chapter 3

Question 1

Summarize the three principles of ‘cell doctrine’.

Answer 1

1. All living things are composed of cells and cell products.
2. A single cell is the smallest unit that exhibits all the characteristics of life.
3. All cells are derived from preexisting cells.

Question 2

Membrane surrounding the cell, consisting of a phospholipid bilayer with embedded cholesterol and proteins. The plasma membrane regulates the passage of substances into and out of the cell.

Answer 2

Plasma membrane

Question 3

General term for a central or essential part. The nucleus of an atom consists of neutrons and protons and contains most of the atomic mass. The nucleus of a eukaryotic cell contains the cell’s DNA

Answer 3

nucleus

Question 4

The cellular material surrounding a cell nucleus and enclosed by the plasma membrane.

Answer 4

cytoplasm

Question 5

that carry out specialized functions, such as digesting nutrients or packaging cellular products.

Answer 5

eukaryotes

Question 6

A single-celled organism that lacks the nucleus and the membrane-bound organelles characteristic of eukaryotes. Bacteria are prokaryotes.

Answer 6

prokaryotes

Question 7

Give an example of how cell structure relates to cell function

Answer 7

Muscle cells have lots of mitochondria to facilitate muscle contraction

Question 8

Summarize why cells must remain small

Answer 8

● The total metabolic activities of a cell are proportional to its volume of cytoplasm, which is in effect its size. To support its activities, every cell needs raw materials in proportion to its size. Every cell also needs a way to get rid of its wastes.
● All raw materials, energy, and waste must cross the plasma membrane to enter or leave the cell.
● As cells get larger, their volume increases more than their surface area. For both spheres and cubes, for example, an eightfold increase in volume is accompanied by only a fourfold increase in surface area.

Question 9

General term for a central or essential part. The nucleus of an atom consists of neutrons and protons and contains most of the atomic mass. The nucleus of a eukaryotic cell contains the cell’s DNA.

Answer 9

Nucleus

Question 10

Within the nucleus is a dense region called the nucleolus, where the components of ribosomes (RNA and ribosomal proteins) are synthesized

Answer 10

Nucleolus

Question 11

It is composed of a soft, gel-like fluid called the cytosol (“cell solution”). The cytosol contains a variety of microscopic structures called organelles

Answer 11

Cytosol

Question 12

Membrane bound vesicle in the cell cytoplasm containing powerful enzymes that detoxify harmful or toxic substances.

Answer 12

Peroxisome

Question 13

are short, rodlike microtubular structures located near the nucleus. Centrioles are essential to the process of cell division because they participate in aligning and dividing the genetic material of the cell.

Answer 13

Centrioles

Question 14

A cell’s internal “skeleton.” The cytoplasm is a system of microtubules and other components that support cellular structures and provide the machinery to generate various cell movements.

Answer 14

Cytoskeleton

Question 15

The smooth ER synthesizes macromolecules other than protein. Most notable among these are the lipids, including some hormones. Numerous enzymes embedded in the inner surface of the ER membrane facilitate the chemical reactions necessary for macromolecule synthesis.

Answer 15

smooth endoplasmic reticulum

Question 16

The rough ER is involved in the synthesis of proteins, as you may guess from the presence of ribosomes. Most of the proteins synthesized by the attached ribosomes are released into the fluid-filled space of the ER. Eventually they enter the smooth ER, where they are packaged for transfer to the Golgi apparatus

Answer 16

rough endoplasmic reticulum

Question 17

Membranous system within a cell that packages proteins and lipids destined for export, packages enzymes into lysosomes for cellular use, and modifies proteins destined to become part of cellular membranes

Answer 17

golgi apparatus

Question 18

Secretory vesicles contain products destined for export from the cell. They migrate to the plasma membrane and release their contents outside the cell. Because most secretory products are made in the Golgi apparatus, secretory vesicles generally derive from Golgi apparatus membrane.

Answer 18

secretory vesicle

Question 19

are small structures composed of RNA and certain proteins that are either floating freely in the cytosol or are attached to the endoplasmic reticulum, the cell organelle that synthesizes most biological molecules. Ribosomes are responsible for making specific proteins. They assemble amino acids into proteins by connecting the appropriate amino acids in the correct sequence according to an RNA template.

Answer 19

Ribosomes

Question 20

Membrane surrounding the cell, consisting of a phospholipid bilayer with embedded cholesterol and proteins. The plasma membrane regulates the passage of substances into and out of the cell.

Answer 20

plasma membrane

Question 21

the organelles responsible for providing most of this usable energy; they are often called the cells’ “power plants.” Not surprisingly, their number within different cells varies widely according to the energy requirements of the cells. A cell with a high rate of energy consumption, such as a muscle cell, may contain over 1,000 mitochondria

Answer 21

Mitochondrion

Question 22

contain powerful digestive enzymes. Lysosomes fuse with endocytotic vesicles within the cell, digesting bacteria and other large objects. Lysosomes also perform certain housekeeping tasks, such as dissolving and removing damaged mitochondria and other cellular debris. When their digestive task is complete, they become residual bodies, analogous to small bags of compacted waste. Residual bodies can be stored in the cell, but usually their contents are eliminated from the cell.

Answer 22

Lysosome

Question 23

Describe the role of fat and glycogen within cells.

Answer 23

They function as energy sources

Question 24

A cell’s internal “skeleton.” The cytoplasm is a system of microtubules and other components that support cellular structures and provide the machinery to generate various cell movements

Answer 24

Cytoskeleton

Question 25

A few cells have hairlike cilia (singular: cilium) or longer flagella (singular: flagellum) that extend from the surface. Cilia are generally only 2 to 10 microns long (1 micron equals one-millionth of a meter). In cells that have them, cilia are numerous (Figure 3.12a). Cilia move materials

Answer 25

cilia

Question 26

short, rodlike microtubular structures located near the nucleus. Centrioles are essential to the process of cell division because they participate in aligning and dividing the genetic material of the cell. We discuss centrioles when we describe how a cell divides in two

Answer 26

centrioles

Question 27

Describe the structure and function of the plasma membrane.

Answer 27

A selectively permeable bi layer with transport proteins embedded in the membrane the admit and expulse molecules as needed

Question 28

What are the three major components of the plasma membrane?

Answer 28

● Phospholipids. Recall that phospholipids are a particular type of lipid with a polar head and neutral nonpolar tails. In the plasma membrane, the two layers of phospholipids are arranged so that the nonpolar tails meet in the center of the membrane. One layer of polar (water-soluble) heads faces the watery solution on the outside of the cell, and the other layer of polar heads faces the watery solution of the cell’s cytoplasm. ● Cholesterol. Cholesterol increases the mechanical strength of the membrane by preventing it from becoming either too rigid or too flexible. It also prevents the phospholipids from moving around too much and helps to anchor the proteins within the membrane. ● Proteins. Various proteins are embedded in the phospholipid bilayer of the plasma membrane. Like the doors, windows, and wires of a house, they provide the means for transporting molecules and information across the plasma membrane. A few membrane proteins anchor the cell’s internal scaffoldlike support network. Some proteins span the entire membrane; others protrude from only one surface. Plasma membrane proteins generally have one region that is electrically neutral and another that is electrically charged (either + or -). The charged regions tend to extend out of the membrane and thus are in contact with water, whereas the neutral portions are often embedded within the phospholipid bilayer.

Question 29

What are the functions of proteins in the membrane?

Answer 29

For transport

Question 30

Differentiate between passive and active transport

Answer 30

Passive transport is “passive” because it transports a molecule without requiring the cell to expend any energy. Passive transport relies on the mechanism of diffusion. active transport can move substances through the plasma membrane against their concentration gradient. Active transport allows a cell to accumulate essential molecules even when their concentration outside the cell is relatively low and to get rid of molecules that it does not need. Active transport requires the expenditure of energy

Question 31

The movement of molecules from one region to another as the result of random motion. Net diffusion proceeds from a region of higher concentration to a region of lower concentration.

Answer 31

Diffusion

Question 32

The net diffusion of water across a selectively permeable membrane, such as a cell membrane.

Answer 32

Osmosis

Question 33

Does water move toward or away from the side with the higher solute concentration?

Answer 33

toward

Question 34

In facilitated transport, also called facilitated diffusion, the molecule does not pass through a channel at all. Instead, it attaches to a membrane protein, triggering a change in the protein’s shape or orientation that transfers the molecule to the other side of the membrane, where it is released (Figure 3.16c). Once the molecule is released, the protein returns to its original form.

Answer 34

Facilitated transport

Question 35

(Na+/K+ pump) An active transport protein of the plasma membrane that simultaneously transports three sodium ions (Na+) out of the cell and two potassium ions (K+) in. The sodium-potassium pump is important for maintaining cell volume and for generating the resting membrane potential.

Answer 35

sodium-potassium pump

Question 36

What is the direct energy source for the Na+/K+

Answer 36

ATP

Question 37

What is the function of the Na+/K+ pump?

Answer 37

The sodium-potassium pump is important for maintaining cell volume and for generating the resting membrane potential.

Question 38

Differentiate between endo and exo-cytosis.

Answer 38

you know this one

Question 39

A small membrane-bound, fluid-filled sac that encloses and contains certain substances within a cell.

Answer 39

vesicle

Question 40

A protein molecule of the cell membrane whose function is to transmit information across the cell membrane. Typically, when a particular molecule in the interstitial fluid binds to the receptor protein, a specific series of events is triggered within the cell.

Answer 40

receptor protein

Question 41

, General term for normal tone or tension. In biology an isotonic solution is one with the same solute concentration as plasma. Cells maintain their normal cell volume in isotonic solutions.

Answer 41

isotonic

Question 42

General term for above-normal tone or tension. In biology, a hypertonic solution is one with a higher solute concentration than plasma. Cells shrink when placed in a hypertonic solution.

Answer 42

hypertonic

Question 43

Would water flow into or out of a cell placed in a hypertonic solution? Is this an example of osmosis or diffusion?

Answer 43

out

Question 44

is the sum of all of the chemical reactions in the organism

Answer 44

metabolism

Question 45

Molecules are assembled into larger molecules that contain more energy, a process that requires energy. The assembly of a protein from many amino acids is an example of an anabolic pathway.

Answer 45

Anabolism

Question 46

Larger molecules are broken down, a process that releases energy. The breakdown of glucose into water, carbon dioxide, and energy is an example of a catabolic pathway.

Answer 46

Catabolism

Question 47

Differentiate between product and substrate in a metabolic pathway

Answer 47

Substrate is an ingredient for making a product

Question 48

Summarize the process of cellular respiration.

Answer 48

1. Glycolysis. The six-carbon glucose molecule is split into two 3-carbon pyruvate molecules. Energy is required to get the process started. 2. The preparatory step. In preparation for the citric acid cycle, pyruvate enters a mitochondrion. A series of chemical reactions yields a two-carbon molecule called acetyl CoA, plus some energy. 3. The citric acid cycle. An acetyl CoA molecule is broken down completely by mitochondrial enzymes, and its energy is released. Most of the energy is captured by certain high-energy electron transport molecules. 4. The electron transport system. Most of the energy derived from the original glucose molecule is used to phosphorylate ADP, producing high-energy ATP.

Question 49

When oxygen is available, how many ATP are ultimately produced from the catabolism of one glucose?

Answer 49

36ATP

Question 50

Other than glucose what other major organic molecules can be used to produce ATP by cellular respiration?

Answer 50

Carbohydrates, Lipids, and Proteins are used to make ATP.

Question 51

What is different about an anaerobic pathway compared to normal cellular respiration?

Answer 51

It produces only 2 atp

Question 52

In the absence of oxygen only glycolysis can occur. How many ATP are produced in the absence of oxygen?

Answer 52

2

Question 53

What product builds up due to anaerobic metabolism?

Answer 53

Lactic acid