BIOL 2255 EXAM 2 PRACTICE QUESTIONS
WITH DETAILED EXPLANATIONS 2026
◉ unsaturated fats.
Answer: - carbon=carbon double bonds
- kinked structure
- reduced tightness of packing --> enhances mobility (fluidity)
◉ cholesterol.
Answer: makes up 30% of cell membrane
◉ which part of cholesterol is hydrophilic?.
Answer: hydroxyl group on steroid ring A
◉ what role does cholesterol play in a cell membrane?.
Answer: helps with tight-packing
◉ what is the orientation of cholesterol?.
Answer: amphipathic
- hydrophobic, rigid planar group of rings & hydrophobic
hydrocarbon tail
,(interacts w/ hydrophobic fatty acid tails of phospholipid)
- hydrophilic head group
(interact w/ hydrophilic head of phospholipid)
◉ 2 types of membrane proteins.
Answer: 1. integral
2. peripheral
◉ integral membrane proteins.
Answer: permanently associated w/ membrane
- unable to be separated
- hydrophilic AND hydrophobic regions
◉ peripheral membrane proteins.
Answer: temporarily associated w/ membrane
- internal or external
- weak noncovalent interactions w/ polar heads or integral proteins
- transmits info from external signals
◉ fluid mosaic model.
Answer: proposes that lipid bilayer --> fluid structure
- allows molec to move laterally within membrane
, - mosaic of lipids/proteins
◉ FRAP.
Answer: Fluorescent Recovery After Photobleaching
◉ how does FRAP demonstrate the dynamic property of the plasma
membrane?.
Answer: plasma membrane...
- regulates movement of molec into/out of the cell
- maintains homeostasis
(FRAP measures the fluidity of a membrane by shooting a laser that
bleaches fluorescent markers on the membrane & measures the
time of fluorescence as gradual recovery occurs)
◉ semipermeable membrane.
Answer: (non-living)
excludes substances from crossing based on SIZE
◉ selectively permeable membrane.
Answer: (living)
regulates what passes through based on SIZE, CHARGE, & POLARITY
WITH DETAILED EXPLANATIONS 2026
◉ unsaturated fats.
Answer: - carbon=carbon double bonds
- kinked structure
- reduced tightness of packing --> enhances mobility (fluidity)
◉ cholesterol.
Answer: makes up 30% of cell membrane
◉ which part of cholesterol is hydrophilic?.
Answer: hydroxyl group on steroid ring A
◉ what role does cholesterol play in a cell membrane?.
Answer: helps with tight-packing
◉ what is the orientation of cholesterol?.
Answer: amphipathic
- hydrophobic, rigid planar group of rings & hydrophobic
hydrocarbon tail
,(interacts w/ hydrophobic fatty acid tails of phospholipid)
- hydrophilic head group
(interact w/ hydrophilic head of phospholipid)
◉ 2 types of membrane proteins.
Answer: 1. integral
2. peripheral
◉ integral membrane proteins.
Answer: permanently associated w/ membrane
- unable to be separated
- hydrophilic AND hydrophobic regions
◉ peripheral membrane proteins.
Answer: temporarily associated w/ membrane
- internal or external
- weak noncovalent interactions w/ polar heads or integral proteins
- transmits info from external signals
◉ fluid mosaic model.
Answer: proposes that lipid bilayer --> fluid structure
- allows molec to move laterally within membrane
, - mosaic of lipids/proteins
◉ FRAP.
Answer: Fluorescent Recovery After Photobleaching
◉ how does FRAP demonstrate the dynamic property of the plasma
membrane?.
Answer: plasma membrane...
- regulates movement of molec into/out of the cell
- maintains homeostasis
(FRAP measures the fluidity of a membrane by shooting a laser that
bleaches fluorescent markers on the membrane & measures the
time of fluorescence as gradual recovery occurs)
◉ semipermeable membrane.
Answer: (non-living)
excludes substances from crossing based on SIZE
◉ selectively permeable membrane.
Answer: (living)
regulates what passes through based on SIZE, CHARGE, & POLARITY
