module 11

Question 1

Genomes are ___________?

Answer 1

dynamic

Question 2

What is a failed chromosome and/or sister chromatid segregation during cell division called?

Answer 2

Nondisjunction

Question 2

What occurs when an
organism carries one or more
complete extra sets of
chromosomes?

Most common in _______

polyploids may be __________
or ______________

Answer 2

Polyploidy

plants

autopolyploid
allopolyploids

Question 3

Extra chromosomes from within
same species

tetraploid ex:

triploid ex:

Answer 3

Autoployploids

• peanuts
• bananas

Question 4

Three mechanisms lead to autopolyploidy

Answer 4

▪ multiple fertilizations (sexual)
▪ meiotic nondisjunction (sexual)
▪ mitotic nondisjunction (asexual)

Question 5

______________is thought to be
the most common form of
polyploidy in plants

diploid ex:
tetraploid ex:

Answer 5

alloployploid

einkorn wheat
emmer wheat

Question 6

Two species of goatsbeard, Tragopogon miscellus and T.
mirus, have arisen multiple times in the past 80 years
through hybridization of other Tragopogon species.
Following hybridization, the genome doubled, resulting in
the new, fertile species. These speciation events are an
example of:

a) autopolyploidy
b) allopolyploidy
c) euploidy
d) aneuploidy
e) all the above

Answer 6

Banding pattern during metaphase:
more condensed = ?
less condensed = ?

Question 7

Banding pattern during metaphase:
more condensed = ?
less condensed = ?

________ _____ provides consistent banding
patterns across human chromosomes.

Answer 7

lower resolution
finer resolution
Giemsa staining

Question 8

Organisms with one normal and
one terminally deleted
chromosome are called what?

▪ Example?
- terminal deletion on what chromosome?

Answer 8

partial deletion heterozygotes
human cri-du-chat
syndrome
▪ terminal deletion on chromosome 5

Question 9

Define interstitial deletion

Answer 9

loss of an internal portion of a chromosome

Question 10

Wagr syndrome, Series of conditions
caused by deletion on
chromosome 11, is what type of deletion?

Answer 10

Interstitial (internal) deletion

Question 11

Define WAGR syndrome

Answer 11

W=Wilms tumor
A=aniridia
G=genitourinary abnormalities
R=mental retardation

Question 12

Occasionally an unequal crossover takes
place where?

what does this cause?

Answer 12

between two homologs

partial duplication on one homolog and
partial deletion on the other

Question 13

What syndrome with a deletion on chromosome 7 is an example of unequal crossover?

Answer 13

Williams-Beuren syndrome

Question 14

chromosome _____________: reattachment
in the wrong orientation

▪ chromosome ____________: reattachment
to a nonhomologous chromosome

these two things can result from?

Answer 14

inversion
translocation

chromosome breakage

Question 19

what is Chromosome Translocation

Answer 19

Attachment of all or parts of
non-homologous chromosomes

Question 19

differing by ONE extra or ONE fewer
chromosome than normal (sometimes a few)

_____________ = three of a particular chromosome
___________= one of a particular chromosome

Define Euploidy

Answer 19

Aneuploidy

trisomy
monosomy

differ by ONE OR MORE entire sets of chromosomes (triploid, tetraploid)

Question 20

what are translocation heterozygotes

Answer 20

one normal copy and one translocated copy of each chromosome

Question 21

Three Types of Translocations

1.arise when a piece of one chromosome is translocated to a non-homolog and there is no
reciprocal event

2. Reciprocal balanced translocations:
3. also called chromosome fusions, involve fusion of two nonhomologous chromosomes

Answer 21

1. unbalanced translocations
2. occur when pieces of two non-homologs
   switch places
3. Robertsonian translocations

Question 22

ANEUPLOIDY

Either sex chromosomes or ____________

▪ Severe _______ ____________(e.g., Down’s syndrome = trisomy
of chromosome 21)

▪ Do Plants or animals tolerate aneuploidy better?

Problems arising from aneuploidy are typically due to?

Answer 22

autosomes

genetic imbalance

Plants tolerate aneuploidy better than animals

altered gene dosage

Question 23

what are the consequences of translocations during meiosis?

Answer 23

partially homologous chromosomes can synapse during meiosis for reciprocal balanced translocations, this leads to formation of a tetravalent complex

Question 24

What is the leading cause of congenital birth defects and miscarriages? T/F Estimated 1 in every 170 live births is at least partially aneuploid

Answer 24

aneuploidy TRUE

Question 25

DNA sequences that can move around the genome. Enzyme-driven process called transposition -make up large portion of genome in many species

Answer 25

Transposable genetic elements (TEs)

Question 26

If two pairs of chromosomes fuse by Robertsonian translocation, the number of chromosomes drops to what?

Answer 26

2n − 2

Question 27

Transposable Genetic Elements Move throughout the Genome and can disrupt gene function via?

Answer 27

insertional inactivation

Question 28

Transposable elements typically share a similar general structure, which may include: 1. _______ ____ repeats: (not part of element) 2. __________ _______ repeats (part of element) 3. central region with ______ or more genes

Answer 28

1. flanking direct repeats 2. terminal inverted 3. one

Question 29

During gamete formation in an adult male, a nondisjunction event occurs during anaphase of meiosis II. As a result, _____ gamete(s) resulting from this meiosis will carry an aneuploidy. a) 1 b) 2 c) 3 d) 4 e) none of the

Question 30

_______________ can develop from mitotic nondisjunction early in embryogenesis.

Answer 30

Mosaicism

Question 31

25–30% of Turner syndrome cases occur in mosaic females mix of 2n=45 XO, 2n=46 XX (and 2N=47 XXX cells) T/F

Answer 31

TRUE

Question 32

Transposition mechanism

Answer 32

Staggered cut at the insertion site generated by transposase (or integrase)

Question 33

individuals with both male and female characteristics

Answer 33

gynandromorphs

Question 34

Class I TEs: 1. ____________ ▪ 2.________________ (replicative) transposition ▪ TE transcribed into RNA, reverse-transcribed to 3.______ for insertion 4. __________ in copy number, can disrupt gene function ▪ examples: LINEs, SINEs

Answer 34

1. retrotransposons 2. ‘copy and paste’ transposition 3. DNA 4. expansion

Question 35

Class 1.___ TEs: DNA transposons 2.___________ (non-replicative) transposition no RNA intermediate, TE is cut out and re-inserted in another location no expansion in copy number, can disrupt 3. ______ function ▪ examples: Ds and Ac elements in maize

Answer 35

1. Class II 2. ‘cut and paste’ transposition 3. gene function

Question 35

which elements can move by themselves? ▪ example: LINEs ▪ which elements require other TEs for transposition? ▪ example: SINEs

Answer 35

autonomous non-autonomous

Question 36

Most bacterial transposons are what class?

Answer 36

DNA transposons (Class II)

Question 37

1.________ transposons (aka insertion sequences) ▪ transposase gene and terminal inverted repeats 2. ______________ transposons ▪ two flanking insertion sequences and one or more additional genes ▪ often carry antibiotic resistance gene

Answer 37

1. simple transposons 2. composite transposons

Question 38

Simple transposons (insertion sequences) are found in ?

Answer 38

bacteria, archaea, viruses and plasmids

Question 39

what transposons are up to ~10,000 bp, with flanking insertion sequences?

Answer 39

Bacterial composite transposons

Question 40

T or F Eukaryotes carry ONLY class I and not class II transposable elements

Answer 40

FALSE, Eukaryotes carry both class I and class II transposable elements

Question 41

Retrotransposons (Class I transposable elements) are composed of what, are found in what and are replicative?

Answer 41

composed of DNA, are found in eukaryotes

Question 42

How is RNA copied back into DNA?

Answer 42

reverse transcriptase

Question 43

LINEs and SINEs make up roughly ___% and ___% of the human genome, respectively

Answer 43

roughly 20% and 10%

Question 44

1. Retrotransposons are related to ? 2. gene(s) carried on retrotransposons are often flanked by what?

Answer 44

1. retroviruses 2. long terminal repeats (LTRs)

Question 45

wild-type C allele results in purple kernels ▪ mutant c1 allele produces yellow kernels ▪ closely linked genes produce plump/wrinkled (Sh/sh) and shiny/waxy (Wx/wx) kernels

Question 46

Class II elements Activator element (Ac) often leads to chromosome breakage at Ds gene

Question 47

1. Ac element (activator) contains transposase gene, ‘activates’ transposition of Ds gene 2. loss of Wx, Sh and C results in colorless/shrunken/waxy phenotype

Question 48

1. insertion of Ds (dissociation) gene disrupts C gene 2. Ac-activated excision of Ds from C is a reversion mutation ▪ C allele restored, purple color results

Question 49

Many duplicate copies eventually lose some or all function ▪ referred to as pseudogenes

Question 50

‘neo-functionalization’ = new function ▪ ‘sub-functionalization’ = division of function