Ch. 2 - The Cell Flashcards
Functions of the plasma membrane
Separate the cell’s internal environment from its
external environment
Regulate what move in and out of the cell
Hold the cell in place
Communicate with neighboring cells and the rest of the body
Hold proteins in place
Water as a Solvent
Salt dissolves in it, oils and fats do not. Ions interact with its electrical charge. Oils and fats have an equal charge making them hydrophobic
Cholesterol
Important component in the cell membrane
Precursor for bile and steroid hormones
Fluid Membrane
Holds things in place, but like many boats on a lake
Membrane permeability
Molecules with no charge can pass through
Oxygen, carbon dioxide, steroids, fats
Charged molecules need channels or transport
Some very small molecules can pass through
Water, urea
Proteins in the cell membrane
Like the membrane, it has hydrophilic ends, and a hydrophobic middle
Transporter Proteins
The protein is involved in moving the molecule across
the membrane, usually the molecules are larger (glucose)
Receptor Proteins
A signal molecule (hormone) arrives at the cell and binds
with the receptor
This causes a change in the cell; the cell responds to the signal
Enzymes
Often bound in membranes
The cell regulates where chemical reactions take place
and assembly lines of enzymes can be formed to help reactions take place
Linker proteins
Proteins that pass through the cell membrane hold the cell in place
Identity marker proteins
Cell recognition proteins (egg and sperm)
Cell products are displayed (immune system)
Ion channels
A signal (ACh) causes channel to open When open, the channel allows Na+ ions to move in or out of the cell
Diffusion
The random movement of particles produces an equal
concentration in all areas of the solution
Osmosis
When particles are prevented from moving, water will move to equalize the concentration of dissolved particles
This will push water against gravity (energy)
Facilitated diffusion
The molecules are “helped” into the cell along the concentration gradient.
No energy is needed
Revolving door to the cell
Primary active transport
Energy is used to move particles against the concentration gradient
(i.e. the sodium / potassium pump)
Endocytosis
The cell extends itself around an object and brings it in inside the cell membrane in a vacuole
Exocytosis
A vacuole from the cell binds with the cell membrane
The content is dumped into the interstitial fluid or the blood
Cytoplasm
Contains cytosol and organelles
Cytosol
The fluid inside the cells and dissolved and suspended molecules
Organelles
Areas of the cell isolated from the rest of the cell by membranes; each with a specific function
Ribosomes
The assembly of proteins from amino acids (the primary structure of a protein)
Endoplasmic reticulum
Membrane folds outside the nucleus. Rough and smooth ER
RER
Holds ribosomes in place
Assembly of proteins
SER
Holds enzymes in place
Modification of proteins
Golgi complex
Modification of proteins
Transport from SER and transport to cell membrane through vesicles
Cell Assembly Line
From the nucleus, to the RER, to the SER, to the golgi complex, secreted into vesicles, and expelled through exocytosis
Lysosomes
Vesicles containing digestive enzymes
Fuse with vesicle that is around bacteria in endocytosis
Mitochondria
Power house of the cell, produces majority of the bodies ATP
Most of glucose catabolism takes place in the mitochondria
Has its own DNA and ribosomes
Structures: cristae (folds), inner and outer membrane, matrix
Actin and microfilaments
Part of the cytoskeleton
Provides mechanical support for cell shape
Growth of microfilaments generate a change in cell shape
Intermediate filaments
Part of the cytoskeleton made of up several proteins that stabilize position of organelles and attach cells to one another
Microtubule
Part of the cytoskeleton, made up of tubulin, Assembled in the centrosome, affects cell shape and the movement of organelles
Cilia
Short, hair-like projections
Move fluid along the surface of the cell
Flagella
In humans, only occurs in sperm, moves the cell
Nucleus
Consists of a nuclear envelope with pores, the nucleolus, and chromatin
DNA
Structure: double helix
Forms chromatin
The Cell Cycle
Interphase (G1, S, G2 phase)
M Phase (prophase, metaphase, anaphase, telophase)
Cytokinesis
Interphase
G1: Cell is growing, chromosomes have one chromatid
S: DNA synthesis
G2: More metabolism, Chromosomes have two chromatids
M Phase (Mitosis)
Prophase
Metaphase
Anaphase
Telophase (opposite of propose)
Prophase
Nuclear membrane disappears, Chromosomes condense, Nucleolus disappears, Spindle forms
Metaphase
Chromosomes line up in the equatorial plane
Anaphase
Chromatids separate, Daughter chromosomes move to the poles of the cell
Telophase
(opposite of propose) Nuclear membrane reforms, Nucleolus reappears, Chromosomes uncoil
Cytokinesis
The plasma membrane pinches off
We end up with two identical cells entering G1 phase
Telomeres and aging
Chromosomes have caps on their ends: Telomeres
Telomeres break in each cell division
Limited number of divisions = Aging
