Gene Regulation

CRISPR-Cas9 is a genetic modification technique that edits parts of the genome of an organism. Using this technique scientists can add, remove, or modify sections of the DNA sequence. How can scientists use this technique to control gene expression?

• by activating or deactivating specific genes

• by calculating the number of genes different organisms produce

• by identifying how closely related one individual is to another

• by determining the number of chromosomes in an organism

Human bone, muscle, and nerve cells all contain the same number of chromosomes with the same complement of genes. What enables these cells to perform specialized activities?

• the ability of some cells to remove unnecessary DNA sequences

• the regulation of gene expression within each cell type

• the mutation of genes within each cell type

• the use of different methods of cell division

In 1917 the biologist Thomas Hunt Morgan conducted studies in which he kept some caterpillars in the dark and placed some others under red, green, or blue lights. Exposure to red light produced butterflies with brightly colored wings. Exposure to green light resulted in dark-colored wings. Exposure to blue light or no light resulted in pale-colored wings. What was the most likely conclusion of Morgan's research?

• the pigment in butterfly wings absorbs light from the environment

• the phenotypic expression of wing shape depends on color pigmentation in butterflies

• the genes regulating wing color in butterflies are influenced by environmental factors

• caterpillars exposed to red and green light are healthier than caterpillars exposed to no light or blue light

The "on/off" switch for an operon is called the

• promoter
• repressor
• operator
• gene

what does a promoter do?

• it allows a gene to be transcribed
• it creates a DNA segment
• it is another word for ribosomes
• it is another word for RNA

A protein that binds to the operator and blocks the RNA polymerase

• regulator
• repressor
• activator
• corepressor

A small molecule that binds to a repressor and makes it active

• repressor
• regulator
• activator
• corepressor

A small molecule that binds to the repressor and makes it inactive is

• corepressor
• inducer
• promoter
• operator

When a gene transcribes unless turned off by a repressor, it is considered _____ control

• negative
• positive

When a gene does not transcribe unless turned on by activator , it is considered _____ control

• positive
• negative