MCDB 1A: Cell Biology

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Biology

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146 Terms

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epitope
the antigen's binding site -- used in process of finding a protein in a cell
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How do we find a protein in the cell?
an antibody is used to bind to a specific antigen's epitope. A secondary antibody tagged w/a fluorescent cmpd is added and binds to primary antibody. The image can be seen w/a fluorescent microscope.
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Cell theory: what is it and who discovered it
all life comes from preexisting life -- discovered by Louis Pasteur .
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Why are cells so small?
Large SA:V ratio allows for quicker rate of diffusion for monitoring what goes in and out of a cell. We want to bring in nutrients and release waste
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Unicellular
a single cell, like bacteria. Bc they're single cells, they can develop into biofilm or communities like coral
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Multicellular
many cells, like humans. Carry out different functions
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What are the 3 major domains of life?
Bacteria, Archaea, Eukarya
BA= prokaryotes E=eukaryotes (fungi, protists, plants, animals)
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What is the cell wall in prokaryotes made of?
peptidoglycan
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How many membranes do prokaryotes have?
some have 2 membranes: the outer and inner
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What is the inner membrane in a prokaryotic cell called?
periplasmic space
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Where is DNA stored for a prokaryotic cell?
the nucleoid contained in the cytoplasm
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What is the flagella?
a tail that allows the cell to swim. Can make bacteria spin: clockwise is a forward motion while counterclockwise is TUMBLING
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What is the pili?
It's used for sex amongst bacteria; allows adhesion to other bacteria or surfaces.
It builds bridges between inferiors and exchange cytoplasmic material
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What is another word for bacterial sex?
conjugation
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bacterial sex
1. the pili connects them together
2. plasmids that enclose circular DNA are transferred through the pili during replication
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Who discovered penicillin and how?
Alexander Fleming; grew penicillin mold and saw that bacteria couldn't grow near it. Discovered it killed bacterial cells and prokaryotes b/c they tend to have a cell wall
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pencillin
it links peptides to sugars
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What is the nucleolus?
a part of the nucleus with ribosomal genes. It's where ribosomes are made and assembled
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What is the double membrane of the nucleus called and what supports it?
The nuclear envelope; it is supported by the lamina ['laminates"=support] and is contiguous of the ER. Holds different proteins and keeps nucleus from being compressed
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What is the function of nuclear pores?
to regulate what comes in and out of a cell
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What does a mutation in lamin-A cause?
early aging due to a collapsed nucleus
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Describe the nuclear pore complex
it forms channels to allow passage of macromolecules and is important for trafficking. '
it is inside the nuclear envelope
- mRNAs binded to proteins go out while nuclear proteins go in. They must have a NLS attached in order to be recognized by the pores
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cytosol
Where are proteins sythesized?
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What protein recognizes a NLS?
an importin protein
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NLS are ______ for import of protein into nucleus and __________ to direct a normally cytoplasmic protein into the nucleus
necessary; sufficient
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What is C-myc?
a transcription factor; binds to DNA & turns on transcription of genes associated with replication.
- if turned back on unnecessarily it leads to cancer due to overexposure
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What size are mitochondria?
about the size of a bacterial cell
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What are the 3 functions of mitochondria?
1. produce energy, ATP
2. regulate calcium levels
3. regulate signals that mediate cell death
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how do mitochondria grow and divide?
binary fission; pinching off in the middle
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describe the structure of mitochondria
- it has an inner and outer membrane
- the outer is smooth and semipermeable
- the inner has a lot of folds (cristae)
- it has a matrix inside & mitochondrial localization sequence
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what is the matrix?
- the matrix is the inner part of the mitochondria. It holds rna, trna, ATP synthases, and the electron transport chain.
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a mutation in NADH leads to this
blindness
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how is the pH gradient created and what is its purpose
it is part of the electron transport chain; hydrogen is pumped out to create a gradient across the inner membrane and then hydrogen flows in to create ATP.
- it is more acidic bc of the hydrogen drive
- it is a source of energy
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what are plastids?
plants; they have a double membrane
- serve for photosynthesis and storage
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what is the third membrane of the cytoplasm? Function?
the thylakoid; has proteins to bind chlorophyll & light pigments for photosynthesis
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what is the middle of the cytoplasm called? What is its function?
the stroma; holds DNA & ribosomes
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what are the 2 reactions of chloroplasts?
1. light --> takes energy from the sun to make O2, ATP, NADPH
2. dark --> use ATP and NADPH to make CO2 which is then sugar
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endosymbiosis
the belief that mitochondria & chloroplast originated when large eukaryotes ate small prokaryotes
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Peroxisomes
squared granular or crystalline arrays of enzymes that catalase to destroy toxic peroxides
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Chromoplasts
pigment storage
- attract insects for pollinating
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Plant vacuole (3 functions)
1. store toxic waste materials, food & nutrients
2. provide TURGOR aka stiffness for structure
3. can contain hydrolytic enzymes
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leucoplasts- what and found where?
store starch, lipids or proteins
found in roots/nonphotosynthetic tissue
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amyloplasts
store starch in potatoes
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diabetes: 2 types
- high blood sugar, weakness, lethargy, and weight loss
- Type 1: juvenile--lack of insulin. The own immune system attacks beta cells of pancreas
- Type II: lack of insulin responsiveness
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insulin: what and discovered by who
- peptide hormone secreted into blood by beta cells in pancreas
- binds to cell surface of muscle & fat cells : signals to import and store glucose
- discovered by Banting and Best
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Endomembrane system
- network of closed membrane tubules, closed vesicles, and closed sacs
- divides cytoplasm in 2 (inside and outside membrane sacs)
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3 Functions of Endomembrane System (STC)
Sequestration: of molecules/particles into cysternal space of vesicles
Transport: of sequestered molecules/particles from place to place w/in cytoplasm or to nucleus
Chemical modification
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What makes up the endomembrane system?
1. Rough ER
2. Smooth ER
3. Golgi Complex
4. Vesicles
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Rough ER
- has ribosomes attached
- is where integral membrane proteins & proteins that are secreted are made
- they're then translocated across the membrane into cysternal space
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Smooth ER
- lipid synthesis
- detoxification of hydrophobic toxins
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Golgi complex (post office)
- modifies carbs/proteins and ships them to the cell surface
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Vesicles
- lysosomes, peroxisomes, secretory ; move to cell surface
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Secretory pathway
rough ER --> golgi --> vesicles
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Integral Membrane proteins
- secreted proteins with signal sequence at N-terminus
- direct ribosome to rough ER
signal removed in lumen of ER
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Golgi apparatus
- has a cis/trans region
- vesicles from ER fuse with the cis region
- pinch off and fuse with medial and trans region
- pinch off trans and fuse with plasma membrane
- proteins inside vesicle secreted outside cell
- proteins in vesicle membrane inserted in plasma membrane
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lysosomes
pinched off the golgi
- cells recycling center
- has digestive enzymes break down old cellular materials
- digest ingested bacteria
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Tay-Sachs Disease
- lysosomal storage disease
- mutation in gene for hexose-aminidase A prevents lysosomes from breaking down certain membrane glycolipids
- leads to blindness, dementia, death
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Phagocytosis
- when macrofuge ingests bacteria
- the phagosome fuses with lysosome to kill bacteria
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Randy Schekman (schek, shake)
- isolated yeast cells that had secretion defects
- called them sec genes
encode membrane proteins that are involved in membrane traffic
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The eukaryotic cytoskeleton's 3 different skeletal fibers
1. Microfilaments
2. Intermediate Filaments
3. Microtubules
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Microfilaments
- made up of actin monomer
- polarization on plus end
- depolarization on minus end
- assembled by noncovalent bonds at the end of filaments
- partakes in treadmilling
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Intermediate filaments
- build similar cable like filaments
- very stable
NOT DYNAMIC
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Cell shape of microfilaments
- Stress fibers: bundled actin, maintain skin cell shape attach to focal adhesion
-Microvili: project from cell surface
most found in intestine
- actin join integrin
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Movement of Eukaryotic Cytoskeleton
- DUE TO MICROFILAMENTS
proven bc of amoeba experiment
where Cytochalisin B blocks formation of microfilaments leading to movement
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An example of intermediates
nuclear lamins
- support nucleus, attachment points for DNA
keratin filaments
- support skin, hair
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Microtubules
- made of alpha beat tubulin dimers
- both ends have different properties
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Two functions of microtubules
- Dynamic instablity: switching b/w growth and shortening ends
- Treadmilling
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Function of microtubules in animals
centrioles surrounded by pericentriolar matrix
- centriole = set of 9 triplet microtubules
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Dynein motor proteins
- help move the cilia and flagella
- negative directed
- make microtubules slide past each other
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Type of microtubules vesicles use to move
- dynein and kinesin motors
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How microtubules move
using the cilia or flagella!
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Lipid rafts
-high in cholesterol --> less fluidity
- more rigid
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3 types of molecule transportation
1. Passive diffusion
2. Carrier mediated diffusion
3. Active transport
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Passive diffusion
- no ATP required
- from high concentration to low
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Type of molecules that can't diffuse passively
- most water soluble
- any with a positive or negative charge
ex. sugars, AA, proteins
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How do molecules that can't diffuse passively get across the membrane?
- channel proteins
ex. Ion channels
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Carrier mediated diffusion
ex. glucose carrier protein
NO ENERGY REQUIRED
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Active transport
- needs energy and ion gradient
- moves molecules against their concentration gradient
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Uniporter
- active transport: moves one substance in one direction
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Symporter
- active transport: two substances in same direction
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Antiporter
- active transport: two substances moving in opposite directions
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Types of gated ion channel
ligand binding and voltage
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Endocytosis & exocytosis
moving complex molecules into cells
fusion of membrane vesicle to plasma membrane
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3 types of endocytosis
1. Phagocytosis: large particles and small cells engulfed inside vesicles
2. Pinocytosis: cell drinking; taking up water into vesicles
3. Receptor mediated endocytosis: specialized form--takes in certain kinds of macromolecules into cells
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Process of receptor mediated endocytosis
-clathrin coats cytoplasmic side of membrane
- creates a coated pit
- vesicle forms on cell surface
- gets brought into cytoplasm
- becomes uncoated and released
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Cholesterol
- a steroid
- in animal membranes
- makes membrane less fluid
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Endocytosis of LDL
- low density lipoprotein particles bind to LDL receptors at cell surface
- particles taken into clathrin coated vesicle
- vesicle uncoats, LDL binds off the receptor
- receptor forms new vesicle recycled to plasma membrane
- vesicle fuses with lysosome
- lysosome digests contents of vesicle releasing the cholesterol
- inserted into plasma membrane
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Extracellular matrix
- GLUE
- connective tissue in animals
- acts as filter in kidneys
- instruct a cell what to be
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basal lamina
- is between blood and urine
- separates kidney cells from blood vessel
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collagen
most abundant protein in the body
- provides strength
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cartilage
made of proteoglycans
found in joints
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integrins
- on cell surface
- integral membrane proteins receptors for ECM
- dimer of 2 subunits
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apoptosis
- programmed cell death
- due to lost attachment to matrix
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plant cell walls
- made of cellulose
- rigidity and strength
- hold shape
- glue cells together
- limit entry of large molecules
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cell junctions
1. cell-cell adhesion: holds tissues together
2. cell-cell communication: transport of molecules b/w cells
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Animal cell junction: tight junction
link cells together
- prevent passage of materials between cells
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animal cell junction: desmosomes
anchor to int. filaments
- give strength, hold cells together, coupled to keratin
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gap junctions
cellular communication
- link cells
- form channels made up of CONNEXINS b/w proteins to allow passage of molecules
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prokaryotic cell division
DNA replication, elongation, segregation, fission
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Eukaryotic cell division
Mphase, G1, S phase, G2