CELL STRUCTURES AND THEIR FUNCTIONS Flashcards
Organelles and Their Locations and Functions
Contains genetic material of cell (DNA) and nucleoil; sit of RNA synthesis and ribosomalsubunit assembly
nucleus
Location of ribosomes:
cytoplasm
Site of protein synthesis
Ribosomes
Has many ribosomes attached; site of protein synthesis
Rough endoplasmic reticulum (rough ER)
site of lipid synthesis; participates in detoxification
smooth endoplasmic reticulum
modifies protein structyre and packages proteins in secretory vesicles
golgi apparatus
contains materials produced in the cell; formed by the Golgi apparatus; secreted by exocytosis
secretory vesicleg
contains enzymes that digest material taken into the cell;formed by the Golgi apparatus
lysosome
breaks down fatty acids, amino acids, and hydrogen peroxide
perixsome
site of aerobic respiration and the major site of ATP synthesis
mitochondrion
supports cytoplasm; assists in cell division and forms components of cillia and flagella
microtubule
facilitate the movement of chromosomes during cell division
centrioles
move substances over surfaces of certain
cillia
propel sperm cells
flagella
increase surface area of certain cells
microvilli
The chemical reactions that occur within cells are collectively called:
cell metabolism.
Energy released during metabolism is used for cell activities, such as the:
synthesis of new molecules, muscle contraction, and heat production, which helps maintain body temperature.
Simplest
organisms consist of a single cell.
Single-Celled Organisms:
Humans and other complex organisms are
composed of multiple cells.
Multicellular Organisms:
Specialized structures within cells that
perform specific functions
Organelles:
Contains the cell’s
genetic material.
Nucleus
The living
material surrounding the nucleus, containing many
types of organelles.
Cytoplasm
Contain well-developed organelles specialized for
synthesizing and secreting proteins.
Protein-Secreting Cells
The outermost component of a cell.
Cell Membrane or Plasma Membrane
Contain proteins and
organelles that enable them to contract.
Muscle Cells
Encloses the cytoplasm and forms the boundary between material inside the cell and
material outside it.
Cell Membrane or Plasma Membrane
Substances outside the cell
Extracellular substances
Substances inside the cell
Cytoplasmic or Intracellular substances
The cell membrane is primarily made up of two major types of molecules:
(1) phospholipids and (2) proteins.
This model arises from studies on the arrangement of molecules within the cell membrane.
FLUID MOSAID MODEL
The polar, phosphate-containing ends face the extracellular fluid and cytoplasm.
Hydrophilic (Water-Loving) Ends:
The nonpolar, fatty acid ends face away from the fluid on either side of the membrane, toward the center of the double layer of phospholipids.
Hydrophobic (Water-Fearing) Ends:
Adds strength and stability to the membrane by limiting phospholipid movement.
Cholesterol
“float” within the phospholipid membrane, with some spanning from the inner to the outer surface.
Proteins
Can bind to proteins, modifying their functions.
Membrane Protein
Facilitate the movement of
substances
membrane.
through the cell
Membrane Channels and Carrier Molecules:
Play a key role in intercellular
communication.
Receptor Molecules:
Enable cell recognition and
coordination of cellular activities.
Receptor Molecules:
Higher concentrations of enzymes, glycogen, and
potassium ions (K+).
Cytoplasmic (inside the cell):
Higher
concentrations of sodium (Na+), calcium (Ca2+), and chloride (Cl−) ions.
Extracellular (outside the cell):
Does not require energy expenditure by the cell.
Passive Transport
Substances dissolved in a solvent.
SOLUTES
Requires energy expenditure by the cell, typically in the form of
ATP.
Active Transport
The predominant liquid or gas in
which solutes are dissolved.
Achieved when net movement of
solutes stops, but random motion
continues.
Equilibrium
larger concentration difference and/or shorter distance
steeper gradient
Solute
moves from higher to lower
concentration (diffusion).
Down (With) the Gradient:
Solute moves from lower to higher concentration (requires energy, not diffusion).
Up (Against) the Gradient
The force needed to prevent water from diffusing through a selectively permeable membrane.
Osmotic Pressure
It reflects the tendency of water to move toward areas of higher solute concentration.
Osmotic Pressure
It can be measured by placing a solution in a tube closed at one end by a selectively permeable membrane and immersing the tube in distilled water.
Osmotic Pressure
lower concentration of solutes compared to the cytoplasm of the cell.
Hypotonic
same concentration of solutes as the cytoplasm of the cell.
Isotonic
higher concentration of solutes compared to the cytoplasm of the cell.
Hypertonic
The cell swells and may burst (lysis) if too much water enters.
Hypotonic
The cell remains unchanged in size.
Isotonic
The cell shrinks and may undergo crenation (the process of shrinking and becoming crenated).
Hypertonic
Can diffuse between phospholipid molecules in cell membranes.
Small Water-Soluble Substances:
Require specific mechanisms to cross the membrane.
Ions and Larger Water-Soluble Substances:
A mediated transport process involving membrane proteins (channels or carrier proteins).
Facilitated Diffusion
Membrane proteins that form passages for ions and some water-soluble substances.
Channels
Proteins that bind and transport substances across the membrane.
Carrier Molecules
A process that uses membrane proteins to move substances from regions of lower concentration to regions of higher concentration, against a concentration gradient.
Active trasnport
A process where the active transport of one substance (e.g., Na+) creates a concentration gradient.
SECONDARY ACTIVE TRANSPORT
The process where the diffusing substance and the transported substance move in the same direction across the cell membrane.
Cotransport:
The process where the diffusing substance and the transported substance move in opposite directions across the cell membrane.
Countertransport:
Large water-soluble molecules, small particles, and whole cells are transported across cell membranes in membrane-bound sacs called vesicles.
Vesicle Transport
The process of taking material into the cell through vesicle formation.
Endocytosis
It is crucial for white blood cells to destroy harmful substances in the body.
Phagocytosis
The release of substances from the cell through the fusion of a vesicle with the cell membrane
EXOCYTOSIS
A form of endocytosis where solid particles are ingested by the cell.
PHAGOCYTOSIS (CELL-EATING)
It is a large organelle within the cell, resembling a little nut or the stone of a fruit.
nucleus
The nuclear envelope consists of two membranes:
an outer membrane and an inner membrane, with a narrow space between them.
Serve as passageways for
materials to move into or out of the nucleus.
Nuclear Pores
The nucleus contains most of the cell’s genetic material.
● This genetic material is organized into:
23 pairs of chromosomes
During most of a cell’s life, chromosomes are _____ and collectively referred to as _____.
loosely coiled, chromatin.
Genes are portions of ____ _____ within the chromosomes.
DNA molecules
Are diffuse bodies with no surrounding membrane that are found within the nucleus.
NUCLEOLI
Also called the Golgi complex, consists of closely packed stacks of curved, membrane-bound sacs .
GOLGI APPARATUS
It collects, modifies, packages, and distributes proteins and lipids manufactured by the ER.
GOLGI APPARATUS
Organelles where proteins are produced
RIBOSOMES
Ribosomes that are not attached to any other
organelle are called:
free ribosomes.
It is a series of membranes forming sacs and tubules that extends from the outer nuclear membrane into the cytoplasm.
endoplasmic reticulum (ER)
●ER with attached ribosomes.
● A large amount of rough ER in a cell indicates that it is synthesizing large amounts of
Rough Endoplasmic Reticulum
● ER without attached ribosomes
● Smooth ER is a site for lipid synthesis and participates in detoxification of
chemicals within cells.
● In skeletal muscle cells, the smooth ER
stores calcium ions (Ca2+).
Smooth Endoplas mic Reticulum
pinches off from the Golgi apparatus and move to the cell membrane.
SECRETORY VESICLES
Membrane-bound vesicles formed from the Golgi apparatus.
LYSOSOMES
They contain a variety of enzymes that function as intracellular digestive systems.
LYSOSOMES
It is caused by the inability of lysosomal enzymes to break down the carbohydrate glycogen produced in certain cells.
Pompe disease
Small, membrane-bound vesicles containing enzymes that break down fatty acids, amino acids, and hydrogen peroxide (H2O2).
PEROXISOMES
It is a byproduct of fatty acid and amino acid breakdown and can be toxic to a cell.
Hydrogen peroxide
Small organelles with inner and outer membranes separated by a space
MITOCHONDRIA
The internal framework of the cell.
CYTOSKELETON
It consists of protein structures that support the cell, hold organelles in place, and enable
the cell to change shape.
CYTOSKELETON
CYTOSKELETON
These protein structures are:
(1) microtubules,
(2) microfilaments, and (3) intermediate filaments.
Hollow structures formed from protein subunits.
MICROTUBULES
Perform a variety of roles, including helping to support the cytoplasm of cells, assisting in cell division, and forming essential components of certain organelles, such as cilia and flagella.
MICROTUBULES
Small fibrils formed from protein subunits that structurally support the cytoplasm, determining cell shape.
MICROFILAMENTS
Fibrils formed from protein subunits that are smaller in diameter than microtubules but larger in diameter than microfilaments.
INTERMEDIATE FILAMENTS
A specific type of intermediate filament is
keratin, a protein associated with skin cells
INTERMEDIATE FILAMENTS
Hair-like projections from the surface of cells.
Cilia
Have a structure similar to that of cilia but are much longer, and they usually occur only one per cell.
Flagella
Specialized extensions of the cell membrane that are supported by microfilaments, but they do not actively move as cilia and flagella do.
Microvilli
is the process by which information stored in DNA directs the production of proteins in cells.
Gene expression
