October 18th

Today we learned how we get sick. Pathogens are one way to get sick.
Viruses are considered both life and non life, since they ahve characteristics of both.
Life: Highly organized with genes
Non-Life: not cellular, cannot reproduce on own

Viruses infect a living cell. one way they do this is the lyctic cycle, where DNA is injected by virus into host cell to produce copies of virus.
DNA viruses usually reproduce in host cell's cytoplasm, sometimes in nucleus.
Prokaryotes have been around for 2 billion years.

Next Scribe - Nick

MITOSIS 10/8/10

James
Unit 2 - CELLS
MITOSIS = cell division
Scribe Post for Friday, 10/8/10

Cells divide to replace damaged cells, reproduce organisms, to grow, to transfer genes from cell to cell, and for a unicellular organism to become multicellular

TYPES OF REPRODUCTION
Sexual (MEIOSIS)- fertilization of an egg by sperm (each contain half of the parent cell's chromosomes), occurs in reproductive organs (ovaries/testes)

Asexual (MITOSIS)- no fertilization at all, parent and offspring have the same genes, binary fission (organism splits into 2, found in single celled organisms)

Chromosomes

-Contain almost all genes of a eukaryotic cell
-Visible with light microscope during cell division
-Chromatin (invisible) are masses of long thin fibers, contain DNA/protein
-Before cell division, chromatin coils up to form chromosomes
-Humans have 46 chromosomes (varies by species)
-Each chromosome can have over 1,000 genes

Chromosome Replication

-Genetic material must be doubled before cell division to make sure that the daughter cells match the parent cell
--Sister chromatids are identical copies of each other connected at the centromere
--Daughter cells are the result of cell division, DOES NOT IMPLY GENDER

The Cell Cycle

Interphase (Pre-Mitosis) - 90% of cell cycle
-GI (Gap 1) - cell grows 2x bigger, protein synthesis, more organelles, 2x cytoplasm
-S (Synthesis) - chromosome replication (in nucleus)
-G2 (Gap 2) - Final preparation before division



Prophase - CHROMOSOMES AND SPINDLE FIBERS COME, NUCLEAR ENVELOPE GOES!
-Chromosomes coil/condense to become visible
-Nucleoli disappears
-Sister chromatids connected at centromere
-Spindle forms

-Nuclear envelope breaks down
-Spindle attaches to centromeres and move chromosomes to center of cell

Metaphase - DUPLICATED CHROMOSOMES CENTER UP!
-Spindle completely formed
-Centromeres on chromosomes are lined up on equator between the poles
-Spindle is attached to each sister chromatid, pushes chromosomes to center

Anaphase - DUPLICATED CHROMOSOMES SEPARATE AND MIGRATE!

-Sister chromatids are separated and each are now known as daughter chromosomes
-Motor proteins on centromeres move chromosomes toward opposite pole of cell
-Spindle attached to chromosomes shorten
-Spindle not attached to chromosomes lengthen to extend cell and force poles further apart to prepare for daughter cells

Telophase - NUCLEAR MEMBRANE FORMS AROUND NEW CHROMOSOMES!

-Begins once chromosomes reach poles
-Opposite of Prophase
--Nuclear envelope REAPPEARS
--Nucleoli REAPPEAR
--Chromosomes UNCOIL
--Spindle DISAPPEARS
--MITOSIS IS NOW FINISHED

Cytokinesis - CYTOPLASM DIVIDES TO FORM 2 DAUGHTER CELLS!

-Begins during telophase
-'CLEAVAGE' in animal cells
-cleavage = indent at equator of cell that pinches cell in 2
-Formed by ring of microfilaments inside cell membrane
-In plant cells, cell plate forms by starting in center of cell and moving outward to bisect cell

Cell Cycle Control

-Cells that are not directed by the cell cycle divide out of control
-Result is a benign tumor (abnormal mass of normal cells)
--can cause problems depending on location
--as it grows, displaces normal tissue

Cancer

-Cancer cells have faulty cell cycle, divide out of control
-Malignant tumor = lump that results from division of cancer cell
-Metastasis = spreading of cancer cells to other organs
-Cancer is named for where they begin
--Carcinomas - originate in external/internal coverings of body
--Sarcomas - originate in tissues that support body
--Leukemia - cancer of blood forming tissue (bone marrow)
--Lymphomas - cancer of blood forming tissue (lymph nodes)

Cancer Treatments

Radiation Therapy

-Cancer cells exposed to high-energy radiation disrupt cell division
-Radiation destroys cancer cells without harming normal cells
-Bad side effects (sterility)

Chemotherapy

-Drugs that disrupt cell division
-Antimitotic drugs - prevent cell division by interfering with spindle formation

NEXT SCRIBE: Davin L

October 7, 2010

Justin Abraham


First Mrs. Andrews collected the UP pages 41 and 42.

IMPORTANT DATE CHANGE- Unit 2 test will be Thursday Oct.
Naked Egg Demo #3:
We looked at the egg. This time it was in corn syrup. Here is how it looked like...
• There was almost no shell left.
• The top was caved in a little.
• The inside of the egg was hypotonic and the corn syrup outside was hypertonic because the syrup has a much higher concentration of solute.
• The color of the egg was not pure white anymore, it had a little yellow color.
Went to the Computer Room
• Started UP pages 49-51.
• The websites were about Mitosis.

Homework:

• Finish UP pages 49-51
• Read lab on UP pages 53-60
• Study for Unit 2 Test on Thursday

Next Scribe - James C

Demos and Notes

Egg Osmosis Demo Day 2
Egg soaked in vinegar:
Hard shell gradually broken down by vinegar
- surrounded by bubbles (slowly eat away shell)
- soft, gooey feeling

Normal and Plasmolyzed Cells Demo

Purpose: To see the differerence(s) between a normal and plasmolyzed cell

Hypotonic: normal elodea leaf cell (good)
- tap water added
- cell membrane doesn't change

Hypertonic: plasmolyzed elodea leaf cell (bad)
- salt water added
- vacuole shrunk
- empty space between membrane and cell wall

Notes

• Exocytosis
• Endocytosis: 3 types

-Phagocytosis
-Pinocytosis
-Receptor-Mediated
Homework

• Finish Lab
• Read Chapter 8 p.121-129 (Mitosis and Cancer)

Next Scribe: Justin

Scribe Post 10/5/10 Diffusion Lab and Quiz

Agenda:

First we talked about the naked egg experiment, in which an egg is placed in various substances to prove the diffusion that takes place while the egg is in the substances.

Next we set up for the lab.

Then we took a quiz and when we were finished recorded our results from the lab.

Lab Summary:

The lab was about diffusion, and was a cellophane dialysis tube with starch, water, and glucose, sitting in a beaker of iodine and water. When the tube was observed after the quiz the water had turned almost black inside the tube and the beaker seemed to have stayed the same. The color change was because of the combination of iodine and starch within the tube. The iodine got in the tube because of diffusion and because it started with a higher concentration in the beaker and moved to lower concentration in the tube.

Lab Questions:

You know the iodine diffused in the lab because of the color change in the tube, showing the presence of iodine and starch.

The starch however did not diffuse to the outside of the tube, because if it had, the water in the beaker outside the tube would have been black like the inside of the tube, because the iodine and starch would have mixed. It didn't diffuse because it was a lower concentration than the occupants of beaker around the tube.

The glucose didn't obviously diffuse during the lab, or the water would have been a bit darker in the beaker because glucose and iodine turn dark brown when mixed.

Iodine and water diffused through the membrane of the cellophane tube.

Starch and glucose did not, that we could observe, diffuse through the cellophane tube membrane.

The failure of starch to diffuse through the membrane could have been because the molecules were bigger and less concentrated and didn't need to diffuse to an area of lower concentration to be spread out.

Materials can't pass through selectively permeable membranes going different directions at the same time, because it's selectively permeable and only certain amounts of certain substances can pass through at once.

The materials that diffused in opposite directions during this experiment were water and iodine.

A cell is dead when it is in complete equilibrium with its surroundings because nothing is being transferred. No energy or materials are being passed back and forth therefore the cell isn't functioning and would be dead.

It's harmful to add salt water to a fresh water plant because the salt soaks up the water that the plant needs to absorb, and the plant becomes dehydrated.



Next scribe Christine K.

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