Lesson 1 - chapter 2 - cell Flashcards
2 major parts of cell
nucleus
cytoplasm
nucleus is separated from the cytoplasm
by a
nuclear membrane
cytoplasm is separated
from the surrounding fluids by a
cell membrane, also
called the plasma membrane.
different substances that make up the cell
protoplasm
Protoplasm is composed
mainly of five basic substances
water 70-85%
electrolytes,
proteins 10-20%
lipids, and
carbohydrates.
principal fluid medium of the cell
present in most cells, except for fat cells,
70-85%
Many cellular chemicals are dissolved
water
ions/electrolytes:
K+ potassium,
MG+2 magnesium,
PO4 -3 phosphate,
SO4 -2 sulfate,
CHO3- bicarbonate
smaller quantities of sodium, chloride, and calcium
provide inorganic chemicals for cellular reactions and also are necessary for operation of some of the
cellular control mechanisms
IONS
2nd most abundant substances
in most cells are
proteins
present in the cell mainly in
the form of long filaments that are polymers of many
individual protein molecules.
A prominent use of such intracellular filaments is to form microtubules that provide
the “cytoskeletons” of such cellular organelles as cilia,
nerve axons, the mitotic spindles of cells undergoing
mitosis, and a tangled mass of thin filamentous tubules that hold the parts of the cytoplasm and nucleoplasm together in their respective compartments.
structural proteins
mainly the enzymes of the cell and, in contrast to the
fibrillar proteins, are often mobile in the cell fluid.
functional proteins
are found outside the cell, especially in the collagen and elastin fibers of connective tissue and in blood vessel walls, tendons, ligaments, and so forth.
Fibrillar proteins
soluble in fat solvents
lipids
Especially important lipids which together constitute only about 2% of the total cell mass
phospholipids and cholesterol
triglycerides, also called neutral fat
fat cells, triglycerides often account for
as much as ________ of the cell mass
95%
The fat stored in
these cells represents the body’s main storehouse of
energy-giving nutrients that can later be used to provide
energy wherever in the body it is needed
lipids
1% of total cell mass,
3% in muscles,
6% in liver): glycogen
carbohydrates
which is an insoluble polymer of glucose that can
be depolymerized and used rapidly to supply the cells’ energy needs.
glycogen
MEMBRANOUS STRUCTURES
OF THE CELL:
cell membrane,
nuclear membrane,
membrane of the endoplasmic reticulum,
membranes of the mitochondria, lysosomes, and Golgi apparatus
_________ in the membranes provide a barrier that
impedes movement of water and water-soluble substances from one cell compartment to another because water is not soluble in lipids
lipids
molecules providing specialized pathways, often organized into actual pores, for passage of specific substances through the membrane
protein
proteins that catalyze a multitude of
different chemical reactions, discussed here and in subsequent chapters
enzymes
cell membrane (also called the plasma membrane)
envelops the cell and is a thin, pliable, elastic structure
only 7.5 to 10 nanometers thick.
cell membrane (also called the plasma membrane)
approximate composition or cell membrane:
proteins, 55%
phospholipids, 25%
cholesterol, 13%
other lipids, 4% and
carbohydrates, 3%
basic lipid bilayer is composed of three main types
of lipids:
phospholipids,
sphingolipids, and
cholesterol
most abundant, has 2 sides
Phospholipids
(fatty acid portion) hydrophobic and
soluble only in fats (e.g. O2, CO2, alcohol);
faces each other
Outer side of phospholipid
(phosphate end) hydrophilic and
soluble in water (e.g. ions, glucose, urea);
faces interstitial fluid & cell cytoplasm
inner side of phospholipid
derived from the amino alcohol
sphingosine, functions to protect from harmful
factors, signal transmission, and adhesion sites for
extracellular proteins
Sphingolipids
Cholesterol - help determine the degree of
permeability of the bilayer to water- soluble
constituents of body fluids. Also controls much of the
fluidity of the membrane as well.
Cholesterol
2 Membrane proteins “glycoproteins”:
○ Integral proteins
○ Peripheral proteins
protrude all the way through the
membrane.
Provide structural channels “pores” that
allow preferential diffusion of some
substances over others
Carrier proteins for transporting substances
that otherwise could not penetrate the lipid
bilayer (e.g. through active transport
Receptors/ second messengers relaying the
signal from the extracellular part of the
receptor to the interior of the cell.
Integral proteins
attached only to one surface and
do not penetrate all the way through; function almost
entirely as enzymes or as controllers of transport of
substances through cell membrane pores
Peripheral proteins
loose carbohydrate (proteoglycans) coat on the outside of the entire surface of the cell
Membrane carbohydrates “glycocalyx”
○ overall negative surface charge that repels other
negatively charged objects
○ attaching cells to one another through glycocalyx
○ act as receptors for binding hormones
○ Some moieties enter into immune reactions
Membrane carbohydrates “glycocalyx”
Cytosol - jelly like fluid portion of the cytoplasm and contains mainly dissolved proteins, electrolytes, and glucose
Cytosol
Dispersed in the cytoplasm are neutral fat globules, glycogen granules, ribosomes, secretory vesicles, and five especially important organelles:
○ Endoplasmic reticulum (ER)
○ Golgi apparatus
○ Mitochondria
○ Lysosomes
○ Peroxisomes
○ a network of tubular structures (cisternae) and flat
vesicular structures in the cytoplasm
○ Manufacture: proteins, carbohydrates, lipids
○ helps process molecules made by the cell and
transports them to their specific destinations
Endoplasmic Reticulum
Attached with minute granular particles
“ribosomes — composed of a mixture of
RNA and proteins; they function to
synthesize new protein molecules in the cell
Rough (Granular) ER + Ribosomes
functions for the synthesis of lipid
substances and for other processes of the
cells promoted by intrareticular enzymes
Smooth (Agranular) ER
○ composed of four or more stacked layers of thin, flat, enclosed vesicles lying near one side of the nucleus
Golgi Apparatus
Function in association with ER — small transport
vesicles/ ER vesicles continually pinch off from the ER
and shortly thereafter fuse with the Golgi apparatus
—> transported substances from ER are processed in
the here to form lysosomes, secretory
vesicles, and other cytoplasmic components
Golgi apparatus
vesicular organelles that form by breaking off from the
Golgi apparatus that provide an intracellular digestive
system to digest the following:
■ damaged celllar structures;
■ food particles ingested by the cell;
■ unwanted matter such (e.g. bacteria)
Lysosomes
lysosomes Uses _________ to splits organic compounds into two or more parts by combining hydrogen from a water molecule with one part of the compound and combining the hydroxyl portion of the water molecule with the other part of the compound — to become highly diffusible (e.g. protein hydrolyzed to form
amino acids)
hydrolytic enzymes