The Cell

Question 1

Carbohydrates

Answer 1

• The body’s primary source of energy
• ex. glycogen, glycose, and lactose

Question 2

Proteins

Answer 2

• Chains of amino acids
• Structural function, and work as carrier molecules, ion channels, receptors, and enzymes

Question 3

Lipids

Answer 3

• Storing energy
• ex. triglycerides, steroids, fatty acids, fat-soluble vitamins, and phospholipids

Question 4

Nucleic Acids

Answer 4

Carries and store genetic information

Question 5

Phospholipids

Answer 5

• Contain 1 glycerole molecule with a phosphate group + 2 chains of fatty acids
• Glycerin group = polar, hydrophilic “head” → reacts with water, rejects fat soluble substances
• Fatty acids = nonpolar, hydrophobic “tails” → reject water, react with fat soluble substances

Question 6

THE CELL MEMBRANE - structure

Answer 6

• A flexible wall of lipid bilayer → 2 layers of phosphlipids in a tail-to-tail construction
• glycolipids = Carbohydrate + lipids where lipids connect to lipid part of the phospholipid membrane →forms glycokalyx (slimy fur-like outer layer)
• Steroids → stability
• Integral proteins in or through the membrane → receptors, enzymes, and channels

Question 7

CELL MEMBRANE - Functions

Answer 7

• Seperates cell’s internal environment from the external
• Protects cell
• Galycokalyx = identity marker
• Transportation of substances in and out of cell:
→ nonpolar, hydrophobic substances pass freely due to hydrophobic tails of phospholipids inside membrane
→ polar, hydrophilic, and/or charged substances/molecules need help from membranes proteins
→ water can pass freely through aquaporines

Question 8

PASSIVE TRANSPORT

Answer 8

• Transport that does not need energy in form of ATP
• Diffusion: high → low concentration
• Filtration: high → low fluid pressure
• Osmosis: transport of water, low → high concentration of particles

Question 9

PASSIVE TRANSPORT - Diffusion

Answer 9

• Simple diffusion = molecules pass membrane on their own
ex. oxygen, carbondioxide, steroids, fattyacids (hydrophobic)
• Facilitated diffusion = diffusion with help from integral proteins forming channels for specific molecules
ex. ion-channels (charged and hydrophilic molecules)

Question 10

ACTIVE TRANSPORT

Answer 10

• Requires energy → ATP
• Against concentration gradient = low → high
• Active pumps: change shape, “Iifting” molecules from low → high
• Vesicle = sac from existing membrane: 2 types → endocytosis entering cell, and exocytosis leaving the cell

Question 11

ACTIVE TRANSPORT - Active pumps

Answer 11

• Energy of splitting ATP → ADP + 1 phosphate group causes pump (protein) to change shape
• ex. Sodium-potassium pump
3 Na+ ions in cell bind to pump → ATP attaches and splits → pump changes shape → releases Na+ out and 2 K+ ions binds to pump → pump go back to normal shape → K+ released into cell

Question 12

ACTIVE TRANSPORT - Endocytosis

Answer 12

• Substances brought into cell via vesicles
• substance is surrounded by a piece of cell membrane → buds off inside the cell forming a sac with substance
• 2 types:
→ Phagocytosis = “Cell eating” large solid particles
→ Bulk-phase endocytosis = “Cell drinking” tiny droplets of fluid from outside cell (extracellular fluid)

Question 13

ACTIVE TRANSPORT - Exocytosis

Answer 13

• Transport of substances out of the cell
• Vesicles formed inside the cell, secretory vesicles, fuse together with cell membrane → releases it’s content out from cell

Question 14

CYTOPLASM

Answer 14

• Consists of all cellular content between cell membrane and nucleus
• Cytosol = the liquid portion, water + dissolved solutes
• Organells = small organs inside the cell with specific functions

Question 15

NUCLEUS

Answer 15

• Largest organell and is the control center
• Nuclear envelope = double membrane
• Nuclear pores = substances can get through
• Nucleolus = clusters of protein → DNA
• Genes = control cellular structure and activities arranged around chromosomes

Question 16

ENDOPLASMATIC RETICULUM

Answer 16

• Large network of folded membranes forming tubes
• Rough ER = surrounded of ribosomes, protein synthesis
• Smooth ER = extends from rough ER, lipid synthesis
• Substances synthesized → transported out of cell in vesicles

Question 17

RIBOSOMES

Answer 17

• Where protein synthesis takes place
• Contains rRNA (ribosomal RNA)
• Free ribosomes → synthesizes protein used in the cytosol
• Membrane bound (to ER)

Question 18

GOLGI APPARATUS

Answer 18

• First step in proteins passage through the cell
• Modifies and package proteins
• Proteins from ribosomes on ER → modified to form glycoproteins and lipidproteins → sorted and packed into vesicles

Question 19

LYSOSOMES

Answer 19

• Membrane-enclosed vesicles with digestive enzymes
• Fuse together with vesicles during endocytosis → digest resides content
• Integral proteins allowing products of digestion out to cytosol → can recycle components → old organells replaced

Question 20

MITOCHONDRIA

Answer 20

• The “power- houses” of the cell
• 2 membranes: smooth outer membrane and folded inner membrane
• Produces most of a cell’s ATP

Question 21

CYTOSKELETON

Answer 21

• Network of protein filaments extending through cytoplasm
• Generates movements and a structural framework for the cell
• Components: microfilaments, intermediate filaments, microturbulens

Question 22

Intracellular volume (ICV)
and
Extracellular volume (ECV)

Answer 22

• ICF = fluid inside body cells
• ECV = fluid outside body cells

Question 23

RESTING MEMBRANE POTENTIAL

Answer 23

• The difference in electrical charge across the plasma membrane
• Arises due to unequal distribution of ions on each side of the membrane → difference is -70mV (negative inside the cell)