1.1. Cell Physiology

Question 1

Passive Transport Processes

Answer 1

• Requires no energy (ATP)
• Diffusion
• Osmosis

Question 2

Diffusion

Answer 2

• Random movement due to intrinsic kinetic energy movement is down a concentration gradient (downhill) does not require
• There should be Concentration Gradient

Question 3

Net Diffusion

Answer 3

Movement from high to low concentration

Question 4

Osmosis

Answer 4

Diffusion of water or solvent molecules across a selectively permeable membrane from a region of higher water concentration to one of lower water concentration

Question 5

Osmotic Pressure

Answer 5

• Force required to prevent membrane of water across cell membrane
• The higher the concentration, the higher the osmotic pressure

Question 6

Isotonic

Answer 6

• Equal osmotic pressures
• Equal solute concentration
• Isotonic environments show no effect on cells
• Isotonic solutions are not helpful in food presentation
• Water does not move
• Cells remain intact

Question 7

Hypotonic

Answer 7

• Lower osmotic pressure
• Lower concentration of solute
• Hypotonic environments cause cells to swell (water moves by osmosis)
• Hypotonic solutions are not helpful in food presentation
• Has lower concentration of solutes and a higher concentration of water relative to the cytoplasm of the cell

Question 8

Lysis (Hypotonic)

Answer 8

Cells swell enough to rupture

Question 9

Hemolysis (Hypotonic)

Answer 9

Bursting of RBC

Question 10

Hypertonic

Answer 10

• Have comparatively higher osmotic pressure
• High concentration
• Hypertonic environments cause cells to shrink (water molecules move out of the cells by exosmosis, faster than they enter the cell)
• Hypertonic solutions are helpful in food presentations
• Cell shrinkage = Crenation

Question 11

Diffusion Through Membrane Channels

Answer 11

• Passive diffusion of a substance down its electrochemical gradient
• Passes through channels, and some channels are open all the time, while some are gated

Question 12

Facilitated Diffusion

Answer 12

• Passive but mediated
• Movement of molecules down a concentration gradient
• There are transmembrane proteins that act as transporters
• Maximum diffusion rate is limited by the number of transporters
• Transports polar or charged solutes (glucose, fructose, galactose, urea, and some vitamins)

Question 13

Filtration

Answer 13

• Passive transport
• Movement of water and solutes through a membrane or through a capillary wall by hydrostatic pressure
• If diffusion occurs by means of a concentration gradient, filtration occurs through presence of pressure gradient (there is a difference in pressure on both sides)
• Transports Filtrate (solute-containing fluid)

Question 14

Active Transport Processes

Answer 14

• Mediated transport requiring energy in the form of Adenosine Triphosphate (ATP)
• Movement of molecules is against the concentration gradient
• Molecules can move from a region of lower concentration to a region of higher concentration (which is why energy is required)

Question 15

Primary Active Transport

Answer 15

• Involves solute pumps wherein substance is transported against its concentration gradient
• Makes use of transmembrane proteins that require Adenosine Triphosphate or ADP
  (Sodium pumps / Potassium pumps)

Question 16

Secondary Active Transport

Answer 16

• Coupled transport of 2 substances
• Energy is supplied by a sodium ion or hydrogen concentration gradient
• Involves the presence of
  ANTIPORTERS - opposite direction
  SYMPORTERS - same direction

Question 17

Vesicular Transport

Answer 17

• Movement of substances into and out of the cells in the vesicle occurs.
• Requires energy in the form of ATP

Question 18

Vesicle

Answer 18

• Small membranous sac formed by budding off from an existing membrane

Question 19

2 Forms of ATP

Answer 19

Endocytosis - movement into the cell

Exocytosis - movement of substances out of the cell

Question 20

Endocytosis

Answer 20

Substances brought into the cell by endocytosis are surrounded by a piece of plasma membrane, which buds off inside the cell to form a vesicle containing the ingested substances

Question 21

2 Types of Endocytosis

Answer 21

PHAGOCYTOSIS - Ingestion of large particles (bacteria, viruses, aged cells, or dead cells)
PINOCYTOSIS - Ingestion of extracellular fluid

Question 22

Phagocytosis

Answer 22

(1) Begins as the particle binds to a plasma membrane receptor, causing the cell to extend projections of its plasma membrane in cytoplasm called PSEUDOPODS (2) that surround the particle
(3) and portions of their membrane fused to form a vesicle that enters the cytoplasm
(4) Vesicles fuse with 1 or more lysosomes
(5) Lysosomal enzymes break down the ingested material
- Only occur in PHAGOCYTES (specialize in engulfing and destroying bacteria and foreign substance
- Include white blood cells and macrophages
- Protect body from diseases

Question 23

Exocytosis

Answer 23

• Secretion, deliberation of materials from a cell
• Secretory Vesicles (membrane-enclosed vesicles) used with the plasma membrane, and release their contents into the extracellular fluid

Question 24

2 Types of Cell

Answer 24

SECRETORY CELLS - Liberate digestive enzymes, hormones, mucous, and other secretions
NERVE CELLS - Release substances called neurotransmitters via Exocytosis

Question 25

Cell Cycle

Answer 25

Sequence of changes that a cell undergoes, from the time it forms until it duplicates its contents, and divides itself into two

Question 26

2 Major Periods of Cell Cycle in Somatic Cells

Answer 26

INTERPHASE - when a cell is not dividing
MITOSIS PHASE (M Phase) - when the cell is dividing

Question 27

Cell Cycle 1: Interphase

Answer 27

• Cell replicates its deoxyribonucleic acid (DNA)
• Manufactures additional organelles and cytosolic components, in anticipation of cell division
• G1
• S Phase
• G2

Question 28

Cell Cycle 1: Interphase G1

Answer 28

• Cell becomes metabolically active

- Duplicates organelles and cytotoxic components

Question 29

Cell Cycle 1: Interphase S Phase

Answer 29

DNA and centrosome are replicated

Question 30

Cell Cycle 1: Interphase G2

Answer 30

• Cell growth continues

- Enzymes and other proteins are synthesized

Question 31

Cell Cycle 2: Mitosis Phase

Answer 31

Prophase
Metaphase
Anaphase
Telophase

Question 32

Cell Cycle 2: Mitosis Phase Prophase

Answer 32

• Chromatid fibers condense chromosomes that are visible under the microscope
• Condensation process may prevent the entangling of the long DNA strands
• Each prophase chromosome consists of identical, double-stranded chromatids, which are held together by CENTROMERE
• Later, pericentriolar material of two centrosomes start to form the MITOTIC SPINDLE (football-shaped assembly of microtubules)
• Lengthening of the microtubules between centrosomes pushes centrosomes to opposite poles of the cell
• Spindle extends from pole to pole, then nucleolus and nuclear envelope break down

Question 33

Cell Cycle 2: Mitosis Phase Metaphase

Answer 33

• Centromeres of the chromatid pairs are aligned along the microtubules of the mitotic spindle
• METAPHASE PLATE (at exact center of the mitotic spindle)

Question 34

Cell Cycle 2: Mitosis Phase Anaphase

Answer 34

• Centromeres split, separating the two members of each chromatid pair, which move to opposite poles of the cell
• Once separated, chromatids are now called CHROMOSOMES
• As chromosomes are pulled by the microtubules of the mitotic spindle during anaphase, they appear to be V shaped
• The pull is caused by the Depolymerization Process

Question 35

Depolymerization Process

Answer 35

Removal of tubulin proteins from the spindle fibers which will cause the shortening of spindle fibers

Question 36

Cell Cycle 2: Mitosis Phase Telophase

Answer 36

• Begins after chromosomal movement stops
• Identical set of chromosomes, now at opposite poles of the cell, uncoil and revert to the thread-like chromatid form
• New nuclear envelope forms around each chromatin mass, nucleoli appears, and eventually the mitotic spindle breaks
• Cells are reconstructed

Question 37

Mitosis

Answer 37

• Cell Division undergone by somatic cells and primordial germ cells
• Parent cell with the diploid number of chromosomes, divides to form two daughter cells, each with the same number and identical set of chromosomes

Question 38

Cytokinesis

Answer 38

• Begins late in anaphase, with formation of a cleavage furrow, a slight indentation of the plasma membrane, that extends around the center of the cell
• Microfilaments in cleavage furrow pull the plasma membrane progressively inward, constricting the center of the cell like a belt around a waist
• After cytokinesis, there are 2 new and separate cells, each with equal portions of cytoplasm and organelles, and identical sets of chromosomes
• When cytokinesis is complete, interphase can begin

Question 39

Meiosis

Answer 39

• Cell Division that is undergone by reproductive cells, wherein a parent cell divides to form daughter cells, each with a haploid number of chromosomes

Question 40

Protein Synthesis

Answer 40

• DNA serves as the master blueprint for protein synthesis
• GENE is a DNA segment that carries the information building one protein or polypeptide chain.
• Much of the cellular machinery is devoted to synthesizing large numbers of diverse
  The instructions for protein synthesis are found in the DNA in the nucleus.
  Protein synthesis involves transcription and translation

Question 41

Proteins

Answer 41

• Key substances for all aspects of cell life

- Determine the physical and chemical characteristics of cells