Ch 4: Cell Structure Flashcards
What is the cell wall/ cell membrane?
The outer layer of a cell
What is the cytoplasm or cytosol?
Contains the organelles
What is the nucleus?
Bounded by a nuclear membrane, contains chromosomes
What organisms has only a cell membrane and not also a cell wall?
Animals
What are plant cell walls made up of?
Cellulose (a polysaccharide)
What are bacteria cell walls made up of?
Peptidoglycan (protein and sugar)
What are fungi cell walls made up of?
Chitin- a polysaccharide similar to cellulose
What is the cell membrane made up of?
Lipids and proteins
What are the primary lipids found in cell membranes?
Phospholipids (polar and nonpolar regions, form lipid bilayers)
Why do cell membranes (made of lipid bilayers) make good barriers?
The inside of the cell is aqueous (water based), as well as the external environment. The lipid bilayer cell membrane forms a fatty layer between them.
The cell membrane is _____ permeable.
selectively
What is simple diffusion?
Movement of a substance from an area of high concentration to lower concentration until a dynamic equilibrium is reached
What is facilitated diffusion?
The molecules that try to cross are hydrophilic, so can’t interact with the oily barrier. So they need help from proteins.
What is active transport?
The cell must expend energy to move something across the membrane, can move it from an area of low concentration to one of higher concentration.
What is bulk transport?
The movement of large items across the cell membrane, either endocytosis (into the cell) or exocytosis (out of the cell)
How does endocytosis work?
The cell takes in a particle by surrounding it within a vesicle.
What is osmosis?
The movement of water across a cell membrane (through facilitated diffusion)
What is a vacuole?
An organelle that stores waste and other material
What are ribosomes?
Sites of protein synthesis; not bound by the membrane
What is the smooth endoplasmic reticulum?
System of membrane and tubes that transports substances around the cell
What is the rough endoplasmic reticulum?
Endoplasmic reticulum with ribosomes bound to it; ribosomes on the rough ER specifically synthesize membrane proteins or secreted proteins
What is the golgi apparatus?
Sorts and packages proteins made by ribosomes on rough ER
What is the mitochondria?
Produces ATP for the cell
What are lysosomes?
Digest foreign substances and worn-out organelles
What are centrioles?
Help to form the spindle during mitosis
What is the nucleus?
Control center of the cell; contains DNA
What is the nucleolus?
Structure in nucleus, site of ribosome synthesis
What is the cell membrane?
Outer membrane that regulates what goes in and out of cell
Do animal cells have cell walls?
No
What are bacteria cell walls made of?
Peptidoglycan
Engulfing large particles in a vesicle is know as:
Endocytosis
Facilitated diffusion is a way for _______ substances to cross the cell membrane
Hydrophilic
Fungi have cell walls made of ______ and plants have cell walls made of ______.
Chitin, cellulose
Does simple diffusion require energy?
No
Hydrophobic substances cross the membrane by ________.
Simple diffusion
A type of movement that requires energy and moves substances against their concentration gradients is called ______.
Active transport
What happens when a cell is placed in a hypertonic (more concentrated) solution?
There are more particles outside, so there is less water outside. Water will move to outside the cell, so it will shrivel up.
What happens when a cell is placed in a hypotonic (more dilute) solution?
There are less particles outside, so there is more water inside. Water will move from outside the cell to inside, so the cell will swell up.
What happens if a cell is placed in an isotonic (same concentration) solution?
It will neither shrivel nor swell
What is a prokaryotic cell?
No organelles
The fact that enzymes interact with substrate by physically fitting together has given rise to the phrase “________ and _______”
Lock and key
Enzymes are known as organic _______
Catalysts
When an enzyme has catalyzed a chemical reaction and the products are formed, is the enzyme itself consumed?
No, it is available to catalyze additional reactions.
The location on an enzyme where substrate binds is called the ______.
Active site
When an enzyme catalyzes a reaction, is it used up?
No. It is reusable.
What are reactants in an enzyme-catalyzed reaction called?
Substrates
What type of molecules are enzymes?
Organic (proteins)
If enzymes lose their shapes (become denatured) what happens?
They can’t run reactions.
What can denature enzymes?
Heat, acids, and bases
What are molecules that help enzymes catalyze reactions called?
Coenzymes
What act as coenzymes in the body?
Vitamins
