Cells

Cells

Cytoskeleton

• The cytoskeleton is a network of fibers extending throughout the cytoplasm and it helps to hold the cells shape together.
• They are the "muscles" for movement.
• The three types are microfilaments, intermediate filaments, and microtubules.

Microfilaments

• Helical rods made out of a globular protein called actin.
• These help the cell move and change their shape.
• Actin and other fibers work together to make muscles contract.

Intermediate Filaments

• These are ropelike fiberous proteins.
• They have reinforced rods to bear tension and they anchor organelles.

Microtubules

• Straight, hollow tubes that are made of globular proteins. They are called tubulins.
• Globular molecules are like small marbles.
• They make themselves longer by adding tubulin subunits to one end.
• Their functions are providing shape, tracks for organelles to move within teh cytoplasm, they guide the movement of chromosomes during cell division, and move the cilia and flagella.

Cilia

• Shorter than flagella and they are more numerous.
• Propel protists; single celled organisms.
• Can be damaged by smoking and line the respiratory tract.
• The cilia push debri up and out of the body.

Flagella

• A type of transport.
• Propel sperm, other animals, and protists.

Microtubule Structure

• Microtubules form a 9 + 2 arrangement which means that there are 9 doubles of microtubules forming a ring around one double.
• These make up one cilia or one flagella
• To move the cilia or flagella, a motor protein called dyneins is needed. It grabs ontioo an adjacent microtubule doublet.
• These structures are flexible.
• Basal bodies and centrioles have identical structures.
• Basal bodies are anchor cilia or flagella in the cytoplasm.

Plasma Membrane

Membranes of the Cell

• Plasma Membrane - cell's outer membrane (Cell Membrane)
• Endomembranes - smooth and rough endoplasmic reticulum, golgi, vacuole, and lysosome (only these internal oragnelles can break apart)
• Membranous envelopes - nucleus, chloroplast, and mitochodria (have 2 membranes)

Membrane Features

• Semi-permeable - allow some substances to pass through, but blocks the passage of other substances. (only small things can go through)
• Membranes enclose and maintain the specific chemical environment.
• Every membrane carries out its specific functions.

Membrane Structure

• Two layer membrane called phospholipid bilayer.
• Made of proteins and lipids
• Contains two fatty acids instead of three (hydrophobic)
• Contains a phosphate group in the place of the third fatty acid (hydrophilic)

Membranes and Proteins

• Specific proteins are inserted into the phosolipid bilayer to:

1. Attach to the cytoskeleton
2. Talk to other cells
3. Enzyme Activity
4. Transporting passively and actively
5. Two cells holding each other, intercellular joining
6. Cell-cell recognition

Flexibility

• Membranes are not rigid.
• Protiens move freely on the membrane and do not just stay in one spot.
• This is called the fluid mosaic model.

Diffusion and Osmosis

• In diffusion, the molecules move.
• In osmosis, the water moves.
• Diffusion: the tendency of molecules to move from a high concentration to a low concentration until equilibrium is reached.
• Equilibrium is when the conecentration of either side it equal.

Passive Transport

• Diffusion across a membrane.
• Cell does not use any energy for diffusion.
• Selectively permeable membrane.
• Water, O2, and CO2 go through the membrane because they are small.

Osmosis

• Osmosis: passive transport of water across a semi-permeable membrane.
• Solute = what is dissolved.
• Solvent = what the solute is dissolved in.
• Water moves across the membrane, not the solute.

Hypertonic

• High concentration of solute and lower for solvent.
• Hyper = above.
• Plasmolysis = losing water.
• Cells will shrivel up if there is not enough water.

Hypotonic

• High concentration of solvent and lower for solute.
• Hypo = below.
• Lysing = bursting of a cell.
• Good for plant cells.

Isotomic

• Everything is equal.
• Isos = equal.
• Animal cells like this, but plant cells do not.

Effect on living animal cells

• Osmoregulation - control of water balance.
• Animals must use this to survive.
• Blood cells love this.

Effect on living plant cells

• Most plants thrive in a hypotonic environment when the vacuole is full.
• Plants become wilted in a isotonic environment.

Posted on 10/4/2010

Next Scribe: Katie B.

Cells: Structure and Function


Today in class, we took notes on cells and their functions in the green packet.
What are the structures? What do they do?

All cells come in different shapes and sizes, and it is impossible to see a plant or animal cell with the naked eye.

1. Light Microscope – visible light passes through the specimen, glass lenses enlarge the image. (the microscopes we use in class)

· Resolving power = 0.2 micrometers (one thousand micrometers in a millimeter)

2. Electron Microscope – uses beam of electrons instead of light

· Resolving power = 0.2 nanometers ( hundred thousand in a millimeter)

A. Scanning electron microscopes look at the actual surface of a cell

B. Transmission electron microscopes explore the inside of a cell

I. Prokaryotic vs. Eukaryotic

Prokaryotic: Eukaryotic:

Prokaryotic cells contain bacteria and archaea. Eukaryotic cells contain protists, plants, animals, and fungi.

Pro = before Eu = true

Karyon = kernel (nucleus) Karyon = kernel (nucleus)

II. Plant Cells and Animal Cells

Plant Cells Contain:
· Plasma membrane
· Nucleus
· Cytoplasm/Cytosol
-Chloroplasts/plastids (not green)
· Cell walls (forms a rigid, rectangular shape, not flexible)
· Square morphology

Animal Cells Contain:
· Plasma membrane
· Nucleus
· Cytoplasm/Cytosol
· Centriole (cell division)
· Round morphology (a more circular shape, flexible)

III. Cell Organelles

Organelle – (little organs) structure with a specialized function within a cell.

Organelles are eukaryotic.

Organelles are made up of a cell membrane that contains a nucleus, within a cytoplasm.

IV. Nucleus

The nuclear envelope contains a double membrane with pores that surround the nucleus. Little things are allowed to get in while big things stay inside. DNA is attached to a protein found in the nucleus in the form of chromatin (uncondensed, not currently dividing).

46 chromosomes in humans

Nucleolus is found in the nucleus. Ribosome production occurs in the nucleolus.

Nucleolus --> Ribosomes --> Protein

There may be one or more nucleolus per nucleus.

V. Ribosomes

Ribosomes look like small dots in the cytoplasm and in the Rough Endoplasmic Reticulum (RER). Ribosomes assist in protein synthesis by making enzymes and proteins for an organism. Ribosomes are responsible for providing proteins/enzymes.

VI. Rough Endoplasmic Reticulum

RER’s look rough and grain-like due to ribosomes. They produce membranes and secretary proteins.

VII. Smooth Endoplasmic Reticulum

Lacks ribosomes

Functions –

Makes lipids (steroids and hormones)

Cells in the liver detoxify (take toxins out) drugs and other poisons inside the blood.

VIII. Golgi Apparatus

Also known as the “UPS truck”

Finishes, stores, and distributes chemical products of the cell.

Final products are disturbed to other organelles or out of the cell membrane.

IX. Lysosomes

Means breaking down the body

Breaks down proteins, fats, polysaccharides, and nucleic acids.

Fuses with food vacuoles for digestion.

Useful products of digestion leave the lysosome and nourish the cell.

Destroys harmful bacteria.

Recycles damaged organelles.

Lysosomal Storage Diseases –

Lysosomes become enlarged and interferes with other cellular functions.

Ex: Tay-Sachs disease – ravages the nervous system

· Lacks lipid digesting enzyme and nerve cells in the brain which accumulates excess lipid and results in functioning improperly.

X. Vacuoles

Sizes and functions:

Food vacuole

Contractile vacuole

Central vacuole in a plant

· Store organic nutrients

· Absorb water – cells expand

· Pigments in petals to attract insects

· Contain poisons to deter plant eating animals

XI. Chloroplasts

Organelles of plants and protists that perform photosynthesis.

Stroma – thick fluid inside inner membrane

Grana – located in stroma, network of membrane enclosed tubes and disks, solar power packs (traps the sun’s energy and convert is)

XII. Mitochondria

Site of cellular respiration

Takes chemical energy from sugars and converts it to ATP (for of energy our cells use).

Found in most eukaryotic cells

Outer membrane and inner membrane that has multiple folding called cristae.

XIII. Cytoskeleton

A network of fibers extending throughout the cytoplasm

Functions:

Skeleton for support and cell shape.

The muscles are used for movement, rearrangement of cytoskeleton can cause cell or parts of the cell to move.

3 types of fibers:

Microfilaments

Intermediate filaments

Microtubules
Next scribe - Sonali

Cell Lab

Some Parts of a Cell:

Mitochondrion: provide the energy a cell needs to move divide, etc.

Gogli Apparatus: important in packaging and transporting macromolecules.

Nucleolus: produces ribosomes.

Cytoskeleton: helps maintain cell shape.

Cytosol: where all the cell organelles reside.

Lysosome: help in intracellular digestion.

Chloroplast: give the green color and take part in photosynthesis.

Vacuole: storage of water.

Eukaryotic cells have a nucleus.

Prokaryotic cells do not have a nucleus.

Facts:

Only bacterial cells and plant cells have cell walls.

Only plant cells have central vacuoles and chloroplasts.

Only animal cells have centrioles, lysosomes, and flagellum.

Flagellum help the cell move around its environment.

Cilia also help the cell navigate around its environment.

Plant cells are rectangular.

Animal cells are circular.

All specimens in the lab contain RNA, DNA, cell membranes, and ribosomes.

Cell Lab done in class on 9/29-30/10.

Specimen viewed under microscope:

Onion cells

Streptococcus cells

Elodea leaf cells

Human cheek cell

Frog blood cells

Tomato skin cells

Potato cells

Spirogyra cells (Algae)

Posted on 9/30/10

Next Scribe: Sally

9/27/10

Yunsu Y.

Enzyme Lab

Today the whole class time was devoted to the Enzyme Lab.

1. Catalase:

• An enzyme thats speeds up the reaction which breaks down hydrogen peroxide (H2O2) into two harmless substances: water (H2o) and oxygen (O2).
• This ties into the Enzyme Lab that we did today because if the bubbles were seen as a reaction in the test tubes, then the catalase was in action and broke up the hydrogen peroxide into water and oxygen.

2. Control Group:

• Test tube filled with catalse to 1cm and 4cm of hydrogen peroxide.
• This is the control group because the rest of the experiments are based off of this result.

* Purpose:The catalase is present to break down the hydrogen peroxide, but when substituted with a different substrate then will the same reaction occur? This was the focus of the lab.

3. Temperature

• We all know that when something is colder in temperature then the slower chemical reactions are. The warmer the temperature the chemical reaction speeds up.
• On the other hand, for enzymes the temperature has to be optimal for it to work properly. If the temperature is too hot then the heat will cause the enzyme to uncomfortable and even to denature. This goes the same when the temperature is too cold for the enzyme.
• By testing the tubes in the refrigerator, incubator, and in the boiling water, we could look at the results to see at what temperature the enzymes find optimal. (At which temperature the catalase works the best, breaking down the hydrogen peroxide.)

4. pH Level

• We used 3 different liquids with 3 different pH levels. One with HCl solution pH3-acidic, distilled water pH7-neutral, and NaOH pH11-base.
• The optimum pH level for catalase is 7, which is neutral, in this case the distilled water. Similar to the temperature, if the pH level is too acidic or too much of a base then the enzyme will denature causing it to be unable to breakdown the hydrogen peroxide=no bubbles.

Homework:

-Finish Enzyme Lab (questions)

-Mini Assignment due TOMORROW! (pg. 3 Tanning Beds and Skin Cancer)

Next Scribe: Sonali P.

9/24/10

Carey E.
Today we did notes from the organics packet(green packet) pages 5-8.

I. Acids

• When ions dissociate, the positives and negatives must equal zero. ex: 2+'s + 2-'s=0
• Most acids start with hydrogen.

II. Neutral

• Solution where concentration of H+ and OH ions are equal

III. Substrate and Active Site

• Substrate is putting together or breaking apart binds to an enzyme that fits. Called an induced fit. This is an action that takes place on site.
• Enzymes are recycled and do not change shape.
• When the substrate is in the enzyme, water is added to break the bond of the substrate.
• Most enzymes' suffix is ase. ex: glucose and fructose.
• Enzymes keep working until there are no more substrates.
• Every enzyme has a different tolerance of Ph.

IV. Enzyme Inhibition

• Drugs and bacteria can inhibit-slow down-enzymes.
• An inhibitor blocks the substrate from reacting with the enzyme.
• Inhibitors can bind to another part of the enzyme and change the shape of the active site. ex: A water balloon changes its shape when something touches it.
• Good and Bad
• Good: it stores some food for reserve
• Bad: you aren't getting the products you need
• This reaction speeds up or slows down based on you're activity level. Helps control metabolism.

E + S----->ES-------->E+P
E=enzyme
S=substrate
P=product
V. Vocabulary

• degradation: substrate is broken down
• synthesis: substrates join to form product

next scribe: Yunsu Y.

9/23/10

In class on 9/23/10, we finished the organic notes that we started yesterday. Yesterday we stopped on mono/disaccharides, and we started from polysaccharides and into the proteins notes up to acids. Otherwise, there wasn't much else done in class. And, of course, we had homework, which was only the mini assignment that is due on Tuesday and preview and put hypotheses for each statement for UP pgs. 11-18, due tomorrow.

The following are the answers for each blank in the notes, from top to bottom in each box in the notes. The statements in parentheses indicates that there were extra statements provided by Mrs. Andrews: Starting with the last blank in the polysaccharides box: hydrophilic (water is hydrophilic, this statement was stared). Lipids box: hydrophobic, triglyceride, hydrocarbon, dehydrations. In steroids box: left mini box; lipids, hydrophobic, right mini box; anabolic steroids. Hazards of steroid use: east german, testostorone, organ damages, birth defects. Effects on teens: left column; pimples, breasts, tumors, violent, shorter, right column; hormones, development, gender mix-ups. Proteins box: specific sequence of amino acids (20 amino acids, like alphabet), hydrogen (weak), 2 or more (no more than 4) (peptide- bonds between amino acids, covalent bonds- strong bonds, hydrogen bonds- weak). Nucleic acids box: nucleic acids, DNA, RNA. (Next section) PROTEINS= Enzymes. Proteins box: proteins, amino acids. Amino acids box: 20 (stared), carboxl, amino (Remember: most proteins are hydrophilic). Forming Polymers: Dehydration synthesis, peptide (both stared). What is an enzyme?: enzyme, catalysts (Recycled), metabolism, activitation energy (stared). How to speed up a chemical reaction?: heating (a little bit), decrease. Enzymes are affected by...: temperature, pH, concentrations of enzymes or substance, specificity (example under it: 100 enzymes= 100 substrates). pH scale box: 0, 14. Ions box: charged particle, electron, dissociate).

9/22/10

CJ P.

Atoms and molecules

Today we received our unit one biology tests back. Class average of 75% woohoo!(see Andrews during your lunch period to see tests)

Homework: read Chapters 2, 3, and 5 in the textbook for Thursday.
Mini assignment in "Cells R Us" packet (pg. 3) due Tuesday.Are tanning beds a skin cancer risk?We began our Cell Unit notes, pages 1-4

I. Carbon
Carbon is an abundant atom. It can bond to 4 other atoms.
a. commonly bonds with hydrogen, nitrogen, and oxygen.
1.A drawn line in a molecule model resembles a bond.
carbon skeletons - chain of carbon atoms.
hydrocarbons - simplest organic compound.

2. Hydrocarbons can take up many different structures
i. ringed, double bonded, single bonded, branched, unbranched.

<---Carbon skeletons can vary in length.














II. Functional groups

Functional groups allow molecules to bond. A molecule can have one or more functional groups attached.
The types of functional groups:

• Hydroxyl group - found in alcohols and sugars
• Carbonyl group - found in sugars (carbon)
• Amino group - found in amino acids (nitrogen)
• Carboxyl group - molecules with carboxyl groups are called carboxylic acids; found in amino acids, fatty acids, some vitamins. Combination of alcohol and carbon.

NOTICE: Carbonyl and CarBOXyl are two different groups.


III. Building larger molecules
Macromolecules - biological molecules like DNA, proteins, and carbohydrates. A.K.A: big molecule.
Monomer - chemical subunit. Building block for polymers, macromolecules consisting of many identical/similar monomers bonded together.
a. How do I remember this? MONOmer, a SINGLE chemical subunit that makes up a POLYmer, many monomers bonded.
b. 4 major macromolecules:
1. Proteins
2. Carbohydrates
3. Nucleic acids
4. LipidsIV. H2O
Dehydration - linking of monomers together to form a polymer. WATER IS REMOVED BY TAKING A HYDROGEN (H) FROM ONE MOLECULE AND AN ALCOHOL (OH) FROM THE OTHER.
bonds cannot be left open.
a. If you take H (hydrogen) from one molecule and OH (alcohol) from another molecule, the bonds are open causing them to join together.
1. from those open bonds comes water, H2O (H+HO)
b. Hydrolysis - to break with water.
1. this is the opposite of dehydration. The polymer breaks into monomers because you are breaking the bonds of the polymer by ADDING a water molecule.

To make a bond, you must lose water.

Matter gets changed, not eliminated or added. That is why you must add the bond along with the monosaccharides

V. Carbohydrates

Monosaccharides
All monosaccharides are C6H12O6

a. They are simple sugars. Glucose and fructose.

DisaccharidesFormed by synthesis of two monosaccharides.
a. broken down by hydrolysis into two monosaccharides.

Polysaccharides
Starch - storage polysaccharide.
Glycogen - stores excess sugar, found in animals (it is branched. Remember what branched is? It's another structure of carbon skeletons.)
Cellulose - most abundant organic compound;; found in plants.
CANNOT be hydrolyzed. (what does hydrolyzed mean? Cannot be broken up by water. AKA Fiber).
Almost all carbohydrates are hydrophilic. (love water!)

Next scribe: Skyler S.