Download Revision sheet Biology Grade 12 A Genes in Action In the space

Revision sheet Biology Grade 12
A
Genes in Action
In the space provided, write T if the statement is true or F if it is false.
_____ 1. An insertion is the change of one nucleotide from one kind of base to another.
_____ 2. A missense mutation has no effect on the resulting amino acid sequence.
_____ 3. A frameshift mutation causes a change in the reading frame of a DNA sequence.
_____ 4. A deletion can occur as a small change in the DNA or a larger change in the
chromosome.
In the space provided, write the letter of the term or phrase that best completes each
statement.
_____ 5. Germ cell mutations are
a. heritable (passed on to the next generation).
b. not heritable
c.similar in effect to body cell mutations.
d.
_____ 10. Nondisjunction can result in
a. polyploidy.
b. a normal number of chromosomes.
c. a gene rearrangement.
Using the word bank below, fill in each blank provided.
intron
lac
operator
operon
promoter
repressor
splicing
transcription
11. Exons are joined together during RNA _______________________.
12. A(n) _______________________ is the collective name for a group of genes with related
functions, along with their promoter site, and their operator.
13. A(n) _______________________ protein binds to the operator and this inhibits
transcription (turns off the operon).
14. The _______________________ operon controls the metabolism of lactose.
15. The _______________________ comes before the structural genes in an operon.
16. RNA polymerase binds to the _______________________ region.
17. The ____________________ factor serves as an on-off genetic switch for transcription in
eukaryotes.
18. A segment of DNA that has no coding information is a(n) _______________________.
B
_____ 1. Point mutations involve a change in
a. a single nucleotide.
c. a few genes.
b. a single gene.
d. an entire chromosome.
_____ 2. After mRNA has been transcribed in eukaryotes,
a. its promoters are cut out.
b. its operons are joined together.
c. it leaves the nucleus through pores.
d. its introns are removed.
_____ 3. The mutation that has no effect on a gene’s function is called
a. missense.
b. silent.
c. frameshift.
d. enhancer.
_____ 4. The mutation in which a chromosome carries repetitive sets of alleles for a gene is
called a(n)
a. duplication.
b. deletion.
c. translocation.
d. inversion.
_____ 5. An operon is composed of which of the following?
a. a group of proteins, their promoter site, and their operator
b. a group of genes, their operator, and RNA polymerase
c. a group of genes, their promoter site, and their operator
d. an enhancer, an operator, and RNA polymerase
_____ 6. Regulatory proteins in eukaryotes that are involved in controlling the onset of
transcription are called
a. repressors.
c. operators.
b. transcription factors.
d. enhancers.
_____ 7. If a deletion mutation eliminated all of the guanine bases from the codon sequence
GAT-CGC-CAA-TAG, the altered sequence would read
a. ATC-TCA-ATA.
c. ACC-CAA-ATA.
b. ATC-CCA-ATA.
d. AAT-CCA-TAC.
_____ 8. In which of the following would a heritable mutation occur?
a. skin cell
b. liver cell
c. somatic cell
d. egg cell
_____ 9. When a group of cells grows in an uncontrollable manner, it becomes a
a. carrier.
b. sickle cell.
c. tumor.
d. genetic disorder.
_____ 10. Which of the following represents the portion of a protein molecule that has a
specific structure and function?
a. exon
b. intron
c. subunit
d. domain
In the space provided, write the letter of the description that best matches each term.
_____ 13. plasmid
_____ 14. genetic disorder
_____ 15. polyploidy
_____ 16. exon
_____ 17. transposon
_____ 18. transcription factor
a. coding segment of DNA
b. having more than two sets of
chromosomes
c. caused by inherited mutations
d. can turn the lac operon “on” and “off”
e. cell specialization
f. extra piece of DNA in a bacterium
g. initiate transcription by binding to
enhancers and RNA polymerases
h. “jumping” genes
_____ 19. cell differentiation
_____ 20. repressor
Descriptive part
1)What is the difference between an inversion and a translocation?
______________________________________________________________
______________________________________________________________
3)How is RNA polymerase affected by the presence of lactose in bacterial cells?
______________________________________________________________
______________________________________________________________
4)What are introns?
______________________________________________________________
______________________________________________________________
5)Give two examples of chromosome mutations.
______________________________________________________________
______________________________________________________________
Answer key( A)
1.F
2. F
3. T
4. T
5a.
11.splicing
12.
operon
13.
repressor
14. lac
15.operator
16.
promoter
17.
transcription
18. intron
Answer key( B)
1. a
2.
3.
4.
5.
6.
7.
8.
9.
10.
d
b
a
c
b
b
d
c
d
13.
14.
15.
16.
17.
18.
19.
20.
f
c
b
a
h
g
e
d
Descriptive part
1) Inversions lead to a DNA region being reversed 180 degrees. Translocations involve a piece of one chromosome
moving to another chromosome.
3)When present in prokaryotic cells, lactose binds to the repressor protein. The repressor prevents RNA polymerase
from binding to the promoter. With the blocking effect eliminated, the transcription of genes that code for
lactose-metabolizing enzymes proceeds.
4).Introns are segments of nucleotides in eukaryotic genes with no coding information. After transcription, enzymes
remove introns from the mRNA molecule.
5) a piece of a chromosome breaks off; duplication—a chromosome fragment attaches to its homologous
chromosome, which then has two copies of the genes in the fragment; inversion—a chromosome fragment
attaches to the same chromosome in the reverse orientation; translocation—a chromosome fragment attaches to
another chromosome.