bio exam 2

most of a cells enzymes are

most of a cells enzymes are

proteins

in the plasma membrane, the phospholipid heads

are both hydrophilic and face outward toward the aqueous solution on both sides of the membrane

aquaporin's

allow water to cross the plasma membrane via facilitated diffusion

kinetic energy differs from chemical energy in that

kinetic energy is the energy of a moving object, whereas chemical energy is the potential energy of molecules

you are told that the cells on a microscope slide are plant, animal, or bacterial. you look at them through a microscope and see cell walls and membrane bound organelles. you conclude correctly that the cells

are plant cells

anything that prevents atp formation will most likely

result in cell death

which metabolic pathway is common to aerobic and anaerobic metabolism

glycolysis

in fermentation ___________ is _____________

nadh; oxidized

when a cell uses chemical energy to perform work, it uses the energy released from a(n) ____________ reaction to drive a(n) ___________ reaction

exergonic; endergonic

what is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?

rough er, golgi, vesicles that fuse with plasma membrane

the tertiary structure of a protein is the

unique three-dimensional shape of the fully folded polypeptide

which organelle or structure is absent in plant cells

centrosomes

according to the fluid mosaic model of membrane structure, proteins of the membrane are mostly

embedded in a lipid bilayer

which cell would be best for studying lysosomes

phagocytic white blood cell

which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly

CO2

which of the following is a major cause of the size limits for certain types of cells

the need for a surface area of sufficient area to support the cells metabolic needs

how many molecules of water are needed to completely hydrolyze a polymer that is 11 monomers long

10

when chemical, transport, or mechanical work is done by an organism, what happens to the heat generated

it is lost to the environment

the bonding of two amino acid molecules to form a larger molecule requires which of the following

removal of a water molecule

which level of protein structure do the helix and the beta pleated sheet represent

secondary

which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperature

the double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly

which of the following is true of both starch and cellulose

they are both polymers of glucose

which of these experimental treatments would increase the rate of sucrose transport into the cell

decreasing extracellular pH

the r group or side chain of the amino acid serine is -CH2-OH. the r group or side chain of amino acid leucine is -CH2-CH-(CH3)2. where would you expect to find these amino acids in a globular protein in aqueous solution

leucine would be in the interior, and serine would be on the exterior of the globular protein

in receptor mediated endocytosis, receptor molecules initially project to the outside of the cell. where do they end up after endocytosis

on the inside surface of the vesicle

which or the following statements correctly describes the normal tonicity conditions for typical plant and animal cells

the animal cells is in an isotonic solution, and the plant cell is in a hypotonic solution

how might an amino acid change at a site distant from the active site of the enzyme alter the enzymes substrate specifically

by changing the shape of the protein

which of the following correctly lists the order in which cellular components will be found in the pellet when homogenized cells are treated with increasingly rapid spins in a centrifuge

nucleus, mitochondria, ribosomes

enzymes that break down dan catalyze the hydrolysis of the covalent bonds that join nucleotides together. what would happen to dns molecules treated with these enzymes

the phosphodiester linkages of the polynucleotide backbone would be broken

which of the following statements about the 5' end of a polynucleotide strand of dna is correct

the 5' end has a phosphate group attached to the number 5 carbon of carbon deoxyribose

if cells are grown in a medium containing radioactive 32P labeled phosphate, which of these molecules will be labeled

both phospholipids and nucleic acids

the element present in all organic molecules is

carbon

which of the following is not a monomer/polymer pairing

triglyceride/phospholipid bilayer

which of the following is an example of potential rather than kinetic energy

a molecule of glucose

an animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function

cell-cell recognition

what is the chemical reaction mechanism by which cells make polymers from monomers

dehydration reactions

the golgi apparatus has a polarity or sidedness to its structure and function. which of the following statements correctly describes this polarity

proteins and lipids in the membrane of the golgi may be sorted and modified as they move from one side of the golgi to the other

a biologist wants specifically to examine the surface of different types of cells in kidney tubules of small mammals. the cells in question can be distinguished by external shape, size, and 3-D characteristics. which of the following would be the optimum method for her study

scanning electron microscopy

protein kinases are enzymes that catalyze phosphorylation of target proteins at specific sites, whereas protein phosphates catalyze removal of phosphate(s) from phosphorylated proteins. phosphorylation and dephospho rylation can function as an on-off switch for a proteins activity, most likely through

the change in a proteins charge leading to a conformational change

which of the following is true for all exergonic reactions

the reactions proceeds with a net release of free energy

a dietary calorie equals 1 kilocalorie. which of the following statements correctly defines 1 kilocalorie

1000 calories, or the amount of heat required to raise the temperature of 1 kg by 1C

dehydration reactions are used in forming which of the following compounds

triacylglycerides, polysaccharides, and proteins

all of the following are part of a prokaryotic cell except

a cell wall

what is another name for a condensation reaction

dehydration

what is the name of the process during which a bond between two monomers is broken

hydrolysis

nucleic acid polymers are made up of ____________ monomers

nucleotide

carbohydrate polymers are made up of _______________ monomers

simple sugar

protein polymers are made up of _____________ monomers

amino acid

which element is closely associated with the field of organic chemistry

carbon

what does the term amino acid signify about the structure of the molecule

it consists of an amino group and a carboxyl group

polymers that contain sugars ...

may store hereditary information, may store energy, and may protect cells

what one characteristic is shared by sucrose and maltose

they are disaccharides

glycogen is _____________

a polysaccharide found in animals

glucose + glucose --> _________ by _________

maltose + water ; dehydration synthesis

which of these is a source of lactose

milk

which of these is a polysaccharides

cellulose

________ is the most abundant organic compounds on earth

cellulose

lipids are diverse compounds that are grouped together because they are _________

hydrophobic

a fat molecule is composed of two typer of smaller molecules: ___________ and fatty acids

glycerol

a fatty acid consists of a ________________ and a long hydrocarbon chain

carboxyl group

________________ have one or more double bonds in their hydrocarbon chains and are usually found in vegetable oils

unsaturated fatty acids

the hydrocarbon chains of _______________ are not kinked, and thus pack closely together, making animal fats solid at room temperature

saturated fatty acids

____________ are a major component of cell membranes. they form a bilayer with their hydrophobic tails mingling together and their hydrophilic heads facing the watery environment on both sides of the membrane

phospholipids

________ are lipids with a structure consisting of four fused rings. many sex hormones are made from this type of lipid

steroids

which of these is not a lipid

RNA

which of these is rich in unsaturated fats

olive oil

a function of cholesterol that does not harm health is its role _______

as a component of animal cell membranes

the lipids that form the main structural component of cell membranes are _______

phospholipids

some athletes use anabolic steroids to build their body mass. why is this considered a problematic practice, especially in adolescents

anabolic steroids can prevent bone growth

defensive proteins are manufactured by the _______ system

immune

your body contains thousands of different types of proteins, each with a specific function. a proteins function is largely determined by its ___________

shape

the primary structure of a protein is like the arrangement of beads on a string. in this analogy, the beads are _________

amino acids

a proteins alpha helices and beta sheets form their shapes at the _______ level of protein structure

secondary

what happens to the shape and function of a protein if one of the amino acids is replaced with a different type of amino acid

it depends on the role of the amino acid that is altered. one amino acid might be replaced with no measurable effect on the proteins function; replacing another might cause a total loss of function

large proteins, like dna polymerase and hemoglobin, are often composed of several polypeptides that are linked together. the _______ level of protein structure describes how the polypeptides are joined to create a larger complex

fourth

which of these functional groups is found in all amino acids

-NH2

proteins are polymers of ________

amino acids

what type of bond joins the monomers in a proteins primary structure

peptide

the secondary structure of a protein results from __________

hydrogen bonds

tertiary structure is not directly dependent on __________

peptide bonds

which of the following would be affected when a protein is denatured

tertiary structure

if a dna double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain

75

the two strands of a dna double helix are held together by ________ that form between pairs of nitrogenous bases

hydrogen bonds

a nucleotide is composed of a(n) _________

phosphate group, a nitrogen-containing base, and a five-carbon sugar

nucleic acids are polymers of _________

nucleotides

the monomers of nucleic acids consist of phosphate group, a five carbon sugar, and a _________________

nitrogenous base

________ provides directions for its own replication. it also directs cell activities by providing instructions for building proteins

dna

a gene provides the directions to build a molecule of ________; the genetic instructions it carries are then translated into the amino acid sequence

rna

a polynucleotide has a repeating ___________ backbone

sugar-phosphate

the structure of dna is a __________, held together by the complementary base-pairing of cytosine with guanine, and adenine with thymine

double helix

ran usually consists of a single _______ strand

polynucleotide

which of the following statements regarding lactose tolerance is true

lactose tolerance has evolved independently in multiple different human population

________ are surface appendages that allow a bacterium to stick to a surface

fimbriae

what is the function of bacterium capsule

protection

where is a bacterial cells dna found

nucleoid region

in a bacterium, where are proteins synthesized

ribosomes

what name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell

cell wall

the ________ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell

plasma membrane

which plant cell organelle converts chemical fuel into packets of chemical energy that can power the cell

mitochondrion

the plant cell wall

is a protective structure made of cellulose fibrils