Chapter 3 Flashcards
What 3 parts can a cell be divided to:
1) plasma membrane or plasmalemma
2) cytoplasm → cytosol (intracellular fluid) and organelles
3) nucleus
• chromatin
What is chromatin and where is it found
It is the condensed form of DNA in the nucleus.
It is found in the nucleus
The most condensed form of DNA is
Chromosomes
What are the 2 types of membrane proteins
1) integral proteins: permanently attached to biological membrane
2) peripheral proteins: Attached to the surface
Plasma membrane
flexible yet sturdy barrier that surrounds and contains the cytoplasm of a cell
Carbohydrates purpose in plasma membrane
are only located on the extracellular face of the cell and it is used for identification
Cholesterol purpose in cells
makes the cell membranes more solid and reduces fluidity of the membrane
What are the two types of transport proteins and their purpose
Channel proteins and carrier proteins that help transport specific substances across the membrane
Channel proteins (integral)
forms a pore through which a specific ion can flow to get across the membranes. example: NA+
Carrier proteins (integral)
transports a specific substance across the membrane by undergoing a change in shape. For example: amino acids
Receptor (integral)
recognizes specific bonds, and alters the cells function in some way. example: ADH hormone binds to receptors in the kidneys and changes the water permeability of certain plasma membranes.
Enzyme (integral and peripheral)
catalyzes a reaction inside or outside your cells.
Linker (integral and peripheral)
connects cells to cells
What can directly go through a membrane
small, nonpolar molecules such as O2, CO2 and H2O can go through without transport proteins
Membrane fluidity
membrane lipids and proteins are mobile in their own half of the bilayer and can move easily
Plasma membranes allow small, non polar uncharged molecules and not charged molecules and therefore are
selectively permeable
What is a concentration gradient
difference in the concentration gradient of a chemical between one side of the plasma membrane and the other
What is an electrical gradient
difference in concentration of ions between one side of the plasma membrane and the other
Transport processes that move substances across a cell membrane are…
passive processes (diffusion and osmosis) and active processes ( primary, secondary and vesicular transport)
Passive transport never requires…
energy
Active transport requires…
energy
Diffusion is influenced by these 5 factors:
- steepness of the concentration gradient
- Temperature: the higher the temp, the more movement
- Mass of diffusing substance: lower the mass, the faster the diffusion
- Surface area
- Diffusion distance: longer distance = longer time
Simple diffusion
Does not require transport proteins, and moves particles from an area of higher concentration to lower until equilibrium . Normally moves particles that are nonpolar and uncharges.
Facilitated diffusion
transmembrane proteins help solutes that are too polar or too highly charged move through the lipid bilayer
What are the two types of proteins involved in facilitated transport
channel and carrier
Sodium potassium pump; channel mediated facilitated diffusion
inward movement of NA+ and outward movement of K+ (important for nerve function)
Glucose transporter (carrier protein)
insulin tells cells to put more glucose transporters to allow for more glucose to enter the cells to prevent high blood sugar levels
Osmosis
net movement of a solvent (water) through a selectively permeable membrane from an area of higher concentration to an area of lower concentration. –> water always follows solutes
Tonicity
relates to how the solution influences the shape of body cells
Isotonic solution
the same concentration
Hypotonic solution
more water (solvent) in solution than cells. causes cells to swell
Hypertonic solution
less water (solvent) in solution than cells. causes cells to shrink
Active transport: Primary
energy derived from ATP changes the shape of a transporter protein which pumps a substance across a plasma membrane against its concentration gradient. (like pushing a ball up a hill)
Example of primary active transport
an example of this would be sodium potassium pump which goes against the concentration gradient. (to turn on a nerve cell, sodium needs to rush in - depolarization-)
Active transport: Secondary
energy stored (in a hydrogen or sodium concentration gradient) is used to drive other substances against their own concentration gradients. (example: when a pore is opened, it uses the energy from the sodium moving in to move a substance out)
Antiporters (secondary active transport)
membrane protein that transports two molecules at the same time in opposite directions
Symporters (secondary active transport)
membrane protein that transports two molecules at the same time in the same direction
Active transportation in vesicles: Receptor mediated endocytosis
ATP is requires bc the shape of the cell physically gets change to form the vesicle to allow the substance to enter
What happens to a vesicle once it enters the cell
vesicle fuses with lysosome and gets digested “broken down”
Active transport in vesicles: Phagocytosis
cellular process for ingesting and eliminating foreign substances and cells that are no longer needed
Active transport in vesicles: bulk phase endocytosis (Pinocytosis)
does not use receptors, non specifically eats stuff around cell
Exocytosis (vesicular transport)
membrane-enclosed secretory vesicles fuse with plasma membrane and release their contents into the extracellular fluid. (exporting something)
Transcytosis (vesicular transport)
a combination of endocytosis and exocytosis used to move substances from one side of a cell, across it, and out to the other side.
Why is transcytosis used?
Sometimes cells are too close together such as; epithelial cells, and transcytosis is required to get across.
What is a cytoplasm and it’s two components?
cellular contents between plasma membrane and nucleus; contains cytosol and organelles
Cytosol
known as the intracellular fluid portion of the cytoplasm
Organelles
the specialized structures that have specific shapes and perform specific functions
Function of cytoplasm
site of all intracellular activities except those occurring in the nucleus
Function of cytosol
fluid in which many of the cells metabolic reactions occur
Cytoskeleton
network in the cytoplasm composed of; microfilaments, intermediate filaments and microtubules
Cytoskeleton function
maintains the shape and general organization of cellular contents; responsible for cell movements
Centrosome
contains tubulins that are used for growth of the mitotic spindle and microtubule formation.
Cilia and flagella
motile cell surface projections that contain 20 microtubules and a basal body.
Function of cilia
move fluids over cells surface
Function of flagella
move entire cell
Ribosome
may be free in cytosol or attaches to rough ER
Function of ribosomes
protein synthesis
Endoplasmic reticulum
flattened sacs or tubules covered in ribosomes and attached to the nuclear envelope. Smooth ER lacks ribosomes.
Rough ER function:
synthesizes glycoproteins and phospholipids that are transferred to cellular organelles, inserted into plasma membrane and secreted during exocytosis
Smooth ER function
synthesizes fatty acids and steroids, inactivates or detoxifies drugs, removes phosphate group from glucose -6- phosphate, and stores and releases calcium ions in muscle cells
Golgi complex
3-20 flattened membranous sacs called saccules; structurally and functionally divided into entry (cis) and exit (trans) face
Golgi complex function:
entry (cis) accepts proteins from the rough ER; medial saccules form glycoproteins, glycolipids and lipoproteins; exit (trans) modifies the molecules further, then sorts and packages them for transport to their destinations
Lysosome
vesicle formed from golgi complex
Lysosome function
breaks down/digests using digestive enzymes
Lysosome: Autophagy
destruction of worn out organelles using lysosomal enzymes
Lysosome: Autolysis
destruction of entire cell by lysosomal enzymes
Peroxisomes
similar in shape to lysosomes, uses oxygen to oxidize (break down) organic substances.
Proteasomes
proteins shaped like a cylinder (barrel shaped) and break down proteins only
Mitocondria
site of aerobic cellular respiration reactions that produce most of a cell’s ATP. Plays an important role in early apoptosis
Nucleus
contains the hereditary units of the cell called genes, arranged in chromosomes
Function of nucleus
consists of genes that control cellular structure and direct cellular functions
Cytoskeleton: intermediate filaments function
anchors organelles (nucleus to center of cell)
Help attach cells to one another
Cytoskeleton: microtubules function
used to separate DNA during cell division, used as roads for vesicles to move around.
Gene expression: Protein synthesis
Process by which the information encoded in a gene is turned into a function
Protein synthesis: transcription
occurs in the nucleus and genetic information encoded in DNA is copied onto a strand of RNA to direct protein synthesis
Steps in transcription
- Messanger RNA directs protein synthesis
- Ribosomal RNA joins with ribosomal proteins to make ribosomes
- Transfer RNA binds to amino acids and holds it in place during translation
Protein synthesis: translation
translation occurs outside the nucleus as a process of reading the mRNA nucleotide sequence to determine the amino acid sequence of the newly formed protein
Free floating ribosomes
free ribosomes produce proteins used within the cell
Rough ER ribosomes
produce proteins that are used in the plasma membrane or secreted from the cell
