Part A -

Genetics Practice Problems

1. The allele for round seeds (R) is dominant to the allele for wrinked seeds (r).  You cross two plants that are heterozygous at the R locus.  Draw the Punnett Square.  What is the probability of getting an offspring plant with wrinkled seeds?

2. You buy a pea plant that has round seeds.  You want to know whether it is homozygous or heterozygous. How would you test this (be very specific - what cross would you perform)? 

3. In humans, brown eyes (B) are dominant over blue (b). A brown-eyed man marries a blue-eyed woman and they have three children.  Three are brown-eyed and one is blue-eyed. Draw the Punnett square that illustrates this marriage. What is the father's genotype? What are the genotypes of the children? (There are a handful of genes involved in eye color, but blue eyes are specified by a mutation in a single gene, HERC2.)

4. Polydactyly (extra fingers or toes) is (usually) an autosomal dominant trait. If a person who is heterozygous for the allele that causes polydactyly has children with a person that has the normal number of fingers and toes, what is the probability that they will have a child with polydactyly?

5. A man with group AB blood marries a woman with group O blood. What blood types are possible in this couple's offspring and what is the probability of each blood type?

6. Ichthyosis is an X-linked recessive disorder that causes scaly skin. If a female carrier of the disease has children with a normal male, what is the probability of their sons having the disease? What is the probability of their daughters having the disease?

7. Lubber grasshoppers are black with stripes. Individuals homozygous for the S allele have red stripes, while individuals homozygous for the s allele have yellow stripes. Heterozygotes have both red and yellow stripes. What kind of inheritance is this? If you crossed a red-and-yellow striped grasshopper to a yellow-striped grasshopper, what kind of offspring would you expect?

Part B -

Matching: Match the phase of the cell cycle to its description and write the correct word. Some will be used more than once.

G1          S              G2          G0          Prophase                             Prometaphase                  Metaphase        

Anaphase                            Telophase                           Cytokinesis

____________________1.       Chromosomes are replicated.

____________________2.       The cytoplasm is divided.

____________________3.       Chromosomes "relax" into chromatin.

____________________4.       The chromosomes are at the cell equator.

____________________5.       The nuclear membrane disappears from view.

____________________6.       The spindle apparatus begins to form.

____________________7.       The sister chromatids are pulled apart.

____________________8.       The kinetochores attach to the spindle apparatus

____________________9.       Genes are transcribed to make mRNA.

____________________10.     The cell is not dividing, although it may be metabolizing.

____________________11.     The microtubules attached to kinetochores get shorter.

____________________12.     A checkpoint occurs during this phase.

____________________13.     Nuclear envelope forms around DNA.

____________________14.     Chromatin condenses to form distinct chromosomes.

____________________15.     The cell grows during this phase.

Part C -

Transcription and Translation

1. Which process takes place in the nucleus?  ___ transcription     ___ translation

2. Complete the following table.

3. Fill in the blanks in this table to summarize the differences between DNA replication and transcription.

4. This table gives some examples of tRNA anti-codons with their corresponding amino acids. Complete this table to show the mRNA codon that is complementary to each tRNA anti-codon.

Different versions of the same gene are called different alleles.  These different alleles share the same general sequence of nucleotides, but they differ by at least one nucleotide in the sequence. 

Different alleles can result in different characteristics as follows:

Different alleles of a gene have a different nucleotide sequence

Different nucleotide sequence in mRNA(transcription)

Different amino acid sequence in a protein (translation)

Different structure and function of the protein (e.g. normal enzyme vs. defective enzyme)

Different characteristics (e.g. normal skin and hair color vs. albinism)

5. Complete this table.(Use the genetic code to complete translation).

6. These sequences are a small part of the tyrosinase gene in normally colored cats and Siamese cats. Circle the mutated nucleotide. What kind of mutation is this?

7. This is a different mutation in the tyrosinase gene. Circle the mutated nucleotide. What kind of mutation is this?

8. What do you predict the phenotype of a cat that is homozygous for the mutated tyrosinase allele will be?

Attachment:- Assignment Files.rar