Day 4_Semester 1_TEKS 5B/5C_DOL

When a stem cell divides, it produces two daughter cells. One daughter cell will remain a stem cell, while the other daughter cell will differentiate into a specialized cell. Which factor will most directly determine what type of a specialized cell will be produced?

• The size of the cell

• The length of the cell cycle

• The number of chromosomes that are replicated

• The geans that are expressed

What is the role of mRNA and expressing specialized structures?

• Making energy available for cellular activities

• Creating bond to form biomolecules

• Producing sugars that assist with replication

• Providing information to form proteins

The diagram shows how specialized body cells can develop. Which of the following best explains why cells that contain the same genetic material, do not develop into the same type of cells?

• Because internal or external stimuli can trigger the activation of a specific genes in the DNA of the cells

• Because random mutations can occur in the DNA of cells during early embryonic development

• Because messenger RNA is converted to transfer RNA when cell differentiation begins

• Because chemical signals that are released during the cell cycle can result in the linking of similar genes

From a single fertilized ovum undergoing a series of rapid cell divisions, a human infant develops. The embryonic cells become specialized for a variety of functions. Which of these statements best describes how different cell types develop?

• each cell type contains only the active parts of the DNA needed for that cell type

• each cell type has only one chromosome containing the DNA needed for that cell type

• each cell has an identical copy of DNA with enzymes controlling the expression of specific genes, leading to a variety of cells

• each cell has multiple copies of DNA that are affected in different ways by the environment to change the function of the cell at regular intervals

As a fertilized egg divides, the cells differentiate because they -

• contain a lipid bilayer

• can clump together

• metabolize sugars rapidly

• have specific genes activated

Researchers Robert Briggs and Thomas King used ultraviolet radiation to destroy the nuclear DNA of frog eggs. Nuclei from adult skin cells and from tadpole-gut epithelial cells were cultured and then injected into eggs that had their nuclei destroyed. The results were tadpoles. Which conclusion is supported by the data from this investigation?

• the DNA information for development was silenced in differentiated cells

• the transplanted DNA functioned as the original nuclear DNA of the egg cell would have

• the DNA from skin cells and epithelial cells was not transcribed

• the transplanted DNA mutated during culturing

Cell differentiation is critical during embryonic development. The process of cell differentiation results in the production of many types of cells, including germ, somatic, and stem cells. Cell differentiation is most directly regulated by -

• ATP

• DNA

• Lipids

• Sugars

When cells lose their ability to regulate the cell cycle, they can divide at an accelerated rate and form a mass of cells. This mass of cells is referred to as -

• a tumor

• an embryo

• a gland

• an organ

Oncogenes are mutated forms of genes. Oncogenes can transform a cell into a tumor cell. Some tumor cells are benign, while others are malignant. How does they presence of an oncogene lead to the formation of a tumor?

• ATP production is inhibited

• Cell division is unregulated

• Somatic cell growth is inhibited

• Antibody activity is unregulated

Cells typically respond to DNA damage in three ways: by ceasing to grow and divide until the damage is repaired, by permanently ceasing to grow and divide, or by dying. In 2010 a group of scientists reported that a certain kind of immune reaction can cause DNA damage that leads to a fourth response. DNA damage can turn off genes involved in cell-signaling pathways. Turning off these genes can cause less-mature cells to divide too rapidly, often leading to the development of -

• tumors

• allergies

• hemophilia

• cardiovascular disease