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205 terms

Bio Exam #2

STUDY
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Which 4 elements are critical in all biology?
Hydrogen
Oxygen
Nitrogen
Carbon
How much of a living cell consists of H2O?
70-95%
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/cu.cm.
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
Cohesion
(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
Adhesion
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?
Hydroxyl
Carbonyl
Carboxyl
Amino
Sufidyl
Phosphate
What are the four macromolecules?
Protein
Carbohydrates
Lipids
Nucleic Acids
Do all organisms contain these four kinds of macromolecules?
Yes
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?
triose,
What is an example 5-carbon sugar?
pentose,
What is an example 6-carbon sugar?
hexose,
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?
C6H12O6
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?
yes
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?
plants
What organisms make glycogen?
animals
Can humans make glycogen? Can you digest it?
no
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?
Fats
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
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?
Cholesterol
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)
or
-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?
nucleotide
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?
Organelles:
Smooth ER
Rough ER
Golgi
Nucleus
Chloroplast
Mitochondria
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?
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?
no
Does it have a chromosome?
no
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?
Yes.
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?
Both
What components make up the cytoskeletal of a cell?
Microtubules
Microfilaments
Angometifilaments
What do microtubules do in a cell?
Transport
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?
Eukaryotic

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
cytoplasm
ribosomes
DNA
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
Report
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?
...is an enzyme (EC 3.6.3.9) 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: http://wiki.answers.com/Q/The_sodium-potassium_pump_is_called_an_electrogenic_pump_because_it#ixzz1ahIVvycQ
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.
What is the difference between anabolic and catabolic pathways? Are they linked?
Catabolic reactions breaks down organic matter, for example to harvest energy in cellular respiration. Anabolic reactions, on the other hand uses energy to construct components of cells such as proteins and nucleic acids.
Exergonic
chemical reaction that releases some form of energy, such as light or heat.
Endergonic
chemical reaction requiring free energy in addition to enzymes and activation energy
What is ATP?
Adenosine triphosphate (ATP) is the energy currency for a cell to use for work.
What is an enzyme?
An enzyme is a protein that catalyzes a specific biochemical reaction.
What is feedback regulation?
Process by which biological systems regulate biological processes
Polar Covalent Bond
When one atom is non equal in sharing (carbon with 4 oxygens
Non Polar Covalent Bond
equal 1/2 1 atom 1/2 the other atom
Saturated fats
Animals - Maintain fluidity through cholesterol
Unsaturated Fats
Plants - At least 1 double bond within the chain link. Maintain fluidity with the changing of the weather
Strongest to Weakest hydrogen bonds
Covalent
Ionic
Hydrogen
Isomer
2 different molecules with same molecular formula with a different shape
Mitochondria
Powerhouse of the cell, organelle that is the site of ATP (energy) production
Isotope
atoms of the same element that have different numbers of neutrons
Why does ice float?
Because it is less dense than liquid water.
Different monomers that go into polymers
...
Lipid
The main biological functions of lipids include energy storage, as structural components of cell membranes, and as important signaling molecules.[4]
Steroid
a type of organic compound that contains a specific arrangement of four cycloalkane rings that are joined to each other
What is a phospholipid?
are a class of lipids and are a major component of all cell membranes as they can form lipid bilayers - 2 fatty acids
What is a triglycerole?
An ester formed from glycerol and three fatty acid groups. Triglycerides are the main constituents of natural fats and oils.
Carbohydrate
Carbohydrates, or saccharides, are the most abundant of the four. Carbohydrates have several roles in living organisms, including energy transportation, as well as being structural components of plants and arthropods.
Nucleic Acid
DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)
Polypeptides
Symbiosis
Peroxisome
organelles found in virtually all eukaryotic cells.[1] They are involved in the catabolism of very long chain fatty acids, branched chain fatty acids, D-amino acids, polyamines, and biosynthesis of plasmalogens, etherphospholipids critical for the normal function of mammalian brains and lungs.
Peripheral vs Integral
Peripheral proteins are under the phospholipid bilayer, while integral proteins are inscribed in the bilayer.
Integral proteins pass entirely through the lipid bilayer of the plasma membrane and have domains that go from the outside of the cell to the cytoplasm inside the cell. While peripheral proteins are only on the one side of the lipid bilayer, either the outside of the cell or the cytoplasmic side inside the cell, but not both.
Hydrophobic vs Hydrophilic
Hydrophilic is having an affinity for water; readily absorbing or dissolving in water.( love water)

Hydrophobic is repelling, tending not to combine with, or incapable of dissolving in water.(hate water)
Diffusion
High to low concentration
Osmosis
Move water from high concentration to low concentration
Spontaneous vs Non spontaneous
G>0 - non
G<0 - spontaneous
A covalent bond is likely to be polar when...
1. one of the atoms sharing electrons are equally electronegative
2. the two atoms sharing electrons are of the same element
3. the two atoms sharing electrons are equally electronegative
4. the bond between two atoms that are both very strong electron acceptors
5. the two atoms sharing electrons are different elements
One of the atoms sharing electrons is much more electronegative then the other atom
The element ----- is a major component of an animals body while the element ----- is only found in trace amounts
carbon and iodine
Which of the following is not considered to be a weak molecular interaction?
1. a covalent bond
2. a van der waals interaction
3. an ionic bond in the presence of water
4. a hydrogen bond
5. hydrophobic interactions
A covalent bond
Certain groups of atoms, such as -COOH and -NH2, when attached to a larger molecule, give specific properties to the molecule. These groups of atoms are called...
1. ions
2. functional groups
3. molecular orbitals
4. structural isomers
5. modifier groups
functional groups
Which statement about carbon is false?
1. carbon can form 4 covalent bonds to other atoms
2. carbon can be incorporated into organic molecules by plants
3. carbon forms 4 van der waals bonds with other atoms
4. organic molecules contain carbon atoms
5. carbon-carbon bonds have different shapes depending on orbital hybridization
carbon forms 4 van der Waals with other atoms
Which of the following statements correctly describes geometric isomers?
1. They have variations in arrangement around a double bond
2. They have asymmetric carbon that makes them mirror images
3. They have the same chemical properties
4. They have different molecular formulas
5. They have different atoms in their structure.
They have variations in arrangement around a double bond
Why is it important for albuterol to consist of only one enantiomeric form rather than a mixture of enantiomeric?
1. Only the R form of albuterol has been studied until more info is available physicians prefer to use the pure r form
2. it is impossible to synthesize mixtures of enentiomers
3. it is much less expenisve to synthesize one enantiomer at a time
4. albuterol is an example of a compound for which only one enantiomer exists.
5. Different enantiomers may have different or opposite physiological effects
different enantiomers may have different or opposite physiological effects
Which of the following statements about saturated fatty acids is true?
1. They are more common in proteins then in starch
2. they are common in lard and butter animal products
3. they are generally liquid at room temperature
4. They contain multiple double bonds between adjacent carbon atoms
5. They are carbohydrates
multiple double bonds between adjacent carbon bonds
Polysaccharides, lipids, and proteins are all similar in that they...
1. are synthesized from monomers by the process of hydrolysis
2. are synthesized as a result of peptide bond formation between monomers
3. are decomposed into their subunits by dehydration reactions
4. all contain nitrogen in their monomer building blocks
5. are synthesized from monomers by dehydration reactions.
are synthesized from monomers by dehydration reactions
The tertiary structure of a protein is the...
1. bonding together of several polypeptide chains by weak bonds
2. order in which amino acids are joined in a polypeptide chain
3. unique three dimensional shape of the fully folded polypeptide
4. organization of a polypeptide chain into an a helix or b pleated sheet
5. overall protein structure resulting from the aggregation of two or more polypeptide subunits
overall protein structure resulting from the aggregation of two or more polypeptide units
A cells cytoskeleton has many roles. Which of the following is a component of the cytoskeleton?
1. the nuclear envelope
2. microtubule
3. mitochondrion
4. lysosomes
5. ribosomes
The nuclear envelope
Regarding the mitochondrion and chloroplast both, which of the following is incorrect?
1. they both contain some DNA
2. they both contain ribosomes
3. both are believed to have originally been bacterial cells
4. both are enclosed by a double membrane system
5. bother are part of an endomembrane system
Both are enclosed in double membrane systems
Regarding the cell size, which of the following is a false statement?
1. prokaryotic cells are generally smaller then eukaryotic cells
2. plant and animals are about the same size
3. cells are small because they are maximizing their surface area to volume ration
4. cell size is determined by the lipid composition of the plasma membrane
5. cells are larger than ribosomes
Cells are small because they are maximizing their surface area to volume ratio
All of the following can be found in a bacterial, archael and animal cells except...
1. nucleus
2. ribosomes
3. DNA
4. proteins
5. phospholipids
phospholipids
Animal cells package powerful hydrolic enzymes into specialized structures called ----- which prevent general destruction of cellular components
1. lysosomes
2. vacuoles
3. mitochondria
4. golgi apartatus
5. peroxisomes
lysosomes
Which of the following conditions would produce a cell with lots of free ribosomes?
1. a cell that is secreting proteins
2. a cell that is producing cytoplasmic enzymes
3. a cell that is constructing its cell wall or extracellular matrix
4. a cell that is digesting food particles
5. a cell that is enlarging its vacuole
a cell that is secreting proteins
When a potassium ion moves from the soil into the vacuole of a cell of a plant root, it must pass through several cellular structures. Which of the following describes the order in which potassium will cross these structures (from outside to inside)?
1. plasma membrane - cell wall - cytoplasm - vacuole
2. cell wall - plasma membrane - smooth er - nucleus
3. cell wall - cytoplasm - plasma membrane - vacuole
4. cell wall - plasma membrane - cytoplasm - vacuole
5. vacuole - cell wall - plasma membrane - cytoplasm
cell wall ---> cytoplasm ---> plasma membrane --->vacuole
Which of the following is one of the ways that the membranes of plant cells are able to remain fluid when it is extremely cold?
1. the cells increase the amount of cholesterol molecules in their membrane
2. the cells decrease the number of hydrophobic proteins in their membranes
3. the cells have increased amount of unsaturated phospholipids in their membrane
4. the cells have increased hydrophobic bonds between phospholipids in their membrane
The cells decrease the number of hydrophobic proteins in their membranes
Which of the following is true of integral membrane proteins?
1. They are usually transmembrane proteins
2. they are not mobile within the bilayer
3. they lack secondary structure
4. they are tightly bound to the surface of the lipid bilayer
5. they serve only a structural role in membranes
They are tightly bound to the surface of the lipid bilayer.
The voltage across a cells membrane is called
1. the water potential
2. the chemical gradient
3. the membrane potential
4. the osmotic potential
5. the charged gradient
the charged gradient
Proteins associated with the cell membrane can be involved in all of the following activities except...
1. diffusion
2. facilitated diffusion
3. attachment of the cytoskeleton
4. signal transduction
5. active transport
a signal transduction
Which of the following would likely diffuse MOST rapidly through the lipid bilayer of a plasma membrane?
1. ATP
2. CO2
3. a glucose polymer
4. AH4 - ammonium
5. glycogen
ATP
A liquid crossing a semipermeable lipid bilayer...
1. always requires ATP
2. can only happen if channel proteins are present
3. is called facilitated diffusion and only occurs in prokaryotes
4. is phagocytosis
5. is called osmosic
is called osmosis
The movement of potassium ions into an animal cell requires...
1. low cellular concentrations of sodium
2. high cellular concentrations of potassium
3. an energy source such as ATP
4. a cotransport protein
5. a gradient of protons across the plasma membrane
an energy source such as ATP
Which of the following is TRUE for anabolic pathway?
1. they release energy as they degrade polymers to monomer
2. they are usually highly spontaneous chemical reactions
3. they only occur if steroids are the catalyst
4. they consume everygu to build up polymer from monomer
5. they do not depend on enzymes
The consume energy to build up polymers from monomers
A competitive inhibitor decreases the rate of an enzyme reaction by...
1. acting as a coenzyme for the reaction
2. changing the shape of the enzymes activity
3. changing the free energy change of the reaction
4. binding at the active site of the enzyme
5. decreasing the activation energy of the reaction
binding at the active site of the enzyme
Which of the following statements about enzyme catalyzed reactions is true?
1. the reaction occurs faster than the same reaction without the enzyme
2. the free energy change of the reaction if opposite from the reaction in the absence of the enzyme
3. the reaction is not affected by the presence of an inhibitor
4. the activation energy is increased
5. the enzymes slow down the reaction so there is time for it to occur
the reaction occurs faster than the same reaction without the enzyme