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Which 4 elements are critical in all biology?


How much of a living cell consists of H2O?


What are the next most abundant elements that make up about 4% of living cells?


What are trace elements?

Required by an organism in only minute quanties, needed in certain forms of life
- copper
- boron
- zinc
- manganese
- molybdenum

An element's properties depend

on the structure of atoms

The formation and function of molecules depends on

the type of bonding possible between the atoms involved

Covalent Bonds

when electrons are shared between at least 2 atoms

Ionic Bonds

formed when one or more electrons are transferred from one atom to another

Hydrogen Bonds

bond created by the weak attraction of a slightly positive hydrogen atom to a slightly negative portion of another molecule

Van der Waals

Weak interactions that occur when atoms and molecules are very close together; based on the fact that because electrons are in constant motion, they may accumulate by chance in one part of the molecule or another, thus creating a charge for that instant. Very long molecules

Properties of a carbon atom

Atomic Number 6
Atomic Mass Average: 12.011
Melting Point: 3823 K (3550°C or 6422°F)
Boiling Point: 4098 K (3825°C or 6917°F)
Density: 2.267g/
Velocity of sound [/m s-1]: 18350
Hardness Scale Mohs: 0.5
Stable Isomers (2)

How can water absorb heat without losing oxygen?


What types of molecules form hydrogen bonds?

polar molecules that contain a hydrogen bonded to an electronegative atom

The polarity of water molecules allow

hydrogen bonding

Hydrogen bonds allow

Hydrogen bonds allow emergent properties of water and these are important to sustain life on earth


(physics) the intermolecular force that holds together the molecules in a solid or liquid

Specific Heat

the amount of heat required to raise the temperature of 1g of a substance 1 degree Celsius

Solvent. Why is water a good solvent?

a liquid substance capable of dissolving other substances


the property of sticking together (as of glue and wood) or the joining of surfaces of different composition

How do hydrogen bonds contribute to adhesion?

Water molecules stick to other molecules.

Water is a polar molecule because of oxygen is more electronegative.
Hydrogen bonds create surface tension and result it water's cohesive and adhesive properties.

Organic molecules contain...

Hydrogen, oxygen, carbon and nitrogen atoms

Molecules can be...

isomers of one another

How can organic molecules be modified?

Through the addition of functional groups

Macromolecules are....

a molecule containing a very large number of atoms. a way of packing a lot of energy into a compact molecule that can be moved around relatively easy

What is a polymer?

A large number of monomers chemically bonded in a repeating pattern

What is a monomer?

A molecule that can be bonded to other identical molecules to form a polymer.

What are macromolecules based on?

Carbon Skeleton

Why is the carbon atom so important?

it has four bonds and can form an extremely wide range of compounds and molecular structures. Also, being in the middle of the periodic table it can bond with both metals and non metals

What are structural isomers?

a form of isomerism in which molecules with the same molecular formula have bonded together in different orders

What are geometric isomers?

are molecules that are locked into their spatial positions with respect to one another due to a double bond or a ring structure.

What are optical isomers?

Two molecules are optical isomers of one another if they are mirror images of one another, and
nonsuperimposible on one another

What are functional groups?

are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules

What are the most common functional groups?


What are the four macromolecules?

Nucleic Acids

Do all organisms contain these four kinds of macromolecules?


Most macromolecules are formed through

condensation reactions and broken down by hydrolysis reactions

What is a condensation reaction? (dehydration reaction)

When two monomers bond together through loss of water molecule. It forms polymers

What is involved in breaking a macromolecules down using a hydrolysis reaction?

It breaks polymers.

Carbohydrates (glucose, starch, cellulose) are

polymers of sugar, and they store a lot of energy. Sugar monomers come in different lengths with different characteristics

What is an example of a 3-carbon sugar?


What is an example 5-carbon sugar?


What is an example 6-carbon sugar?


What is the major different between aldehyde sugars and ketone sugars?

The difference between an aldehyde and a ketone is the presence of a hydrogen atom attached to the carbon-oxygen double bond in the aldehyde. Ketones don't have that hydrogen - ketones are C=O while aldehydes are H-C=O

What is glucose?


How does it differ from galactose?

they are called isomers (same formula different chemical structures) they exist seperately as C6H12O6

What is a galactose?

a sugar with the same molecular formula

What is a glycosidic linkage?

covalent bond formed between 2 sugars by dehydration

When can sugar molecules form rings?


Can all sugar molecules form rings? Why or why not?


Glucose is one of the most abundant sugars on the planet, and it can form rings in two basic ways

creating a glucose and b glucose: a glucose is strung together into polymers forming starch or glycogen; B glucose is strung together to form polymers called cellulose

What is A glucose and what is B glucose?

-alpha glucose has the OH group below the ring on carbon 1.
-beta glucose has the OH group above the ring of carbon 1.

alpha glucose fold up into a helix
beta glucose folds up into a pleated sheet

How do they differ from each other?

-alpha glucose has the OH group below the ring on carbon 1.
-beta glucose has the OH group above the ring of carbon 1.

alpha glucose fold up into a helix
beta glucose folds up into a pleated sheet

How do starch and glycogen differ from each other?

Starch and glycogen are both plysaccharides that are used in storage of organisms. they both have the same monomer or building block called alpha glucose. Starch is the storage molecule in plants and glycogen is the storage molecule in animals.

What organisms make starch?


What organisms make glycogen?


Can humans make glycogen? Can you digest it?


What is cellulose?

An insoluble substance that is the main constituent of plant cell walls and of vegetable fibers such as cotton. It is a polysaccharide...

How does it differ from starch and glycogen?

Cellulose is exclusively a plant product (cell wall).
Glycogen is nicknamed "animal starch" and is found in the liver and in muscle tissue.
Plants produce starch from monosaccharides as a result of photosynthesis.

What organisms make cellulose?

Cellulose is the substance that makes up most of a plant's cell walls. Since it is made by all plants, it is probably the most abundant organic compound on Earth. Aside from being the primary building material for plants, cellulose has many others uses.

Can you digest cellulose?

Humans can't digest cellulose because we don't have the necessary enzymes to break down

What organisms can break down cellulose?

the organisms which feeds on raw plants are able to digest cellulose since they secrete an enzyme cellulase for cellulose digestion.

There are three kinds of lipids in a biological system

fats, phospholipids and steroids

What are some examples of different fats?

There are animal fats (butter, lard, cream, fat in and on meats, etc.) saturated fats. and vegetable fats (olive oil, peanut oil, flax seed oil, corn oil, etc.) unsaturated fats

What are phospholipids found?

Phospholipids are found in cell membranes. Dietary wise they are in egg yolks, liver, soybeans and peanuts.

Fats are made up mostly of hydrocarbon molecules called fatty acids

three fatty acid molecules attach to a glycerol molecule, making up a triacylglycerol.

What is a hydrocarbon?

A compound of hydrogen and carbon, such as any of those that are the chief components of petroleum and natural gas.

What are triacylglycerols?


What is a triacylglycerol?

a lipid made with three fatty acids and glycerol

Why are saturated fats solid at room temperature?

Unsaturated fats contain double bonds which distort the long chain of the molecule, meaning it can't pack together as tightly as unsaturated molecules which have no double bonds.

What is transfat?

trans fatty acids (trans fats)- formed when unsaturated fats are partially hydrogenated ("partially hydrogenated soybean oil")
Raise LDL (bad) and lower HDL (good) cholesterol- bad for your health!

What is the primary role of fat?

maintaining healthy skin and hair, insulating body organs against shock, maintaining body temperature, and promoting healthy cell function

Phospholipids have special properties that make them able to

self assemble into biological membranes

How is a phospholipid different from a fat?

To be more specific, a fat is composed of glycerol (an alcohol) and fatty acids (triglycerides).

A phospholipid has a hydrophobic tail, and a hydrophilic phosphate group.

How are phospholipids arranged in a biological membrane?

in a dual layer; the tails are facing towards each other, so there is a layer of phospholipid heads on the outer surface of the cell membrane, & another layer of heads on the inner surface of the membrane.


Steroids are an important group of lipids that look different from the other types of lipids. Any of a large class of organic compounds with a characteristic molecular structure containing four rings of carbon atoms

What are some specific examples of steroids found in your own body?


What is not found in plant cell membranes?


Proteins are

polypeptides, which means they are polymers of amino acids.

What is an amino acid?

amino acids are the building blocks of proteins in our bodies.

How are amino acids hooked together?


How would you describe the primary, secondary, tertiary and quaternary levels of structure of a protein?

String of amino acids - order of those amino acids is the primary structure - some get secondary structure - those fold in on themselves to have the tertiary structure the then 3 tertiary structures coming together is a quaternary. Get over all shape

What in general is the function of proteins?

it is much of the structure of cells is made up of proteins
Proteins form parts of cell membranes
They also make up organelles within the cell

Nucleic acids are

the genetic material of an organism, and they therefore hold information and pass on information

What are the two major groups of nucleic acids?

RNA Ribonucleic Acid
DNA Deoxyribonucleic Acid

Nucleotides are the basic units of nucleic acids. What are the three major components of any nucleotide?

)A nitrogeneous base
- purine (adenine or Guanine)
-pyrimidine (cytosine or thymine [ uracil if its RNA])
* these are the AGCTand U letters in the chain

2)A sugar
-deoxyribose or ribose

3) A phospate group

What are the nitrogenous bases that are used to make DNA? To make RNA?


What are the two major difference that distinguish DNA molecules from RNA molecules in terms of what they are composed of?

(a) RNA contains the sugar ribose, while DNA contains the slightly different sugar deoxyribose (a type of ribose that lacks one oxygen atom), and (b) RNA has the nucleobase uracil while DNA contains thymine.

What are the major functions of DNA?

DNA is the code from which all protein is synthesised

DNA also contains all the genetic coding which is used to control functions, behaviour and development of an organism. DNA is also used as a long term storage device to store the genetic instructions.

What are the major functions of RNA?

RNA molecules are involved in protein synthesis and sometimes in the transmission of genetic information.

What are some of the specific structures that define a cell?

Smooth ER
Rough ER

What organisms are we talking about when we say prokaryotes?

are a group of organisms that lack a cell nucleus - bacteria and archaea

What organisms are we talking about when we say eukaryotes?

is an organism whose cells contain complex structures enclosed within membranes.

Are humans prokaryotes or eukaryotes?


What properties are the same in both prokaryotic and eukaryotic cells?

They both have DNA as their genetic material. Both are membrane bound and contain ribosomes. They are diverse in forms and have a similar pattern of metabolism.

What properties distinguish a prokaryotic and eukaryotic cells?

Eukaryote cells are larger in diameter than prokaryote cells. Eukaryotes have a true nucleus and membrane enclosed organelles. The cell walls of prokaryotes are thick as compared to that of a eukaryote, which may or may not be present. Eukaryotes have a cytoskeleton. Prokaryotes do not. Cell division in eukaryotes is accomplished by mitosis, where in prokaryotes it is carried out by binary fission.
Prokaryotes are unicellular organisms. There are also many unicellular eukaryotes as well as more complexed multicellular ones.

How are the phospholipids arranged in a biological membrane?

In a dual layer; the tails are facing towards each other, so there is a layer of phospholipid heads on the outer surface of the cell membrane, & another layer of heads on the inner surface of the membrane.

Do all cells have a cell membrane? Cytoplasm? A nucleus? mitochondria? Ribosomes? DNA? one or more chromosomes?

Not all cells have a nucleus,

Does a prokaryotic cell have a nucleus?


Does it have a chromosome?


What is the genetic material of a prokaryotic cell?

circular loop called plasmid

What surrounds a bacterial cell?

capsule and slime layer

Does a bacterial cell have a membrane?


Is there anything outside of the cell membrane?


What distinguishes an animal cell form a plant cell?

Cell wall

What structures are common to both animal cells and plant cells?


What are some characteristics that distinguish a mitochondria from a chloroplast?

in size: mitocondria are 1-10micrometers in diameter. chloroplasts are a little larger : 2-10 micrometers in diameter.

-in function: mitochondria generate ATP from glucose during cellular respiration. chloroplasts generate ATP from light (via process of photosnthesis) to produce glucose for storage.

-in structure: cristae of the mitochondria are continuous with the inner membrane. thylakoids in the chloroplasts are discontinuous with the inner membrane, i.e. thylakoids and inner membrane are separate entities.

-in naming: the space within the mitochondria, equivalent to the cytosol of the cell, is called the mitochondrial matrix. the same space within the chloroplasts is called the stroma. the space within the thylakoids is called the thylakoid space

-there are starch grains in the stroma of chloroplasts but none in mitochondria

-chloroplasts only found in plant cells, mitochondria found in plants, animals, and unicellular organisms

In general what is the function of mitochondria? Of chloroplasts?

make ATP

Are mitochondria found in animal or plant cells?


What components make up the cytoskeletal of a cell?


What do microtubules do in a cell?


Can they be used to traffic things around within a cell? If so how?


What are some of the characteristics of the nuclear membrane?


What is the nuclear lamina?

It lines the inner membrane of the nuclear envelope, stiffening the envelope and helping organize the chromosomes.

What is the nucleolus?

a dark area of the nucleus that stores materials and begins to make ribosomes

What is the endoplasmic reticulum?

an extensive series of membrane bound channels in which a number of different types of molecules are processed. The smooth ER and the rough ER

What are the differences between the smooth and rough ER?

rough Endoplasmic Reticulum is with ribosomes attached .helps in protein synthesis

Smooth Endoplasmic Reticulum no ribosomes

What are some specific functions of the smooth ER?

several metabolic processes, including synthesis of lipids, metabolism of carbohydrates and calcium concentration, drug detoxification, and attachment of receptors on cell membrane proteins. It is connected to the nuclear envelope

What are some specific functions of the rough ER?

The functions of RER are providing an internal structural skeleton to support the cell's shape, as storage of the synthesised materials and minerals, such as calcium in myocytes, forming an internal network through which materials can be transported; and providing a large surface area on which chemical reactions can occur.

What is the golgi?

An extensive series of membrane stacks. Vesicles form the ER attach to the golgi (cis side) and deposit proteins. Proteins leave from the opposite side (trans side) for their final destination. While proteins move from the cis to the trans side they are modified.

List the main role of the Golgi

Cells synthesise a large number of different macromolecules. The Golgi apparatus is integral in modifying, sorting, and packaging these macromolecules for cell secretion[10] (exocytosis) or use within the cell.

What are lysosomes?

Bags of enzymes that degrade macromolecules and defective old organelles for recycling

What are vacuoles?

Used to sequester things: food vacuoles, contractile vacuoles and central vacuoles all sequester different things

How can each of these different types of vacuoles be used: food, contractile, central?

central vacuole - helps maintain plants' shape and structure by storing water (hypotonic).

contractile vacuole - pumps water out of protist cells to maintain a suitable concentration.

food vacuole - storage for molecules that is a food source for the cell (phagocytosis).

What is the endomembrane system?

A series of membrane bound organelles that are connected wither by direct connection or by vesicles blebbing off of one another and fusing with another

Is the endomembrane system found in eukaryotic cells, prokaryotic cells or both?


prokaryotes endomembranes are rare, although in many photosynthetic bacteria the plasma membrane is highly folded and most of the cell cytoplasm is filled with layers of light-gathering membrane

What organelles are included in the endomembrane system?

The nuclear envelope, SER, RER, Golgi apparatus, plasma membrane, lysosome, vacuole, transport vesicle

What structures do all cells have?

Plasma membrane

What structures of eukaryotic cells have that prokaryotic cells don't have?


What macromolecules are cell membranes made out of?

phospholipids and tryglyceride

What role does the cholesterol play in a cell membrane?

These molecules provide stability, helping the membrane to maintain its shape and resist breakdown from heat or light damage

What is a cytoskeleton? Why is the cell membrane anchored to the cytoskeleton - what do you think this accomplishes?

A microscopic network of protein filaments and tubules in the cytoplasm of many living cells, giving them shape and coherence.

What is the extracellular matrix?

non-living substance found surrounding the cells. together the matrix and cells form connective tissue.

What are some of the general functions of proteins within a cell membrane?

They are used to join cells together in cell adhesion.
2. They attach the membrane to the cytoskeleton. This is important in keeping the shape of the cell and to hold the membrane in a certain place when needed.
3. Sometimes the proteins gather together as enzymes and carry out the different steps of the metabolic reactions which take place near the cell membrane.
4. Proteins act as receptors , or sites for messenger molecules which signal the cell to start or stop metabolic activity.
5. Most importantly the proteins make the membrane selectively permeable. That is, they control the movement of substances through the membrane Anonymous

What are some molecules that that readily pass through a cell membrane?

small and hydrophobic

What is an aquaporin?

It's an integral membrane protein that allows rapid passage of water, through the cell membrane. It also contains positive charges to keep cations out.

Why can't large molecules easily pass through a cell membrane?

Because the cell membrane is selectively permeable

What is hypotonic?

Having a lower osmotic pressure than a particular fluid, typically a body fluid or intracellular fluid.

What is hypertonic?

Having a higher osmotic pressure than a particular fluid, typically a body fluid or intracellular fluid.

What is isotonic?

balanced concentrations of solute and water

Will more water flow to the hypertonic side or will more water flow to the isotonic side? Or will there be no net flow of water on either side?


What is facilitated diffusion?

When there is no energy used when a carrier or channel protein helps something get through the membrane

What is the different between passive transport and active transport across a membrane?

Active transport: Energy used to get things across the membrane against the concentration gradient. ATP used. High to low concentration

Passive transport:

What is a sodium potassium pump? an enzyme (EC located in the plasma membrane (specifically an electrogenic transmembrane ATPase). It is found in the plasma membrane of virtually every human cell and is common to all cellular life. It helps maintain cell potential and regulate cellular volume.

What is the electrogenic pump?

sodium potassium pump

What are some instances when an electrogenic pump is used?

producing a net movement of positive charge out of a cell.

Read more:

What is endocytosis?

The taking in of matter by a living cell by invagination of its membrane to form a vacuole.

What is exocytosis?

A process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell...

What is a metabolism?

a process that transforms matter and energy in both directions

Metabolism is structured into pathways. What is a pathway?

are series of chemical reactions occurring within a cell.

See more

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