Foundations in Biology- Biological membranes Flashcards
suggest one change that occurs to plasma membranes at high temperatures
membrane structure is disrupted, membrane becomes permeable
suggest one way you can increase the accuracy of an experiment
Take readings more often between a smaller range of temperatures
suggest one way you can increase the reliability of an experiment
take more readings at each temperature
outline the process of budding in yeast
- Budding is when cells split and the nucleus divides during mitosis.
- the cells swell on one side so the nucleus/ cytoplasm/ organelles move into the bulge
- a cell wall forms so the bud becomes a separate cell.
what is the function of glycoproteins in the cell surface membrane?
- acting as antigens
- identification/ recognition of cells as self/ non-self
- cell signalling
- receptor binding for hormones
- cell adhesion to hold cells together in a tissue
- facilitates diffusion
- active transport
what is a function of carrier proteins?
they allow polar/ charged particles to pass through the cell membrane
what is a function of cholesterol?
regulate fluidity and stabilise the membrane.
what happens to cholesterol at high temperatures?
at high temperatures cholesterol makes membranes less fluid by restraining movement of phospholipids, ensuring that the cell membrane remains flexible and functional across different temperatures.
Explain what is meant by the term cell signalling?
- communication between cells
- cells coordinate to trigger a response/ reaction in a cell
what is the role of the cell surface membrane in cell signalling?
- they release signal molecules by exocytosis
- proteins act as receptors- the shape of the receptor is complementary to the signal
- the attachment of signal proteins causes changes on cell surface
- cell membrane allows entry of some signal molecules
explain how a glycoprotein can act as a receptor
- glycoproteins have a shape complementary to the molecule
- molecule(signal) attaches to the receptor.
how can small, non-polar substances enter through the plasma membrane?
through diffusion/ facilitated diffusion
how can large substances enter through the plasma membrane?
- using transport/ carrier proteins through endocytosis/ phagocytosis.
- uses active transport/ ATP
how can polar substances enter through the plasma membrane?
- using transport/ carrier proteins
- uses active transport/ ATP
what is the difference between endocytosis and phagocytosis?
Endocytosis= a process where cells take in substances from outside the cell, inside the cell. The cell membrane wraps around the material and forms a vesicle (a small bubble).
Phagocytosis= a process where cells (usually a white blood cell) engulfs large particles like bacteria/ dead cells. The cell extends its membrane around the particle, forming a large vesicle, then fuses with a lysosome to break down the material.
what is similar between endocytosis and phagocytosis?
both endocytosis and phagocytosis refer to processes where cells take in materials
Explain why facilitated diffusion via GLUT proteins require no metabolic energy?
- particles have their own kinetic energy
- they have movement down a concentration gradient ( from an area of high to low conc.)
outline the role of membranes within cells
- provides attachment sites for enzymes
- sites of chemical reactions
- compartmentalisation
why might a low PH cause the red pigment to leak out of beetroot cells?
- low PH denatures/ changes tertiary structure of membrane proteins
- therefore membrane permeability to pigment is increased
what is a buffer?
a solution that can resist PH, even if an acid or base is added at a constant temperature
Describe the structure of a plasma membrane
- Hydrophillic phosphate heads facing outwards
- hydrophobic tails facing inwards
- contains pores for cell diffusion and is tightly tacked
- cholesterol in bilayer between phospholipids
- glycoproteins/ glycolipids stick out of bilayer
what is the difference between an intrinsic and extrinsic protein?
intrinsic proteins are embedded in the membrane, while extrinsic proteins are associated with the membrane surface.
name functions of membranes within cells
- compartmentalisation= separate organelles into compartments
- forms vesicles
- provides surface for attachment of enzymes/ ribosomes
- partially permeable/ selectively permeable
what is the model of the cell membrane structure called?
Fluid mosaic
how are vesicles moved from one organelle to another?
vesicles move along microfilaments/ microtubule. It uses ATP (metabolic energy).
examples of active transport in cells
- mineral ions into root hair cells
- hydrogen ions out of companion cells
what ways can substances pass through the cell membrane?
- diffusion
- facilitated diffusion
- active transport
- osmosis
- bulk transport (endocytosis/ exocytosis).
why do plant cells not burst when left in pure water?
they have a strong cell wall and they limit the uptake of water
