Chap 3: Parts of the cell

Question 1

Parts of the cell

Answer 1

plasma membrane
Cytoplasm
Nucleus

Question 2

The cell

Answer 2

is the basic living, structural, and functional unit of the body.

Question 3

Functions of the Plasma Membrane

Answer 3

1. Acts as a barrier separating inside and outside of the cell.
2. Controls the flow of substances into and out of the cell.
3. Helps identify the cell to other cells (e.g., immune cells).
4. Participates in intercellular signaling.

Question 4

the lipid bilayer

Answer 4

the basic structural framework of the plasma membrane, two back-to-back layers made up of three types of lipid molecules—phospholipids, cholesterol, and glycolipids

Question 5

amphipathic (am-fē-PATH-ik) molecules,

Answer 5

which means that they have both polar and nonpolar parts

Question 6

Integral proteins

Answer 6

extend into or through the lipid bilayer and are firmly embedded in it

Question 7

peripheral proteins (pe-RIF-er-al)

Answer 7

are not as firmly embedded in the membrane. They are attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane.

Question 8

ion channels,

Answer 8

pores or holes that specific ions,

Question 9

the ligand of that receptor.

Answer 9

A specific molecule that binds to a receptor

Question 10

carriers,

Answer 10

selectively moving a polar substance or ion from one side of the membrane to the other.

Question 11

enzymes

Answer 11

catalyze specific chemical reactions at the inside or outside surface of the cell.

Question 12

linkers

Answer 12

anchor proteins in the plasma membranes of neighboring cells to one another or to protein filaments inside and outside the cell

Question 13

selective permeability

Answer 13

Plasma membranes permit some substances to pass more readily than others.

Question 14

A concentration gradient

Answer 14

is the difference in the concentration of a chemical between one side of the plasma membrane and the other

Question 15

electrical gradient

Answer 15

is the difference in concentration of ions between one side of the plasma membrane and the other

Question 16

electrochemical gradient

Answer 16

concentration gradient & electrical gradient make up the electrochemical gradient

Question 17

passive processes,

Answer 17

a substance moves down its concentration or electrical gradient to cross the membrane using only its own kinetic energy

Question 18

active processes,

Answer 18

cellular energy is used to drive the substance “uphill” against its concentration or electrical gradient

Question 19

Simple diffusion

Answer 19

is a passive process in which substances move freely through the lipid bilayer of the plasma membranes of cells without the help of membrane transport

Question 20

facilitated diffusion,

Answer 20

a substance moves across the lipid bilayer aided by a channel protein or a carrier protein.

Question 21

facilitated diffusion

Answer 21

Solutes that are too polar or highly charged to move through the lipid bilayer by simple diffusion can cross the plasma membrane by a passive process

Question 22

Channels

Answer 22

are integral membrane proteins that allow specific, small, inorganic ions to pass across the membrane by facilitated diffusion.

Question 23

Carriers

Answer 23

are integral membrane proteins that undergo changes in shape in order to move substances across the membrane by facilitated diffusion.

Question 24

Osmosis (oz-MŌ-sis)

Answer 24

is the movement of water molecules through a selectively permeable membrane.

Question 25

tonicity (tō-NIS-i-tē; tonic = tension)

Answer 25

is a measure of the solution’s ability to change the volume of cells by altering their water content.

Question 26

isotonic solution

Answer 26

A solution that has the same salt concentration as cells and blood

Question 27

Active transport

Answer 27

is considered an active process because energy is required for carrier proteins to move solutes across the membrane against a concentration gradient

Question 28

Primary Active Transport

Answer 28

In primary active transport, energy derived from the hydrolysis of ATP changes the shape of a carrier protein, which “pumps” a substance across a plasma membrane against its concentration gradient

Question 29

pumps.

Answer 29

carrier proteins that mediate primary active transport are often called

Question 30

Sodium–potassium pumps

Answer 30

maintain a low intracellular concentration of sodium ions.

Question 31

Secondary Active Transport

Answer 31

In secondary active transport, the energy stored in a Na+ or H+ concentration gradient is used to drive other substances across the membrane against their own concentration gradients.

Question 32

Receptor-mediated endocytosis

Answer 32

imports materials that are needed by the cell

Question 33

Exocytosis

Answer 33

– membrane-enclosed secretory vesicles fuse with the plasma membrane and release their contents into the extracellular fluid

Question 34

Transcytosis

Answer 34

– a combination of endocytosis and exocytosis used to move substances from one side of a cell, across it, and out the other side

Question 35

Phagocytosis

Answer 35

is a vital defense mechanism that helps protect the body from disease

Question 36

Bulk-phase endocytosis

Answer 36

Most body cells carry out bulk-phase endocytosis, the nonselective uptake of tiny droplets of extracellular fluid.

Question 37

cytosol (intracellular fluid)

Answer 37

is the fluid portion of the cytoplasm that surrounds organelles

Question 38

cytoskeleton

Answer 38

- is a network of three types of protein filaments—microfilaments, intermediate filaments, and microtubules—that extend throughout the cytoplasm 1. Serves as a scaffold that helps determine a cell’s shape and organize the cellular contents. 2. Aids movement of organelles within the cell, of chromosomes during cell division, and whole cells such as phagocytes.

Question 39

Microfilaments (mī-krō-FIL-a-ments)

Answer 39

are the thinnest elements of the cytoskeleton. They are composed of the proteins actin and myosin and are most prevalent at the edge of a cell

Question 40

Intermediate Filaments

Answer 40

As their name suggests, intermediate filaments are thicker than microfilaments but thinner than microtubules

Question 41

Microtubules (mī-krō-TOO-būls′),

Answer 41

the largest of the cytoskeletal components are long, unbranched hollow tubes composed mainly of the nonmotile,

Question 42

microvilli (mī-krō-VIL-ī; micro- = small; -villi = tufts of hair; singular is microvillus),

Answer 42

microscopic fingerlike projections of the plasma membrane tubulin

Question 43

organelles

Answer 43

are specialized structures within the cell that have characteristic shapes, and they perform specific functions in cellular growth, maintenance, and reproduction

Question 44

centrosome (SEN-trō-sōm), or

Answer 44

microtubule organizing center, located near the nucleus, consists of two components: a pair of centrioles and the pericentriolar matrix

Question 45

pericentriolar matrix (per′-ē-sen′-trē-Ō-lar),

Answer 45

which contains hundreds of ring-shaped complexes composed of the protein tubulin

Question 46

Cilia and Flagella

Answer 46

Microtubules are the dominant components of cilia and flagella, which are motile projections of the cell surface.

Question 47

Cilia (SIL-ē-a = eyelashes; singular is cilium)

Answer 47

are numerous, short, hairlike projections that extend from the surface of the cell

Question 48

Ribosomes (RĪ-bō-sōms; -somes = bodies)

Answer 48

are the sites of protein synthesis. The name of these tiny structures reflects their high content of one type of ribonucleic acid (ribosomal RNA, or rRNA), but each ribosome also includes more than 50 proteins.

Question 49

The endoplasmic reticulum

Answer 49

is a network of membrane-enclosed sacs or tubules that extend throughout the cytoplasm and connect to the nuclear envelope.

Question 50

Golgi complex

Answer 50

Most of the proteins synthesized by ribosomes attached to rough ER are ultimately transported to other regions of the cell. The first step in the transport pathway is through an organelle

Question 51

cisterns,

Answer 51

small, flattened membranous sacs with bulging edges that resemble a stack of pita bread

Question 52

Lysosomes

Answer 52

are membrane-enclosed vesicles that form from the Golgi complex

Question 53

autophagy,

Answer 53

the digestion of worn-out organelles.

Question 54

autolysis,

Answer 54

the digestion of an entire cell

Question 55

autophagosome

Answer 55

the organelle to be digested is enclosed by a membrane derived from the ER to create a vesicle

Question 56

peroxisomes

Answer 56

Another group of organelles similar in structure to lysosomes

Question 57

proteasomes

Answer 57

The continuous destruction of unneeded, damaged, or faulty proteins is the function of tiny barrel-shaped structures consisting of four stacked rings of proteins around a central core

Question 58

mitochondria

Answer 58

they generate most of the ATP through aerobic (oxygen-requiring) respiration, the mitochondrion is referred to as the “powerhouses” of the cell

Question 59

apoptosis

Answer 59

the orderly, genetically programmed death of a cell

Question 60

The nucleus

Answer 60

``` contains most of the cell’s genes, which are located on chromosomes Functions of the Nucleus 1.Controls cellular structure. 2.Directs cellular activities. 3.Produces ribosomes in nucleoli. ```

Question 61

nucleoli

Answer 61

Inside the nucleus are one or more spherical bodies, that function in producing ribosomes.

Question 62

chromatin

Answer 62

the complex of DNA, proteins, and some RNA

Question 63

genome

Answer 63

total genetic information carried in a cell or an organism

Question 64

A chromosome

Answer 64

is a highly coiled and folded DNA molecule that is combined with protein molecules.

Question 65

nucleosome (NOO-klē-ō-sōm)

Answer 65

that consists of double-stranded DNA wrapped twice around a core of eight proteins called histones

Question 66

histones,

Answer 66

which help organize the coiling and folding of DNA

Question 67

linker DNA

Answer 67

The string between the beads, which holds adjacent nucleosomes together.

Question 68

chromatin fiber

Answer 68

cells that are not dividing, another histone promotes coiling of nucleosomes into a larger-diameter, which then folds into large loops.

Question 69

gene expression,

Answer 69

a gene’s DNA is used as a template for the synthesis of a specific protein

Question 70

transcription,

Answer 70

the information encoded in a specific region of DNA is transcribed (copied) to produce a specific molecule of RNA (ribonucleic acid)

Question 71

translation,

Answer 71

the RNA attaches to a ribosome, where the information contained in RNA is translated into a corresponding sequence of amino acids to form a new protein molecule

Question 72

During transcription,

Answer 72

- which occurs in the nucleus, the genetic information represented by the sequence of base triplets in DNA serves as a template for copying the information into a complementary sequence of codons 1. Messenger RNA (mRNA) directs the synthesis of a protein. 2. Ribosomal RNA (rRNA) joins with ribosomal proteins to make ribosomes. 3. Transfer RNA (tRNA) binds to an amino acid and holds it in place on a ribosome until it is incorporated into a protein during translation.

Question 73

homologous chromosomes

Answer 73

they contain similar genes arranged in the same (or almost the same) order

Question 74

diploid (2n) cells

Answer 74

somatic cells contain two sets of chromosomes

Question 75

interphase (IN-ter-fāz)

Answer 75

the cell replicates its DNA

Question 76

G1 phase

Answer 76

is the interval between the mitotic phase and the S phase

Question 77

G2 phase

Answer 77

is the interval between the S phase and the mitotic phase

Question 78

In somatic cell division,

Answer 78

a single starting cell divides to produce two identical diploid cells.

Question 79

mitotic (M) phase of the cell cycle,

Answer 79

which results in the formation of two identical cells, consists of a nuclear division (mitosis) and a cytoplasmic division (cytokinesis) to form two identical cells.

Question 80

Aging

Answer 80

is a normal process accompanied by a progressive alteration of the body’s homeostatic adaptive responses

Question 81

Gerontology

Answer 81

is the scientific study of the process and problems associated with aging.

Question 82

telomeres (TĒ-lō-mērz),

Answer 82

specific DNA sequences found only at the tips of each chromosome

Question 83

Carcinogenesis (kar′-si-nō-JEN-e-sis)

Answer 83

is a multistep process of cancer development in which as many as 10 distinct mutations may have to accumulate in a cell before it becomes cancerous

Question 84

Anaplasia (an′-a-PLĀ-zē-a; an- = not; -plasia = to shape)

Answer 84

The loss of tissue differentiation and function that is characteristic of most malignancies.

Question 85

Atrophy (AT-rō-fē; a- = without; -trophy = nourishment)

Answer 85

A decrease in the size of cells, with a subsequent decrease in the size of the affected tissue or organ; wasting away.

Question 86

Dysplasia (dis-PLĀ-zē-a; dys- = abnormal)

Answer 86

Alteration in the size, shape, and organization of cells due to chronic irritation or inflammation; may progress to neoplasia (tumor formation, usually malignant) or revert to normal if the irritation is removed.

Question 87

Hyperplasia (hī-per-PLĀ-zē-a; hyper- = over)

Answer 87

Increase in the number of cells of a tissue due to an increase in the frequency of cell division.

Question 88

Hypertrophy (hī-PER-trō-fē)

Answer 88

Increase in the size of cells without cell division.

Question 89

Metaplasia (met′-a-PLĀ-zē-a; meta- = change)

Answer 89

The transformation of one type of cell into another.

Question 90

Progeny (PROJ-e-nē; pro- = forward; -geny = production)

Answer 90

Offspring or descendants.

Question 91

Proteomics (prō′-tē-Ō-miks; proteo- = protein)

Answer 91

The study of the proteome (all of an organism’s proteins) in order to identify all of the proteins produced; involves determining the three-dimensional structure of proteins so that drugs can be designed to alter protein activity to help in the treatment and diagnosis of disease.

Question 92

Tumor marker

Answer 92

A substance introduced into circulation by tumor cells indicates the presence of a tumor, as well as the specific type. Tumor markers may be used to screen, diagnose, make a prognosis, evaluate a response to treatment, and monitor for recurrence of cancer.