Biological Membranes quiz #3 Flashcards
Biological Membranes quiz #3
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What is selectively permeable?
Selectively permeable refers to a membrane's ability to allow certain substances to pass while blocking others. What is a plasma membrane?
A plasma membrane is a selectively permeable barrier composed of a phospholipid bilayer with embedded proteins. Why is it important for the cell membrane to be selectively permeable?
Selective permeability is important for maintaining homeostasis and allowing necessary substances to enter while keeping harmful ones out. What is the primary structural component of biological membranes?
The primary structural component of biological membranes is the amphipathic phospholipid bilayer. How are biological membranes commonly referred to in textbooks and lectures?
Biological membranes are also called cell membranes or plasma membranes. What does the 'fluid' aspect of the fluid mosaic model refer to?
The 'fluid' aspect refers to the semi-fluid nature of the membrane, where molecules can move and shift within the bilayer. What percentage of a biological membrane's mass can be made up of proteins?
Proteins can make up 20-80% of a biological membrane's mass. How do proteins contribute to the function of biological membranes?
Proteins serve various functions such as transport, signaling, and structural support within the membrane. Why are phospholipids able to form bilayers in water?
Phospholipids form bilayers because their hydrophilic heads face water while their hydrophobic tails avoid water, creating a stable structure. How do membrane proteins move within the biological membrane?
Membrane proteins can move laterally within the membrane, contributing to its fluid nature. What are the two main regions of a phospholipid molecule?
The two main regions are the hydrophilic (polar) head and the hydrophobic (nonpolar) tail. What types of molecules are embedded in the phospholipid bilayer besides phospholipids?
Proteins, cholesterol, and sometimes carbohydrates are embedded in the phospholipid bilayer. What is the significance of the term 'bilayer' in phospholipid bilayer?
'Bilayer' means the membrane is composed of two layers of phospholipids. What is the role of cholesterol in animal cell membranes?
Cholesterol modulates membrane fluidity and stability in animal cell membranes. How does the fluid mosaic model explain the dynamic nature of membranes?
It describes how lipids and proteins can move laterally, making the membrane flexible and dynamic. Why are biological membranes described as selectively permeable?
Because they allow some substances to pass through while blocking others, maintaining cellular homeostasis. How do carbohydrates attached to proteins and lipids contribute to membrane function?
They play roles in cell recognition, signaling, and adhesion. What is the main function of the phospholipid bilayer in the membrane?
It acts as a barrier to separate the cell's interior from the external environment. What is the significance of proteins making up a large percentage of membrane mass?
It highlights the importance of proteins in membrane function, such as transport and communication. What is the role of the hydrophilic head of a phospholipid?
The hydrophilic head interacts with water, facing the aqueous environments inside and outside the cell. Why is the fluidity of the membrane important for cell function?
Fluidity allows for membrane flexibility, movement of proteins, and proper functioning of the membrane. How does cholesterol affect membrane fluidity at different temperatures?
Cholesterol stabilizes membrane fluidity by preventing it from becoming too rigid at low temperatures and too fluid at high temperatures. What is the function of glycolipids in the membrane?
Glycolipids play roles in cell recognition and communication. What is the significance of the term 'semi-fluid' in describing membranes?
It means that the membrane is flexible and its components can move, but it is not as fluid as a liquid. What is the main difference between integral and peripheral membrane proteins?
Integral proteins are embedded within the bilayer, while peripheral proteins are attached to the membrane surface. Why is the biological membrane considered a dynamic structure?
Because its components are constantly moving and rearranging within the bilayer. How do phospholipids arrange themselves in an aqueous environment?
They form a bilayer with hydrophilic heads facing water and hydrophobic tails facing inward. How does the presence of cholesterol differ between animal and plant cell membranes?
Cholesterol is abundant in animal cell membranes but less common in plant cell membranes. How do biological membranes participate in cell signaling?
Membrane proteins and carbohydrates act as receptors and signaling molecules. How does the membrane's selective permeability benefit the cell?
It allows the cell to control its internal environment and respond to external changes. How do membrane proteins contribute to cell adhesion?
Some membrane proteins help cells stick to each other and to the extracellular matrix. How does the fluid mosaic model explain the adaptability of membranes?
The model shows that the membrane can change shape and composition as needed. How do biological membranes help maintain concentration gradients?
They regulate the movement of ions and molecules, maintaining different concentrations inside and outside the cell. How do carrier proteins differ from channel proteins in the membrane?
Carrier proteins bind and transport specific molecules, while channel proteins form open pores for passage. How do biological membranes facilitate communication between cells?
Membrane proteins and carbohydrates act as signals and receptors for cell communication. How does the structure of the biological membrane allow for flexibility and movement?
The fluid nature of the bilayer and the mobility of its components provide flexibility and movement. How do biological membranes contribute to energy production in cells?
Membranes house proteins involved in processes like cellular respiration and photosynthesis. How do biological membranes support the function of organelles?
They create compartments for specialized reactions and processes within organelles. How do biological membranes participate in endocytosis and exocytosis?
They allow the cell to engulf or release materials by forming vesicles from the membrane.
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