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BMSC 220 > Lecture #15 > Flashcards

Lecture #15 Flashcards

1
Q

DNA that is more compact than its relaxed counterpart is called ________

A

supercoiled

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2
Q

Underwound DNA is _______ supercoiled, and overwound DNA is ________ supercoiled

A

negatively, positively

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3
Q

________ supercoiling plays a role in allowing chromosomes to fit within the cell nucleus

A

Negative

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4
Q

Enzymes called ________ change the level of DNA supercoiling

A

topoisomerases

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5
Q

Type __ Topoisomerases – change the supercoiled state by creating a transient break in one strand of the duplex.

A

I

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6
Q

Type __ Topoisomerases – make a transient break in both strands of the DNA duplex.

A

II

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7
Q

In addition, supercoiling and relaxing DNA, type __ topoisomerases can tie a DNA molecule into knots or untie a DNA knot. They can ______ (catenate) independent DNA circles, or separate interlinked circles into individual components.

A

II, interlink

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8
Q

________ – the ability to separate into its separate components

A

Denaturation

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9
Q

________ denaturation (or DNA melting) can be monitored by following the increase in absorbance of UV light by the dissolved DNA

A

Thermal

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10
Q

Temperature where the shift in absorbance is half completed is the ______ ________ (Tm).

A

melting temperature

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11
Q

The higher the ____ content of the DNA, the higher the Tm.

A

GC

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12
Q

__________ or reannealing is when single-stranded DNA molecules are capable of reassociating

A

Renaturation

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13
Q

In ?, complementary strands of nucleic acids from different sources can form hybrid molecules; this is important in DNA sequencing, cloning, and amplification

A

nucleic acid hybridization

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14
Q

Studying reannealing rates of different genomes has provided insight into various types of _______

A

sequences

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15
Q

Three broad classes of DNA sequences, differing in number of times their _______ sequence is repeated

A

nucleotide

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16
Q

Three broad classes of DNA sequences:
______ repeated fraction
_______ repeated fraction
________ fraction

A

highly, moderately, non-repeated

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17
Q

______ Repeated DNA Sequences – represent about 1–10% of total DNA

A

Highly

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18
Q

_______ DNAs – short sequences that tend to evolve very rapidly

A

Satellite

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19
Q

_________ DNAs – unstable and tend to be variable in the population; form the basis of DNA fingerprinting

A

Minisatellite

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20
Q

_________ DNAs (STRs) – shortest sequences and typically found in small clusters; implicated in genetic disorders

A

Microsatellite

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21
Q

Fluorescent probes are generated towards a specific DNA ________. Allows determination of its location(s) within the ______ of an organism.

A

sequence, genome

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22
Q

FISH can be used to visualize repetitive sequences like that found in _______ DNA localized in the centromeric regions of the chromosome, or for determining the position of _____ copy genes

A

satellite, single

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23
Q

The ________ repeated fraction of the genomes of plants and animals can vary from 20% to more than 80% of total DNA. This fraction includes sequences that are repeated within the genome anywhere from a few times to tens of thousands of times.

A

moderately

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24
Q

Some sequences code for _______ gene products, (e.g. rRNAs or histones), but most sequences lack a ______ function. These noncoding elements are ________ (i.e., interspersed) throughout the genome and can be grouped into SINEs (?) or LINEs (?).

A

abundant, coding, scattered, short interspersed elements, long interspersed elements

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25
Q

The ________ (or single-copy) DNA sequences include genes that exhibit Mendelian patterns of inheritance and ______ to a particular site on a particular chromosome

A

non-repeated, localize

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26
Q

Included within the non-repeated fraction are the DNA sequences that code for virtually all proteins other than _______, which comprise less than 1.5% of the human genome.

A

histones

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27
Q

Even though these sequences are not present in multiple copies, genes that code for _________ are usually members of a family of related genes, like the globins, actins, myosins, collagens, tubulins, integrins, and most other _______ in a eukaryotic cell

A

polypeptides, proteins

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28
Q

Most of our cells are ______ (2n, n is the number of chromosomes) meaning that they have two complete sets of chromosomes, with each parent contributing a chromosome to each pair

A

diploid

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29
Q

_____________ refers to possessing more than two complete sets of chromosomes. This is common in higher plants

A

Polyploidization

30
Q

These are the mechanisms for polyploidation:
- Two related species can mate to form a ______ organism with the combined chromosomes from both parents (plants)
- 1-cell embryo can undergo chromosome _______ and retain the DNA. (animals)

A

hybrid, duplication

31
Q

Gene duplication occurs within a portion of a ______ chromosome

A

single

32
Q

Duplication may occur by ? between misaligned homologous chromosomes

A

unequal crossing over

33
Q

Duplication has played a major role in the evolution of ________ families

A

multigene

34
Q

The ______ gene family includes hemoglobin, myoglobin, and plant leghemoglobin

A

globin

35
Q

Ancestral forms have given rise to recent forms by duplication, gene fusion, and ________

A

divergence

36
Q

Some sequences, called ________, resemble globin genes but are nonfunctional

A

pseudogenes

37
Q

_______ ________ suggested that genetic elements were capable of moving around the genome. She called this genetic rearrangement __________, and the mobile genetic elements ________ ________.

A

Barbara McClintock, transposition, transposable elements

38
Q

Only certain sequences can act as _______, but these insert into target sites randomly. It requires the enzyme _______ to facilitate insertion into target site

A

transposons, transposase

39
Q

Integration of the element creates a small duplication in target DNA, which serves as a “footprint” to identify sites occupied by ________ _______

A

transposable elements

40
Q

_________ use an RNA intermediate which produces a complementary DNA via _________ ___________

A

Retrotransposons, reverse transcriptase

41
Q

Transposable elements can carry ______ parts of the host genome with them as they move from one site to another

A

adjacent

42
Q

DNA sequences originally derived from transposable elements are found as parts of eukaryotic genes and DNA segments that regulate gene _______

A

expression

43
Q

________ _______ themselves appear to have given rise to genes.

A

Transposable elements

44
Q

A number of recent studies have found evidence that mammalian brain cells have a greatly elevated level of L1 ___________ compared to that of other tissues

A

retrotransposition

45
Q

The genomes of hundreds of organisms have been sequenced. In 2004 the “finished” version of the human genome was reported, revealing that it contains about ______ genes

A

20,000

46
Q

______ ______ is when a single gene can encode a number of related proteins

A

Alternative splicing

47
Q

__________ are noncoding RNAs that can have gene regulatory functions.

A

MicroRNAs

48
Q

Proteins work together as complex networks rather than individual actors. Modest increase in protein numbers can generate ______ network complexities

A

significant

49
Q

Genome regions that encode protein sequences or contain regulatory sequences that control gene expression are subject to _______ ________, which tends to eliminate individuals whose genome contains ________

A

natural selection, mutations

50
Q

If these sequences tend to be conserved, the best way to identify functional sequences is to compare the genomes of _______ types of organisms

A

different

51
Q

Recent studies have shown a significant proportion of functional DNA sequences are constantly evolving and are not highly _______

A

conserved

52
Q

Majority of the genome lies between protein coding genes and is termed ________

A

intergenic

53
Q

Much of the @21,000 protein coding regions consists of non-coding portion (_______ DNA)

A

intronic

54
Q

Human chromosomes 12 sequence aligns roughly to _______ sequences on the indicated _______ chromosomes

A

mouse, mouse

55
Q

Which percentage range of the nucleotide sequence is repeated sequences, and which percentage range is unique sequences?

A

0-50% = repeated sequences
50-100% = unique sequences

56
Q

CRISPR-Cas9 and other DNA editing technologies have now made it possible to introduce ______ changes in the genomes of diverse organisms. These edits tend to be ______ and _______ – the addition or deletion of a short sequence at a specific site in the genome

A

specific, small, targeted

57
Q

_______ in human differs very little from that in chimps, and is called the “speech gene”

A

FOXP2

58
Q

_____, which also differs little between humans and chimps and its function is unknown

A

HAR1

59
Q

_____ encodes the enzyme amylase and its frequency is remarkably different between humans and chimps

A

AMY1

60
Q

Genetic ________ are sites in the genome that vary among different individuals, and usually refers to a genetic ______ that occurs in at least 1 percent of a species population

A

polymorphisms, variant

61
Q

The most common type of genetic variability in humans occurs at sites where single _______ differences are found in a population

A

nucleotide

62
Q

When present in at least 1 percent of the population, these sites are called ? (SNPs) and occur as two alternate alleles, such as A or G.

A

single nucleotide polymorphisms

63
Q

On average, two randomly selected human genomes have about __ million single nucleotide differences between them, or one every thousand base pairs

A

3

64
Q

Current estimates suggest that each person harbors over ____ rare single nucleotide variants in his or her _____ (the portion of the genome that codes for proteins)

A

100, exome

65
Q

What are GWAS?

A

Genome-Wide Association Studies

66
Q

_____ are used to find gene candidates or genome regions that contribute to a disease by testing for a correlation between disease status and genetic variation on the full genome

A

GWAS

67
Q

Genotyping high-density panels of polymorphisms in several thousand cases and controls to identify _______ ______

A

common variants

68
Q

Segments of the genome can change as the result of ?

A

duplications, deletions, insertions, and inversions

69
Q

Large changes range from hundreds to millions of base pairs in length and are called ______ ______

A

structural variants

70
Q

A typical human genome carries approximately _____ structural variants, ranging in length from about 500 bases to 1.3 million bases (Mb)

A

1000

71
Q

The lengths of minisatellite sequences depend on the number of copies of the sequence that are present at particular sites in the chromosomes, an example of a ?

A

copy number variation (or CNV).

72
Q

Larger-sized CNVs (<1 kb) affect approximately ___-___% of the human genome, including large numbers of protein-coding genes. Many carry extra copies of one or more genes that encode important physiological _____, generally associated with _________ of a protein.

A

10–15, proteins, overproduction

BMSC 220 (22 decks)

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