Cell Biology and Membrane Transport Practice Flashcards

Comprehensive practice questions covering cell theory, prokaryotic vs. eukaryotic structures, membrane dynamics, and transport mechanisms based on the lecture transcript.

What are the three principles of Cell Theory?

1. All organisms are made up of cells. 2. The cell is the fundamental unit of life. 3. Cells come from preexisting cells.

What is the purpose of the biconcave shape of a red blood cell?

It maximizes surface area for gas exchange and allows the cell to alter its shape as it passes through the circulatory system.

How do neurons communicate with other cells based on their structure?

They utilize long, slender extensions of the cell membrane.

What is the function of microvilli on intestinal cells?

These thin, comblike projections increase the absorptive surface area of the cells.

Compare the size and DNA location of prokaryotes and eukaryotes.

Prokaryotes are small ($1-2 ext{ µm}$) with DNA in a nucleoid; Eukaryotes are large ($10-20 ext{ µm}$) with DNA in a nucleus.

What are the three domains of life as classified in the lecture notes?

Domain Bacteria, Domain Archaea, and Domain Eukarya.

What does it mean for a phospholipid to be amphipathic?

It contains both hydrophilic (“water-loving”) polar heads and hydrophobic (“water-fearing”) nonpolar tails.

What are the three lipid structures identified in the notes?

Micelle, Bilayer, and Liposome.

How do unsaturated fatty acids affect membrane packing compared to saturated fatty acids?

Unsaturated fatty acids have double bonds that introduce kinks, reducing the tightness of packing, whereas saturated fatty acids lack double bonds and favor tight packing.

How does cholesterol affect membrane fluidity at different temperatures?

The amphipathic structure of cholesterol allows it to impact fluidity; at low temperatures, it prevents packing to maintain fluidity, while at high temperatures, it decreases fluidity.

What are the four types of proteins found in the cell membrane?

Transporter, Receptor, Enzyme, and Anchor.

What is the difference between integral and peripheral membrane proteins?

Integral membrane proteins (including transmembrane proteins) span the entire membrane; peripheral membrane proteins are temporarily associated with either the internal or external side.

What are the key functions of the plasma membrane?

It defines the space of the cell, separates internal contents from the external environment, maintains homeostasis, and is selectively permeable.

Differentiate between passive and active membrane transport.

Passive transport moves substances from HIGH to LOW concentration without energy; active transport moves substances from LOW to HIGH concentration and requires energy.

What is the difference between simple diffusion and facilitated diffusion?

Simple diffusion involves small, nonpolar molecules moving without transport proteins; facilitated diffusion requires transport proteins for ions or polar molecules.

Define osmosis.

The movement of water from an area of high water concentration to an area of low water concentration across a semipermeable membrane.

What happens to a red blood cell when placed in a hypertonic vs. a hypotonic solution?

In a hypertonic solution, the cell shrinks; in a hypotonic solution, the cell lyses (bursts).

What is the role of a contractile vacuole in single-celled organisms?

It absorbs excess water in the cell and expels it to prevent cell lysis.

Describe the two steps of secondary active transport.

Step 1: Active transport is used to establish a proton or electrical gradient. Step 2: Passive transport of another substance occurs using that gradient.

Distinguish between symport and antiport transport.

In symport, two substances are moved in the same direction; in antiport, two substances are moved in opposite directions.

What are the three types of endocytosis?

Phagocytosis (cellular eating), Pinocytosis (cellular drinking), and Receptor-mediated endocytosis (requires a receptor).

What is the chemical formula for stearic acid provided in the notes?

$$CH_3(CH_2)_{16}COOH$$

What is the chemical formula for oleic acid provided in the notes?

$$CH_3(CH_2)_2CH=CH(CH_2)_2COOH$$