What is the difference in the functions of the proteins & the carbohydrates attached to a cell membrane?
Some of the proteins form channels & pumps that help to move material across the cell membrane. Many of the carbohydrates act like chemical identification cards, allowing cells to identify one another.
In what organisms are cell walls found?
Cell walls are found in many organisms, including plants, algae, fungi, and nearly all prokaryotes.
True or False: The cell wall lies inside the cell membrane.
FALSE! It lies outside of the cell membrane.
What is the main function of the cell wall?
Provide support & protection for the cell
What are plant cells mostly made of?
fibers of carbohydrates & protein
What is the concentration of a solution?
The mass of a solute in a given volume of solution (mass/volume)
What is diffusion?
The process by which molecules tend to move from an area where they are more concentrated to an area where they are less concentrated
Examples: drops of food coloring in water, open perfume bottle in room, etc.
What it meant when a system has reached equilibrium?
The concentration of the substance on both sides of the membrane will be the same.
What does it mean that biological membranes are selectively permeable?
It means that some substances can pass across them, while others cannot.
What is osmosis?
The diffusion of water through a selectively permeable membrane
True or False: Water tends to diffuse from a region where it is less concentrated to a region where it is highly concentrated.
FALSE! Water tens to diffuse from a region where it is highly concentrated to a region where it is less concentrated.
When will water stop moving across a membrane?
When equilibrium is reached
What is an isotonic solution?
Concentration of solute outside the cell is equal to the concentration inside the cell
Water diffuses in & out of the cell at an equal rate
Two solutions are isotonic if the solutions are the same strength
What is a hypertonic solution?
Concentration of solute outside the cell is greater than inside the cell
Water diffuses out of the cell
A solution is hypertonic if the solution is above strength in solute
What is a hypotonic solution?
Concentration of solute inside the cell is greater than outside the cell
Water diffuses out of the cell
A solution is hypotonic if the solution is below strength in solute
On which side of a selectively permeable membrane does osmosis exert a pressure?
Exerts a pressure known as osmotic pressure on the hypertonic side
What happens during the process of facilitated diffusion?
Molecules tend to move from an area where they are more concentrated to an area where they are less concentrated
What is the role of protein channels in the cell membrane?
Allow particular substances to cross different membranes
True or False: Facilitated diffusion does not require the cell to use energy.
What is active transport?
The energy-requiring process that moves material across a cell membrane against a concentration difference
True or False: Active transport always requires transport proteins during the process.
FALSE! It requires energy.
What are the 3 types of active transport?
What is endocytosis?
Process by which a cell takes materials into the cell by infolding of the cell membrane
What is phagocytosis?
Process by which extensions of cytoplasm surround & engulf large particles & take them into the cell
What is exocytosis?
Process by which a cell releases large amounts of materials
During endocytosis, what happens to the pocket in the cell membrane when it breaks loose from the membrane?
It forms a vacuole within the cytoplasm.
What is a unicellular organism?
A single-celled organism
What is cell specialization in a multicellular organism?
The process by which cells develop in different ways to perform different tasks
What are 4 levels of organization in a multicellular organism?
What is a tissue?
A group of similar cells that perform a particular function
What are the 4 main types of tissue in most animals?
What is an organ?
A group of tissues that work together to perform a specific function
What kinds of tissues can be found within a muscle in your body?
There is much more than muscle tissue. There are nervous tissues & connective tissues (each type of tissue performs an essential task to help the organ function).
What is an organ system?
A group of organs that work together to perform a specific function
What is a cell?
The structure that makes up every living thing
What was Anton van Leeuwenhoek one of the first to see in the 1600s?
Tiny living organisms (cells) through the microscope
What did a thin slice of cork seem like to Robert Hooke when he observed it through a microscope?
It seemed to be made up of thousands of tiny, empty chambers he called "cells"
What did the German botanist Matthias Schleiden conclude?
All plants were made of cells
What did the German biologist Theodor Schwann conclude?
All animals were made of cells
How did Rudolph Virchow summarize his years of work?
Concluded that new cells could be produced only from the division of existing cells
Summarized his years of work in the cell theory
What are the 3 concepts that make up the cell theory?
1) All living things are composed of cells
2) Cells are the basic unit of structure & function in living things
3) New cells are produced from existing cells
Why are electron microscopes capable of revealing details much smaller than those seen through light microscopes?
Because the wavelengths of electrons are much smaller than those of light
What are prokaryotes?
Organisms whose cells lack nuclei
They grow & reproduce
They have cell membranes & cytoplasm
What are eukaryotes?
Organisms whose cells contain nuclei
Generally larger & more complex than prokaryotic cells
Have defined chromosomes & nucleus
Contain membrane bound organelles
Have a definite nucleus & nuclear membrane
What is an organelle?
A specialized structure that performs important cellular functions within a eukaryotic cell ("little organs")
What do animal cells contain?
What do plant cells contain?
What is the function of the nucleus?
The control center of the cell
Controls most cell processes
Contains the hereditary information of DNA
Contains nearly all the cell's DNA & with it the coded instructions for making proteins and other important molecules
What important molecules does the nucleus contain?