Cell Membrane and Respiration Functions

These flashcards cover key concepts related to cell membranes and aerobic respiration as discussed in the lecture notes.

Functions of membranes

Membranes act as barriers to separate the internal cellular environment from the external environment, facilitate communication, and transport substances.

Components of cell membranes

Cell membranes comprise phospholipids, cholesterol, proteins, and carbohydrates.

Structure of phospholipids

Phospholipids consist of a hydrophilic (water-loving) head and two hydrophobic (water-fearing) tails; there are various types of phospholipids.

Structure of a bilayer

The lipid bilayer forms when phospholipids align with their hydrophobic tails inward, preventing water from entering, creating a fluid mosaic due to the mobility of its components.

Factors influencing membrane fluidity

Factors such as temperature, lipid composition (saturation), and cholesterol levels influence fluidity, where increased temperature and unsaturated fats increase fluidity.

Asymmetrical cell membranes

Cell membranes are asymmetrical due to the different distribution of lipids and proteins between the inner and outer layers.

Ion concentration difference importance

Different internal and external ion concentrations are crucial for maintaining gradients necessary for processes like nerve impulses and muscle contraction.

Control of concentration differences

Concentration differences are controlled by transport proteins and pumps in the cell membrane.

Permeable and impermeable substances

Cell membranes are permeable to small nonpolar molecules and impermeable to large polar molecules; this is due to the lipid bilayer's amphipathic nature.

Types of transport proteins

Transport proteins include channel proteins, carrier proteins, and pumps that facilitate molecule movement across membranes.

Movement influences across membranes

Factors influencing movement include concentration gradients, electric gradients, and membrane permeability.

Mechanisms of crossing membranes

Substances cross membranes via passive transport (e.g., diffusion), active transport (e.g., pumps), and facilitated diffusion (e.g., carrier proteins).

GLUT transporters

GLUT transporters mediate facilitated diffusion and transport glucose across cell membranes.

Water movement across membranes

Water movement occurs primarily through aquaporins, which facilitate faster transport.

Active transport pumps

Active transport pumps move substances against their concentration gradient using energy, such as the Na+/K+ pump.

Na+/K+ pump mechanism

The Na+/K+ pump transports 3 Na+ ions out for every 2 K+ ions pumped in against their concentration gradients using ATP.

Roles of Na+/K+ pump

This pump is crucial for maintaining cell potential and volume, impacting nerve and muscle function.

Ca++ pump location

The Ca++ pump is found in the sarcoplasmic reticulum of muscle cells, regulating calcium ion concentrations.

H+ pumps vs Na+-K+ pumps

H+ pumps transport protons across membranes, while Na+/K+ pumps regulate sodium and potassium; both are active transport mechanisms.

Cellular respiration purpose

Cells undergo cellular respiration to convert biochemical energy from nutrients into ATP, the energy currency of the cell.

ATP

ATP (adenosine triphosphate) is a nucleotide that serves as the primary energy carrier in cells.

ATP-generating pathways

The two ATP-generating pathways are aerobic respiration and anaerobic respiration (fermentation), with different efficiencies.

Stages of aerobic respiration

Aerobic respiration includes glycolysis, citric acid cycle, and oxidative phosphorylation; total ATP generated is 30-32 ATP per glucose molecule.

Stage with highest ATP production

The oxidative phosphorylation stage results in the most ATP production due to the electron transport chain.

Mitochondria structure and functions

Mitochondria have a double membrane; aerobic respiration stages take place in different parts: glycolysis (cytoplasm), citric acid cycle (matrix), oxidative phosphorylation (inner membrane).

Chemiosmosis

Chemiosmosis is the process of ATP generation driven by the movement of protons across a membrane, with ATP synthase as the crucial protein.

Common electron transport proteins

Common electron transport proteins include cytochromes, which pass electrons down the chain; oxygen acts as the final electron acceptor.

Overall reaction of aerobic respiration

The overall reaction of aerobic respiration is: C6H12O6 + 6O2 -> 6CO2 + 6H2O + ATP.

Metabolizing other substrates

We do not only metabolize glucose; other carbohydrates, fats, and proteins can also be used as energy sources.

Types of anaerobic respiration

Types of anaerobic respiration (fermentation) include lactic acid fermentation and alcoholic fermentation.

Why is building up a concentration gradient important for the Na+/K+ pump?

Building up a concentration gradient for the Na+/K+ pump is crucial for maintaining the resting membrane potential of cells, facilitating the secondary active transport of other molecules, and ensuring proper cellular function through the regulation of ion balance

What is passive transport?

Passive transport is the movement of substances across a cell membrane without the need for energy, moving from an area of higher concentration to an area of lower concentration.

What is active transport?

Active transport is the movement of substances against their concentration gradient, requiring energy (usually from ATP) to move molecules from lower to higher concentration.

What is facilitated diffusion?

Facilitated diffusion is a type of passive transport that uses transport proteins to help molecules cross the cell membrane more easily.

What is osmosis?

Osmosis is the diffusion of water across a selectively permeable membrane, moving from an area of low solute concentration to an area of high solute concentration.

What is bulk transport?

Bulk transport is the process of moving large quantities of materials into or out of the cell, often involving vesicles, including endocytosis and exocytosis.

What is glycolysis?

Glycolysis is the first stage of aerobic respiration that occurs in the cytoplasm, where glucose is broken down into two molecules of pyruvate, producing a small amount of ATP and NADH.

What is the Krebs cycle?

The Krebs cycle, also known as the citric acid cycle, is the second stage of aerobic respiration that takes place in the mitochondria, where acetyl-CoA is oxidized to produce NADH, FADH2, ATP, and CO2.

What is the electron transport chain?

The electron transport chain is the final stage of aerobic respiration, occurring in the inner mitochondrial membrane, where electrons from NADH and FADH2 are passed through a series of proteins, leading to the production of a large amount of ATP and the formation of water from oxygen.

What are co-activators?

Activators are proteins that do not bind directly to DNA but interact with transcription factors to enhance the transcription of a gene by forming a bridge between transcription factors and the RNA polymerase complex.

What are co-repressors?

Repressors are proteins that bind to transcription factors or silencers to repress gene transcription, often by modifying chromatin structure to inhibit access of the transcriptional machinery

What are gene regulatory proteins?

Gene regulatory proteins are proteins that interact with specific DNA sequences to regulate the transcription of genes, including transcription factors, co-activators, co-repressors, enhancers, and silencers.

What are integral membrane proteins?

Integral membrane proteins are proteins that are permanently attached to the membrane and span across the lipid bilayer, playing roles in transport, signal transduction, and cell recognition.

What are peripheral membrane proteins?

Peripheral membrane proteins are proteins that are temporarily attached to the lipid bilayer or to integral membrane proteins, often involved in signaling pathways and cytoskeletal interactions.

What are channel proteins?

Channel proteins are integral membrane proteins that form pores in the membrane, allowing specific ions or molecules to pass through the membrane by facilitated diffusion.

What are carrier proteins?

Carrier proteins are integral membrane proteins that bind to specific molecules and change shape to shuttle them across the membrane, enabling active or passive transport.

What are receptor proteins?

Receptor proteins are integral membrane proteins that bind to signaling molecules (ligands) and initiate cellular responses, playing crucial roles in communication between cells

What are the types of phospholipid movement within a cell membrane?

Phospholipids can move within a cell membrane through several mechanisms:

• Lateral diffusion: Phospholipids can move sideways within the same layer (monolayer) of the membrane.
• Flexion: The hydrophobic tails can bend or flex, allowing for more fluidity.
• Rotation: Phospholipids can rotate around their long axes.
• Flip-flop: Phospholipids can occasionally move from one layer of the bilayer to the other, though this is less common and requires energy or enzyme assistance (such as flippases).

What is isotonic osmotic concentration?

Isotonic osmotic concentration refers to a solution having the same solute concentration as another solution, resulting in no net movement of water across the membrane and maintaining cell shape.

What is hypertonic osmotic concentration?

Hypertonic osmotic concentration refers to a solution that has a higher solute concentration compared to another solution, leading to water moving out of the cell, causing it to shrink.

What is hypotonic osmotic concentration?

Hypotonic osmotic concentration refers to a solution that has a lower solute concentration compared to another solution, resulting in water moving into the cell, causing it to swell

What is ubiquinone?

Ubiquinone, also known as coenzyme Q, is a lipid-soluble molecule found in the inner mitochondrial membrane that plays a critical role in the electron transport chain, facilitating the transfer of electrons between complexes I, III, and IV.

What is cytochrome?

Cytochromes are heme-containing proteins that function as electron carriers in the electron transport chain, transferring electrons between various complexes and playing a vital role in cellular respiration

What is combinational control in gene expression?

Combinational control in gene expression is a regulatory mechanism where multiple transcription factors interact with a promoter region to determine the level and timing of gene expression, allowing for a precise response to internal and external signals