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Cellular and Molecular Biology > Exam 2: Ch 6 > Flashcards

Exam 2: Ch 6 Flashcards

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1
Q

noncoding DNA constitutes ___% of human chromosomal DNA

A

98.5%

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2
Q

DNA fingerprint

A

variations between repetitious stretches of DNA can be used to identify a person

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3
Q

transposable (mobile) DNA elements

A

within cellular genomes these mobile elements can copy themselves and move throughout the genome

45% of human genome

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4
Q

gene

A

the entire nucleic acid sequence that codes for synthesis of a protein or functional RNA

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5
Q

intron and exons

A

intron: noncoding regions of DNA found between genes and within genes
exon: relatively similar sequences in coding region selected for by evolution

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6
Q

2 types of short noncoding RNAs and basic functions

A

siRNA and miRNA

miRNA: regulate translation and mRNA stability

siRNA: breaks down mRNA after transcription so no translation

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7
Q

introns can process some RNA…

A

siRNA

miRNA

long noncoding RNA (regulate transcription by influencing chromatin structure)

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8
Q

where did mitochondria and chloroplasts evolve from?

A

intracellular eubacteria that developed symbiotic relationships with ancient eukaryotic cells

their DNA is an evolutionary remnant

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9
Q

chromatin

A

complex of DNA and the proteins that organize it

can be visualized as chromosomes during mitosis

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10
Q

genomics

A

computer based methods for analyzing and interpreting vast amounts of sequence DNA

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11
Q

nucleosomes

A

fundamental building blocks of chromatin

complex of DNA and histones

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12
Q

coding region

A

the nts that code an amino acid sequence or functional RNA

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13
Q

what does a gene contain

A

the coding region

all the DNA sequences required to synthesize a particular RNA transcript (these sequences can be located anywhere… not just in coding region)

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14
Q

enhancer

A

transcription control region

can be >50kb away from the coding region

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15
Q

cistron

A

a genetic unit encoding a single pp

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16
Q

most eukaryotic mRNAs are ____cistronic

A

mono

each mRNA encodes a single pp

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17
Q

in a bacterial polycistronic mRNA where is the ribosome located?

A

near the start site for each of the cistrons

translation initiation can begin at any of these sites

produces multiple proteins

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18
Q

in eukaryotic monocistronic mRNA where is the ribosome located?

A

5’-cap structure where ribosome binds

translation begins at closest AUG start codon

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19
Q

are introns usually longer than exons?

A

yes

longest in tintin gene…17,106bp

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20
Q

mutations in ____, _____, and _________ ______ ______ may all influence expression of the protein encoded by a simple transcription unit

A

exons, introns, transcription control regions

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21
Q

approximately ___% of human transcription units are ____

A

90%, complex

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22
Q

alternative splicing in fibronectin

A

multiple copies of 5 types of exons separated by introns

determines whether or not the secreted protein contains domains that adhere to cell surfaces

in fibroblasts and hepatocytes…ECM component

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23
Q

a mutation in the control region or in an exon shared by alternatively spliced mRNAs will affect…

A

all the alternative proteins

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24
Q

a mutation in an exon present in only one alternative mRNA will affect…

A

only the protein encoded by that mRNA

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25
isoform
various proteins encoded by alternatively spliced mRNAs expressed from a single gene
26
solitary gene
25-50% of protein-coding genes are represented only once in the haploid genome
27
lysozyme
an enzyme that cleaves polysaccharides in bacterial cell walls found in egg white protein and human tears
28
duplicated gene
genes with close but nonidentical sequences often located within 5-50kb of one another
29
gene family
a set of duplicated genes that encodes proteins with similar but nonidentical aa sequences ex. genes encoding beta-like globins
30
protein family
the encoded, closely related, homologous proteins produced by a gene family ex. kinases, vertebrate immunoglobulins, olfactory receptors
31
all hemoglobins formed from the different beta-like globin gene family carry oxygen in the blood, but....
exhibit different properties that are suited to their specific functions in human physiology ex. A(y) and G(y) pp are expressed only during fetal life and have a higher affinity for oxygen
32
pseudogene
nonfunctional sequences even though they have exon-intron structure mark location of gene duplication that occurred in our ancestors not deleterious
33
segmental duplication
duplication of segments of a chromosome occurred fairly often during evolution of multicellular plants and animals
34
members of gene families that arose relatively recently in evolution are often found...
near each other on the same chromosome could also be found on different chromosomes
35
major cytoskeletal proteins
actins tubulins intermediate filaments (keratin)
36
heavily used gene products are encoded by...
multiple copies of genes
37
tandemly repeated arrays
genes encode identical or nearly identical proteins or functional RNAs for genes encoding rRNA and nonprotein-coding RNAs like those involved in RNA splicing
38
why are tandemly repeated RNA genes needed?
to meet the great cellular demand for their transcripts ex. during early embryonic development cells have a doubling time of 24 hrs and need enough rRNA to manage this
39
smRNA
small nuclear function in RNA splicing
40
snoRNA
small nucleolar RNA function in rRNA processing and base modification in the nucleus
41
miRNA
micro RNA regulates the translation and stability of specific mRNAs
42
non-protein coding genes can encode...
functional RNAs
43
globin proteins comprise > __% of the total protein in developing red blood cells
50% globin genes expressed at maximum rate
44
2 types of repetitious DNA
interspersed repeats (more common) simple-sequence/satellite (less common)
45
satellite DNA (simple sequence DNA)
perfect or nearly perfect repeats of short sequences 6% of genome 1-500 bp
46
interspersed repeats
more common type of repetitious DNA longer sequences of repeated DNA consisting of several types of transposable elements
47
microsatellite DNA
1-13 bp (most common is 1-4) causes Huntington disease and myotonic dystrophy type 1
48
2 functions of satellite DNA
formation of centromeric heterochromatin that is necessary for proper segregation of chromosomes to daughter cells in mitosis telomeres
49
minisatellites
larger than microsatellites slight differences in lengths in individuals can be directed with Southern blotting used for DNA fingerprinting
50
unclassified ____ DNA occupies a significant portion of the genome
spacer 25%, occurs between transcription units and is not repeated elsewhere in the genome enhancers found here sometimes
51
what are transposable/mobile DNA elements
interspersed repeats, moderately repeated DNA, intermediate repeat DNA sequences are copied and inserted into new sites in the genome by transposition "selfish DNA" exist only to maintain themselves
52
during transposition of a mobile element, adjacent DNA...
is sometimes also mobilized 2nd mechanism for causing chromosomal DNA rearrangements
53
2 categories of mobile elements
those that transpose directly as DNA those that transpose via an RNA intermediate that is transcribed from the mobile element by an RNA polymerase then converted back into dsDNA by reverse transcriptase
54
DNA transposons (transposons)
mobile elements that transpose directly as DNA
55
retrotransposons
mobile elements that transpose using an RNA intermediate move but also remain at original location analogous to infection by a retrovirus
56
insertion sequence
IS element inserted stretches of DNA into the middle of a gene
57
inverted repeat
region that encodes transposase (enzyme required for transposition of IS element to new site)
58
3 functions of transposase in transposons
excise IS element in donor DNA makes staggered cuts in a short sequence in target DNA ligates 3' termini of IS element to 5' ends of cut donor DNA
59
2 types of retrotransposons
those containing long terminal repeats those lacking long terminal repeats (most common)
60
long terminal repeats
250-600bp that are found on either end of the coding region in LTR retrotransposons can function as a promoter and directs RNA processing
61
most common LTR retrotransposons in humans are
ERVs: endogenous retroviruses
62
nonviral retrotransposons
lack LTRs and are most common in mammals moderately repeated DNA sequences form 2 classes
63
2 classes of nonviral retrotransposons
long interspersed elements (LINEs) short interspersed elements (SINEs)
64
key step in retroviral life cycle
forming retroviral genomic RNA from integrated retroviral DNA
65
LINEs are found in... and in humans...?
found in protozoans, insects, plants, and mammals in humans... 3 families similar in mechanism of transposition but different in sequence (only L1) functional
66
LINE structure
flanked by short direct repeats 2 long ORFs ORF1: encodes an RNA binding protein ORF2: encodes a reverse transcriptase protein w/ DNA endonuclease activity
67
SINEs
2nd most abundant class of mobile elements in human genome do not encode protein transcribed by same nuclear polymerase used for tRNA
68
processed pseudogene
nonfunctional genomic copies of mRNA flanked by short direct repeats
69
mobile element human diseases
hemophilia, Duchenne muscular dystrophy
70
exon shuffling
recombination between mobile DNA elements in introns of 2 separate genes generates new genes made from new combinations of preexisting exons
71
3 ways mobile DNA elements are not parasitic selfish molecules, and have contributed to evolution
promote generation of gene families creation of new genes via exon shuffling forming complex regulatory regions that provide multifaceted control of gene expression
72
multiple genetic systems of eukaryotes
primary nuclear system secondary systems with their own DNA: ribosomes, tRNAs in mitochondria and chloroplasts
73
mtDNA
mitochondrial DNA some cells contain more than others mitochondria contain multiple mtDNA molecules inherited maternally and cytoplasmically
74
products of mitochondrial genes are not _____
exported
75
heteroplasmy
when mutations in mtDNA are found, cells contain a mix of mutant and wild-type mtDNAs
76
chloroplast transformation has led to the engineering of plants that are resistant to...
bacterial and fungal infections, drought, and herbicides
77
bioinformatics
use of computers to analyze sequence data (genomes)
78
by comparing aa sequences of a protein encoded by a newly cloned gene with he sequences of proteins of known function an investigator can look for...
sequence similarities that provide clues to the function of the encoded protein related proteins exhibit more sequence similarity than the genes encoding them BLAST computer program
79
BLAST
basic local alignment search tool divides new protein sequence into shorter fragments and searches database for matches--assigns P values
80
low vs high p values
low p value: higher sequence similarity high p value: less sequence similarity
81
structural motifs
short sequences recurring in many different proteins similar functions
82
homologous (BLAST)
sufficiently similar in sequence to suggest a common ancestral sequence ex. tubulin family of genes
83
paralogous (BLAST)
sequences that diverged as a result of gene duplication
84
orthologous (BLAST)
sequences that arose due to speciation (different species)
85
ORF
open reading frame where protein-coding sequences are found stretch of DNA >100 codons beginning with start codon and ending with a stop codon
86
expressed sequence tag (EST)
aligned to a partial cDNA sequence
87
phenomena that generate more complexity in expressed proteins of higher eukaryotes
alternative splicing yielding multiple functioning mRNAs variations in post-translational modification of proteins increased numbers of cells built of the same kinds of proteins

Cellular and Molecular Biology (34 decks)

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