Exam 2 Biology

What happens to a cell in a hypertonic extracellular solution?

Water moves out of the cell by osmosis, causing the cell to shrink.

What occurs to a cell in a hypotonic extracellular solution?

Water moves into the cell by osmosis, causing the cell to swell.

What is the condition of a cell in an isotonic extracellular solution?

There is no net water movement, and the cell size remains the same.

Define osmosis.

The diffusion of water through a membrane.

What is turgor pressure and why is it important for plants?

Turgor pressure is the fluid pressure that pushes the plasma membrane against the cell wall, essential for maintaining plant structure.

What is the role of phospholipids in cell membranes?

They provide the basic structure of the membrane.

What are the functions of proteins in cell membranes?

Proteins perform multiple functions, including transport and signaling.

What are integral (transmembrane) proteins?

Proteins that span the membrane and are involved in transporting selected ions and molecules.

What are the three broad classes of transport proteins?

Channels, carrier proteins (transporters), and pumps.

What is facilitated diffusion?

The process where molecules move through protein channels or carrier proteins down their concentration gradients.

What is an electrochemical gradient?

A gradient formed when ions build up on one side of a plasma membrane, allowing diffusion through ion channels.

What are gated channels and how do they function?

Gated channels open or close in response to signals such as ligand binding, voltage changes, or mechanical stimuli.

What is the glymphatic system?

A system that helps clean the brain and replenish cells, mostly occurring at night.

Differentiate between passive and active transport.

Passive transport requires no energy and moves substances from high to low concentration, while active transport requires energy to move substances from low to high concentration.

What is an example of active transport?

The sodium-potassium pump (Na+/K+ - ATPase) uses ATP to cotransport Na+ and K+.

What is a symporter?

A transport protein that moves two substances in the same direction across the membrane.

What is an antiporter?

A transport protein that moves one substance into the cell while moving another substance out.

What are the four macromolecules found in all cells?

Proteins, nucleic acids, carbohydrates, and lipids.

What distinguishes eukaryotic cells from prokaryotic cells?

Eukaryotic cells have a membrane-bound nucleus, while prokaryotic cells do not.

Name the three domains of life based on phylogeny.

Eubacteria, Archaea, and Eukarya.

What is the function of the nucleus in a cell?

It stores and processes genetic information and contains the cell's chromosomes.

What are euchromatin and heterochromatin?

Euchromatin is lightly stained and contains actively transcribed genes, while heterochromatin is darkly stained and contains inactive genes.

What is the role of ribosomes in cells?

Ribosomes are complex machines that manufacture proteins.

What is the function of the endoplasmic reticulum?

It is an organelle that extends from the nuclear envelope and is involved in the synthesis of proteins and lipids.

What distinguishes rough endoplasmic reticulum (RER) from smooth endoplasmic reticulum (SER)?

RER has ribosomes attached, while SER lacks ribosomes and has various functions including lipid synthesis.

What is the role of the Golgi apparatus?

It modifies proteins and lipids synthesized in the ER and prepares them for export or transport within the cell.

What are the two processes of transport involving the cell membrane?

Exocytosis (secretion out of the cell) and endocytosis (intake into the cell).

What is the function of lysosomes?

They act as recycling centers that hydrolyze macromolecules and export monomers to the cytosol.

What is the endomembrane system composed of?

It includes the lysosomes, Golgi apparatus, and endoplasmic reticulum.

What are the three types of endocytosis?

Phagocytosis (large materials), pinocytosis (liquids), and receptor-mediated endocytosis (specific proteins).

What is the primary function of vacuoles in plant cells?

They maintain turgor pressure to support the cell structure.

What is the role of peroxisomes?

They are involved in redox reactions and detoxification of harmful substances.

What is the primary function of mitochondria?

They produce ATP through cellular respiration and contain their own ribosomes and DNA.

What is the endosymbiosis theory?

It suggests that mitochondria and chloroplasts originated from engulfed bacteria that formed a mutually beneficial relationship.

What is metabolism?

The sum of all chemical reactions in the body, including anabolic and catabolic pathways.

What are anabolic pathways?

They synthesize larger molecules from smaller components and require energy.

What are catabolic pathways?

They involve the breakdown of molecules and release energy.

What are redox reactions?

Reactions that involve the transfer of electrons, including oxidation (loss of electrons) and reduction (gain of electrons).

What is glycolysis?

The first step in cellular respiration that breaks down glucose into pyruvate, producing ATP and NADH.

What is the net yield of ATP from glycolysis per glucose molecule?

Two ATP, two NADH, and two pyruvates.

What happens to pyruvate under anaerobic conditions?

It remains in the cytoplasm and is fermented into lactate or ethanol.

What is the purpose of lactate fermentation?

To convert NADH back to NAD+ without producing ATP.

What is the main product of pyruvate processing?

Acetyl CoA, along with CO2 and NADH.

What is the final electron acceptor in the electron transport chain?

Oxygen.

What is substrate-level phosphorylation?

The production of ATP by transferring a phosphate group from an intermediate substrate to ADP.

What regulates glycolysis?

Feedback inhibition, where high levels of ATP inhibit the enzyme phosphofructokinase-1 (PFK-1).

What is the role of common electron carriers like NAD+ and FAD?

They transport electrons during redox reactions in cellular respiration.

What is the significance of C-H bonds in reduced compounds?

They have high potential energy due to the similar electronegativity of carbon and hydrogen.