Structure and Function of Cell Membrane

Comprehensive flashcards covering cell membrane structure, components, signaling pathways, and transport mechanisms based on the lecture notes.

In 1972, the hypothesis for membrane structure put forward by Singer and Nicolson is known as the __________.

fluid mosaic model

The cell membrane is described as __________ because the phospholipids and proteins can move about by diffusion.

fluid

The term __________ describes the pattern produced by scattered protein molecules when the surface of the membrane is viewed from above.

mosaic

Phospholipids have a __________ head and __________ tails, making them amphipathic.

hydrophilic; hydrophobic

Membrane fluidity is increased by the presence of __________ phospholipids.

unsaturated

The __________ the phospholipid tail, the less fluid the membrane will be due to increased intermolecular interactions.

longer

At low temperatures, __________ increases membrane fluidity by preventing the regular packing of phospholipids.

cholesterol

At high temperatures, cholesterol helps to __________ cells by decreasing membrane fluidity.

stabilise

Hydrophilic carbohydrate chains on glycolipids and glycoproteins form __________ bonds with surrounding water molecules to stabilise the membrane structure.

hydrogen

Glycolipids and glycoproteins can act as __________ or antigens, which allow for cell–cell recognition.

cell markers

Proteins that are found in the inner layer, outer layer, or spanning the whole membrane are called __________ proteins.

intrinsic

__________ proteins provide hydrophilic channels or passageways for ions and polar molecules to pass through the membrane.

Transport

The relaying of a message from a signaling molecule to the inside of a cell via a membrane receptor is called __________.

signal transduction

In cell signaling, the signaling molecule is known as the __________ and its corresponding protein is the receptor.

ligand

Small, __________ ligands, such as steroid hormones, can enter the cell and bind to intracellular receptors.

hydrophobic

The three common types of cell-surface receptors are ligand-gated ion channels, G protein-coupled receptors, and __________.

receptor tyrosine kinases

__________ signaling occurs when a cell secretes a messenger that binds to receptors on the same cell.

Autocrine

__________ signaling involves chemical messengers called hormones that enter the bloodstream for long-distance transport.

Endocrine

The net movement of molecules from a region of higher concentration to a region of lower concentration is called __________.

diffusion

Diffusion of substances through transport proteins, such as channel or carrier proteins, is known as __________.

facilitated diffusion

The net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane is __________.

osmosis

The formula for water potential is __________.

$$\psi = \psi_s + \psi_p$$

By definition, the water potential ($\psi$) of __________ at atmospheric pressure is $0$.

pure water

A plant cell placed in a __________ solution will become turgid as water moves into the cell.

hypotonic

__________ involves the movement of molecules against their concentration gradient using energy from $ATP$.

Active transport

The bulk uptake of solid material by a cell is specifically called __________.

phagocytosis

__________ is the process by which materials, such as digestive enzymes, are removed from cells via secretory vesicles.

Exocytosis

The bulk uptake of liquid into a cell is known as __________.

pinocytosis