Chapter 8: Concept Of Genetics

Front 1

What is trisomy?

Back 1

It is where two copies of a given chromosome are in a single nuclei, thus resulting in developmental abnormalties. Also known, as the gain of one chromosome

Front 2

What is tripoidy

Back 2

Having three complete sets of chromosomes

Front 3

What is aneuploidy?

Back 3

Having an odd number of chromosomes

Front 4

What is monosomy?

Back 4

A single loss of a chromosome from an diploid genome

Front 5

What is euploidy?

Back 5

A complete haploid set of chromosomes is present

Front 6

Condition of more than two haploid sets of chromosomes is present

Back 6

polyploidy

Front 7

Organism with four sets of chromosomes

Back 7

tetraploid

Front 8

Three ways in which a normally diploid individual could have a variation on the two haploid sets

Back 8

-change in total number of chromosomes
-deletion or duplication of genes or chromosome segment
-rearrangement of genes on chromosom

Front 9

What is autopolyploidy?

Back 9

multiples of the same genome

Front 10

If nondisjunction occurs between P and the F1 generation, what will be the N number for the offspring of the F2 generation when mated with a haploid gamete; how is this different than if the nondisjunction occus between the F1 and F2 generations?

Back 10

2 Trisomic and 2 monosomic

2 disomic (normal) and one trisomic and monosomic

Front 11

What is the name for a 2nd-1 individual and is this condition tolerated if the -1 is an autosome?

Back 11

It is called monosomy; no, if it is autosome it is poorly tolerated in the animal kingdom

Front 12

Give an example of an organism tolerating monosomy of an autosome

Back 12

Drosophila; Chromosome 4, they develop more slowly and have impaired viability, and usually are smaller

Front 13

Where is monosomy most tolerated?

Back 13

In sex chromosomes

Front 14

What are two causes for autosomal monosomic inviability

Back 14

-unmasks recessive lethals
-single copy of a recessive gene may be insufficient to provide adequate function for sustaining the individual (haploinsiffinciency)

Front 15

When can trisomy be somewhat more tolerated than monosomy in individuals?

Back 15

When the chromosome involved is relatively small

Front 16

Trisomy for the sex chromosome has a __ dramatic phenotype than trisomies for autosomes, which are often lethal

Back 16

less

Front 17

What is the symbol for downsydrome?

Back 17

47, 21+

Front 18

What is the main phenotypic similarity among people with down syndrome?

Back 18

prominent epicanthic fold

Front 19

in trisomy, at any particular region along the chromosome length only 2 of the 3 homologs may ____, though different regions of the trio may be ___

Back 19

synapse, paired

Front 20

What is the down syndrome critical region?

Back 20

the hypothetical portion of chromosome 21 that is thought to contain the genes that are dosage sensitive and responsible for many phenotypes associated with the syndrome

Front 21

What is the configuration of three copies that are synapsed called?

Back 21

trivalent

Front 22

In some cases, prior to the first division, one bivalent and one ___ may be present instead of a trivalent

Back 22

univalent

Front 23

Where does the nondisjunction of chromosome 21 occur during anaphase 1 in meiosis?

Back 23

maternal

Front 24

Name and describe three techniques for determining if a fetus has down syndrome?

Back 24

Chrionic villus sampling- fetal cells obtained from chorin of placenta
amniocentisis- fetal cells obtained from amniotic fluid
noninvasive prenatal diagnosis- 10 mL of maternal blood sample

Front 25

Name of downsydrome where it runs in families and what does it involve?

Back 25

it is a translocation of chromosome 21 and is called familial down sydrome

Front 26

Name two other trisomies that survive to term

Back 26

Edwards syndrome trisomy 18
Patau syndrome - trisome 13

Front 27

The percentage of all conceptions that are terminated in spontaneous abortions

Back 27

20%

Front 28

Name the percentage of spontangeously aborted fetuses that demonstrates some form of chromosomal imbalance

Back 28

50%

Front 29

Name the percentage of fertalized eggs that contain some error in chromosomal number

Back 29

10-30%

Front 30

What is the percentage of all chromosomal anomalies are spontaneously terminated before birth

Back 30

90%

Front 31

Give evidence that monosomic gametes may be very functionally impaired compared to trisomic?

Back 31

trisomies are often found in spontaneously aborted fetuses; monosomies are hardly found at all

Front 32

In what organisms is polyploidy very common?

Back 32

Lizards, amphibians, fish and plants

Front 33

Name two ways polyploidy can originate. Name two words that associate with these ways

Back 33

-the addition of one or more extra sets of chromosomes identical to the normal haploid complement of the same species
-autoploidy
-combination of chromosome sets from different species occuring as a consequence of hybridization
-alloploidy

Front 34

In ___ each additional set of chromosomes is identical to the parent species

Back 34

autopolyploidy

Front 35

What are several ways in which autotriploids arise

Back 35

-failure of chromosomes to segregate during meiotic divisions
-two sperm may fertilize an ovum resulting ina triploid zygote
-corssing a diploid with a tetraploid
-producing a diploid gamete

Front 36

What is the combination of chromosome sets from different species as a consequence of interspecific matings

Back 36

allopolyploidy

Front 37

What effect does colchicine have on the cell cycle?

Back 37

It interferes with spindle formation and thus replicated chromosomes cannot separate during anaphase or move to the poles. When colchicine is removed, the cell can recenter interphase. When the paired sister chromatids separate and uncoil, the nucleus contains twice the diploid number of chromosomes and is therefore 4n

Front 38

Are autopolypoids typically smaller or larger than their diploid relatives

Back 38

larger

Front 39

What are several examples of large autopolyploids?

Back 39

winesap apples, seedless watermelon, commercial bananas

Front 40

The commerical strawberry is an

Back 40

octaploid