2 Cell Structure and Function

Question 1

smallest functional unit that performs essential vital functions (metabolism, growth, movement, reproduction, and hereditary transmission).

Answer 1

cell

Question 2

a double layer of phospholipid molecules with protein molecules embedded within it. It is responsible for separating the cell from its environment and controls the movement of substances in and out of the cell

Answer 2

cell membrane (CM) or plasma membrane

Question 3

Proteins in the CM that act as pores/channels, carrier proteins, receptors, enzymes are classified into

Answer 3

integral CM proteins

Question 4

mainly act as enzymes attached to integral proteins.

Answer 4

peripheral CM proteins

Question 5

What substances do not easily pass through the membrane

Answer 5

Water-soluble substances (such as ions, glucose, and urea)

Question 6

What substances can easily move in and out of the membrane.

Answer 6

fat-soluble substances (such as oxygen, carbon dioxide, and alcohol)

Question 7

a loose carbohydrate coat found on the entire outside surface of the cell composed of proteoglycans glycoproteins/glycolipids. The presence of this structure brings a negative charge, serves as an attachment and receptor, and is also important to immune reactions.

Answer 7

glycocalyx

Question 8

a selectively permeable membrane which means that certain substances can easily move into the cells while other substances may require specialized transport systems.

Answer 8

Cell membrane

Question 9

specialized transport systems (4)

Answer 9

1. Pores in the CM
2. Diffusion
3. Active transport mechanisms
4. Endocytosis

Question 10

small molecules can pass through these pores.

Answer 10

Pores in the CM

Question 11

-it is the random molecular movement of substances molecule by molecule, either through intermolecular spaces in the membrane or combination with a carrier protein.

-continual movement of molecules among one another in liquids or gases

Answer 11

Diffusion

Question 12

a kinetic movement of molecules or ions occurs through a membrane opening or intermolecular spaces without any interaction with carrier proteins in the membrane and the rate of diffusion is determined by the amount of substance available, the velocity of kinetic motion, and the number and sizes of openings in the membrane through which the molecules or ions can move.

Answer 12

Simple diffusion

Question 13

Two pathways of simple diffusion

Answer 13

(1) through the interstices of the lipid bilayer if the diffusing substance is lipid soluble

(2) through watery channels that penetrate through some of the large transport proteins

Question 14

a carrier-mediated diffusion in which a substance diffuses through the membrane using a specific carrier protein.

Answer 14

Facilitated diffusion

Question 15

The rate of diffusion approaches a maximum, called ____ as the concentration of the diffusing substance increases.

Answer 15

Vmax,

Question 16

*Gating of Protein Channels

is when the molecular conformation of the gate or its chemical bonds responds to the electrical potential across the cell membrane.

Answer 16

Voltage gating

Question 17

is when a protein channel gates are opened by the binding of a chemical substance (a ligand) with the protein.

Answer 17

Chemical (ligand) gating

Question 18

is when the cell membrane moves molecules or ions “uphill” against a concentration gradient (or “uphill” against an electrical or pressure gradient).

Answer 18

Active transport mechanisms

Question 19

– the energy is derived directly from the breakdown of ATP or some other high energy phosphate compound

– Sodium-Potassium Pump, Primary Active Transport of Calcium Ions, Primary Active Transport of Hydrogen Ions

Answer 19

Primary Active Transport

Question 20

– the energy is derived secondarily from the energy that has been stored in the form of ionic concentration differences of secondary molecular or ionic substances between the two sides of a cell membrane, created originally by primary active transport.

Answer 20

Secondary Active Transport

Question 21

a specialized function used by very large particles to enter the CM. Two principal forms of this include pinocytosis and phagocytosis.

Answer 21

Endocytosis

Question 22

fluid that fills the interior of the cell providing support. The nucleus and organelles are found within here together with neutral fat globules, glycogen granules, ribosomes, and secretory vesicles.

Answer 22

Cytoplasm

Question 23

clear fluid portion of the cytoplasm.

Answer 23

cytosol

Question 24

structure that helps cells maintain their shape and internal organization, and it also provides mechanical support that enables cells to carry out essential functions like division and movement.

Answer 24

Cytoskeleton

Question 25

Structures that comprise the cytoskeleton include (3)

Answer 25

microfilaments or actin filaments

intermediate filaments

microtubules.

Question 26

important in muscle contraction, cytokinesis of mitosis, diapedesis, and phagocytosis of white blood cells.

Answer 26

Microfilaments or actin filaments

Question 27

serve as anchors of attachment between cell to cell, cell to extracellular membrane, and cell to organelles.

Answer 27

Intermediate filaments

Question 28

made of a and b tubulin and are important in intracellular transport, separation of chromatids in cell division, and form cell extensions like cilia and flagella.

Answer 28

Microtubules

Question 29

control center of the cell. It is surrounded by a nuclear membrane and contains the chromosomes which are composed of DNA that determine the characteristics of the cell’s proteins, including the structural proteins, and controls and promotes the reproduction of the cell itself. It also contains several nucleoli where the ribosomes are manufactured.

Answer 29

Nucleus

Question 30

responsible for cellular respiration and are the site where energy in the form of ATP is stored.

Answer 30

Mitochondria

Question 31

Chemical energy produced by the mitochondria is stored in a small molecule called

Answer 31

adenosine triphosphate (ATP).

Question 32

these floats within the cytoplasm and are the site of protein synthesis.

Answer 32

Ribosome

Question 33

contains ribosomes thus it functions in the transport of proteins synthesized from ribosomes.

Answer 33

Rough or granular ER

Question 34

its functions include the synthesis and transport of lipids and steroids.

Answer 34

Smooth or agranular ER

Question 35

Other functions of the ER include

Answer 35

1. It provides the enzymes that control glycogen breakdown when glycogen is to be used for energy.
2. It provides a vast number of enzymes that are capable of detoxifying substances,

Question 36

process ER vesicles to form lysosomes, secretory vesicles, and other cytoplasmic components, add carbohydrate molecules in proteins, and synthesize carbohydrates that cannot be formed in the ER (hyaluronic acid, chondroitin sulfate).

Answer 36

Golgi Apparatus

Question 37

contains hydrolases and provide an intracellular digestive system that allows the cell to digest (1) damaged cellular structures, (2) food particles that have been ingested by the cell, and (3) unwanted matter such as bacteria.

Answer 37

Lysosomes

Question 38

formed by self-replication (or perhaps by budding off from the smooth endoplasmic reticulum) rather than from the Golgi apparatus. These structures contain oxidases rather than hydrolases which combine oxygen with hydrogen ions producing hydrogen peroxide (H2O2). H2O2 works with catalase to oxidize poisonous substances.

Answer 38

Peroxisomes

Question 39

centrosome contains one pair of centrioles. These are involved in cell division.

Answer 39

Centrosome and centrioles

Question 40

extensions of the plasma membrane responsible for the locomotion of certain cells.

Answer 40

Cilia and flagella

Question 41

usually found at the surface of cells responsible for the wave-like motion of fluid-like mucus (lining of the respiratory system).

Answer 41

Cilia

Question 42

moves the cell along by undulating movements (spermatozoa).

Answer 42

Flagella

Question 43

include all the cells of the body except for those included in reproduction. These cells divide by mitosis and contain the diploid number of chromosomes.

Answer 43

somatic cells

Question 44

type of cells, include the ova and the spermatozoa. These cells divide by meiosis and contain the haploid number of chromosomes.

Answer 44

germ cells

Question 45

stage wherein the new daughter cells grow and prepare for the next division.

Answer 45

interphase

Question 46

This includes four active stages followed by interphase

Answer 46

Mitosis

Question 47

The resting cell is in interphase before this stage begins, this has eight stages

Answer 47

meiosis

Question 48

takes longer than prophase in mitosis. Homologous (identical) chromosomes lie side by side and duplicate; each pair is joined at the centromere. These chromosomes may become entangled and pieces of one chromosome may become attached to another – this process is known as ‘crossing over’ and may influence the characteristics of the offspring.

Answer 48

Prophase I

Question 49

the cytoplasm begins to divide but the nuclear membrane does not reform. In some cells, the cytoplasm does not divide completely, and a dumb- bell-shaped cell is seen – this is known as a syncytium. This is the first meiotic division.

Answer 49

Telophase I

Question 50

this may be transitory as there is no need to replicate the chromosomes.

Answer 50

Prophase II

Question 51

the cytoplasm begins to divide; the nuclear membrane reforms and four identical daughter cells are formed. This is the second meiotic division.

Answer 51

Telophase II