Ch.3 Movement of substances across cell membrane Flashcards
What are the main components of the cell membrane?
- phospholipids (磷脂)
- proteins
The structure of the cell membrane can be presented by ______ ______ model.
fluid mosaic (流動鑲嵌)
Phospholipid molecules are arranged in a ______, with { hydrophilic / hydrophobic } heads pointing outwards and { hydrophilic / hydrophobic } tails pointing inwards.
bilayer (雙層);
hydrophilic (親水的);
hydrophobic (疏水的);
[T/F]
Phospholipid molecules can move vertically.
F
Phospholipid molecules can move laterally (橫向地).
Protein molecules are interspersed among the ___________ molecules in a ______ pattern.
phospholipids; mosaic
a. embedded half-way | b. span | c. attached to
Some of the protein molecules are () to the surface of the phospholipid bilayer, some are () in the bilayer and others (_) the entire bilayer.
attached; embedded half-way; span
Carbohydrates are attached to some proteins to form ____________.
glycoproteins
i) channel proteins
ii) carrier proteins
(__) bind to certain substances and transport them to the other side of the cell membrane.
(__) provide channels for certain substances to move across the cell membrane.
ii. carrier proteins
i. channel proteins
i) receptors ii) antigens iii) enzymes
(__) are glycoproteins for cell recognition.
(__) bind to chemical messengers (e.g. hormones) outside cells; the binding may turn on certain activities in the cells
(__) speed up chemical reactions
ii. antigens
i. receptors
iii. enzymes
________ proteins provide channels for certain substances to move across the cell membrane.
Channel
_______ protiens bind to certain substances and transport them to the other side of the cell membrane.
Carrier
_______s bind to chemical messengers (e.g. hormones) outside cells; the binding may turn on certain activities in the cells
Receptors
________ are glycoproteins for cell recognition(識別).
Antigens
______s speed up chemical reactions.
Enzymes
The cell membrane is mainly made up of phospholipids and proteins → make the cell membrane ___________ _________.
differentially permeable
The phospholipid molecules are arranged in a bilayer with a hydrophobic core → only small, { polar / non-polar } molecules can dissolve in and move across the phospholipid bilayer.
non-polar
Some protein molecules on the cell membrane act as channels or carriers → small, { polar / non-polar } molecules and small _____s are transported by channel proteins or carrier proteins.
polar; ions
The phospholipid molecules can move laterally → makes the cell membrane _____ in nature; allows the cell membrane to change shape and _____ during phagocytosis(吞噬) and cell division.
fluid(流質的); fuse(融合)
Factors affecting the structure of the cell membrane and hence its premeability include ___________ and the presence of organic _______ (e.g. alcohol).
temperature; solvents(溶劑)
When the __________ rises, the permeability of the cell membrane increases. _______ can even damage the membrane, causing it to become fully premeable.
tempreature; Boiling
Organic solvents dissolve the phospholipids and damage the cell membrane, causing the __________ of the membrane to increase.
permeability
Diffusion is the ____ ________ of particles from a region of higher concentration to a region of lower concentration (i.e. down the concentration _______) until the particles are _____ly distributed.
net movement; gradient; evenly
How concentration gradient affect the rate of diffusion?
The steeper the concentration gradient is, the higher the rate of diffusion.
How surface area affect the rate of diffusion?
The larger the surface area over with diffusion occurs, the higher rate of diffusion.
How distance affect the rate of diffusion?
The shorter the diffusion distance is, the higher the rate of diffusion.
How tempreature affect the rate of diffusion?
The higher the temperature is, the higher the rate of diffusion.
How size of particles affect the rate of diffusion?
Smaller particles diffuse faster than large particles.
How nature of particles affect the rate of diffusion?
Non-polar substances usually diffuse faster than polar substances.
Diffusion enables cells to _________ materials with the environment.
exchange
Cells { obtain / remove } useful substances (e.g. oxygen and nutrients) and { obtain / remove } waste (e.g. carbon dioxide).
obtain; remove
Diffusion is involved in process like:
- absorption of nutrients in human _____ ________
- ____ exchange in human lungs
- reabsorption in human ________
small intestine; gas; kidneys
T/F: Osmosis is a special type of diffusion.
T
Osmosis is the ____ movement of water molecules from a region of { lower / higher } water potential to a region of { lower / higher } water potential across a d__________ p________ membrane.
net; higher; lower; differentially permeable
T/F: Pure water has the lowest water potential, which is defined as zero.
F. (Pure water has the highest water potential, which is defined as zero.)
All solutions have a water potential { lower / higher } than that of the pure water, which is a { positive / negative } value.
lower; negative
H________ solution has a higher water potential as compared to the other solution.
Hypotonic
H_______ solution has a higher water potential as compared to the other solution.
Hypotonic (低滲的)
I_______ solution has the same water potential as compared to the other solution.
Isotonic (等滲的)
H________ solution has a lower water potential as compared to the other solution.
Hypertonic (高滲的)
Animal cells in hypotonic solution:
Net movement of water - { into / out of } the cell
Changes - s____ and finally b____
into; swell; burst
Animal cells in _______ solution:
Net movement of water - No
Changes - No
isotonic
Animal cells in hypertonic solution:
Net movement of water - { into / out of } the cell
Changes - s______ and become w_______
out of; shrink(萎縮); wrinked(皺褶)
Plant cells in hypotonic solution:
Net movement of water - { into / out of } the cell
Changes - become t_____
into; turgid(膨脹)
Plant cells in hypotonic solution:
Net movement of water - { into / out of } the cell
Changes - become t_____
into; turgid(膨脹)
Plant cells in _______ solution:
Net movement of water - No
Changes - No
isotonic
Plant cells in hypertonic solution:
Net movement of water - { into / out of } the cell
Changes - become f______ and p_________; vacuoles shrink
out of; flaccid(軟縮); plasmolysed(質壁分離)
Osmosis is the main mechanism by which ______ enter or leaves cells in all organisms.
water
Osmosis allows the _________ of water in human intestines and plant roots.
absorption
Active transport is the movement of substances across the cell membrane from a region of { lower / higher } concentration to a region of { lower / higher } concentration (i.e. _______ the concentration gradient) using energy.
lower; higher; against
Why does active transport consume energy?
The carrier protein change its shape using energy.
Active transport allows the uptake of additional useful substances wich are already { low / high } in concentration in the cells.
high
Active transport is involved in the absorption of _______s in the human small intestine and the absorption of _______s from the soil into plant roots.
nutrients; minerals
___________ is the uptake of large particles into cells by packaging the particles into vacuoles formed from the cell membrane.
Phagocytosis
During phagocytosis, foot-like extensions of cytoplasm called ___________ are formed to surround the particle to be taken in.
pseudopodia (偽足)
During phagocytosis, the large paricles is broken down in vacuoles with the help of the _______s, and hence be absorbed into the _________.
emzymes; cytoplasm
Phagocytosis allows some _________ organisms to engulf food particles for nutrition.
unicellular
Phagocytosis allows certain { red / white } blood cells in humans to engulf harmful ____________s for body defense against diseases.
white; microoganisms
Active or passive? Diffusion: \_\_\_\_\_\_\_ Osmosis: \_\_\_\_\_\_\_ Active transoprt: \_\_\_\_\_\_\_ Phagocytosis: \_\_\_\_\_\_\_
passive; passive; active; active
Energy needed?
Diffusion: { Yes / No }
Osmosis: { Yes / No }
Active transoprt: { Yes / No }
Phagocytosis: { Yes / No }No; No; Yes; Yes
