Mastering Biology Ch 6 HW

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

Gap (communicating) junctions

Motor proteins are responsible for moving vesicles and organelles within the cell. Motor proteins move along protein "tracks." In the example shown in the Visualizing figure, what are those tracks made of?

actin

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

desmosomes

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?

insulin, ER protein, lysosomal enzyme

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

tight junctions

Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____.

transferring of information from DNA to messenger RNA

Drag each cell structure to the appropriate bin.

*Only bacteria and archaea have prokaryotic cells, which lack a nucleus and other membrane-enclosed organelles. Prokaryotic cells are smaller and, at the level of the individual cell, are generally less versatile than eukaryotic cells, which compartmentalize many of their metabolic pathways into organelles. Nevertheless, prokaryotes are indispensable in every known ecosystem, and certain species are capable of surviving in some of the harshest and most nutrient-limiting environments on Earth.

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

Both have their own DNA.

Drag the terms on the left to the appropriate blanks in the sentences on the right. Terms can be used once, more than once, or not at all.

In eukaryotic flagella, the fibers that slide past one another due to the activity of dynein proteins are microtubules. Many cell organelles, most notably the nucleus, are anchored by intermediate filaments which are assembled from a diverse class of proteins. Centrosomes are sites where protein dimers assemble into microtubules. The extension of pseudopodia in amoeba is due to the regulated assembly and destruction of microfilaments. The only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion are the intermediate filaments.

Cellular proteins may be embedded within a cellular membrane (integral protein), loosely bound to the surface of a cellular membrane (peripheral protein), or not associated with a membrane at all (free protein). Identify the types of proteins shown in the figure below, which shows an internal chloroplast membrane. Match the type of protein on the left with the examples on the right. Terms may be used once, more than once, or not at all.

Integral protein: ATP synthase Peripheral protein: NADP+ reductase Peripheral protein: Pc Integral protein: Photosystem II Free protein: Rubisco

Drag the correct description under each cell structure to identify the role it plays in the plant cell.

Plant cell wall- strong protective structure Central vacuole- Regulates cytoplasm composition, creates internal pressure, and stores cell compounds Chloroplast- Makes food by converting light energy into chemical energy Mitochondrion- Converts chemical fuel into packets of chemical energy (ATP) that can power the cell Golgi apparatus- Modifies and packages proteins

Plant cells and animal cells share many of the same structures, but each type of cell also has unique structures. In this activity, you will indicate which cell structures are found only in plant cells, only in animal cells, or in both plant and animal cells. Drag each cell structure to the appropriate bin. If a structure is found in both plant cells and animal cells, drag it to the "both" bin.

Plant- chloroplast, central vacuole, celloulse cell wall Animal- centriole Both- mitochondrion, cytoskeleton, endoplasmic reticulum, nucleus, plasma membrane, Golgi apparatus

The structure of a chloroplast is closely tied to its function as the site of photosynthesis. Some of the following statements are true for chloroplasts; others are true for mitochondria. Which statements are true for chloroplasts? Select the three that apply.

They contain the green pigment chlorophyll. They are the sites of reactions that convert solar energy into chemical energy. They have membranous sacs called thylakoids that are surrounded by a fluid called stroma.

Which of the following choices correctly matches a tool and its proper application?

cell fractionation to study the function of specific organelles

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

Which molecules and cellular components pass through the nuclear pore during normal cellular activity? Select all that apply.

ribosomal subunits mRNA