Cell Structure and Function

Question 1

Prokaryotic Cells

Answer 1

Structurally simple, metabolically diverse cells that lack membrane-bound nucleus; include domains bacteria and archaea

Question 2

Eukaryotic Cells

Answer 2

Possess membrane-bound nucleus, have a higher complexity than prokaryotes due to presence of multiple organelles; includes kingdoms protista, animalia, fungi, and plantae

Question 3

Cell Theory

Answer 3

All organisms are made up of basic living units called cells, and all cells come from previously existing cells

Question 4

Surface-area-to-volume ratio

Answer 4

Dividing a large cube into smaller cubes provides more surface area per volume. A higher surface area to volume ratio increases the efficiency of transporting materials into and out of the cell.

Question 5

Plasma membrane

Answer 5

Consists of phospholipid bilayer embedded with protein molecules. The boundary that separates the living contents of the cells from the surrounding environment. Regulates the entrance and exit of molecules into and out of the cytoplasm.

Question 6

Cytoplasm

Answer 6

Semi-fluid medium inside the cells, composed of water, salts, and dissolved organic molecules.

Question 7

Flagella

Answer 7

Long, thin protein extensions that rotate like a propeller, allowing bacteria to move rapidly in a fluid medium.

Question 8

Fimbriae

Answer 8

Short appendages (hair-like bristles) that help bacteria attach to an appropriate surface. Often increase the ability of pathogenic bacteria to cause disease.

Question 9

Nucleoid

Answer 9

A region within the cytoplasm of Prokaryotic cells that contains a single chromosome (loop of DNA associated with proteins). Nucleoid is not surrounded by a membrane.

Question 10

Plasmids

Answer 10

Small accessory rings of DNA in Prokaryotic cells, located within the cytoplasm and contain small amounts of genetic information. May be moved from one prokaryote to another.

Question 11

Key Bacterial cell features

Answer 11

Capsule, cell wall, plasma membrane, nucleoid, ribosomes, and flagella and/or fimbriae.

Question 12

Cell Walls (Eukaryotic)

Answer 12

Not present in animal/some protist cells. Walls of plants/algae composed of cellulose, which forms fibrils that lie at right angles to one another for added strength. Walls of some fungi composed of cellulose and chitin. Support and protect the cell.

Question 13

Organelle

Answer 13

Membrane-bound well-defined sub-cellular structures within a cell that perform a particular function.

Question 14

Nucleus

Answer 14

Made up of nuclear envelope, nucleoplasm, chromatin, and nucleoli. Stores genetic information, synthesizes DNA and RNA.

Question 15

Ribosomes

Answer 15

Made up of protein and RNA in two subunits - “large and small.” Protein synthesis. Can be found individually in the cytoplasm or in groups called polyribosomes. Can also be found attached to the endoplasmic reticulum.

Question 16

Rough Endoplasmic Reticulum (RER)

Answer 16

Network of folded membranes studded with ribosomes. Folding, modification, and transport of proteins for export or associated with membranes.

Question 17

Smooth Endoplasmic Reticulum (SER)

Answer 17

Network of folded membranes having no ribosomes. Lipid and carbohydrate synthesis in some cells; detoxification of chemicals.

Question 18

Golgi Apparatus

Answer 18

Stack of small, membranous sacs. Processing, packaging, and distribution of proteins and lipids.

Question 19

Lysosomes (animal cells only)

Answer 19

membranous vesicle produced by Golgi apparatus containing digestive enzymes. Intracellular digestion; recycling of cellular components.

Question 20

Vacuoles and vesicles

Answer 20

Membranous sacs of various sizes. Storage of substances. Vacuoles are larger than vesicles. Plant vacuoles are larger than animal - filled with watery fluid to support cell shape.

Question 21

Peroxisomes

Answer 21

Membranous vesicle containing specific enzymes. Breakdown of fatty acids produces hydrogen peroxide (toxic), but also contain catalase, which breaks down H2O2 into water.

Question 22

Mitochondria

Answer 22

Inner membrane (cristae) bound by an outer membrane; cellular respiration. Power plants of the cell. Provided by the mother during reproduction.

Question 23

Chloroplasts (plant cells and some protists)

Answer 23

membranous grana bound by two membranes; photosynthesis.

Question 24

Cytoskeleton

Answer 24

Microtubules, intermediate filaments, actin filaments. Shape of cell and movement of its parts.

Question 25

Cilia and flagella (cilia rare in plant cells)

Answer 25

Made of microtubules - arranged in cylinders of nine microtubule doublets arranged in a circle around two central microtubules. Movement of cell.

Question 26

Chromatin

Answer 26

Substance within the nucleus consisting of DNA and associated proteins. Present during most of a cell’s lifetime.

Question 27

Chromosomes

Answer 27

Coiled and condensed structures created from chromatin when a cell undergoes cell division. Humans contain 46 chromosomes.

Question 28

Nucleoplasm

Answer 28

Semifluid medium housing chromosomes.

Question 29

Nucleolus

Answer 29

Region within the nucleus where ribosomal RNA is produced. rRNA joins with other proteins to form the subunits of ribosomes

Question 30

Nuclear envelope

Answer 30

Double membrane separating the cytoplasm from the nucleus, continuous with the endoplasmic reticulum. disappears during cellular division.

Question 31

Nuclear pores

Answer 31

Openings in the nuclear envelope approx. 100nm that permit the bidirectional transport of proteins and ribosomal subunits.

Question 32

The Endomembrane system

Answer 32

Consists of the nuclear envelope, the endoplasmic reticulum, the Golgi apparatus, and several vesicles. The transportation and product-processing section of the cell. System compartmentalizes the cell to restrict particular enzymatic reaction to specific regions.

Question 33

Autophagy

Answer 33

When parts of the cell are digested by its own lysosomes (ex: finger webbing)

Question 34

Chloroplasts

Answer 34

Organelle specializing in converting energy into a form the cell can use. Uses solar energy to synthesize carbohydrates, broken down by mitochondria, converted to ATP. Green from pigment chlorophyll.

Question 35

Cellular respiration

Answer 35

Process by which the chemical energy of carbohydrates is converted into ATP. Process completed in the mitochondria in Eukaryotic cells.
Carbohydrate+oxygen->carbon dioxide+water+energy

Question 36

Photosynthesis

Answer 36

Process by which chloroplasts use solar energy to synthesize carbohydrates.
solar energy+carbon dioxide+water->carbohydrate+oxygen

Question 37

Stroma

Answer 37

Fluid-filled space bounded by two membranes within a chloroplast. Contains a single circular DNA molecule plus ribosomes.

Question 38

Thylakoids

Answer 38

Interconnected flattened sacs within the stroma. Stacked thylakoids are called grana. There can be hundreds of grana within a single chloroplast.

Question 39

Chlorophyll

Answer 39

Located in the thylakoid membranes of grana, captures solar energy needed to enable chloroplasts to produce carbohydrates.

Question 40

Matrix

Answer 40

Inner fluid-filled space of the mitochondria. Contains ribosomes and enzyme products that break down carbohydrates to release energy for ATP.

Question 41

Cristae

Answer 41

Formed by invagination of the mitochondrial inner membrane. Provide much greater surface area to accommodate protein complexes that produce ATP.

Question 42

Actin

Answer 42

Part of cell cytoskeleton. Long, extremely thin, flexible fibers that occur in bundles or meshlike networks, about 7nm in diameter.

Question 43

Motor molecules

Answer 43

Proteins that can attach, detach, and reattach further along the filament by interacting with actin filaments to produce movement.

Question 44

Intermediate filaments

Answer 44

8-11 nm in diameter. Between actin and microtubules. Ropelike assembly of fibrous polypeptides.

Question 45

Microtubules

Answer 45

Small, hollow cylinders about 25 nm in diameter. Made of globular protein tubulin.

Question 46

Centrosome

Answer 46

Main microtubule organization center, they control the assembly of microtubules. Microtubules radiate from the centrosome - cell shape and tracks for organelles to move.

Question 47

Centrioles

Answer 47

Short cylinders of microtubules surrounding hollow center. In animal cells, 2 centrioles lie at right angles to each other, and replicate before a cell divides.

Question 48

Endosymbiotic Theory

Answer 48

Theory that first cells were prokaryotes, but that chloroplasts and mitochondria arose from prokaryotes that were engulfed by a cell but not digested (“in” “living together”)