Biology Chapter 3: Cells Overview

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Questions and Answers

What are cells?

Structural units of all living things

Which of the following concepts are part of the Cell Theory? (Select all that apply)

The activity of an organism is independent of its cells.

A cell is the basic structural and functional unit of living organisms. (correct)

All cells arise from previously existing cells. (correct)

Cells are only found in multicellular organisms.

What are the three main parts of a cell?

Plasma membrane, cytoplasm, nucleous

What is the function of the plasma membrane?

Acts as a selectively permeable barrier Signup and view all the answers

What is cytoplasm?

Intracellular fluid packed with organelles Signup and view all the answers

What does the nucleous do?

Controls cellular activities Signup and view all the answers

What is extracellular material?

Substances contributing to body mass found outside the cells Signup and view all the answers

What is interstitial fluid?

Fluid in tissues that bathes all of our cells Signup and view all the answers

What is cell signaling?

Plasma membrane proteins interact with chemical messengers Signup and view all the answers

What does the Fluid Mosaic Model show?

The plasma membrane as a bilayer structure Signup and view all the answers

What are glycolipids?

Lipids with attached sugar groups Signup and view all the answers

What are integral proteins?

Proteins that span the entire membrane Signup and view all the answers

What is the difference between hydrophilic and hydrophobic?

Hydrophilic substances are water-loving, hydrophobic are water-avoiding Signup and view all the answers

What is osmosis?

Diffusion of solvent (usually water) through a selectively permeable membrane Signup and view all the answers

What is the primary function of the sodium-potassium pump?

Moves sodium out of the cell and potassium into the cell. Signup and view all the answers

Define tonicity.

The ability of a solution to change the shape of cells by altering their internal water volume. Signup and view all the answers

Which transport process includes the engulfing of large materials by the cell?

Phagocytosis Signup and view all the answers

What is the role of ribosomes?

Synthesize proteins Signup and view all the answers

What are mitochondria known for?

Power plants of the cell, providing ATP supply Signup and view all the answers

What does resting membrane potential refer to?

The inside of the cell is negative compared to the outside. Signup and view all the answers

Study Notes

Cells: Basic Units of Life

Cells are the structural units of all living organisms.
The Cell Theory includes:
- Cells are the basic unit of life.
- Organism activities depend on individual and combined cell functions.
- Complementary structure and function principle.
- Cells arise only from pre-existing cells.

Cell Structure Components

Main parts of a cell:
- Plasma membrane
- Cytoplasm
- Nucleus
Plasma membrane serves as a selectively permeable barrier for the cell.

Cytoplasm and Organelles

Cytoplasm is the fluid within the cell that contains organelles, which perform specific functions.
Nucleus controls cellular activities and is located at the cell's center.

Extracellular Environment

Extracellular materials contribute to body mass but lie outside cells.
Interstitial fluid surrounds cells, providing various nutrients.

Cell Signaling and Membrane Structure

Cell signaling involves interactions of membrane proteins with chemical messengers.
The Fluid Mosaic Model describes the plasma membrane as a bilayer with lipids and proteins.

Membrane Composition

Lipid bilayer includes phospholipids, glycolipids, and cholesterol.
Hydrophilic parts are water-attracting; hydrophobic parts repel water.
Glycocalyx is a carbohydrate-rich area on the membrane surface formed by glycoproteins and glycolipids.

Cell Junctions

Tight junctions create impermeable barriers between cells.
Desmosomes anchor adjacent cells, preventing separation.
Gap junctions allow communication between adjacent cells, facilitated by connexons.

Transport Mechanisms

Passive processes enable substances to cross membranes without energy input.
Active processes require cellular energy (ATP) to transport substances.
Key transport types:
- Diffusion moves substances from high to low concentration.
- Osmosis refers to water movement across membranes.

Solutions and Tonicity

Isotonic solutions have equal solute concentrations inside and outside cells.
Hypertonic solutions cause cells to lose water and shrink.
Hypotonic solutions lead to water gain and cell swelling.

Active Transport

Requires carrier proteins to move substances against concentration gradients.
The sodium-potassium pump is an example that maintains ion concentrations inside cells.

Vesicular Transport

Vesicular transport uses membrane-bound sacs (vesicles) to move large particles.
Phagocytosis engulfs large particles, while pinocytosis involves fluid intake.
Receptor-mediated endocytosis captures specific extracellular materials.

Cytoplasmic Organelles

Mitochondria are the powerhouses of cells, producing ATP.
Ribosomes synthesize proteins, forming either free or membrane-bound types on the rough endoplasmic reticulum (ER).
The Golgi apparatus modifies and packages proteins for secretion.

Structural Elements of the Cell

Cytoskeleton supports cellular structure and movement, composed of microfilaments, intermediate filaments, and microtubules.
Centrosomes organize microtubules and contain centrioles, which assist in cell division.

Cell Surface Structures

Cilia and flagella are projections that assist in movement.
Microvilli enhance surface area for absorption.

Nucleus and its Functions

The nucleus houses genes and regulates cellular activities, with multinucleate cells having multiple nuclei, while anucleate cells cannot reproduce.

Additional Notes

Membrane potential refers to voltage differences across membranes, crucial for cell signaling.
Ligands bind to membrane receptors to trigger cellular responses.

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