Chapter 3 Flashcards
Name the 3 major parts of a cell
cell membrane, nucleus, cytoplasm
What is the function of the cell membrane?
encloses the cell
What is the function of the nucleus?
contains genetic material and controls activities
What is the function of the cytoplasm?
fills out the cells shape
Discuss cell membrane structure
- each cells membrane is extremely thin and delicate
- able to stretch to varying degrees
- usually tiny folds on the surface to help increase surface area
The cell membrane only allows certain substances to enter or leave each cell, what is this called?
selective permeability
Name the two types of cell membrane permeability
deferentially permeable or semipermeable
What does a semipermeable membrane do?
allows certain elements to pass through but not others
What is the cell membrane also known as?
plasma membrane
What are the functions of the cell membrane? (6 points)
- controls movement of substances into and out of the cell
- allows selective communication between intracellular and extracellular components whilst aiding cellular movement
- gives the cell form
- where most of the cells biological activities are conducted
- molecules in the cell membrane form pathways that allow the signals from outside the cell to be detected and transmitted inside
- when cells form tissues the cell membrane assists by adheering the cell to other cells
How does the cell membrance control which substances enter and leave?
active and passive mechanisms
Which mechanism does NOT require cellular energy?
Passive mechanisms
Which mechanisms DO require cellular energy?
Active mechanisms
Define diffusion
Diffusion is the process where substances spontaneously move from HIGH concentration to LOW concentration.
speed is influenced by kinetic energy, molecular size and temperature
What influences the speed of diffusion? (3)
kinetic energy
molecular size
temperature
Define active transport
Active transport is the movement of particles through membranes from LOW concentration to HIGH concentration
Define osmosis
Osmosis is a special type of diffusion that occurs when WATER molecules diffuse from HIGH WATER concentration to LOW WATER concentration
Define endocytosis
involves secretion from the cell membrane moving particles too LARGE to enter the cell by processes within a vesicle of the cell
Define filtration
forces molecules through membranes
Define Exocytosis
OPPOSITE of endocytosis, in which a substance is stored in a vesicle is secreted from the cell
Name the 3 passive mechanisms
Diffusion, osmosis, filtration
Name the 3 active mechanisms
Active transport, endocytosis, exocytosis
What is diffusion also known as?
simple diffusion
what is the process of moving from a high to low concentration called?
concentration gradient
In diffusion do particles move very quickly or very slowly?
very quickly + collide with other particles
Once particles have diffused, what have they achieved?
equilibrium
Why does o2 diffuse from blood to tissues/cells?
because its concentration is always higher in the blood
Why does CO2 diffuse into the blood?
because co2 is higher in the tissues/cells than the blood
What type of membrane does osmosis require?
semi - permeable
What is osmotic pressure?
the ability of osmosis to create enough pressure to raise a volume of water
Via osmosis, water equilibrates throughout the body so the concentration of intracelluar and extracellular fluids is….
nearly the same
Water is highly polar and passes via osmosis through what?
the lipid bilayer
Filtration is commonly used to….
separate solids from water
Which active mechanism requires carrier proteins which combine with transported substances both specifically and reversibly?
active transport
Name the two types of active transport
primary and secondary
What is the name of the energy that active transport requires?
ATP
Why does active transport require ATP?
Because it is moving against the concentration gradient
What does active transport move across cell membranes? (6)
sugar, amino acids, sodium, potassium, calcium, hydrogen particles
Despite being opposites, what doe endocytosis and exocytosis have in common?
They both use energy from the cell to move substances into or out of the cell without crossing the cell membrane
