Cells As Functional Units Flashcards
WHat does cell theory state
- Cells are the fundamental units of life.
– All organisms are composed of cells.
– All cells come from pre-existing cells.
First cell described by
Robert Hooke
Dead cell walls of cork
First LIVE cell
Anton van leeuwenhoek
Saw bacteria when looking at algae
What is cell size limited
SA:V
V = how much chemical activity it can carry out per unit of
time
SA = amount of a substance it can take in from the external environment and how much waste it can release into the environment
Difference between pro and eukaryotic cells
Pro = no nucleus or other membrane-bound compartments. Lack istinct organelles
Euk = have a membrane-enclosed nucleus and other membrane-enclosed compartments
and organelles
Mycoplasma describe
Bacteria that lack a cell wall
• This makes them unaffected by some antibiotics such as penicillin
• Some are pathogenic to
humans
Prokaryotes with capsules
Mostly polysaccharides
Protect bacteria from attack by wbc in infected animals
Stops bacterium drying out
Not necessary for survival
What process to CYanobacterias carry out
Photosynthesis
Features prokaryotic cells have
Flagellum
Pili - string structure to help bacteria exchange genetic material to animal cells, protection or food
Inclusions - starch, lipid reservers
Endospores - resistant to environmental stresses
Three types of prokaryotic cells
Spherical - Cocci bacteria”)
Rod shaped (“Bacillus”)
Spiral shaped (“Spirillia”)
Eukaryotic cells characteristics
Membrane bound nucleus
Membrane bound organelles and cytoskeleton
Nucleus
Replication of dna
Decoding dna for protein production
Contains dna
Rough endoplasmic reticulum
Ribosomes temporarily attached
Moves newly made proteins away from cytoplasm
Transports them to other areas of cell
Proteins chemically modified to alter function and destination
Smooth endoplasmic reticulum
More tubular than rer
No ribosomes
Chemical modification of small molecules taken into cell drugs
Site of hydrolysis of glycogen in animal cells
Site for synthesis of lipids and steroids
Ribosomes
Float freely
Found in Cytoplasm - free or attached endoplasmic reticulum, inside mitoch and chloroplasts
Protein synthesis site
Golgi apparatusq
Flattened membranous sacs - Cisternae
Received proteins from rer and further modify them
Concentrates, packages and sorts proteins before sent to final destination
Site of synthesis of polysaccharides for plant cell walls
Lysosomes
Vesicles containing digestive enzymes from golgi
Sites for breakdown of food and foreign material brought by phagocytosis
Autophagy - digest cellular components
Mitochondria
Independent genome
Energy stored in bonds of carbs and fatty acids converted to ATP by ATP synthase
Plastids
Found in plants and protists
E.g. chloroplast
Vacuoles
Storage, structure, reproduction, digestion
Similarities of euk and pro
They both have DNA as
their genetic material.
• They are both membrane
bound.
• They both have ribosomes
• They have similar basic
metabolism
• Both occur in amazingly
diverse form
Major differences between pro and euk
Eukaryotes have a nucleus
and membrane-bound
organelles, while prokaryotes
do not.
• The DNA of prokaryotes
floats freely around the cell;
the DNA of eukaryotes is held
within its nucleus.
• The organelles of eukaryotes
allow them to exhibit much
higher levels of intracellular
division of labor than is
possible in prokaryotic cells
differences between
prokaryotes and eukaryotes
Eukaryotes have a nucleus
and membrane-bound
organelles, while prokaryotes
do not.
• The DNA of prokaryotes
floats freely around the cell;
the DNA of eukaryotes is held
within its nucleus.
• The organelles of eukaryotes
allow them to exhibit much
higher levels of intracellular
division of labor than is
possible in prokaryotic cells
Fluid mosaic model structures
-Perform vital physiological roles
-Form boundaries between cells and their environments
-Regulate movement of molecules in/ out cell
• Lipid provides a barrier for water-soluble molecules.
• Membrane proteins are in lipid bilayer.
• Carbs attach to lipid/ protein on membrane
What does a phosphlipid bilayer separate
2 awurous regions
Hydrophilic - phosphate group
Hyrophobic - fatty acids
Integral membrane proteins
Hydrophobic regions of amino acids
Penetrate across phospholipid bilayer
Transmembrane prpteins
Specific orientaton
Show different faces on two sides of membrane
Peripheral membrane proteins
Lack hydrophobic regions and are not embedded in bilayer
How do some proteins in the membrane remain stationary
Anchored to components of cytoskeleton or are trapped within regions of lipid rafts
Causes unequal distribution of proteins, allowing for specialization of certain regions of cell membrane
Glycolipid and glycoproteins
Glycolipid - carb bound lipid
Glycoprotein - carb in membrane bonded to proteins
Plasma membrane enables cells to be recognized by other cells and proteins
Homotypic binding vs hetertypic binding
Homo = 2 identical molecules bind to eachother
Hetero = two different
Types of cells junctions
Form between cells in a tissue
1) tight junctions
2) desmosomes
3) gap junctions
Tight junctions
Plasma membrane
Link epithelial cells
1) restrict migration of membrane proteins adn phospholipis from one region of cell to another
2) Prevent substances moving through intercellular space
Desmosomes
Hold adjacent cells together
Dense plaques that are attached to cytoplasmic
fibers and to membrane cell adhesion proteins
Adhesion proteins bind to the proteins of an adjacent cell
Gap junctions
Monitor communication between cells.
Made of specialized protein channels called
connexons.
Connexons span plasma membranes of two adjacent cells and protrude from them
Connexons are made of proteins (connexins), which make a pore.
Passive processes of membrane transport
Membranes selectively permeable - allow substances to pass and others not
Simple diffusion through phospholipid bilayer
Facilitated diffusion
Diffusion def
the process of random movement toward the state of equilibrium
Factors affecting diffusion
Distance
temp
size of molecule
electrical charge of molecule
conc gradient
More lipid soluble = faster
Polar and charged = slower
Osmosis def
Diffusion of water across membranes
Completely passive
Water diffuse high -> low
Hypertonic vs hypotonic §
Hyper = water leaves cell
Hypo = enters
What does facilitated diffusion depend on
Channel proteins and carrier proteins
Describe the type of proteins channel and carrier
Protein:
K+ channel = ion channel
Voltage gated
Carrier:
Shape fits into protein, triggers other side to open letting it in
Active transport def
Energy required
Ions or molecules move against conc gradient
ATP energy currency used directly or indirectly
Three types of proteins for active trnsport
Uniport = one molecule
Symport = two transported ions enter same side of protein
Antiport = one leaves cell as other enters cell
Symport and antiport = coupled transport
Primary vs secondary active transport
Primary = sodium potassium pump - only cations ussed (K+, Na+)
Secondary = use gradients e.g. ATP used for ion gradient. Gradients move substance for symport and antiport
Example f symport system in intestinal cells
Glucose moves up conc gradient while mvinig sodium ions down ion conc gradient
Endcytosis processes
Phagocytosis - largest vesicles, entire cells engulfed
Pinocytosis - vesicles formation, dissolved substances brought inside cell
Receptor mediated endcytosis - on outside of cell in coated pits
What is exocytosis
Process where materials packaged in vesicles ae secreted from the cell
Vesicle membranes fuse with plasma membrane and release vesicle contents into environment
Membranes functions
-Information processing
-Energy transformation:
Inner mitochondrial membrane helps convert the energy of fuel molecules to the energy in ATP
The thylakoid membranes of chloroplasts are involved in the conversion of light energy in photosynthesis
-Organizing chemical reactions (efficiency)
Pinocytosis
vesicle formation
dissolved cells are brought into the cell
layer of cells separating blood capillaries from tissue uses pinocytotic vesicles to get fluids from the blood
Receptor-mediated endocytosis
similar to pinocytosis but highly specific
receptor proteins are exposed on the outside of cell in
coated pits
Clathrin molecules form the “coat” of
the pits.
|Exocytosis def
process by which materials packaged in
vesicles are secreted from the cell.
Exocytosis process
The vesicle membranes fuse with the plasma membrane and
release vesicle contents (wastes, enzymes, hormones, etc.) into
the environment.
Membranes functions
-Information processing
-Energy transformation = mitochondrial membrane convert energy of fuel
molecules to the energy in ATP.
thylakoid membranes of chloroplasts are involved in the conversion of
light energy in photosynthesis.
How are membranes dynamic
actively participate in numerous cellular processes.
Membranes continually form, move, and fuse.
membrane move and change their structures,
and fuse with other membranes.
membranes carry out specific functions.
* Despite the similar appearance and interconvertibility of membranes, they
show major chemical differences depending on their location in the cell and
the functions they serve.
* Dynamic in both structure and activity, membranes are central to life.
