2.5 Homeostasis And Cellular Transport In Eukaryotic Cells

Question 1

Homeostasis

Answer 1

Tendency of living things to maintain a steady state of internal conditions

In a living system it is the maintenance of a dynamic equilibrium

Question 2

Dynamic equilibrium

Answer 2

A point at which the rate of the forward process matches the rate of the reverse process

Question 3

Stimuli

Answer 3

Changes that cause reactions

Question 4

Feedback loop

Answer 4

Homeostatic process that changes the direction of the stimulus

Question 5

Negative feedback loop

Answer 5

Changes the direction of the stimulus

Reduces the stimulus

Question 6

Positive feedback loop

Answer 6

Maintains the stimulus and sometimes even enhances it

Question 7

Thermoregulation

Answer 7

Ongoing stimulus response that allows warm-blooded animals to regulate internal temp

Question 8

Ectotherms

Answer 8

Depend on the external environment to set their body temperatures

Question 9

Endoderms

Answer 9

Maintain their body temperature at set points through thermoregulation

Question 10

Radiation

Answer 10

Loss of electromagnetic radiation as heat waves

Question 11

Evaporation

Answer 11

Loss of heat as a liquid becomes a gas

Question 12

Convection

Answer 12

Loss of heat due to air movement

Question 13

Conduction

Answer 13

Direct transfer of heat by molecules of an organism or object that’s in direct contact

Question 14

Cellular transport

Answer 14

Moving liquids, molecules, proteins, ions, and other solutes into and out of the cell

Question 15

Solute

Answer 15

Any substance that has been dissolved in another substance

Question 16

Hydrophilic

Answer 16

Water-attracting

Question 17

Hydrophobic

Answer 17

Water-repelling

Question 18

Fluid mosaic model

Answer 18

Phospholipids are held together by hydrophobic interactions that are much weaker than covalent bonds so they can shift and move when perturbed, making room for other things to move through and close behind them

Proteins are embedded in the fluid matrix of the lipid layer

Carbohydrates are bonded to either the lipid or proteins of the membrane

Question 19

Integral proteins

Answer 19

Often span the entire membrane (AKA transmembrane proteins)

Hydrophilic regions stick out and hydrophobic regions are between the lipids

Important for transport

Question 20

Peripheral proteins

Answer 20

Not part of the cell membrane but appendages on surface of cell

Add structure by binding with fibers

Attachment sites for enzymes or cell-recognition sites

Question 21

Role of carbohydrates on cell membrane

Answer 21

Bone to either the lipid or the proteins of the cell membrane

Allow cells to recognize each other

Can tell the difference between body cells and foreign invaders

Stimulate the immune system when foreign cells detected

Question 22

Passive transport

Answer 22

The movement of ions and other substances across a cellular membrane along the concentration gradient without the input of energy

Includes diffusion, facilitated diffusion and osmosis

Question 23

Diffusion

Answer 23

Substances move from areas of high concentration to areas of low concentration until concentration is equal throughout a space

Question 24

Concentration gradient

Answer 24

Relative concentration difference between a region with high concentration and a region with low concentration.

Question 25

Semipermeable

Answer 25

Will let only certain substances pass through regardless of the concentration gradient

Question 26

Facilitated diffusion

Answer 26

Transport protein are used as channels or carriers for certain insoluble molecules that are too large or unable to pass through membrane due to charge or polarity

Question 27

Channel proteins

Answer 27

Facilitate movement of molecules through membrane by forming special pores and channels that are big enough to accommodate large molecules or have polarity that accepts polar or charged molecules

Question 28

Carrier proteins

Answer 28

Bind to substances to help them across the membrane

Generally specific for one substance

Question 29

Osmosis

Answer 29

Diffusion of water from areas of high water concentration to areas of low water concentration

Question 30

Isotonic

Answer 30

Concentration of solutes within and outside the cell is equal

Water moving in and out at equal rates

Question 31

Hypotonic

Answer 31

Concentration of solutes outside cell is lower than inside the cell

Water outside the cell will move into the cell

Question 32

Hypertonic

Answer 32

Concentration of solutes outside cell is higher than inside the cell

Water will move outside of the cell

Question 33

Osmotic pressure

Answer 33

Caused by differences in water concentration within and outside the cell

Question 34

Active transport

Answer 34

Cells must use energy to move molecules, ions, proteins, liquids, or solutes into regions that already have high concentration of these substances

Question 35

Membrane potential

Answer 35

Electrical potential or voltage difference between one side of the selectively permeable membrane and the other

Difference usually falls between -40 and -80 millivolts (cells typically more negative on inside than outside)

Question 36

Chemical gradient

Answer 36

Difference in concentration of a specific molecule, protein, or liquid on either side of a membrane

Question 37

Electrical gradient

Answer 37

Difference in the concentration of electrical charges on either side of a membrane

Question 38

Electrochemical gradient

Answer 38

Combined effects of electrical and chemical gradients

Question 39

Sodium-potassium pump

Answer 39

One of the most common active transport found in eukaryotic cells

Keeps concentration of potassium inside the cell high and the concentration of sodium inside the cell relatively low and vice versa

For every 3 sodium ions pumped out of the cell, 2 potassium ions are pumped in

Question 40

Sodium potassium pump steps

Answer 40

1. Open to inside of cell, 3 sodium ions bind to inside
2. ATP binds to pump and energy is used by splitting into ADP and a phosphate group
3. The ADP is released and the phosphate group caused the pump to change shape and open to the outside
4. Sodium ions released and 2 potassium ions attach causing the phosphate group to detach
5. Loosing the phosphate group causes pump to change back to being open to the inside
6. The potassium ions are released to the inside of the cell

Question 41

Endocytosis

Answer 41

Bulk transport of molecules, food and other substances across a membrane into the cell

Question 42

Phagocytosis

Answer 42

Movement of food or other particles through the cell membrane

Cell membrane encases the particle in a food vacuole and eventually fuses with a lysosomes to break it into usable materials

Question 43

Pinocytosis

Answer 43

Plasma membrane wraps itself around liquid outside the cell to absorb dissolved molecules and ions

Non-specific

Question 44

Receptor-mediated Endocytosis

Answer 44

Requires the recognition of the molecule by receptors on a pit in the cell membrane. Once the receptor have filled a signal is sent to close off the pit and the contents are ingested.