Biology Unit 3- Cell Structure

Compare and contrast diffusion, osmosis, and facilitated diffusion.

All three are methods of passive transport, which means that they do not require energy and that materials move from a high concentration to a low concentration. They are different in that osmosis only involves the movement of water and that facilitated diffusion requires a membrane protein.

Lysosomes

An organelle containing digestive enzymes for food and other particles

What happens to the surface area to volume ratio as cells get larger? Why?

As cells get larger, the surface area to volume ratio gets smaller. This means there is less surface area per unit of volume.

How are active transport and facilitated diffusion similar? How are they different?

Both require the use of a membrane protein. However, active transport uses energy to move against the concentration gradient (from low→ high concentration). Facilitated diffusion does not use energy and therefore only allows substances to move down their concentration gradient (from high→ low concentration).

ribosomes

Cellular structures in which proteins are made Ribosomal proteins and RNA are made in the nucleus Ribosomes are partially assembled in a region of the nucleus called the nucleolus

Muscle cells have more mitochondria than some other kinds of eukaryotic cells. In what way would having many mitochondria be beneficial to muscle cells?

Muscle cells use ATP when they contract. Having many mitochondria would help provide the large amount of ATP needed for contraction.

diffusion

The passive movement of molecules from a higher to lower concentration until equilibrium is reached -gases move through plasma membranes by diffusion

Why do the phospholipids arrange themselves in this pattern?

The polar "heads" of the phospholipids are hydrophilic (water loving) and are on the outside of the bilayer so that they face the water on the outside of the cell and in the cytoplasm. The nonpolar, hydrophobic "tails" stay to the inside of the membrane, where they are not near water.

Stage (both)

Compound- Where specimen is viewed Stereo-is where the specimen to be viewed is placed. Pole and track stands have simple stages since lower magnification powers require less subtle movements than high power microscopes.

Hydrophobic

Water fearing non polar tails

compound light microscope

a microscope that shines light through a specimen and has two lenses to magnify an image

Golgi apparatus

a set of flattened, membrane-bound sacs that serves as the packaging and distribution center of the cell

vesicle

a small, membrane-bound sac that transports substances in cells Vesicles containing newly formed proteins move from the ER to the Golgi apparatus

Osmosis in cells

a solution contains a solute (solid) and a solvent (liquid) -cells are normally isotonic to their surroundings, and the solute concentration is the same inside and outside and out of the cell -"iso" means the same as, and "tonicity"refers to the strength of the solution

coarse adjustment knob on compound light

moves stage up and down

Cytoskeleton

network of protein fibers that anchor the cell's organelles and other components of the cytoplasm

Mitochondria

organelles that harvest energy from organic compounds to make ATP ATP is main source of energy in cells mitochondria have inner and outer membrane

movement of materials across a membrane may be passive or active

passive transport does not use chemical energy -diffusion -osmosis -facilitated diffusion active transport requires chemical energy and usually a carrier protein ions or molecules are moved across the membrane against the concentration gradient from an area of lower to higher concentration ATP is required for the carrier protein to combine with the transported molecule - membrane pumps -exocytosis -endocytosis

plasma membrane

separates the insides of the cells from its surroundings - a phospholipid bilayer with embedded proteins -has fluid consistency and a mosaic pattern of embedded proteins

prokaryotic cell

single-celled organisms lacking a nucleus and other internal compartments bacteria They have -cell wall -ribosomes -single circular model of DNA -may have cilia or flagella

Factors that limit sizes of cells

small cells function more efficiently than large cells If a cell's surface area-to-volume ratio is too low, substances cannot enter and leave the cell well enough to meet the cell's needs

pumps

some carrier proteins involved in active transport are called the sodium-potassium pump is active in all animal cells -it causes nerve cells to conduct an impulse - exists in 2 conformations one that moves sodium out of the inside the other that moves potassium into the cell

Nucleus

the nucleus is an internal compartment that houses the cell's DNA. controls most functions of a eukaryotic cell surrounded by double membrane called nuclear envelope scattered over the surface of the nuclear envelope are many small channels called nuclear pores ribosomal proteins and RNA are made in the nucleus, ribosomes are partially assembled in a region of the nucleus called the nucleolus

How to focus a microscope

turn the twisty thing on the left and twisty thing lower than the larger one magnify larger if needed

carbohydrates

use for cell recognition

phospholipid bilayer

water is inside and outside of cells, provides a barrier to make this happen Phsopholipids with bent fatty acid tails cause the membrane to be more fluid

Hydrophilic

water loving heads

hypertonic solution

-sugar water causes cells to lose water, when you eat salt you become thirsty -"hyper" means more than; hypertonic solutions contain more solute -animal cells undergo crenation (shrivel up) in hypertonic solutions -plant cells undergo plasmolysis, the shrinking of cytoplasm

cell theory (3 parts)

1. All living things are made of one or more cells 2. Cells are the basic unit of structure and function in living things, so if the cells don't function, the organism doesn't 3. Cells (except for the first) come from a preexisting cell

When a cell takes in a food particle by endocytosis, the vesicle that is formed may fuse with a lysosome. How would fusion with a lysosome help the cell digest the food particle?

14. Lysosomes contain digestive enzymes that can digest/break down food/macromolecules.

List several differences between plant and animal cells.

Plant cells contain a cell wall made of cellulose, chloroplasts, which they use to carry out photosynthesis, and a large vacuole that they use to store materials. Animal cells lack these things.

The cells in your pancreas produce a protein called insulin. The pancreas cells release insulin into your bloodstream. The job of the insulin protein is to help regulate blood sugar levels. Describe how the pancreas cells are able to produce and release this protein. Start with the cell part that makes proteins in the cell.

Ribosomes in the cell make the insulin protein. Insulin is then transported through the endoplasmic reticulum. Insulin leaves the ER inside a vesicle, and it travels to the Golgi apparatus. The Golgi apparatus finishes and prepares the insulin protein by making any necessary modifications to the protein (such as helping it to finish folding or attaching any carbohydrates that help it perform its function). Then, the Golgi apparatus packages the protein inside another vesicle and sends it to the cell membrane. The insulin proteins are released from the cell into the bloodstream through the process of exocytosis. (See diagram on next page...)

The pain of a sore throat is caused by the swelling of tissues with water. Use your understanding of osmosis to explain why gargling with salt water would help this pain.

Salt water has a greater concentration of dissolved particles than your swollen tissues. As a result, water will move from the swollen tissue into the salt water solution. Another way to think about it is that the swollen tissue has a higher concentration of water, so water moves from the tissue into the salt water. Gargling with salt water will make your throat cells shrink, which will reduce the swelling and help your pain.

What term describes the property of a cell membrane that allows only certain particles to pass through it? Since the cell membrane only allows certain types of ions and molecules through, how would this affect the ability of different types of molecules to reach equilibrium between the cell and the fluid around it?

Selective permeability (or "semipermeable"). Substances that are able to cross the membrane will reach equilibrium. Substances that are not able to cross the membrane will not and will have different concentrations inside and outside the cell.

eukaryotic cells

Singular AND multicellular celled organisms that do have a nucleus and membrane bound organelles. plants animals fungi Have a Nucleus that contains cell's DNA Other internal compartments called Organelles

Transport by carrier proteins

Some biologically useful molecules need help to pass through the plasma membrane -carrier proteins are specific and combine with only a certain type of molecule - just like enzyme specificity -facilitated diffusion and active transport both require carrier proteins part of membrane structure

Compare and contrast the following pairs of terms: A) Light microscope vs. Stereomicroscope B) Coarse focus adjustment vs. Fine focus adjustment C) 4x objective vs. Eyepiece

a)Light microscopes pass light through a sample. The image is magnified twice, once by the objective lens and once by the eyepiece. You can only view samples that are thin enough for light to pass through. These invert the image. Stereomicroscopes have two eyepieces so you can look at a sample with both eyes. This creates a 3D image. Stereomicroscopes bounce light off an object so that you can view opaque objects. These do NOT invert the image. b) Course focus adjustment is used at low power. It changes the distance between the stage and objective lens. Fine focus adjustment is used at medium and high power. It alters the depth of field. c) The 4x objective magnifies an image four times. It is the lowest power of the objective lenses (medium=10x, high=40x). The eyepiece (or ocular) is what you look through- it also magnifies the image (10x).

Endoplastic Reticulum (ER)

an extensive system of internal membranes that move proteins and other substances through the cell the part of the ER with attached ribosomes is called the rough ER the rough ER helps transport proteins formed by attached ribosomes The forming proteins enter into the ER, A portion of the ER containing the completed protein pinches off to form a vesicle

cholestorol

another lipid in animal plasma membranes -related steroids are found in plants - strengthen the plasma membrane

objective lens stereoscope

are the primary optical lenses on a microscope. In a low power microscope, they provide fixed magnification or zoom magnification. Zoom magnification is typically offered in a Greenough design or with a Common Main Objective.

Ocular lens Stereoscope

are what you look through at the top of the microscope. Typically, standard eyepieces have a magnifying power of 10x.

hypotonic solutions

cause cells to swell and possibly burst "hypo" means less than (outside the cell) -animal cells undergo cytolysis in hypotonic solution increased turgor pressure occurs in plant cells in hypotonic solutions - plant cells do not burst because they have a cell wall

cell membrane

cell membrane selectively permeable barrier determines which substances enter and leave the cell selective permeability of the cell is mainly caused by the way phospholipids interact with water phospholipid is a lipid made of a phosphate group and two fatty acids made of a double layer of phospholipids called a bilayer

Plant Cells

cell wall, chloroplasts, central vacuole The cell membrane of plant cells is surrounded by thicc plant cell wall, composed of proteins and carbohydrates Cell Wall- helps support and maintain shape of cell protects cell from damage connects the cell with adjacent cells Chloroplasts- organelles that use light energy to make carbohydrates from carbon dioxide and water Chloroplasts, along with Mitochondria, supply much of the energy needed to power the activities of plant cells Central Vacuole- Most of a plant's volume is taken up by a large, membrane-bound space called central vacuole Central vacuole stores water and may contain ions, nutrients, and wastes

Endocytosis

cells take in substances by pinching a portion of the plasma membrane inward, and forming a vesicle around the substance

Diaphragm (Compound Light Microscope)

controls amount of light that comes through

osmosis

diffusion of water across a selectively permeable membrane due to a concentration gradient -diffusion always occurs from higher to lower concentration -water enters cells due to osmotic pressure within cells

facilitated diffusion

during FD, substances pass through a carrier protein following their concentration gradients -facilitated diffusion does not require energy -the carrier proteins for glucose has two conformations -switches back and forth between the 2 -carrying glucose across the membrane

Exocytosis

during this, vesicles fuse with the plasma membrane for secretion some cells are specialized to produce and release specific molecules examples include: a release of digestive enzymes from cells of the pancreas

Functions of membrane proteins

embedded in plasma membrane plasma membrane is semipermeable tiny charges molecules do not pass through the nonpolar interior of the membrane small, uncharged particles pass through the membrane, following their concentration gradient -transport materials across the membrane -receive specific molecules such as hormones -function as enzymes

stereoscope

form an enlarged 3D image of a specimen

revolving nosepiece (CLM)

holds the things that magnify the image, turns to change from one 4x 10x or 40x to the other