PCB3603 Questions Exam 1

Genetics is the major study of ________. 

1. inheritance and variation 

Which of the following is TRUE about alleles? 

1. Alleles come in two forms, the good form and the bad form. 

2. An allele is a variant form of a gene. 

3. Individuals carry both forms of each allele. 

4. The phenotype of the individual will always indicate with certainty the alleles of the individual. 

 

An allele is a variant form of a gene. 

What term is used to describe the fact that different genes in an organism often provide differences in observable features? 

1) Inheritance 

2. Genotype 

3. Alleles 

4. natural selection 

5. Phenotype 

Phenotype

Which of the following molecules serves the function to express the genetic material by being translated to protein? 

1. DNA 

2. Lipid 

3. Carbohydrate 

4. RNA 

5. cholesterol

RNA

An organism has 13 chromosome pairs. A cell undergoes anaphase, how many chromosomes are there in this cell? 

A. 13 B. 26 C. 52 

 

52

In an organism with 2 chromosome pairs, how many different combinations of gametes are possible (assume no crossing over) 

 

4

In an organism with 23 chromosome pairs, how many different combinations of gametes are possible (assume no crossing over)

8 mil

A G1 somatic cell nucleus in a female diploid Myrmecia pilosula (bulldog ant) contains 2 picograms of DNA. How much DNA would be expected in a metaphase of mitosis? 

 

1. 32 picograms 

2. 16 picograms 

3. 8 picograms 

D.4 picograms 

E. Not enough information is provided to answer the question 

D

If a typical somatic cell at G1 has 12 chromosomes, how many chromosomes are expected in the metaphase of mitosis? 

12

If a typical somatic cell has 64 chromosomes, how many chromosomes are expected in each gamete of that organism? 

 

1. 64 

2. 128 

3. 32 

4. 16 

32

At which stage of meiosis does exchange of genetic information between homologous chromosomes occur?

Prophase I

If one follows 20 primary oocytes in an animal through their various stages of oogenesis, how many secondary oocytes would be formed? 

 

A. 10 B. 20 C. 40 

D. 80 

C

If one follows 30 primary spermatocytes in an animal through their various stages of spermatogenesis, how many spermatids would be formed? 

 

A. 15 B. 30 

C. 60 

D.120 

 

120

During meiosis, chromosome number reduction takes place in ________. 

 

1. Prophase I 

2. Metaphase I 

C.Anaphase I 

4. Telophase II 

5. Anaphase II 

Anaphase I

A couple are both carriers of the cystic fibrosis allele (f), which is recessive to the normal allele (F). If they have 4 children, what is the probability that they have three unaffected children (FF or Ff) and one affected one (ff)? Assuming they are independent events.

.75*.75*.75*.25 = 10.5%

A couple are both carriers of the cystic fibrosis allele (f), which is recessive to the normal allele (F). If they have 4 children, three unaffected children (FF or Ff), what is the probability of the fourth child was the affected one (ff)? Assuming they are independent events

25%

A couple are both carriers of the cystic fibrosis allele (f), which is recessive to the normal allele (F). If they have 4 children, what is the probability that at least one child is the affected one? Assuming they are independent events.

1-(¾)^4= .684

Two specific scenarios formula

look at pic

Chi square formula

look at pic

Coefficient of coincidence

C= Observed DCO/ Expected DCO

I = 1-C

Epistasis

A condition in which one gene pair masks the expression of a nonallelic gene pair.

The cross GE/ge × ge/ge produces the following progeny:  

• GE/ge 404;  

• ge/ge 396;  – gE/ge 97;  

• Ge/ge 103.  

From these data one can conclude that the recombinant progeny are: 

1. gE/GE and GE/ge 

2. GE/ge and GE/ge 

3. gE/ge and Ge/ge 

4. Ge/Ge and gE/gE 

5. GE/GE and ge/ge 

1. gE/ge and Ge/ge 

 Assume that a cross is made between AaBb and aabb plants and that the offspring occur in the following numbers: 126 AaBb, 28 Aabb, 32 aaBb, 114 aabb. What is the distance between genes A and B? 

1. 20 MU 

2. 9 MU 

3. 100 MU 

4. 42 MU 

5. 50 MU 

20 MU

 Recombinants= 32+28 = 60/300 = 0.2

 Somatic cell hybridization analysis can be used to _______.

A. Produce cells that contain only human chromosomes 

2. compare the human and mouse genomes 

3. assign human genes to the chromosomes on which they reside 

4. assign a gene product to a particular gene 

assign human genes to the chromosomes on which they reside 

A linkage group _______. 

1. Represents all of the genes located on the same chromosome 

2. Can occur only on an autosome 

3. Is a collection of genes that never produce recombinant gametes 

4. Is a chromosomal region in which crossing over cannot occur 

Represents all of the genes located on the same chromosome 

Two genes that are 60 map units apart are expected to show _____ 

1. independent assortment 

2. 25% recombination 

3. 30% recombination 

4. 60% recombination 

1. independent assortment  (More than 50)

Synteny testing allows researchers to _____ 

 

1. assign genes to specific chromosomes 

2. map the physical positions of genes on chromosomes 

3. map the relative positions of genes on chromosomes 

4. determine physical distances (in nucleotides) between genes 

5. determine map distances (in recombination frequency) between genes

1. assign genes to specific chromosomes 

The genes A B C occur in that order in fruit flies. A is 10 map units from B, and B is 20 map units from C. 

How far is A from C? 

 

1. 0.2 map units 

2. 10 map units 

3. 20 map units 

4. 30 map units 

5. 40 map units 

30 map units 

The amino acid tryptophan is abbreviated “trp.” An E. coli  trp⁻ auxotroph can grow on _____. 

1. minimal medium 

2. minimal medium without tryptophan (trp) 

3. Minimal medium plus tryptophan (trp) 

4. complete medium 

5. Both c and d are correct 

 

1. Both c and d are correct 

This image shows the result of a serial dilution and culturing of a bacterial sample. The plate shown is a 10⁻⁶ dilution. What is the concentration of cells in the original culture? 

 

1. 12 cells/mL 

2. 120 cells/mL 

3. 12 ´ 10⁻⁶ cells/mL 

4. 1.2 ´ 10⁶ cells/mL 

5. 12 ´ 10⁶ cells/mL 

1. 12 ´ 10⁶ cells/mL 

In an Hfr × F⁻ mating, if the order of transfer of loci is leu – azi – ton – lac, one can conclude that _____. 

1. leu is adjacent to lac 

2. leu is adjacent to the point of origin 

3. the next transferred locus will be gal 

4. there are five time units between azi and ton 

5. all of the above are true 

leu is adjacent to the point of origin 

 Escherichia coli O157:H7 can cause serious food-borne illness. This strain of E. coli has acquired the ability to create a toxin normally produced in the bacterial species Shigella. Which of the following would not explain this ability found in E. coli? 

1. vertical transfer 

2. horizontal transfer 

3. conjugation 

4. transduction 

5. transformation 

vertical transfer 

Auxotrophic to prototrophic with barrier

Transduction

What do transformation, transduction, and conjugation all have in common? 

1. They all require a pilus. 

2. They all require a viral helper. 

3. They all use plasmids. 

4. They all involve the exchange of DNA between different bacteria. 

5. They all only work on bacteria within the same species. 

They all involve the exchange of DNA between different bacteria. 

A karyotype is done on a phenotypically female patient, and it is discovered that she has a Y chromosome. However, the Y chromosome appears to have a deletion. What region is most likely deleted? 

 

1. P A R 

2. S R Y 

3. centromere 

4. M S Y 

5. heterochromatin of M S Y 

S R Y 

A man observed his stained epithelial cells and saw a Barr body. If a karyotype was performed on his cells, what would you expect to see? 

1. 46, X Y 

2. 46 X X 

3. 47 X X Y 

4. 47 X Y Y 

5. Either c or d 

47 X X Y 

Which statement best describes human sex determination? 

1. Females are heterogametic. 

2. Individuals with a Y chromosome are male. 

3. Individuals with two X chromosomes are female. 

4. Individuals with at least twice as many X chromosomes as Y chromosomes are female. 

5. Individuals with one X chromosome are male. 

Individuals with a Y chromosome are male. 

 

Nondisjunction in the first meiotic division in a male human could result at fertilization in _____. 

b. Turner syndrome
c. Klinefelter syndrome

Which of the following best describes the Lyon hypothesis? 

1. Barr bodies are inactivated X chromosomes. 

2. The paternal X chromosome of a female is inactivated in an early embryonic stage. 

3. The maternal X chromosome of a female is inactivated in an early embryonic stage. 

4. One of the two female X chromosomes is randomly inactivated in an early embryonic stage. 

5. Each cell of a female randomly inactivates one X chromosome shortly after mitosis. 

One of the two female X chromosomes is randomly inactivated in an early embryonic stage. 

Drosophila, like humans, have X and Y chromosomes. However, unlike humans, it is the ratio of the number of X chromosomes to sets of autosomes that determines the sex of the fly. A fly has one X chromosome, two sets of autosomes (a diploid set), and no Y. What is its sex? 

1. male 

2. female 

3. intersex 

4. metamale 

5. metafemale 

 

male