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Outline Cell Theory
All living things are made up of cells
All living cells come from pre-existing living cells
The cell is the most basic unit of life
There are always exceptions that come with cell theory
There is debate about how the original cell came to be without spontaneous generation
7 Functions of Life
Metabolism
Homeostasis
Growth
Reproduction
Response
Excretion
Nutrition
Outline SA:V ratio rules
The higher the surface area to volume ratio the more efficient a cell is. More surface area means more transportation of nutrients and other substances in and out of the cell. Cells can die when the volume is too much for the surface area because the nutrients and other materials can't move around the cell fast enough.
How are villi, microvilli, alveoli and nephrons similar?
They provide large surface area for molecular exchange.
What does a surface area to volume ratio graph look like - draw it
What is a negative side effect that comes from increased surface area to volume ratio?
Increased surface area can result in an increase of HEAT LOSS
What are the different categories of stem cells?
Multipotent - grows up into cells of a closely related family from which it is derived
Pluripotent - can grow/differentiate into almost any cell (embryonic)
Totipotent - Can grow/differentiate into any type of cell
What are the 2 different types of cells and their "kingdoms"?
Prokaryotic (2)
Eubacteria
Archaebacteria
Eukaryotic (4)
Animalia
Plantae
Protista
Fungi
What is the major difference between Prokaryotic and Eukaryotic cells?
Procaryotic = no membrane bound nucleus
often unicellular organisms
Eukaryotic = membrane bound nucleus
often multicellular
What is the prokaryotic cell wall made of?
Peptidoglycan
Draw, Label and annotate a prokaryotic cell?
Nucleoid = region of cytoplasm where the DNA resides Genophore = circular DNA Plasmids = autonomous circular DNA molecules that may transfer between bacteria Slime Capsule = a thick layer used for protection against desiccation (drying out) and phagocytosis Flagella = tail - long projections containing a motor protein that enables movement Pilli = hair-like extensions that enable adherence to surfaces (attachment pili) or mediate bacterial conjugation (sex pili) Cytoplasm Cell wall - peptidoglycan Cell membrane
How to most prokaryotic cells replicate?
Binary Fission
Draw, Label and annotate a Animal cell
Draw, Label and annotate a Plant cell
What are the differences between a plant cell and an animal cell?
Plant cells
Cell wall
Chloroplasts
large central vacuole
fixed shape
carbs are stored as starch
Animal cells
no cell wall
no chloroplasts (often more mitochondria - muscle)
vacuoles are small and there are multiple
no fixed shape
carbs are stored as glycogen
What is a polar molecule?
A molecule in which one end of the molecule is slightly positive, while the other end is slightly negative. Can mean that there is no overall charge.
Outline the structure of a phospholipid
Two distinct regions: Hydrophilic head with a polar central phosphate group Hydrophobic tail with two non-polar fatty-acid chains
What is the cell membrane made up of? How does it work?
Phospholipid bilayer
-phospholipids spontaneously arrange to form a bilayer in the presence of water.
-The water loving heads face outwards to interact with the polar liquid environments (mostly water), while the water fearing (or lipophilic) tails face inwards.
Meaning of Amphipathic?
There are regions of both hydrophobic and hydrophilic areas present
What are the properties of the phospholipid bilayer (cell membrane)?
Semipermeable - restrict the passage of many substances Fluidity:
The phospholipids move within the bilayer
The fatty acid lipid tails are held together by weak hydrophobic interactions
Membrane will continuously break and reform allowing for some larger molecules to enter/leave (endocytosis / exocytosis)
What is endocytosis?
Endocytosis is the process of the cell membrane engulfing materials and entering them into the cell
What are the two types of endocytosis?
Phagocytosis and pinocytosis
What is phagocytosis?
"cell eating"
What is pinocytosis?
"cell drinking"
What is exocytosis ?
The process of excreting materials out of the cell membrane
involves secretor vesicles(transportation membrane bound organelles)
Singer-Nicolson model
= Fluid mosaic model
phospholipid bilayer with membrane proteins and cholesterol imbedded within the phospholipids
Davson-Danielli model
= protein sandwich
phospholipid bilayer covered by membrane protein layer on both the intracellular and extracellular regions
Intracellular
inside the cell
Extracellular
outside the cell
What is the universal solvent?
Water
Hypotonic Solution
Hypoosmotic - more solutes in solution - water coming in
Isotonic Solution
an equal concentration of solutes in one solution compared to another solution
Hypertonic Solution
Hyperosmotic - less solutes in solution - water leaving
Osmolarity
is a measure of solute concentration, as defined by the number of osmoles of a solute per liter of solution (osmol/L)
Semi-permeability
The amphipathic nature of the membranes make it semi-permeable for SMALL, NON-POLAR molecules to freely pass. - PASSIVE DIFFUSION
Passive diffusion
diffusion that doesn't require ATP - goes along the concentration gradient
goes through amphipathic bilayer
Selectivity
Protein channels may SELECTIVELY allow LARGE, or POLAR molecules to pass depending on the needs of the cell
Active diffusion
diffusion that requires ATP - goes against the concentration gradient
2 kinds of Passive Transport
Simple and facilitated
Simple Diffusion
no ATP required
goes along the concentration gradient
small nonpolar species are able to move freely through the membrane
Facilitated Diffusion
ATP is NOT required when going against concentration gradient
larger and or polar species pass through protein channels or use carrier proteins to pass through the membrane
If using carrier proteins, active transportation can occur!!(usage of atp)
BIG IDEA - protein channels - CARRIER proteins can go against concentration gradient and use ATP
Proteins in cell membrane
integral membrane proteins
protein channels
carrier proteins
peripheral membrane proteins
Protein channels
integral lipoproteins which contain a pore via which ions may cross from one side of the membrane to the other
only select for specific ions
much faster rate of transport than carrier proteins
only move molecules along a concentration gradient (i.e. are not used in active transport)
Carrier Proteins
integral glycoproteins bind a solute and undergo a conformational change to move the solute across the membrane
only bind a specific molecule via a recognition site
slower rate of transport than channel proteins
May also move molecules against concentration gradients in the using ATP (active transport)
Abiogenesis
The theory that the first cells must have arisen from non-living material
Exceptions/problems with current cell theory
multinucleated cells (striated muscle cells, fungal hyphae and giant algae (some types)
continuous cytoplasm of some large cells that aren't seperated into smaller cells
viruses
'First' cell without the theory of spontaneous generation
Spontaneous generation
a debunked theory that suggests that the first cell came from spontaneous generation of the correct materials that formed a cell
Endosymbiotic theory
2 billion years ago a large bacteria cell 'ate' a bacteria cell
formed a symbiotic relationship
bacteria involved in the mitochondria (providing ATP) reasons:
bacteria same size as mitochondria
mitochondria also divide by fission (bacteria cells do)
mitochondria divide independent of host cell
mitochondria have own ribosomes
mitochondria have own DNA (more similar to prokaryotic cells)
mitochondria have two membranes on exterior - consistent with engulfing process
Louis Pasteur Test
Tests spontaneous generation
conclusion: bacteria can't spontaneously appear in sterilized nutrient broth
State the phases of the cell cycle
Interphase
G1 phase
Synthesis phase
G2 phase
Mitosis
prophase
metaphase
anaphase
telophase
cytokinesis
Interphase is the _________ phase in the cell cycle
longest
G1 phase
major growth in the cell
cell is the smallest it will ever be
S phase
DNA duplicates
once all chromosomes have been replicated cell enters its second growth phase called G2
Cytoskeletal filaments
network of interlinking protein filaments
microtubules (major component of cytoskeleton)
help cell with shape, organization of the cell and spindle microtubules/fibers play a major role in cell division
G2 phase
cell grows and makes preparations for mitosis
organelles double
DNA begins to condense from chromatin to chromosomes
microtubules may begin to form
Histones
DNA proteins
Nucleosomes
A nucleosome consists of a molecule of DNA wrapped around a core of eight histone proteins (an octamer)
Solenoid
coiled string of nucleosomes attached
Looped domains
looped solenoid
Supercoiling
DNA wraps around histones forming nucleosomes (groups of 8 histones)
Nucleosomes wrapped into solenoid
solenoids group together in looped domains
final coiling occurs to produce the chromosome
HAPPENS THROUGHOUT G2 and PROPHASE
Centromere
The center component that holds together eukaryotic sister chromatids
after separation the individual chromosomes has its own centromere
Prophase
nuclear envelope disintegrates and nucleoli disappear
mitotic spindle completely forms during prophase
centromere of each chromosome attaches to the spindles
centroSOMES move towards the opposite poles of the cell as a result of the lengthening microtubules
Metaphase
chromosomes move to middle of cell (referred to as metaphase plate)
chromosomes centromeres lie on the plate
chromosomes movement arise as a result of the action of the spindle
centreSOMES are ate opposite ends
Anaphase
typically shortest stage in mitosis
sister chromatids are split
chromosomes move to opposite sides of cell
movement result of shortening microtubules
each pole has a complete identical set of chromosomes
Telophase
chromosomes at each pole
a nuclear membrane begins re-form around each set of chromosomes
chromosomes start to elongate and form chromatin
spindles disappear
the cell is elongated for cytokinesis
Animal Cytokinesis
cleavage furrow forms (contractile ring of microfilaments), pinches and forms two cells
Plant cytokinesis
vesicles align in the middle of the cell, forms cell plate, cell plate attaches to wall of parent cell, new cell wall formed, two cells formed
Phosphorylation
attachment of phosphate group to a molecules or an ion - this transmits signals throughout the cell
side note: common in regulating protein function
image relates to cyclin - up next
Cyclins - what are they and what do they do?
Cyclins are a family of regulatory proteins that control the progression of the cell cycle
Cyclins activate cyclin dependent kinases (CDKs), which control cell cycle processes through phosphorylation
When a cyclin and CDK form a complex, the complex will bind to a target protein and modify it via phosphorylation
The phosphorylated target protein will trigger some specific event within the cell cycle (e.g. centrosome duplication, etc.)
After the event has occurred, the cyclin is degraded and the CDK is rendered inactive again
G0 phase?
G0 is a non-growing state that can at times occurs between G1 and S phase
cells will pause between the G1 and S phase due to inactivation of the CDK enzymes - entering the G0 phase
some cells such as nerve and muscle cells, never progress beyond the G0 phase
Chromatin
loose DNA - easily accessible for DNA replication
Chromatid
replicated DNA strands in pairs - sister chromatids only referred to during mitosis
Chromosome
DNA supercoiled can be replicated (1) or replicated (2)
Humans have _____ chromosomes in the cell?
46
Mutagens
can change genetic material of the organism
Carcinogenes
mutagen capable of causing cancer
Oncogenes (2 types)
potential to cause cancer
proto-oncogenes
promote cell growth and proliferation(cell cycle)
tumor suppressor genes
repress cell cycle progression and promote apoptosis
if mutated - deactivate - result in cancer
when healthy oncogenes work together in cell cycle
Metastasis
spread of cancer form one location (primary tumor) to another forming a second tumor
same cell type as primary - affects the type of treatment required
Benign tumor
tumor may remain in OG location (primary location)
Malignant
tumor that may spread/invade neighboring tissues
Pumps
example: sodium potassium
Why create gradients?
Potential energy = build of usable energy that will erupt = creating larger conc. of energy
What is the role of cholesterol in the cell membrane?
helps with structural integrity of the cell membrane
provides some rigidity to the cell
overall allows the fluidity of the cell without breaking apart
helps with temp changing fluidity of cell