AP BIO Cells (Mika)

Types of cells

Prokaryotic and Eukaryotic

Prokaryote

-no membrane-bound organelles
-Unicellular
-Domains bacteria and archaea
-DNA in nucleoid region
-small

Eukarote

-membrane-bound organelles
-uni- or multicellular
-Domain Eukarya: Animals, plants, fungi
-Nucleus contains DNA
-larger (10x bigger than prokaryotes)

organelles in eukaryotic cells

Nucleus, cytoplasm, ribosome, Rough ER, Smooth ER, Golgi apparatus, Vesicles, vacuoles, lysosomes, mitochondria, chloroplast, centrosomes, cytoskeleton, cell (plasma) membrane, cell walls, cilia, flagella

Nucleus

-contains genetic info (chromosomes, chromatin)
-has nucleolus for ribosome production
-surrounded by phospholipid nuclear membrane

Cytoplasm (cytosol)

-Jelly goo within cell membranes
-has organelles/structures within
-also found in prokaryotes

Ribosomes

-Structures that build proteins during protein synthesis
-Free floating or attached to rough ER
-Also found in prokaryotes

Rough ER (endoplasmic reticulum)

-Helps with protein production and shipping
-have ribosomes attached

Smooth ER

-Synthesis of lipids
-Detoxification
-Storage of calcium ions

Golgi Apparatus/Body

-Warehouse for receiving, sorting and shipping of proteins.

Vesicles

small containers made from ER/golgi membrane that move products around cell

Vacuoles

large vesicles for storing products
-plant cells have a large central vacuole filled with water

Lysosomes

digestive organelle where larger molecules are broken down
-contains hydrolytic enzymes

Mitochondria (Mitochondrion)

-site of cell respiration
-ATP is generated
-found in 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 cells
-contains centrioles

Cytoskeleton

-reinforces cell's shape
-helps with cell movement
-Like a highway
-Includes: microfilaments and microtubules and intermediate filaments.

Cell (plasma) membrane

-phospholipid bilayer
-found in plants, animals, and prokaryotes

Cell walls

-proteins, maintains shape, helps with structure
-made of cellulose
-found in some plant cells and some prokaryotes

cilia (cilium)

-short appendages containing microtubules present on some eukaryotes
-used in locomotion (the hairs)

Flagella (flagellum)

-Tail-like appendages found on some Eukaryotes
-used in locomotion

Plants vs animal cells

Shape: Plant-squareish, animals-varies

Eukaryote/prokaryotes: plant and animal- eukaryote

Border: plant- cell wall and cell membrane, animal- cell membrane

Mitochondria for cell respiration: Plant- yes, animal- yes

Chloroplast for photosynthesis: plant- yes, animal-no

Vacuoles: plant- large, central, filled with water, Animal-small, stores various substances

Why are cells small?

cells need to exchange material with enviroment. This happens largely by diffusion.
Thus, since cells are small, diffusion happens easier more effectively.
cells are small so they do thier jobs right

Diffusion

-more concentrated flows to less concentrated (things move to where it isn't
-Diffusion through surface area

The surface area-to-volume ratio of a cell

Accounts for the size limit of cells
Smaller cell= more surface area relative to volume, which leads to faster diffusion

What determines cell function

1) Size, shape, and surface area
2) Organelles present or absent
3) Quantity of different organelles

endosymbiotic theory

Mitochandria and chloroplasts used to be free-living prokaryotes, then were engulfed by an early ancestor of eukaryotic cells
-engulfed cells formed relationship with host cell
-merged into one organism over evolution

evidence of endosymbiotic theory

Chloroplasts and Mitochondria:
-have their own DNA
-Are like bacteria: Have own ribosomes, divide similarly, about same size
-have double membrane

Protein production steps

1. DNA in nucleus, focus on specific gene
2. This gene is TRANSCRIBED into RNA
3. mRNA pops out of nucleus via nuclear pore
4. Ribosome clamps on, then reads it in 3 letter words, and pops out amino acid primary structure of protein (eg, TRANSLATION)

(4b. This ribosome could be a free floating one, and the protien would be all done now, and float in the cytoplasm)

5. Otherwise, it'd be a bound ribosome on the ER. At which point, it would release the protein into the ER where it is modified.
6. The protein then goes to the golgi via transport vesicle (pouch made of ER membrane)
7. Vesicle gets "pulled" by motor protiens along cytoskeleton
8. vesicle fuses with golgi membrane, releases protein
9. Golgi modifies and packages protien in another vesicle
10. motor protiens take to another organelle, the cell membrane, or out of the cell
11. If it exits the cell, vesicle fuses to membrane and releases protein via exocytosis

Water potential

The physical property predicting the direction in which water will flow, governed by solute concentration and applied pressure.

Osmosis

-Diffusion of water
-movement down its concetration gradient from where there is more water (less solute) to less water (more solute)
-Water wants to even out

Hypotonic

less solute, more water (relative)

Hypertonic

more solute, less water (relative)

Isotonic

same amount of solute and water

animal cells in hypotonic solution

lysed

animal cells in isotonic solution

normal

animal cells in hypertonic solution

shriveled (crenation)

plant cells in hypotonic solution

turgid (normal)

plant cells in isotonic solution

flaccid

plant cells in hypertonic solution

plasmolyzed

water potential equation

Ψ = Ψs + Ψp (Unit= bars)

Water moves from regions of ______ water potential to regions of _____ water potential

High to low

solute potential (Ψs)

Determined by solute concentration, always negative

pressure potential (Ψp)

pressure from mebrane/walls, can be positive or negative.

Find ΨP

given / open beaker (0 bars)

Equation Ψs

-iCRT

As molarity increases, solute potential ....

Decreases (gets more negative)

Components of cell membrane (4)

phospholipids, proteins, carbohydrates, steriods

Phospholipid bilayer

hydrophilic heads and hydrophobic tails
Amphipathic (has both hydrophilic and phobic region)

Protein types in cell membrane

Peripheral
Integral
Transmembrane

Peripheral protiens

bound to the surface of the membrane

Integral protiens

penetrates the hydrophobic core

transmembrane protien

spans entire membrane (specific type of integral protien)

Carbohydrate types in membrane

glycoprotiens
glycolipids
(both help with cell to cell recognition)

Glycoprotiens

olligosacchride bonded to protien

glycolipids

oligosachrides bonded to lipids

Lipids in membrane

steriods. ex: cholesterol

cholesterol in membranes

regulates cell membrane fluidity

Fluid mosaic model

-membrane in a "mosaic" of proteins molecules in a semi-fluid bilayer of phospholipids
-selectively permeable
-semi permeable

Functions of membrane proteins (6)

1. Transport
2. Signal transduction
3. Attachment to cytoskeleton and extracellular matrix
4. Enzymatic activity
5. Intercellular joining
6. Cell-cell recognition

Diffusion

-movement of particles from area of high concentration to low concentration
-movement down its own concentration gradient
-does NOT require energy

Passive transport types

NO ENERGY REQUIRED:
-Diffusion through phospholipid bilayer
(small non polar, hydrophobic molecules- ex: O2 and CO2)
-Facilitated diffusion through transport proteins
(can move larger, polar molecules.)

Two types of transport protiens

Chanel and carrier

Active transport

-moves substances against their concentration gradients
-requires ATP

Bulk transport

ENERGY REQUIRED
-moves large molecules across membrane (endo and exocytosis)
-Requires ATP
-Molecules packaged in transport vesicles

Exocytosis

Moving of molecules out of the cell using active transport
-vesicle fuses with membrane, releases contents outside

Endocytosis

Moving molecules from outside to inside membrane
-new vesicles formed of cell membrane containing molecules to be moved inside

Endocytosis types

phagocytosis, pinocytosis, receptor-mediated endocytosis

Phagocytosis

Cell eating (large molecules)

Pinocytosis

Cell drinking (cell fluid)

Receptor medicated endocytosis

a form of endocytosis in which receptors catch certain particles to bring into the cell.