Biology Chapter 6 HW

All proteins are synthesized by ribosomes in the cell. Some ribosomes float freely in the cytosol, while others are bound to the surface of the endoplasmic reticulum. Most proteins made by free ribosomes function in the cytosol. Proteins made by bound ribosomes either function within the endomembrane system or pass through it and are secreted from the cell. Which of the following proteins are synthesized by bound ribosomes? Select all that apply.

- ER Protein - Insulin - Lysosomal Enzyme Most proteins that function in the cytosol (such as actin) or in the nucleus (such as DNA polymerase) are synthesized by free ribosomes. Proteins that function within the endomembrane system (such as lysosomal enzymes) or those that are destined for secretion from the cell (such as insulin) are synthesized by bound ribosomes. As a protein destined for the endomembrane system is being synthesized by a ribosome, the first amino acids in the growing polypeptide chain act as a signal sequence. That signal sequence ensures that the ribosome binds to the outer membrane of the ER and that the protein enters the ER lumen.

The various parts of the endomembrane system serve different functions in the cell. In this activity, you will identify the roles of each part of the endomembrane system. Drag each function to the appropriate bin.

The endomembrane system is critical for the synthesis, processing, and movement of proteins and lipids in the cell. The smooth ER functions mainly in lipid synthesis and processing. The rough ER is the site of secretory protein synthesis. These proteins are processed further in the Golgi apparatus, from where they are dispatched in vesicles to the plasma membrane. Lysosomes, whose enzymes and membranes are made and processed by the rough ER and Golgi apparatus, function in the hydrolysis of macromolecules, such as in phagocytosis and autophagy.

Which structure is common to plant and animal cells?

mitochondrion

Which of the following are common traits of chloroplasts and mitochondria?

Both have their own DNA; Mitochondria and chloroplasts contain their own DNA and ribosomes.

The structure that regulates the passage of material into and out of this bacterial cell is indicated by the letter _____.

C; The plasma membrane is selectively permeable (same image as number 5)

What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?

Cell wall; The cell wall is a rigid supporting structure.

The DNA-containing region of this bacterial cell is indicated by the letter _____.

D; The nucleoid region contains DNA.

_____ are surface appendages that allow a bacterium to stick to a surface.

Fimbriae; Fimbriae enable bacterial cells to stick to a surface.

_____ aid in the coordination of the activities of adjacent animal cells.

Gap (communicating) junctions; Gap junctions allow for the passage of material between cells, thus facilitating communication between these cells.

Scientists can track the movement of proteins through the endomembrane system using an approach known as a pulse-chase experiment. This experiment involves - the "pulse" phase: Cells are exposed to a high concentration of a radioactively labeled amino acid for a short period to tag proteins that are being synthesized. - the "chase" phase: Any unincorporated radioactively labeled amino acids are washed away and large amounts of the same, but unlabeled, amino acid are added. Only those proteins synthesized during the brief pulse phase are radioactively tagged. These tagged proteins can be tracked through the chase period to determine their location in the cell. The data below were obtained from a pulse-chase experiment in which cells were examined at different times during the chase period. The numbers represent the radioactivity (measured in counts per minute) recorded at each of the indicated sites. The higher the number, the greater the radioactivity.

Phagocytosis; The cells in this experiment were macrophages. These immune system cells have many lysosomes for the destruction of bacteria and other invaders brought into the cell via phagocytosis. The enzymes (hydrolases) that carry out this catabolic activity are synthesized in the endoplasmic reticulum, modified in the Golgi, and transported to the lysosomes.

What is a function of a bacterium's capsule?

Protection; A bacterium's capsule has a protective role

Proteins that are secreted from a eukaryotic cell must first travel through the endomembrane system. Drag the labels onto the diagram to identify the path a secretory protein follows from synthesis to secretion. Not all labels will be used.

Protein Synthesis a. endoplasmic recticulum b. cis Golgi cisternae c. medial Golgi cisternae d. trans Golgi cisternae e. Plasma membrane Extracellular Space As they are being synthesized, secretory proteins enter the lumen of the endoplasmic reticulum. From the ER, vesicles transport these proteins to the Golgi, where they are sequentially modified and concentrated in a cis-to-trans direction. Secretory vesicles bud from the Golgi and move along cytoskeletal filaments to eventually fuse with the plasma membrane, secreting their protein cargo. Each of these transport steps requires specialized proteins to ensure that the cargo is sent to the proper location and is able to fuse with the target membrane.

Which statement correctly describes the nuclear envelope of a eukaryotic cell? See Concept 6.3

The nuclear envelope is continuous with the endoplasmic reticulum.

Which of the following expresses the concept of emergent properties?

The parts of a car, once assembled, result in a structure that can provide transportation; If you had trouble with this question, review the following material: The study of life on Earth extends from the molecular scale to the microscopic scale of the cells that make up organisms to the global scale of the entire living planet. We can divide this enormous range into different levels of biological organization. Starting at the molecular level and zooming out, novel properties emerge at each level that are absent from the preceding one. These emergent properties are due to the arrangement and interactions of parts as complexity increases.

The primary role of _____ is to bind animal cells together.

desmosomes; The primary role of desmosomes (anchoring junctions) is to bind cells together.

The cytoskeleton of a eukaryotic cell plays a major role in organizing the structures and activities of the cell. The cytoskeleton consists of three main types of fibers: microfilaments, intermediate filaments, and microtubules. The three types of fiber differ in size, composition, and the functions they perform in the cell.

https://docs.google.com/document/d/1UkKgW01NpcQhUKCtO5gb0qc88BOcW0n_qvoUHvEP8F8/edit?usp=sharing

To understand how cells function as the fundamental unit of life, you must first become familiar with the individual roles of the cellular structures and organelles. Drag the labels on the left onto the diagram of the animal cell to correctly identify the function performed by each cellular structure.

https://docs.google.com/document/d/1UkKgW01NpcQhUKCtO5gb0qc88BOcW0n_qvoUHvEP8F8/edit?usp=sharing

Two fundamental types of cells are known to exist in nature: prokaryotic cells and eukaryotic cells (like the one shown in the Tour of an Animal Cell animation). Both prokaryotic and eukaryotic cells carry out all of the processes necessary for life, but they differ in some important ways. In this activity, you will identify which cell structures are found only in prokaryotic cells, only in eukaryotic cells, or in both types of cells. Drag each cell structure to the appropriate bin.

https://docs.google.com/document/d/1UkKgW01NpcQhUKCtO5gb0qc88BOcW0n_qvoUHvEP8F8/edit?usp=sharing

Which organelle plays a role in intracellular digestion?

lysosome; The prefix "lyso-" means decomposition.

Where is a bacterial cell's DNA found?

nucleoid region; Bacteria lack a nucleus; their DNA is found in the nucleoid region.

Mitochondria are found in _____.

plant and animal cells; All eukaryotic cells, including plant and animal cells, contain mitochondria.

The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.

plasma membrane; The plasma membrane is selectively permeable.

In a bacterium, where are proteins synthesized?

ribosomes; Ribosomes are involved in the manufacture of polypeptides (proteins).

Which of these cell junctions form a barrier to the passage of materials?

tight junctions; Tight junctions form a barrier that prevents fluids from moving between cells.

Which of the following clues would tell you if a cell is prokaryotic or eukaryotic?

whether or not the cell is partitioned by internal membranes; Prokaryotic cells lack any internal membranous compartmentalization.