Two different types of cells
Prokaryotes and Eukaryotes
Prokaryotes traits
No membrane bound organelles
Unicellular
Domains: bacteria and archaea
Eukaryotes Traits
Membrane-bound organelles
Uni- or multi-cellular
Domain: Eukaryota (animals, plants, fungi, protista)
Prokaryotic Cells
1)No membrane bound organelles** 2) DNA in a "nucleoid" region 4) Unicellular 5) Small 6) Domains: Bacteria and Archaea
Eukaryotic Cells
Has membrane bound organelles**
Nucleus contains DNA
Unicellular or Multicellular
Larger: 10x bigger than prokaryotes
Domain: Eukarya
Nucleus
Contains genetic information in the form of chromosomes or chromatin
Has a nucleolus for ribosome production
Surrounded by a phospholipid nuclear membrane (envelope)
spherical shape
molecules pass in and out of the nucleus through nuclear pores
Cytoplasm
"Jelly goo" that is within the cell membrane
Has organelles/structures in it
Found in eukaryotes and prokaryotes
Ribosomes
Structures that build proteins during protein synthesis
Free-floating or attached to the rough ER
Found in eukaryotes and prokaryotes
Rough Endoplasmic Reticulum
Helps with protein production and shipping
Ribosomes attached make it "rough"
Smooth Endoplasmic Reticulum
Synthesis of lipids
Detoxification
Storage of calcium ions
Golgi Apparatus (body) - Gol-jee
"Warehouse" for receiving, sorting, and shipping of proteins
Vesicles
Small "containers" made from ER or golgi membrane that move products around the cell
Vacuoles
Large vesicles for storing products
Plant cells have a large central vacuole filled with water
Lysosomes
Digestive organelles where macromolecules are broken down
Contain hydrolytic enzymes
autophagy
Mitochondria (mitochondrion)
Site of cell respiration
ATP is generated
Found in both plants and animals
Chloroplast
Site of photosynthesis
Converts energy from the sun into sugar molecules
PLANTS AND ALGAE ONLY
Centrosomes
Helps with cell division (mitosis) in animals
Contains centrioles
Cytoskeleton
Reinforces cells shape
Helps with cell movement
Includes microfilaments, intermediate filaments, microtubules
Cell (plasma) membrane
Found in plants, animals, and prokaryotes
surrounds cytoplasm
phospholipid semi-permeable bilayer
cell wall
Protects, maintains shape, helps with structure
Made of cellulose
Found in plant cells and some prokaryotes
Cilia (Cilium)
Short appendages containing microtubules present on some eukaryotes
Used in locomotion
Flagella (Flagellum)
"Tail-like" appendage found on some eukaryotes
Used in locomotion
Plant Cell Traits
Shape: Square-ish Eu or Prokaryote: Eukaryote Border: Cell wall AND Cell membrane Mitochondria for cell respiration: Yes Chloroplast for photosynthesis: Yes Vacuoles: Large, central, filled with water
Animal Cell Traits
Shape: Varies Eu or Prokaryote: Eukaryote Border: Cell membrane Mitochondria for cell respiration: Yes Chloroplast for photosynthesis: No Vacuoles: Small, stores various substances
What Determines Cell Function?
Size, shape, and surface area
Organelles present or absent
Quantity of different organelles
Examples of size, shape, and surface area affecting cell functions
Neurons (nerve cells) - spread out; electrical signals
Adipose (fat cells) - packed together; only stores fat
Examples of Organelles present or absent affecting cell functions
Red blood cells (moves oxygen/waste) - no nucleus
Lung cells w/ cilia (hairs) - diffusion of oxygen from lungs to blood stream
Examples of the quantity of different organelles affecting cell functions
Smooth ER: detoxify, liver cells have a lot muscle cells have extra mitochondria Endosymbiotic theory
Endosymbiotic theory
theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms (mitochondria and chloroplasts)
Evidence for Endosymbiosis
Mitochondria and chloroplasts have a double membrane
Mitochondria and chloroplasts have their own circular DNA (but no nucleus)
Mitochondria and chloroplasts divide like bacteria
About the same size as bacteria
own ribosomes
Why are Cells small?
Cells are small so their surface area to volume ratio is large, allowing the entrance of oxygen and food to the whole cell and the release of CO2 and wastes from the whole cell. If the cell is too big, it wouldn't be able to release waste properly/fully.
Diffusion
Movement of molecules in a fluid (gas or liquid) from where they are more concentrated to where they are less concentrated
movement DOWN its concentration gradient
Does not require energy
Protein Production Steps (17)
DNA in nucleus
Specific chunk/segment of ATCGs = gene
mRNA built from gene (transcription)
mRNA comes out from nucleus via nuclear pore
Ribosomes clamps onto mRNA, reads in 3 letter sequences
Assembles primary structure of protein (translation)
Could be a free ribosome (protein free in cytoplasm), done
Or could be a bound ribosome
Sticks to rough ER, release protein inside, ribosome free again
Protein modified in the ER (folding, addition of carbohydrate side chains)
Goes to Golgi apparatus via transport vesicle (little pouch of membrane)
Vesicle gets "pulled" along via motor proteins on cytoskeletal fibers
Vesicle fuses w/ Golgi membrane, releases proteins
Golgi modifies and packages proteins
Repackaged in other vesicle
Motor proteins take to another organelle, cell membrane, or out of cell
If exits our of the cell, vesicle fuses to membrane and releases via exocytosis
Osmosis
Diffusion of water through a selectively permeable membrane
Water balance in cells
Cells can be placed in different solutions
Hypotonic: less solute; more water
Hypertonic: more solute, less water
Isotonic: same solute and water
Osmosis Terms
Lysed (burst) (hypotonic)
Turgid (normal) (hypotonic)
Flaccid (isotonic)
Plasmolyzed (hypertonic)
Water Potential
Determined by solute and pressure potential
Water moves from regions of high water potential to regions of low water potential
Water potential equation
Ψ = Ψs + Ψp
Solute potential
Also called osmotic potential
Ψs is pressure from membranes/walls as water moves in or out
Can be positive or negative
Unit = bars ("in an open beaker" = 0 bars)
Solute potential equation
Ψs = -iCRT i - ionization constant (NaCl = 2, Sucrose/glucose = 1) C - molar concentration R - Pressure constant (.0831 LiterBar/MolKelvin) T - Temperature (in Kelvin)
Components of the Cell (plasma) membrane
Phospholipids
Proteins
Carbohydrates
Steroids
Phospholipid Bilayer
Hydrophilic head
Hydrophobic tails
Amphipathic (has hydrophobic and philic parts)
Membrane Proteins
Peripheral proteins: bound to the membrane surface
Integral proteins: penetrate the hydrophobic core 2a) transmembrane protein: spans entire membrane
Carbohydrate
Glycoproteins: oligosaccharides bonded to proteins
Glycolipids: oligosaccharides bonded to lipids Both help with cell to cell recognition
Steroids
Cholesterol: regulates cell membrane fluidity
Fluid Mosaic Model
Membrane is a "mosaic" of protein molecules in a semi-fluid bilayer of phospholipids
Selectively permeable
semi-permeable
Six functions of membrane proteins
Transport
Enzymatic activity
Signal transduction
Cell-cell recognition
Intercellular joining
Attachment to the cytoskeleton and extracellular matrix
Passive transport
No energy required
diffusion through the phospholipid bilayer of small, nonpolar (hydrophobic) molecules like O2 and CO2
Facilitated Diffusion through transport proteins
Can move larger, polar molecules
Two types of transport proteins
Channel proteins
Carrier proteins
Active Transport
Energy required (ATP)
Moves substances AGAINST their concentration gradients through transmembrane proteins
Bulk Transport
Requires energy
Moves larger molecules across cell membrane
Molecules packaged in transport vesicles
Exocytosis
Moving molecules from inside to outside the cell membrane
Vesicle fuses with cell membrane and releases contents outside
Endocytosis
Moving molecules form outside to inside the cell membrane
New vesicle formed from cell membrane containing molecules to be moved inside membrane
Endocytosis types
Phagocytosis
Pinocytosis
Receptor-mediated endocytosis
Structures Present in Prokaryotic Cells
DNA localized in nucleoid
Ribosomes
Cell (plasma) membrane
cell wall
cytoplasm
capsule
Difference between nucleoid region and nucleus
Nucleus:
Found in eukaryotic cells
Stores genetic material
Contains several chromosomes
Spherically shaped
surrounded by double layer membrane
Nucleoid:
Found in prokaryotes
Stores genetic materials
Only one chromosome
Irregular shape
Doesn't contain any surrounding membrane
Proteins synthesized by free ribosomes
Usually stay in cell
Proteins Synthesized by Bound Ribosomes
Usually travel out of cell
Plant vs. Animal Cells
Shape: Plant - Square-ish Animal - Varies Eukaryote or Prokaryote: Both Eukaryotes Border: Plant - Cell Wall and Membrane Animal - Cell membrane Mitochondria: Plant - Yes Animal - Yes Chloroplast: Plant - Yes Animal - No Vacuoles Plant - Large, central, filled with water Animal - Small, stores various substances
Organelles only present in plants
Chloroplasts
Cell Wall
central vacuole
Organelles only present in animal cells
centriole
Organelles present in both animal and plant cells
Nucleus
mitochondrion
cell (plasma) membrane
endoplasmic reticulum
golgi apparatus
cytoskeleton
Organelles involved in endosymbiotic theory
mitochondria and chloroplasts
Cell Membrane Components
Phospholipids Proteins Glycolipids Glycoproteins cholesterol
semi-permeable
membranes that allow some substances through but not others
How do molecules move through the membrane
Passive Transport Active Transport
concentration gradient
A difference in the concentration of a substance across a distance.
Nonpolar molecules crossing cell membrane
1)Hydrophobic 2) Can cross easily 3) No transport protein required
Polar Molecules crossing cell membrane
Hydrophilic
Have difficulty crossing hydrophobic portion of lipid bilayer
transport protein required
Ions crossing cell membrane
Hydrophilic
Have difficulty crossing hydrophobic portion of lipid bilayer
transport protein required
exocytosis steps
molecules to be secreted rest in a secretory vesicle
vesicle fuses with cell membrane
contents released outside
endocytosis steps
molecules to be moved inside cell membrane travel into a new vesicle formed from the cell membrane
vesicle detaches from the cell membrane and brings contents inside
Peroxisomes
Break down fatty acids and produce hydrogen peroxide
located in the cytoplasm
Motor proteins
moves vesicles to other organelles, cell membranes, or out of the cell