Chapter 3 Pt. 2 Flashcards
How are cells measured?
usually measured in micrometers
The small size of a cell is dictated by a physical relationship known as the ________-__-_______ _____
surface-to-volume ratio
What happens as a cell gets larger?
its surface area increases much more slowly than its volume
Why should cells remain small?
the ratio of surface area to volume decreases rapidly as cell size increases
Cells can only be seen though ___________
microscopes
What are the two types of microscopes used on cells?
(1) light microscopes
(2) electron microscopes
The structure of a cell exquisitely reflects its _________
functions
The structure of a cell exquisitely reflects its functions.
What are some examples of this?
- a sperm is specialized to be highly mobile
- an egg (human reproduction) is specialized to be large, immobile, and to be fertilized
What is the outer most surface of the cell called?
Plasma Membrane
The plasma membrane is remarkably _____
thin
Which type of cells have plasma membranes?
prokaryotic and eukaryotic, but only eukaryotic cells also contain internal membranes
The structure of the plasma membrane is composed of ______, _______, and ____________
lipids
proteins
carbohydrates
What are the main structures within the plasma membrane structure?
phospho-lipid bilayer
extracellular fluid
cytoplasm
fluid mosaic
Which main structures within the plasma membrane structure, is this:
a double layer created as a result of molecules with hydrophilic heads and hydrophobic tails
phospho-lipid bilayer
Which main structures within the plasma membrane structure, is this:
the watery solution outside the cell
extracellular fluid
Which main structures within the plasma membrane structure, is this:
the jellylike solution inside the cell
cytoplasm
Which main structures within the plasma membrane structure, is this:
the structure of the plasma membrane
fluid mosaic
__________ _____ interacts with the hydrophilic heads facing outside the cell
extracellular fluid
extracellular fluid interacts with the hydrophilic heads facing ________ the cell
outside
extracellular fluid is also known as ________ _____
interstitial fluid
The _________ interacts with the hydrophilic heads facing inside the cell
cytoplasm
The cytoplasm interacts with the hydrophilic heads facing ______ the cell
inside
What are the functions of the plasma membrane?
- maintain structural integrity of the cell
- regulate movement of substances into and out of the cell
- provide recognition & communication between cells
- stick cells together to form tissues and organs
- selectively permeable
How does the plasma membrane provide recognition & communication between cells?
via receptors
What are receptors?
specialized proteins in the plasma membrane (or inside the cell) that bind particular substances that affect cell activities
How does the plasma membrane stick cells together?
Cell Adhesion Molecules (CAMs)
What are Cell Adhesion Molecules (CAMs)?
extend from the plasma membranes of most cells and help attach the cells to one another, especially during the formation of tissues and organs in an embryo
diffusion tends to eliminate the ___________ _________
concentration gradient
What are the different types of movement methods across the plasma?
Simple Diffusion Facilitated Diffusion Osmosis Active transport Endocytosis Exocytosis
What is the difference between simple and facilitated diffusion?
Simple Diffusion- the random movement of a substance from a region of higher concentration to a region of lower concentration
Facilitated Diffusion- the movement of a substance from a region of higher concentration to a region of lower concentration with the aid of a membrane protein
What is concentration?
the number of molecules of a substance in a particular volume
What is concentration gradient?
a difference in the relative number of molecules or ions of a given substance in two adjacent areas
_________ ________ and ________ do not require energy and is thus a form of passive transport
Facilitated Diffusion
Osmosis
Facilitated Diffusion and Osmosis do not require energy and is thus a form of _______ ________
passive transport
What is osmosis?
a type of diffusion in which water moves across a plasma membrane or any other selectively permeable membrane from a region of higher water concentration to a region of lower water concentration
What are the different types of osmosis solutions?
hypertonic solution
isotonic solution
hypotonic solution
Which type of osmosis solution is this:
a solution whose solute concentration is higher than that inside the bag
hypertonic solution
Which type of osmosis solution is this:
one with the same solute (sugar) concentration as inside the bag, there is no net movement of water in either direction, and the bag maintains its original shape
isotonic solution
Which type of osmosis solution is this:
the concentration of solute is lower than that inside the bag, more water moves into the bag than out, causing the bag to swell and possibly burst
hypotonic solution
What is active transport?
a mechanism that moves substances across plasma membranes with the aid of a carrier protein and energy supplied by the cell
_______ ________ occurs when cells need to concentrate certain substances
Active transport
During Active transport, in most cases, substances are moved from regions of ______ concentration to ______ concentration
lower
higher
Active transport is going “against the ___________ ________”
concentration gradient
What is the difference between endocytosis and exocytosis?
Endocytosis- a region of the plasma membrane engulfs the substance to be digested and then pinches off from the rest of membrane
Exocytosis- the process by which large molecules leave cells
What are the two types of endocytosis?
Phagocytosis
Pinocytosis
Which type of endocytosis is this:
cells engulf large particles or bacteria
Phagocytosis
Which type of endocytosis is this:
“cell eating”
Phagocytosis
Which type of endocytosis is this:
engulf droplets of fluid, thus brining all of the substances dissolved in the droplet into the cell
Pinocytosis
Which type of endocytosis is this:
“cell drinking”
Pinocytosis
Endocytosis encloses the substance in a saclike structure called a _______
vesicle
What is the process of exocytosis?
(1) when the vesicle reaches the plasma membrane, the vesicle membrane fuses with the plasma membrane
(2) then the vesicle opens up to release the hormone outside the cell
(3) nerve cells also release chemicals by exocytosis
