the cellular level of organization Flashcards
what are the 3 subdivision in the cell
- plasma (cell) membrane
- cytoplasm \ cytosol and organelles
- nucleus \ chromosomes and genes
what is the plasma membrane
a flexible yet sturdy barrier that surrounds and contains the cytoplasm of the cell
what are the two type of membrane proteins
- integral protein \ transmembrane
- peripheral protein
what are the functions of membrane proteins
help determine many of the functions of the cell membrane
what is membranes fluidity
membranes are fluid structures because most of the membrane lipids and many of the membrane proteins move easily in the bilayer
membrane lipid and protein are mobile in their own half of the bilayer
what does the cholesterol serve in the membrane
serve to stabilize the membrane and reduce membrane fluidity
what is membrane permeability
plasma membranes are selectively permeable
the lipid bilayer is always permeable to small, nonpolar, uncharged molecules
transmembrane proteins that act as channels or transporters increase the permeability of the membrane
macromolecules are only able to pass through the plasma membrane by vesicular transport
what is a concentration gradient
is the difference in the concentration of a chemical between one side of the plasma membrane and the other
what is an electrical gradient
the difference in concentration of ions between one side of the plasma membrane and the other
electrical and concentration gradient what does it make
these gradient make up an electrochemical gradient
what is a passive processes
simple diffusion
facilitated diffusion
osmosis
what is an active processes
primary and secondary transport
vesicular transport
what is a simple diffusion
the diffusion is influenced by
the steepness of the concentration gradient
temperature
mass of diffusion substance
surface area
diffusion distance
what is a facilitated diffusion
transmembrane protein help solutes that are too polar or too highly charged move through the lipid bilayer
the processes involved are
channel-mediated facilitated diffusion
carrier mediated facilitated
what is osmosis
the net movement of a solvent through a selectively permeable membrane from an area of high concentration to an area of low concentration
what is tonicity
tonicity of a solution relates to how the solution influences the shape of body cells
active transport : primary
energy derived from ATP changes the shape of a transporter protein which pumps a substance across a plasma membrane against it concentration gradient
what is a secondary
energy stored(in a hydrogen or sodium concentration gradient) is used to drive other substances against their own concentration gradient
what is exocytosis
membrane-enclosed secretory vesicles fuse with the plasma membrane and release their contents into the extracellular fluid
what is transcytosis
a combination of endocytosis and exocytosis used to move substances from one side of a cell, across it, and out the other side
cytoplasm has 2 components what are they
- cytosol - also known as the intracellular fluid portion of the cytoplasm
- organelles - they specialized structures that have specific shapes and perform specific functions
what is a plasma membrane
fluid mosaic bilayer studded with proteins; surrounds cytoplasm
what does the plasma membrane do
protects cellular contents; makes contact with other cells; contains channels, transporters, receptors, enzymes, cell-identify markers, and linker proteins; mediates entry and exit of substance
what is cytoplasm
cellular contents between plasma membranes and nucleus; cytosol and organelles
what does cytoplasm do
site of all intracellular activities except those occurring in the nucleus
what is cytosol
composed of water, solutes, suspended particles, lipid droplets, and glycogen granules
what does cytosol do
fluid in which many of the cell’s metabolic reactions occur
what is a cytoskeleton
a network in the cytoplasm composed of three protein filaments; microfilament, intermediate filaments, and microtubules
what does the cytoskeleton do
maintains shape and general organization of cellular contents; responsible for cell movement
what is an organelles
specialized structures with characteristic shapes
what is a centrosome
pair of centrioles plus pericentriolar matrix
what does a centrosome
the pericentriolar matrix contains tubulins, which are used for the growth of the mitotic spindle and microtubule formation
what is a cilia and flagella
motile cell surface projections that contain 20 microtubules and basal body
what cell moves fluids over cell’s surface
cilia
what cell move entire cell
flagella
what is a ribosome
composed of two subunits containing ribosomal RNA and protein; may be free in cytosol of attached to rough ER
endoplasmic reticulum (ER)
membranous network of flattened sacs of tubules, rough ER is covered by ribosomes is attached to the nuclear envelope; smooth ER lacks ribosomes
golgi complex
consists of 3-20 flattened membranous sacs called cisternae; structurally and functionally divided into entry face, medial cisternae, and exit
lysosome
vesicle formed from golgi complex; contains digestive enzymes
peroxisome
a structure that is similar in shape to lysosomes, but is smaller and contain enzymes that use oxygen to oxidize organic substance
proteasome
tiny barrel-shaped structure that destroy unneeded, damaged, or faulty proteins by cutting long proteins into smaller peptides
mitochondrion
consist of an external and an internal mitochondrial membrane, cristae, and matrix; new mitochondria form from preexisting ones
nucleus
consist of a nuclear envelope with pores, nucleoli, and chromosomes, which exist as a tangled mass of chromatin in interphase cell
occurs in the nucleus and is the process by which genetic information encoded in DNA is copied onto a strand of RNA to direct protein systhesis
transcription
occurs outside the nucleus and is the process of reading the mRNA nucleotide sequence to determine the amino acid sequence of the newly formed protein
translation
occur when the nucleus of a cell divides
mitosis
results in the distribution of 2 sets of chromosomes into 2 separate nuclei
mitosis
mitosis is divided into 4 steps what are they
- prophase
- metaphase
- anaphase
- telophase
chromatin condenses into chromosomes and the nuclear membrane disappears and centrosomes move to opposite poles
prophase
centromeres of chromosomes line up at the plate
metaphase
centromeres if chromosomes split and sister chromatids move toward opposite poles of the cell
anaphase
the mitotic spindle dissolves chromosomes regain their chromatin appearance, and a new nuclear membrane forms
telophase
a cleavage furrow forms and eventually the cytoplasm of the parent cell fully splits
cytokinesis
period between cell divisions; chromosomes not visible unde3r light microscope
interphase
metabolically active cell duplicates mots of its organelles and cytosolic components; replication of chromosomes begin
G1 phase
replication of DNA and centrosomes
S phase
control of cell destinies
- remain alive and functioning without dividing
- grow and divide
- die
as we age
our cells gradually deteriorate in their ability to function normally and in their ability to respond to environmental stresses
the numbers of our body cells decrease
we lose the integrity of the extracellular components of out tissues
