an example of which of the following? Check all that apply.

orthologs paralogs pseudogenes

The genes STC1 and STC2, which share a common ancestor, are found in both zebrafish and humans. Human STC1 and zebrafish STC1 are called ________, while zebrafish STC1 and zebrafish STC2 are called ________.

orthologues, paralogues

In plants, _________________ induces elimination of duplicated genes.

polyploidy

Choose the most influential contributing factor to the reduced sense of smell in humans compared with the other great apes.

pseudogenes

Comparisons of human and mouse genomes reveals

the genomes are very similar, with most of the genes unique to mice linked to smell and reproduction.

One of the reasons that pufferfish are a good species to compare to humans is because

they are so distantly related that it's easy to distinguish mutually conserved sequences.

The genomes of Arabidopsis thaliana, a small member of the mustard family of plants, and rice, Oryza sativa, have been sequenced. The findings include

they each have very high copy numbers (slightly divergent copies of a gene), probably indicating episodes of polyploidy and/or segmental duplication.

Plant species regularly hybridize in nature, but only some crosses result in new polyploid species. Of the crosses below, if each one occurred, which would be most likely to result in a new stable polyploid species? (Check all that apply)

A cross between a 2n gamete and a 2n gamete, forming a 4n hybrid. A cross between a species with an A genome and a species with a B genome, followed by a doubling of chromosomes, forming a hybrid with an AABB genome.

Which type of chromosomal mutation will have the MOST detrimental effect on organismal function, and why?

A deletion, because there will be no protein produced for genes in the affected region.

The best explanation for why a mouse develops into a mouse and not a human is

gene expression differs.

The best target for drug development would be

genes that are shared by the organisms causing Chagas disease, African sleeping sickness, and Leishmania but not shared by humans.

The entire DNA sequence of a species is called its ________________.

genome

The human genome

has a lot of foreign DNA scattered throughout the genome, including transposons.

Choose the correct sequence of events involving allopolyploidy that gave rise to modern tobacco.

hybridization, chromosome doubling, duplicate gene loss

The types of human genes most likely to be duplicated, resulting in multiple copies, are

immune system genes. genes for cell surface receptors.

When a chromosome is broken in two places and reconnected so that a region is flipped from the normal order, this is called

inversion

When a segment of DNA duplicates, causing two copies of a gene to be present in the chromosome, the duplicate copy could possibly (Check all that apply)

lose function due to mutation. gain a new function due to mutation. become a pseudogene.

Genes that have DNA sequences similar to functional genes but that do not appear to produce any functional product are ________________.

pseudogenes

Gene inactivation is likely to produce

pseudogenes.

Many genes in the human genome are no longer expressed because mutations have introduced stop codons within the coding sequence or transposons have disrupted gene function. These genes are now considered

pseudogenes.

Which of the following occurs when a piece of one chromosome breaks off and is attached to another chromosome?

simple translocation

The creation of homologous genes though a misaligned crossover of chromosomes typically includes what types of genetic changes? Select all that apply.

Gene duplication DNA sequence divergence though mutation

Today, gene swapping between two species is

infrequent but possible; it happened more often in the distant past.

Vertical gene transfer

is the transfer of DNA during normal cell division.

Which two species have genomes that are the most similar?

Two species that diverged 5 mya

Plant species regularly hybridize in nature, but only some crosses result in new polyploid species. Of the crosses below, if each one occurred, which would be most likely to result in a new stable polyploid species?

A cross between a species with a BB genome and a species with a DD genome, followed by a doubling of chromosomes, forming a hybrid with a BBDD genome.

Why would drugs targeting the apicoplast of Plasmodium falciparum be an effective treatment for malaria?

Fatty acid production only occurs in the apicoplast.

Why do humans and chimpanzees look and act differently even though they are closely related?

The pattern of expression of the many shared genes differs between humans and chimpanzees.

Humans and chimpanzees are closely related. Why can humans speak and chimpanzees can't?

The protein coded by FOXP2 of humans and chimpanzees differs by only two amino acids and makes speech possible in humans and not chimpanzees.

In a translocation, the absolute amount and content of the genome remains the same. Why might some translocations still make an organism inviable?

Translocations may have breakpoints in the middle of a gene, causing it to become nonfunctional.

In simple transposition, what is needed for the transposable element to end up between two direct repeats? Select all that apply.

Transposase DNA ligase DNA polymerase

A misaligned cross over between two homologous chromosomes usually results in

a deletion in one chromosome and a duplication in the other.

In simple transposition,

a double stranded piece of DNA is moved from one site to another.

Except in rare cases, genes are usually passed from generation to generation within a species. This process is called:

vertical gene transfer

Order the species pairs from fewest single nucleotide differences (1) to most single nucleotide differences (4).

chimpanzee and gorilla human and mouse tiger and frog finch and earthworm

Simple transposition is also termed ________ transposition.

conservative

Which of the following statements best describes the evolutionary outcome of a gene duplication event?

Gene duplication allows for higher complexity in organisms, as genes can take on more specialized functions.

What type of genes would be most likely to exhibit different expression patterns between humans and non-human primates, such as gorillas?

Genes controlling brain development.

Petrels (a flying and diving seabird) are thought to be one of the closest living relatives to penguins. What type of genes would be most likely to exhibit different expression patterns between these species?

Genes controlling skeletal development.

Crop sunflowers are attacked by many fungal pathogens, such as downy mildew and Sclerotinia, resulting in economic losses of millions of dollars per year. What genes would be best to target for the development of new fungus-killing crop treatments (fungicides)?

Genes encoding chitin proteins that are shared by downy mildew and Sclerotinia, but absent in sunflower and humans.

Choose the true statements about the human and tiger pufferfish genomes.

Genes regulating the basic cellular metabolism are conserved in both human and pufferfish genomes. About 25% of the human genes have no counterpart in the pufferfish genome.

Choose the true statement about genome size and gene number in animals.

Genome size differences depend to a large extent on the amount of retrotransposon DNA present.

Modern tobacco, Nicotiana tabacum, is an allopolyploid, but its genome is not identical to the sum of its parts, Nicotiana sylvestris and Nicotiana tomentosiformis. Why is this the case?

Modern tobacco has lost some of the chromosomes of its parent species.

Choose the true statement about foreign DNA in the human genome.

Most of the foreign DNA in the human genome is ancient.

Humans have nine times the amount of DNA as the pufferfish genome but about the same number of genes. How is this possible?

Much of the extra DNA in humans consists of introns.

Genome sequencing of our human ancestor, Neanderthals (Homo neanderthalensis), revealed that Neanderthals have a FOXP2 gene with the same two amino acid changes observed in H. sapiens FOXP2. What can be concluded based on this finding? (Check all that apply)

Neanderthals may have had the ability to use language. These two amino acid changes arose prior to the common ancestor of Neanderthals and H. sapiens.

What is the benefit to the receiving bacterial cell of horizontal gene transfer?

The bacterium might receive a gene that aids its survival.

Genes can be transferred through populations of microbes through horizontal gene transfer. If a scientist compares the sequence of one specific gene from many species, what phylogenetic pattern(s) are possible? (Check all that apply)

The gene phylogeny will reflect the phylogenetic relationships of the microbe species. Correct The gene phylogeny will be totally different than the phylogenetic relationships of the microbe species.

Which statement contains the strongest evidence for two species being closely related?

The genomes of Species A and B have a 3% difference in single nucleotides.

How can analysis of mammalian genomes be used to detect and treat human disease? Check all that apply.

The genomes of the mammalian relatives of humans are the best targets for discovering new treatments for human diseases. Comparing the genomes of parasite and host is likely to reveal good drug targets to eliminate the parasite without harming the host. A comparison of mouse and human genomes would help reveal functions for previously unidentified human genes.

Choose the true statements about the human and mouse genomes.

The human genome shares 99% of its genes with the mouse genome. A comparison of genomes confirms that mice and humans shared a common ancestory more recently than humans and pufferfish.

During meiosis, a hexaploid hybrid spontaneously eliminates one set of chromosomes (eliminates 1n). What is the most likely result of this deletion?

The hybrid will no longer be able to reproduce.

A scientist is interested in the genetics of cold stress response in sunflowers. Using a DNA microarray to study gene expression, she should compare these two samples: (Choose two.)

cDNA from stem grown at 20°C cDNA from stem grown at 5°C

One of the unexpected findings to occur in comparing mouse and human genomes is

that "junk" DNA may be more functional than we assumed

When interpreting the results of microarrays, the degree of hybridization between each probe and the sample is indicated by

the color of the spots.