Question

The genome in a retrovirus such as HIV, is composed of?

a. (+) strand RNA          b. (-) strand RNA          c. double-stranded DNA           d. single-stranded DNA

Consider a (+) strand RNA virus such as Covid-19, with sequence 5’ AUGUUUCCG 3’ contained in the genome.

a. Polypeptide encoded in this sequence __________________.

b. Sequence of molecule produced using above sequence as a template ___________________.

c. Name of enzyme which synthesizes molecule in part b _____________________.

d. Why is production of molecule in part b important to the viral life cycle (1 or 2 sentences)?

     __________________________________________________________________________.

___ cells have extra or missing chromosomes; ___ cells contain a normal number of chromosomes.

a. Aneuploid; euploid     b. Polyploid; autosomal     c. Autosomal; polyploid      d. Euploid; aneuploid

____ is a common cause of aneuploidy resulting in a gamete with one extra chromosome and another gamete with one missing chromosome.

a. Chromosome pairing        b. Inversion           c. Crossing over             d. Nondisjunction

Nondisjunction in which parent leads to the sex chromosome aneuploid XYY?

a. Mother        b. Father       c. Either parent       d. Needs to occur in both

Nondisjunction of Chr 21 during meiosis II in females can result in all of the following in a zygote except? Assume the oocyte is fertilized by a sperm with normal chromosome count.

a. no chromosome 21                       b. euploid for chromosome 21     

c. monosomic for chromosome 21    d. trisomic for chromosome 21

Consider the following normal sequence of genes: a b c d e f g h.

The sequence a b f e d c g h represents a(n) _____.

a. Deletion          b. Duplication            c. Inversion             d. Translocation

In a(n) ____, the short arm of two chromosomes break, and the long arms join forming a single large chromosome with two long arms.

a. Reciprocal translocation         b. Duplication         c. Robertsonian translocation     d. Inversion

In the E. coli Lac Operon the order of segments in the DNA is?

a. operator, promoter, ß-galactosidase gene, permease gene, transferase gene

b. ß-galactosidase gene, permease gene, transferase gene, operator, promoter

c. promoter, operator, ß-galactosidase gene, permease gene, transferase gene

d. ß-galactosidase gene, permease gene, transferase gene, promoter, operator

Answer 1

HIV is composed of + strand RNA.

A. Polypeptide from the given sequence - Met-Phe-Pro (AUG codes for methionine, UUU codes for phenylalanine, CCG codes for proline)

B. Sequence of molecule (RNA) produced using above sequence as template: 3' UACAAAGGC 5'

C. Name of enzyme: RNA dependent RNA polymerase

D. Importance: Helps to synthesise more copies of the genome very quickly that can be packed into new virion particles and released from host cells.

Aneuploid cells have an extra or missing chromosome, euploid cells have a normal number of chromosomes.

Nondisjunction is the method by which paired homologous chromosomes fail to separate and stick together in a gamete, resulting in one gamete with both chromosomes of the pair and another gamete with none of the pair.

Father - The extra copy of Y chromosome comes from a defective sperm cell where due to nondisjunction, an extra Y chromosome was retained.

Nondisjunction of chr 21 - no chromosome 21 (whatever happens in the gamete from mother, the zygote still gets one functional chr21 from father, which means there cannot be a way where the zygote contains no chr 21)

Inversion: cdef region inverted to give fedc region in the chr

Robertsonian translocation - short arms break and long arms join to form a single long chromosome

Order of genes - c. promoter, operator, ß-galactosidase gene, permease gene, transferase gene