Cell Structure and Function: Eukaryotic Cells

Question 1

plasma membrane

Answer 1

the phospholipid bilayer that forms the outer boundary of any cell, regulating the cell’s chemical composition

Question 2

cell wall

Answer 2

a fairly rigid polysaccharide supportive and protective layer that lies outside the plasma membrane of all plant cells

Question 3

cytoplasm

Answer 3

the contents of the cell enclosed by the plasma membrane, excluding the nucleus

Question 4

cytosol

Answer 4

the water-based fluid component of the cytoplasm

Question 5

cytoskeleton

Answer 5

a complex network of protein filaments found in the cytosol of eukaryotic cells that maintains a cell’s shape and is necessary for cell division, signaling, and movement

Question 6

extracellular matrix

Answer 6

functions in the support and protection of the cell, as well as in cell-cell communication and association

Question 7

organelle

Answer 7

a discrete, membrane-enclosed cytoplasmic structure with a specific function

Question 8

nucleus

Answer 8

the organelle in a eukaryotic cell that contains the genetic blueprint of DNA organized into chromatin and chromosomes

Question 9

histones

Answer 9

proteins found in the nucleus that function in the packaging of chromatin

Question 10

nucleolus

Answer 10

a region of the nucleus that specializes in ribosomal RNA (rRNA) genes, ribosomal proteins (imported from the cytoplasmic site of rRNA synthesis), and ribosomal subunit assembly

Question 11

Vesicle

Answer 11

a small, membrane-enclosed sac found in the cytosol of eukaryotic cells

Question 12

Vacuole

Answer 12

a water-filled sac that serves various functions in the cell, including transport, structural support, and isolation of waste and harmful materials; formed from the fusion of smaller vesicles

Question 13

central vacuole

Answer 13

a large membranous sac in a mature plant cell that helps to maintain cell shape and can be used to store nutrients and anti-herbivory chemicals

Question 14

lysosome

Answer 14

specialized vesicle with an acidic lumen containing enzymes that break down macromolecules and bacterial cell walls

Question 15

peroxisome

Answer 15

an organelle containing enzymes that transfer hydrogen (H2) from various substrates to oxygen (O2) producing and then degrading hydrogen peroxide (H2O2)

Question 16

chloroplast

Answer 16

organelle found in plants and algae that is the primary site of photosynthesis and is also involved in the biosynthesis of amino acids and lipids; capable of autonomous replication

Question 17

mitochondrion (pl. mitochondria)

Answer 17

an organelle with a double membrane that is the site of cellular respiration in eukaryotes and is also involved in regulated cell death; capable of autonomous replication

Question 18

crista (pl. cristae)

Answer 18

folds in the inner membrane of mitochondria

Question 19

ribosome

Answer 19

a cellular structure composed of proteins and RNA at which new proteins are synthesized; can be either attached to the endoplasmic reticulum (ER) or free in the cytosol

Question 20

rough ER

Answer 20

a region of the endoplasmic reticulum that specializes in protein synthesis; “rough” because of the ribosomes attached to its surface

Question 21

smooth ER

Answer 21

a region of the endoplasmic reticulum specialized for lipid synthesis; “smooth” because it lacks attached ribosomes

Question 22

golgi apparatus

Answer 22

an organelle that routes proteins and lipids to various parts of the eukaryotic cell from the ER and synthesizes certain cellular products, notably non-cellulose carbohydrates

Question 23

intermediate filaments

Answer 23

fibers that stabilize cell structure—for example, maintaining the position of the nucleus and other organelles—composed of helical subunits of fibrous proteins

Question 24

microfilaments

Answer 24

two actin polymers that function in cell shape, muscle action with myosin, cytoplasmic streaming, cell division and motility, and anchoring proteins in the plasma membrane

Question 25

microtubules

Answer 25

cylinders made of tubulin that function in motility (e.g.: flagella and cilia), support of cell shape, or transport of chromosomes and vesicles

Question 26

cilium (pl. cilia)

Answer 26

a hair-like structure found in some eukaryotes that uses a rowing motion to propel the organism or to move fluid over cells

Question 27

flagellum (pl. flagella)

Answer 27

a long cellular extension that lashes and enables that cell to move (structure differently than prokaryotic flagella)