Ch. 4 The Internal Environment of Organisms

What conditions are red blood cells in when placed in an isotonic, hypertonic, and hypotonic environment?

- For an isotonic environment the red blood cells are normal because of the equal concentration of solutes. - For a hypertonic environment the red blood cells are shrunken because of the concentrated number of solutes outside the cell. - For a hypotonic environment the red blood cells are swollen because of the diluted number of solutes outside the cell.

What are the three types of external environments?

- Isotonic (Iso=equal) - Hypertonic (Hyper=over) - Hypotonic (Hypo=under)

Define solvent, give and example, and state the greatest solvent in the world

- The substance that the solute is dissolved into. - ex: when salt or sugar dissolves in water - Water is the greatest solvent in the world

How does your body maintain an internal balance on cold and warm days? Explain

- Through homeostasis - The skin separates the inside of the body from the outside environment - The cell membrane or wall acts as a boundary - Specific internal conditions must be met for life processes to take place in organisms

Define hypertonic environment, and give an example

- a condition in a solution where the concentration of solutes outside the cell is greater than the concentration on the inside - ex: a sugary or salty solution such as corn syrup

Define hypotonic environment, and give and example

- a condition in a solution where the concentration of solutes outside the cell is less than the concentration on the inside - ex: a watery solution such as vinegar or water

Define isotonic environment, and give an example

- a condition in a solution where the concentration of solutes outside the cells equals the concentration of solutes on the inside - no change in movement of molecules - ex: air

List three key points about the nucleolus

- a darkened area inside the nucleus (little nucleus) - responsible for ribosome production - contains RNA, which acts as a messenger that carries instructions from DNA for controlling the production of proteins

List four key points about the cytoskeleton

- a meshwork of tiny protein rods and tubules that provide structure for the cell - microtubules are responsible for many cellular movements and are composed of pairs (dimers) of a protein called tubulin (largest) - microfilaments composed of the protein actin, long thin rod-shaped that provides strength for the cell and helps anchor one cell to another (smallest) - intermediate filaments are made up of different proteins and are abundant in skin cells, abnormality in the intermediate filaments cause epidermolysis bullosa

Define Facilitated Diffusion

- a process in which molecules that cannot directly diffuse across the membrane pass through special protein channels - this process is fast and specific - requires no energy

List three key points about the golgi apparatus

- a stack of membrane-enclosed sacs where sugars are made into starches or attach to proteins to form glycoproteins or to lipids to form glycolipids - they collect and modify chemical compounds - they package compounds to be used elsewhere in that particular cell or body

What are the advantages of having so many compartments in living systems?

- allows for the presence of many different internal environments - provide the conditions for specialized functions - functions can be preformed simultaneously - provides conditions for DNA to perform functions

List five key points about the lipid bilayer that makes up the cell membrane

- also called the phospholipid bilayer - the fat (lipid) molecules are arranged into two layers - phospholipid is a lipid (fat) molecule with attached phosphate groups - the phosphate heads of the phospholipid bilayer are hydrophilic because they are drawn water - the phosphate tails that consist of two fatty acid chains are hydrophobic because they are resistant to water.

Explain why diffusion occurs, give an example, and describe the relationship between diffusion and energy

- diffusion occurs because the universe, and all of the molecules in it, drifts into a less orderly state unless some energy input keeps it orderly - ex: cleaning a messy room - organisms use energy continuously to maintain their own order and unique internal environment

List four key points about the nucleus

- enclosed in a nuclear envelope - nuclear pores allow biochemicals to exit or enter the nucleus - is filled with DNA (genetic code for organisms), and proteins - known as the brain or control center of the cell because it directs the cell's activities

Define entropy and explain its importance

- entropy is the gradual decline into disorder - when you create more disorder, you increase entropy in a system - we need more disorder so we can accomplish more work

List two key points about the chloroplasts

- found in plant cells and not animal cells - capture the energy from sunlight and convert it into food that contains chemical energy in a process called photosynthesis

List key points for Prokaryotes

- has no nucleus - bacteria - consists of only one compartment - no membrane-bound organelles

List key points for Eukaryotes

- higher cells based on cellular complexity - have a nucleus - abundant and diverse organelles that compartmentalize biochemical reactions - human cells are therefore Eukaryotic - membrane-bound organelles - many compartments can only be seen with an electron microscope

List two key points about the cytoplasm (jelly like substance)

- includes all the cell's fluids and organelles within the cell membrane or cell wall - composed mostly of water

List four key points about the rough endoplasmic reticulum

- involves the synthesis of proteins that will be released or secreted from the cell - is abundant in cells that produce large amounts of protein for export - ribosomes are found on the surface - a network of sacs that are responsible for manufacturing, processing, and transporting chemical compounds used by the cell

List eight key points about the cell membrane

- it forms a selective barrier that completely surrounds the cell and monitors the movements of molecules in and out of the cell - it is impermeable to most substances, the membrane prevents most substances from being able to pass in and out the compartment - on the other hand, they are permeable to other substances, so they are said to be selectively permeable - a membrane's selectively permeability (its ability to regulate the passage of molecules) depends on the structure of the membrane - receptors allow signals to be sent across the cell membrane - even though water molecules are not fat soluble, they can move through the membrane because they are very small and their electrical charges are slight - fat molecules can move through the interior with ease, whereas water molecules cannot - the membrane contains many protein molecules positioned among the fat molecules

Define Osmotic Pressure

- it plays a special role in plant cells because of their rigid cell walls - the water in a vacuole exerts osmotic pressure on a cell's contents, pressing the cell membrane tightly against the cell wall - the plant looks healthy because of this

List six key points about proteins found in the cell membrane

- large molecules made up of many small molecules (called amino acids) that are linked together to form a long and folded chain - the proteins act as receptors on the outer surface of the cell membrane - receptors bind specifically to molecules such as hormones that act as chemical messengers - - by binding to their receptors, hormones trigger the cell to respond to some body condition in an appropriate way - carbohydrates attached to proteins span the lipid bilayer - some proteins form channels through which glucose and other sugars move because molecules like these are too big to pass directly through the lipid bilayer part of the membrane.

Define, explain, and give an example of diffusion

- molecules spreading from an area with a higher concentration to an area with a lower concentration - this dispersion continues until the concentration is the same everywhere (reaches an equilibrium) - ex: aromas moving from the kitchen to the entire house

List three key points bout ions

- molecules that have an electrical charge - ions cannot pass through the cell membrane, unlike water and oxygen can - Ex: NaCl ions (Na+ sodium and Cl - chloride) are relatively small but still cannot pass directly through the lipid bilayer because fat molecules in the cell membrane repel charged molecules

List four key points about vacuoles

- one large vacuole is found in plant cells and multiple small vacuoles are found in animal cells - large, saclike membrane-enclosed structures - store materials like water, salts, proteins, carbohydrates, and small amounts of chemicals and other nutrients - for the plant cells the vacuole helps to support the cell and gives it its rigid shape

List two key points about ribosomes

- proteins are assembled on the ribosomes (produce proteins) - they are small particles of RNA and proteins found throughout the cytoplasm and on the rough endoplasmic reticulum

Define Passive Transport

- proteins move substances down their concentration gradient, either into or out of the cell - requires no energy - ex: diffusion, osmosis, and facilitated diffusion

List five key points about mitochondria

- provides energy by breaking down the production of digestion (nutrients) - ATP provides cellular energy - Contains DNA - the powerhouse of the cell that converts nutrients into energy that can be used by the cell - may once have been independent bacteria

Define Active Transport

- requires energy - cells use energy (glucose or ATP), adenosine triphosphate , to move substances (sodium or potassium) with the help of transport proteins across a membrane against, or up the concentration gradient

List three key points about the smooth endoplasmic reticulum

- ribosomes are not found on the surface - a network of sacs that are responsible for manufacturing, processing, and transporting chemical compounds used by the cell - contains collections of enzymes that perform specializes tasks, including the synthesis of membrane lipids and the detoxification of drugs

List three key points about the cilia

- they are not considered to be part of the cytoskeleton - hair-like structures that produce wavelike motion - increases surface area of the cell

Why are the organelles or little organs important?

- they help to divide the labor, partitioning off certain areas (compartmentalizing) - they keep related biochemical structure close enough to one another to interact efficiently - eukaryotic cells hold a thousand times the volume of a bacterial cell, due to the organelles

What do complex organisms contain? Give some examples

Complex organisms contain many smaller compartments, each with its own internal environment. Ex: skin, stomach, waxy coat that covers leaves, veins embedded within the leaves

Is it true or false that during osmosis energy is required?

False

List six key points about lysosomes and three key points about peroxisomes (the cellular digestive systems)

Lysosomes - a membrane bound sac that kills invading bacteria and (viruses) - white blood cells and macrophages engulf bacteria and are loaded with lysosomes - liver cells require lysosomes to break down cholesterol and toxins - small vesicles that contain enzymes and chemicals that help digest materials brought into the cell - they also break down old or non-functioning organelles - formed by the golgi apparatus Peroxisomes - breaks down certain lipids and rare biochemicals - synthesizes bile acids used in fat digestion and detoxifying compounds -abundant in the liver and kidney cells

Define solution

Solutions are uniform mixtures of two or more substances

What forms do solutions come in?

Solutions may be solids, liquid, gases, or a combination of these.

What are cells?

The basic unit of life.

Where does the diffusion of molecules occur?

The diffusion of molecules from high to low concentrations occurs in solutions as well as in the air

Define solute and give a couple examples

The dissolved substance such as salt or sugar

Define osmosis

The movement of water from an area of greater concentration to an area of lesser concentration through a semi-permeable membrane.

Are plant and animal cells eukaryotic?

Yes

Why can your body maintain temperatures?

Your body can maintain temps because it is a compartment with an internal environment that is kept separate from the external environment

Explain concentration gradient

where there is an unequal distribution of concentrations, molecules diffuse from areas of higher concentration to areas of lower concentration, so therefore they move down the concentration gradient